HomeMy WebLinkAboutCT 05-21; GREYHAWK BUSINESS PARK; GEOTECHNICAL ENGINEERING INVESTIGATION; 2005-10-26Geotechnical Engineering Investigation
Proposed Residential/Retail Development
3044 State Street
Carlsbad, California
Prepared For:
3044 State Street LLC
do Anastasi Development company
539 Carlsbad Village Drive, Suite 100
Carlsbad, California 92008
Attn.: Mr. John Simons
Project Number 12539-05
October 26, 2005
TABLE OF CONTENTS
Section Page
1.0 Project Description..............................................................2
2.0 Site Description...................................................................2
3.0 Site Exploration...................................................................2
4.0 Laboratory Tests..................................................................3
4.1 Field Moisture Content............................................................3
4.2 Maximum Density Test ........................................................... 3
4.3 Expansion Index Tests............................................................4
4.4 Corrosion Tests ....................................................................4
4.5 Direct Shear Tests ................................................................4
4.6 Consolidation Tests ...............................................................4
5.0 Seismicity Evaluation...........................................................4
6.0 Liquefaction Evaluation........................................................5
7.0 Conclusions and Recommendations......................................5
7.1 Site Grading Recommendations................................................6
7.2 Temporary Excavations ..........................................................7
7.3 Foundation Design .................................................................8
7.4 Settlement Analysis................................................................8
7.5 Lateral Resistance .................................................................8
7.6 Retaining Wall Design Parameters.............................................8
7.7 Slab Design .............. .............................................................9
7.8 Pavement Section Design ........................................................9
7.9 Corrosion Design Criteria .........................................................10
7.10 Utility Trench and Excavation Backfill..........................................11
7.11 Expansive Soil .......................................................................11
8.0 Closure................................................................................11
A
NorCal Engineering
Soils and Geotechnical Consultants
10641 Humbolt Street Los Alamitos, CA 90720
(562)799-9469 Fax (562)799-9459
October 26, 2005 Project Number 12539-05
3044 State Street LLC
do Anastasi Development company
539 Carlsbad Village Drive, Suite 100
Carlsbad, California 92008
Attn.: Mr. John Simons
RE: Geotechnical Engineering Investigation - Proposed Residential/Retail
Development - Located at 3044 State Street, in the City of Carlsbad,
California
Dear Mr. Simons:
Pursuant to your request, this firm has performed a Geotechnical Engineering
Investigation for the above referenced project in accordance with your approval of
proposal dated September 2, 2005. The purpose of this investigation is to evaluate the
subsurface conditions of the subject site and to provide recommendations for the
proposed residential/retail development.
The scope of work included the following: 1) site reconnaissance; 2) subsurface
geotechnical exploration and sampling; 3) laboratory testing; 4) engineering analysis of
field and laboratory data; and 5) preparation of a geotechnical engineering report. It is
the opinion of this firm that the proposed development is feasible from a geotechnical
standpoint provided that the recommendations presented in this report are followed in
the design and construction of the project.
October 26, 2005 Project Number 12539-05
Page 2
1.0 Prolect Description
It is proposed to construct a two-story residential/retail development on the 80' x 150'
subject project. Other improvements will consist of concrete/asphalt pavement,
hardscape and landscaping. It is assumed that the proposed grading for the
development will include cut and minor fill procedures. Final building plans shall be
reviewed by this firm prior to submittal for city approval to determine the need for any
additional study and revised recommendations pertinent to the proposed development, if
necessary.
2.0 Site Description
The site consists of a residential lot located within the 3300 block and east side of State
Street, in the City of Carlsbad. The generally rectangular shaped lot is elongated in an
east to west direction with topography of the relatively level property descending
gradually from east to west. The site is currently occupied by a residential development
consisting of six buildings.
3.0 Site Exploration
The investigation consisted of the placement of three (3) subsurface exploratory borings
by a hand auger to depths between 10 and 15 feet below current ground elevations.
The explorations were visually classified and logged by a field engineer with locations of
the subsurface explorations shown on the attached Site Plan. The exploratory borings
revealed the existing earth materials to consist of a fill and natural soil.
A detailed description of the subsurface conditions are listed on the excavation logs in
Appendix A. It should be noted that the transition from one soil type to another as
shown on the borings logs is approximate and may in fact be a gradual transition. The
soils encountered are described as follows:
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 3
Fill: A surficial fill soil predominately classifying as a red brown, silty, fine to
medium grained, SAND was encountered to a depth of I to 1 % feet. These soils
were noted to be loose to medium dense and damp.
Natural: An undisturbed native soil classifying as a red brown, silty, fine to medium
grained, SAND was encountered beneath the fill soils. These native soils were
observed to be medium dense and damp to moist.
The overall engineering characteristics of the earth material were relatively uniform with
each excavation. No groundwater was encountered to the depth of our borings and no
caving occurred.
4.0 Laboratory Tests
Relatively undisturbed samples of the subsurface soils were obtained to perform
laboratory testing and analysis for direct shear, consolidation tests, and to determine in-
place moisture/densities. These relatively undisturbed ring samples were obtained by
driving a thin-walled steel sampler lined with one inch long brass rings with an inside
diameter of 2.42 inches into the undisturbed soils. Bulk bag samples were obtained in
the upper soils for expansion index tests and maximum density tests.
Wall loadings on the order of 2,000 lbs./lin.ft. and maximum compression loads on the
order of 20 kips were utilized for testing and design purposes. All test results are
included in Appendix B, unless otherwise noted.
4.1 Field moisture content (ASTM:D 2216) and the dry density of the ring samples were
determined in the laboratory. This data is listed on the logs of explorations.
4.2 Maximum density tests (ASTM: D-1557-00) were performed on typical samples of the
upper soils. Results of these tests are shown on Table I.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 4
4.3 Expansion index tests in accordance with the Uniform Building Code Standard No. 18-
2 were performed on remolded samples of the upper soils. Results of these tests are
provided on Table II.
4.4 Corrosion tests consisting of sulfate, pH, resistivity and chloride analysis to determine
potential corrosive effects of soils on concrete and underground utilities were performed
in the laboratory. Test results are provided on Table IV.
4.5 Direct shear tests (ASTM: D-3080) were performed on undisturbed and disturbed
samples of the subsurface soils. The test is performed under saturated conditions at
loads of 500 lbs./sq.ft, 1,000 lbs./sq.ft., and 2,000 lbs./sq.ft. with results shown on Plate
A.
4.6 Consolidation tests (ASTM: D-2435) were performed on undisturbed samples to
determine the differential and total settlement which may be anticipated based upon the
proposed loads. Water was added to the samples at a surcharge of one KSF and the
settlement curves are plotted on Plate B.
5.0 Seismicity Evaluation
The proposed development lies outside of any Alquist Priolo Special Studies Zone and
the potential for damage due to direct fault rupture is considered very remote. The site
is located in an area of high regional seismicity and a maximum credible horizontal
ground acceleration of 0.47g may occur from a Magnitude 6.9 earthquake along the
Rose Canyon fault zone, which is located approximately 4 miles away. Ground shaking
originating from earthquakes along other active faults in the region is expected to induce
lower horizontal accelerations due to smaller anticipated earthquakes and/ore greater
distances to other faults.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 5
The following earthquake design parameters are based upon the 1997 Uniform Building
Code (UBC) for a Seismic Zone 4 with a Z factor of 0.40 and a Soil Profile Type of SD, a
stiff soil profile.
1997 UBC Seismic Design Parameters
Distance from Site (Rose Canyon Fault) 7 km
Seismic Source Type B
Seismic Coefficient = Ca (Table 16-Q) (0.44) Na
Seismic Coefficient = Cv (Table 16-R) (0.64) Nv
Near-Source Factor Na (Table 16-S) 1.0
Near-Source Factor Nv (Table 16-T) 1.12
6.0 Liquefaction Evaluation
The site is expected to experience ground shaking and earthquake activity that is typical
of Southern California area. It is during severe ground shaking that loose, granular soils
below the groundwater table can liquefy. Our analysis indicates the potential for
liquefaction at this site is considered to be very low due to the depth of groundwater
within the vicinity area. Thus, the design of the proposed construction in conformance
with the latest Building Code provisions for earthquake design is expected to provide
mitigation of ground shaking hazards that are typical to Southern California.
7.0 Conclusions and Recommendations
Based upon our evaluations, the proposed development is acceptable from a
geotechnical engineering standpoint. By following the recommendations and guidelines
set forth in our report, the structures will be safe from excessive settlements under the
anticipated design loadings and conditions. The proposed development shall meet all
requirements of the City Building Ordinance and will not impose any adverse effect on
existing adjacent structures.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 6
The following recommendations are based upon geotechnical conditions encountered in
our field investigation and laboratory data. Therefore, these surface and subsurface
conditions could vary across the site. Variations in these conditions may not become
evident until the commencement of grading operations and any unusual conditions
which may be encountered in the course of the project development may require the
need for additional study and revised recommendations.
It is recommended that site inspections be performed by a representative of this firm
during all grading and construction of the development to verify the findings and
recommendations documented in this report. The following sections present a
discussion of geotechnical related requirements for specific design recommendations of
different aspects of the project.
7.1 Site Grading Recommendations
Any vegetation and/or demolition debris shall be removed and hauled from proposed
grading areas prior to the start of grading operations. Existing vegetation shall not be
mixed or disced into the soils. Any removed soils may be reutilized as compacted fill
once any deleterious material or oversized materials (in excess of eight inches) is
removed. Grading operations shall be performed in accordance with the attached
"Specifications for Compacted Fill Operations".
All fill soils (about 1 to 11/2 feet) shall be removed to competent native material, the
exposed surface scarified to a depth of 12 inches, brought to within 2% of optimum
moisture content and compacted to a minimum of 90% of the laboratory standard
(ASTM: D-1557) prior to placement of any additional compacted fill soils, foundations,
slabs-on-grade and pavement. Grading shall extend a minimum of five horizontal feet
outside the edges of foundations or equidistant to the depth of fill placed, whichever is
greater.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 7
It is possible that isolated areas of undiscovered fill not described in this report are
present on site. If found, these areas should be treated as discussed earlier. A diligent
search shall also be conducted during grading operations in an effort to uncover any
underground structures, irrigation or utility lines. If encountered, these structures and
lines shall be either removed or properly abandoned prior to the proposed construction.
Construction of slabs-on-grade and pavement should be done immediately upon
completion of grading operations. Otherwise, additional testing and grading of the areas
may be necessary prior to continuation of construction operations. Likewise, if adverse
weather conditions occur which may damage the subgrade soils, additional assessment
by the geotechnical engineer as to the suitability of the supporting soils may be needed.
7.2 Temporary Excavations
Temporary unsurcharged excavations in the existing site materials less than 4 feet high
may be made at a vertical gradient unless cohesionless soils are encountered.
Temporary unsurcharged excavations above the vertical may be trimmed at a I to I
(horizontal to vertical) gradient for an additional two feet. In areas where soils with little
or no binder are encountered, where adverse geological conditions are exposed, or
where excavations are adjacent to existing structures, shoring, slot-cutting, or flatter
excavations may be required. The temporary cut slope gradients given do not preclude
local raveling and sloughing. All excavations shall be made in accordance with the
requirements of CAL-OSHA and other public agencies having jurisdiction. Care should
be taken to provide or maintain adequate lateral support for all adjacent improvements
and structures at all times during the grading operations and construction phase.
Temporary shoring design may utilize an active earth pressure of 25 pcf without any
surcharge due to adjacent traffic, equipment or structures. The passive fluid pressures
of 250 pcf may be doubled to 500 pcf for temporary design. The final shoring structural
calculations and drawings should be reviewed by this firm prior to installation.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 8
7.3 Foundation Design
All foundations may be designed utilizing a safe bearing capacity of 2,000 psf for an
embedded depth of 18 inches into dense compacted fill materials or competent native
soils. A one-third increase may be used when considering short term loading from wind
and seismic forces. A representative of this firm shall inspect all foundation excavations
prior to pouring concrete.
7.4 Settlement Analysis
Resultant pressure curves for the consolidation tests are shown on Plate B.
Computations utilizing these curves and the recommended safe bearing capacities
reveal that the foundations will experience settlements on the order of 3/4 inch and
differential settlements of less than 1/4 inch.
7.5 Lateral Resistance
The following values may be utilized in resisting lateral loads imposed on the structure.
Requirements of the Uniform Building Code should be adhered to when the coefficient
of friction and passive pressures are combined.
Coefficient of Friction - 0.40
Equivalent Passive Fluid Pressure = 250 lbs./cu.ft.
Maximum Passive Pressure = 2,500 lbs./cu.ft.
The passive pressure recommendations are valid only for approved compacted fill soils.
7.6 Retaining Wall Design Parameters
Active earth pressures against retaining walls will be equal to the pressures developed
by the following fluid densities. These values are for granular backfill material placed
behind the walls at various ground slopes above the walls.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 9
Surface Slope of Retained Materials Equivalent Fluid
(Horizontal to Vertical) Density (lb./cu.ft.)
Level 30
5 to I 35
4 to I 38
3 to 1 40
2 to I 45
Any applicable short-term construction surcharges and seismic forces should be added
to the above lateral pressure values. All walls shall be waterproofed as needed and
protected from hydrostatic pressure by a reliable permanent subdrain system.
7.7 Slab Design
All concrete slabs-on-grade shall be at least four inches in thickness and placed on
approved subgrade soils. A vapor barrier sandwiched between a four-inch sand layer
should be utilized in areas, which would be sensitive to the infiltration of moisture. The
subgrade soils shall be moistened to over optimum moisture content prior to pouring of
concrete. All concrete slab areas to receive floor coverings should be moisture tested to
meet all manufacturer requirements prior to placement.
7.8 Pavement Section Design
The table below provides a preliminary pavement design based upon an estimated R-
Value of 40 for the proposed pavement areas. Final pavement design may need to be
based on R-Value testing of the subgrade soils near the conclusion of rough grading to
assure that these soils are consistent with those assumed in this preliminary design.
Traffic Asphaltic Base
Type of Traffic Index Concrete (in) Material (in)
Automobile Parking Stalls 4.0 3.0 3.0
Light Vehicle Drive Circulation 5.0 3.0 4.0
NorCal Engineering
October 26, 2005 Project Number 12539-05
- Page 10
All concrete slabs to be utilized for pavement shall be a minimum of six inches in
thickness and placed on approved subgrade soils. The recommendations are based
upon estimated traffic loads. Client should submit anticipated traffic loadings, when
available, so that pavement sections may be reviewed to determine adequacy to support
these loads.
Any approved base material shall consist of a Class II aggregate or equivalent and
should be compacted to a minimum of 95% relative compaction. All pavement materials
shall conform to the requirements set forth by the City of Carlsbad. The base material
and asphaltic concrete should be tested prior to delivery to the site and during
placement to determine conformance with the project specifications. A pavement
engineer shall designate the specific asphalt mix design to meet the required project
specifications.
7.9 Corrosion Design Criteria
Representative samples of the surficial soils, typical of the subgrade soils expected to
be encountered within foundation excavations and underground utilities were tested for
corrosion potential. The minimum resistivity value obtained for the samples tested is
representative of an environment that may be corrosive to metals. The soil pH value
was considered mildly acidic and may have a significant effect on soil corrosivity.
Consideration should be given to corrosion protection systems for buried metal such as
protective coatings, wrappings or the use of PVC where permitted by local building
codes.
According to the latest "Uniform Building Code (UBC) Table 19A-A-4 - Requirements for
Concrete Exposed to Sulfate-Containing Solutions', these contents revealed negligible
levels of sulfate exposure. Therefore, a Type II cement according to latest UBC
specifications may be utilized for building foundations at this time. Additional sulfate
tests shall be performed at the completion of site grading to assure that these soils are
consistent with the recommendations stated in this design. Sulfate test results may be
found on the attached Table Ill.
NorCal Engineering
October 26, 2005 Project Number 12539-05
- Page 11
7.10 Utility Trench and Excavation Backfill
Trenches from installation of utility tines and other excavations may be backfihled with
on-site soils or approved imported soils compacted to a minimum of 90% relative
compaction. All utility lines shall be property bedded with clean sand having a sand
equivalency rating of 30 or more. This bedding material shall be thoroughly water jetted
around the pipe structure prior to placement of compacted backfill soils.
7.11 Expansive Soil
If expansive soils are encountered, special attention should be given to the project
design and maintenance. The attached Expansive Soil Guidelines should be reviewed
by the engineers, architects, owner, maintenance personnel and other interested parties
and considered during the design of the project and future property maintenance.
8.0 Closure
The recommendations and conclusions contained in this report are based upon the soil
conditions uncovered in our test excavations. No warranty of the soil condition between
our excavations is implied. NorCal Engineering should be notified for possible further
recommendations if unexpected to unfavorable conditions are encountered during
construction phase. It is the responsibility of the owner to ensure that all information
within this report is submitted to the Architect and appropriate Engineers for the project.
This firm should have the opportunity to review the final plans to verify that all our
recommendations are incorporated. This report and all conclusions are subject to the
review of the controlling authorities for the project.
A preconstruction conference should be held between the developer, general contractor,
grading contractor, city inspector, architect, and soil engineer to clarify any questions
relating to the grading operations and subsequent construction. Our representative
should be present during the grading operations and construction phase to certify that
such recommendations are complied within the field.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 12
This geotechnical investigation has been conducted in a manner consistent with the
level of care and skill exercised by members of our profession currently practicing under
similar conditions in the Southern California area. No other warranty, expressed or
implied is made.
We appreciate this opportunity to be of service to you. If you have any further
questions, please do not hesitate to contact the undersigned.
Respecifully r
NORCAL EN
ot;~k
Keith D. Tuck
Project Engin
R.G.E. 841
Scott D. Spensiero
Project Manager
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 13
SPECIFICATIONS FOR PLACEMENT OF COMPACTED FILL
Excavation
Any existing low density soils and/or saturated soils shall be removed to competent
natural soil under the inspection of the Soils Engineering Firm. After the exposed
surface has been cleansed of debris and/or vegetation, it shall be scarified until it is
uniform in consistency, brought to the proper moisture content and compacted to a
minimum of 90% relative compaction (in accordance with ASTM: D-1557-00).
In any area where a transition between fill and native soil or between bedrock and soil
are encountered, additional excavation beneath foundations and slabs will be necessary
in order to provide uniform support and avoid differential settlement of the structure.
Material For Fill
The on-site soils or approved import soils may be utilized for the compacted fill provided
they are free of any deleterious materials and shall not contain any rocks, brick,
asphaltic concrete, concrete or other hard materials greater than eight inches in
maximum dimensions. Any import soil must be approved by the Soils Engineering firm
a minimum of 24 hours prior to importation of site.
Placement of Compacted Fill Soils
The approved fill soils shall be placed in layers not excess of six inches in thickness.
Each lift shall be uniform in thickness and thoroughly blended. The fill soils shall be
brought to within 2% of the optimum moisture content, unless otherwise specified by the
'Soils Engineering firm. Each lift shall be compacted to a minimum of 90% relative
compaction (in accordance with ASTM: D-1557-00) and approved prior to the placement
of the next layer of soil. Compaction tests shall be obtained at the discretion of the Soils
Engineering firm but to a minimum of one test for every 500 cubic yards placed and/or
for every 2 feet of compacted fill placed.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 14
The minimum relative compaction shall be obtained in accordance with accepted
methods in the construction industry. The final grade of the structural areas shall be in
a dense and smooth condition prior to placement of slabs-on-grade or pavement areas.
No fill soils shall be placed, spread or compacted during unfavorable weather conditions.
When the grading is interrupted by heavy rains, compaction operations shall not be
resumed until approved by the Soils Engineering firm.
Grading Observations
The controlling governmental agencies should be notified prior to commencement of any
grading operations. This firm recommends that the grading operations be conducted
under the observation of a Soils Engineering firm as deemed necessary. A 24 hour
notice must be provided to this firm prior to the time of our initial inspection.
Observation shall include the clearing and grubbing operations to assure that all
unsuitable materials have been properly removed; approve the exposed subgrade in
areas to receive fill and in areas where excavation has resulted in the desired finished
grade and designate areas of overexcavation; and perform field compaction tests to
determine relative compaction achieved during fill placement. In addition, all foundation
excavations shall be observed by the Soils Engineering firm to confirm that appropriate
bearing materials are present at the design grades and recommend any modifications to
construct footings.
NorCal Engineering
October 26, 2005 Project Number 12539-05
- Page 15
Expansive Soil Guidelines
The following expansive soil guidelines are provided for your project. The intent of
these guidelines is to inform you, the client, of the importance of proper design and
maintenance of projects supported on expansive soils. You, as the owner or other
interested party, should be warned that you have a duty to provide the
information contained in the soil report including these guidelines to your design
engineers, architects, landscapers and other design parties in order to enable
them to provide a design that takes into consideration expansive soils.
In addition, you should provide the soil report with these guidelines to any property
manager, lessee, property purchaser or other interested party that will have or assume
the responsibility of maintaining the development in the future.
Expansive soils are fine-grained silts and clays which are subject to swelling and
contracting. The amount of this swelling and contracting is subject to the amount of
fine-grained clay materials present in the soils and the amount of moisture either
introduced or extracted from the soils. Expansive soils are divided into five categories
ranging from "very low" to "very high".
Expansion indices are assigned to each classification and are included in the laboratory
testing section of this report. If the expansion index of the soils on your site, as stated in
this report, is 21 or higher, you have expansive soils. The classifications of expansive
soils are as follows:
Classification of Expansive Soil*
Expansion Index Potential Expansion
0-20 Very Low
21-50 Low
51-90 Medium
91-130 High
Above 130 Very High
*From Table 18A-1-B of California Building Code (1988)
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 16
When expansive soils are compacted during site grading operations, care is taken to
place the materials at or slightly above optimum moisture levels and perform proper
compaction operations. Any subsequent excessive wetting and/or drying of expansive
soils will cause the soil materials to expand and/or contract. These actions are likely to
cause distress of foundations, structures, slabs-on-grade, sidewalks and pavement over
the life of the structure. It is therefore imperative that even after construction of
improvements, the moisture contents are maintained at relatively constant levels,
allowing neither excessive wetting or drying of soils.
Evidence of excessive wetting of expansive soils may be seen in concrete slabs, both
interior and exterior. Slabs may lift at construction joints producing a trip hazard or may
crack from the pressure of soil expansion. Wet clays in foundation areas may result in
lifting of the structure causing difficulty in the opening and closing of doors and windows,
as well as cracking in exterior and interior wall surfaces. In extreme wetting of soils to
depth, settlement of the structure may eventually result. Excessive wetting of soils in
landscape areas adjacent to concrete or asphaltic pavement areas may also result in
expansion of soils beneath pavement and resultant distress to the pavement surface.
Excessive drying of expansive soils is initially evidenced by cracking in the surface of
the soils due to contraction. Settlement of structures and on-grade slabs may also
eventually result along with problems in the operation of doors and windows.
Projects located in areas of expansive clay soils will be subject to more movement and
"hairline" cracking of walls and slabs than similar projects situated on non-expansive
sandy soils. There are, however, measures that developers and property owners may
take to reduce the amount of movement over the life the development. The following
guidelines are provided to assist you in both design and maintenance of projects on
expansive soils:
Drainage away from structures and pavement is essential to prevent
excessive wetting of expansive soils. Grades of at least 3% should be
designed and maintained to allow flow of irrigation and rain water to
approved drainage devices or to the street.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 17
. Any "ponding" of water adjacent to buildings, slabs and pavement after rains
is evidence of poor drainage; the installation of drainage devices or regrading
of the area may be required to assure proper drainage. Installation of rain
gutters is also recommended to control the introduction of moisture next to
buildings. Gutters should discharge into a drainage device or onto pavement
which drains to roadways.
Irrigation should be strictly controlled around building foundations, slabs and
pavement and may need to be adjusted depending upon season. This
control is essential to maintain a relatively uniform moisture content in the
expansive soils and to prevent swelling and contracting. Over-watering
adjacent to improvements may result in damage to those improvements.
NorCal Engineering makes no specific recommendations regarding
landscape irrigation schedules.
Planting schemes for landscaping around structures and pavement should
be analyzed carefully. Plants (including sod) requiring high amounts of water
may result in excessive wetting of soils. Trees and large shrubs may actually
extract moisture from the expansive soils, thus causing contraction of the
fine-grained soils.
. Thickened edges on exterior slabs will assist in keeping excessive moisture
from entering directly beneath the concrete. A six-inch thick or greater
deepened edge on slabs may be considered. Underlying interior and exterior
slabs with 6 to 12 inches or more of non-expansive soils and providing
presaturation of the underlying clayey soils as recommended in the soil
report will improve the overall performance of on-grade slabs.
. Increase the amount of steel reinforcing in concrete slabs, foundations and
other structures to resist the forces of expansive soils. The precise amount
of reinforcing should be determined by the appropriate design engineers
and/or architects.
NorCal Engineering
October 26, 2005 Project Number 12539-05
Page 18
Recommendations of the soil report should always be followed in the
development of the project. Any recommendations regarding presaturation
of the upper subgrade soils in slab areas should be performed in the field
and verified by the Soil Engineer.
NorCal Engineering
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STATE STREET
NorCal Engineering
SOILS AND GEOTECHNICAL CONSULTANTS SITE PLAN
APPROXIMATE LOCATION OF FIELD EXPLORATIONS
PROJECT 12439-05 I DATE OCTOBER 2005 I
October 26, 2005 Project Number 12539-05
Page 19
List of Appendices
(in order of appearance)
Appendix A - Log of Excavations
Log of Borings B-I to B-3
Appendix B - Laboratory Tests
. Table I - Maximum Dry Density
. Table II - Expansion
. Table III - Corrosion
Plate A - Direct Shear
Plate B - Consolidation
NorCal Engineering
October 26, 2005 Project Number 12539-05
Appendix A
NorCal Engineering
MAJOR DIVISION GRAPHIC LETTER TYPICAL DESCRIPTIONS
VMtI SVMRflI
o 0 . GW WELL-GRADED GRAVELS, GRAVEL
- SAND MIXTURES, LITTLE OR NO FINES
GRAVEL CLEAN GRAVELS
AND (LITTLE OR NO
GRAVELLY FINES)
SOILS • GP POORLY-GRADED GRAVELS.
GRAVEL-SAND MIXTURES, LITTLE
COARSE p OR NO FINES
GRAINED
GRAVELS W[GM SILTY GRAVELS, GRAVEL-SAND- SOILS MORE THAN
50% OF WITH FINES SILT
COARSE
MIXTURES
FRACTION (APPRECIABLE R RETAINED ON AMOUNT OF GC
CLAYEY GRAVELS, GRAVEL-SAND-
NO. 4 SIEVE FINES CLAY MIXTURES
.•d. SW WELL-GRADED SANDS, GRAVELLY
SAND CLEAN SAND i..'...
SANDS, LITTLE OR NO FINES
AND (LITTLE OR NO
FINES)
EL 1• . .
MORE THAN
SANDY POORLY-GRADED SANDS, GRAVEL-
50% OF
SOILS ••-'• SP LV SANDS, LITTLE OR NO FINES
MATERIAL
IS LARGER
THAN NO. MORE THAN SM SILTY SANDS, SAND-SILT
200 SIEVE 50% OF SANDS WITH MIXTURES
SIZE COARSE FINE
FRACTION (APPRECIABLE
PASSING ON AMOUNT OF SC CLAYEY SANDS, SAND-CLAY
NO. 4 SIEVE FINES) MIXTURES
INORGANIC SILTS AND VERY FINE
ML SANDS, ROCK FLOUR, SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO
FINE SILTS LIQUID LIMIT CL MEDIUM PLASTICITY, GRAVELLY
GRAINED AND I ThAw n CLAYS, SANDY CLAYS, SILTY
SOILS CLAYS CLAYS, LEAN CLAYS ________________________________
ORGANIC SILTS AND ORGANIC
- - -
OL SILTY CLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR
111111
MH DIATOMACEOUS FINE SAND OR
MORE THAN
SILTY SOILS
50% OF
MATERIAL SILTS LIQUID LIMIT CH INORGANIC CLAYS OF HIGH
IS SMALLER AND GREATER THAN PLASTICITY, FAT CLAYS
THAN NO. CLAYS 50
200 SIEVE /> ,
SIZE " F'> ORGANIC CLAYS OF MEDIUM TO
OH HIGH PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
HIGHLY ORGANIC SOILS PT HIGH ORGANIC CONTENTS
NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS
UNIFIED SOIL CLASSIFICATION SYSTEM
NorCal Engineering
U
KEY:
Indicates 2.5-inch Inside Diameter. Ring Sample.
Indicates 2-inch OD Split Spoon Sample (SPT).
Indicates Shelby Tube Sample.
Indicates No Recovery.
Indicates SPT with 140# Hammer 30 in. Drop.
Indicates Bulk Sample.
Indicates Small Bag Sample.
Indicates Non-Standard
Indicates Core Run.
COMPONENT DEFINITIONS
COMPONENT SIZE RANGE
Boulders Larger than 12 in
Cobbles 3 into 12 in
Gravel 3 in to No 4 (4.5mm)
Coarse gravel 3 in to 3/4 in
Fine gravel 3/4 in to No 4 (4.5mm)
Sand No. 4 (4.5mm ) to No. 200 ( 0.074mm)
Coarse sand No. 4(4.5mm to No. 10(2.0mm)
Medium sand No. 10 (2.0 mm ) to No. 40 ( 0.42 mm)
Fine sand No. 40 ( 0.42 mm ) to No. 200 ( 0.074 mm)
Silt and Clay Smaller than No. 200 ( 0.074 mm)
COMPONENT PROPORTIONS
DESCRIPTIVE TERMS RANGE OF PROPORTION
Trace 1-5%
Few 5.10%
Little 10-20%
Some 20 -35%
And 35-50%
MOISTURE CONTENT
DRY Absence of moisture, dusty,
dry to the touch.
DAMP Some perceptible
moisture; below optimum
MOIST No visible water near optimum
moisture content
WET Visible free water, usually
soil is below water table.
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N -VALUE
COHESIONLESS SOILS COHESIVE SOILS
Density N ( blows/fl) Consistency N (blows/ft) Approximate
Undrained Shear
Strength (psf)
Very Loose 0 to 4 Very Soft 0 to 2 < 250
Loose 4t010 Soft 2to4 250-500
Medium Dense 10 to 30 Medium Stiff 4 to 8 500-1000
Dense 30 to 50 Stiff 8 to 15 1000 -2000
Very Dense over 50 Very Stiff 15 to 30 2000 -4000
Hard over 30 > 4000
NorCal Engineering
Log of Boring B-I
Project Anastasi Development Company
Date of Drilling: 10-18-05 Groundwater Depth: None Encountered
Drilling Method: Hand Auger
Hammer Weight j Drop:
_________________
Depth
Samples Laborato ry
(feet) Geotechnical Description Lith-
ology - .2 O . 0 ' CL W-
CD
Surface Elevation Not Measured
0 -
-
c.
FILL SOILS -:
- Silty SAND
- \jed brown, loose to medium dense, damp :: i 7.1 107.5
- NATURAL SOILS
- Silty SAND
Red brown, medium dense, damp to moist
8.6 112.9
- SAND fine to medium grained
Brown medium dense moist
—10 57 1089
Boring completed at depth of 12' -
—15
—20
-25
—30
—35
NorCal Engineering
Project No.
Log of Boring B-2
Project Anastasi Development Company
Date of Drilling: Groundwater Depth: None Encountered
Drilling Method:
Hammer Weight Drop:
'I- DepthpLll
Samples Laboratory
.- (feet) Geotechnical Description Lith- ology C>L .2 I- m° 0 a G Surface Elevation Not Measured
-
-
FILL SOILS
Silty SAND /
- \ Red brown, loose, damp
-
5.1 105.1
- NATURAL SOILS
- Silty SAND
Red brown, medium dense, damp to moist
- -: 5.6 109.9
- SAND fine to medium grained
-10 Brown, medium dense, moist
- Boring completed at depth of 10'
—15
-20
—25
—30
-35
Project No.
NorCal Engineering 12539-05 2
Log of Boring B-3
Project Anastasi Development Company
Date of Drilling: 10-18-05 Groundwater Depth: None Encountered
Drilling Method: Hand Auger
Hammer Weight: Drop:
Depth
Samples Laboratorv_
(feet) Geotechnical Description Lith- o 09Y
-. -
.2 24 a .E. LL Surface Elevation Not Measured
0 - FILL SOILS
Silty SAND
- '\Red brown, loose to medium dense, damp
NATURAL SOILS
Silty SAND
Red brown, medium dense, damp to moist -
6.3 113.2
-10 Boring completed at depth of 10 -
—15
—20
—25
—30
—35
Project No.
NorCal Engineering 12539-05
October 26, 2005 Project Number 12539-05
Appendix B
NorCal Engineering
October 26, 2005 Project Number 12539-05
Sample
B-I @2'
TABLE I
MAXIMUM DENSITY TESTS
Optimum
Classification Moisture
Silty SAND 9.0
Maximum Dry
Density (Ibs./cu.ft.)
127.0
Soil Type
B-i @ 2'
TABLE II
EXPANSION INDEX TESTS
Classification
Silty SAND
Expansion
Index
03
TABLE III
CORROSION TESTS
Sample pH Electrical Resistivity (ohm-cm) Sulfate (%) Chloride (ppm)
B-i @ 2' 7.2 2,150 0.011 45
NorCal Engineering
I 2500-
2600
1500 -
1000-
r
500
'
0 500 1000 1500 2000 2500 3000
NORMAL STRESS (PSF)
SYMBOL BORING 1 DEPTH
(FEET)
0 c
(DEGREES)I DENSITYNUMBER (PSF)(PCF)
DRY
M
x 1 2 32 100 107.5 7.1
o 2 3 35 75 105.1 5.1
0
NOTE: TESTS PERFORMED ON SATURATED SAMPLES UNLESS SHOWN BELOW.
(FM) FIELD MOISTURE
TESTS PERFORMED ON UNDISTURBED SAMPLES UNLESS SHOWN BELOW.
(R) SAMPLES REMOLDED AT 90% OF MAXIMUM DRY DENSITY
NorCal Engineering
SOILS AND GEOTECHNICAL CONSULTANTS DIRECT SHEAR TEST RESULTS
Anastasi Development Company Plate A
PROJECT 12539-05 1 DATE 10/26/05
-2- iir I
NOTE: WATER ADDED AT NORMAL
PRESSURE AT 1.0 KSF
_ 11111 1__
2-_-
-,-- - -
1 +1 1
- -.---- - -
6-
8-
10-
0.1 0.5 1.0 5 10 ZO 40
NORMAL PRESSURE (KSF)
BORING DEPTH 1 DRY DRY MOISTURE LIQUID PLASTICITY
SYMBOL NUMBER (FEET) CONTENT LIMIT INDEX
(PCF) (%) (%) (%)
x J 1 5 112.9 8.6
o J_1 10 108.9 5.7
DI
COMPRESSION (FM) FIELD MOISTURE - NO WATER ADDED
REBOUND (R) SAMPLE REMOLDED AT 90% OF MAXIMUM DRY DENSITY
NorCal Engineering
SOILS AND GEOTECHNICAL CONSULTANTS CONSOLIDATION TEST RESULTS
Anastasi Development Company Plate B
PROJECT 12539-05 1 DATE 10/26/05