HomeMy WebLinkAboutCT 85-24; CARLSBAD RESEARCH CENTER UNIT 5; GEOTECHNICAL INVESTIGATION LOT 54; 1999-10-1110-11-99 CT ~5- 9,4
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CHRISTIAN WHEELER- EN G IN EER-I N G
REPORT OF GEOTECHNICAL INVESTIGATION
PROPOSED RESEARCH AND DEVELOPMENT BUILDING
LOT 54 CARLSBAD RESEARCH CENTER
DARWIN COURT
CARLSBAD, CALIFORNIA
PREPARED FOR:
C & D AEROSPACE
do SMITH CONSULTING ARCHITECTS
12220 EL CAMINO REAL, SUITE 200
SAN DIEGO, CALIFORNIA 92130
PREPARED BY:
CHRISTIAN WHEELER ENGINEERING
4925 MERCURY STREET
SAN DIEGO, CALIFORNIA 92111
RECEIVED
JUN15 2000
ENGINEERING
DEPARTMENT FILE COPY
4925 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758
CHRISTIAN WHEELER-
EN GIN EERANG
October 11, 1999
C & D Aerospace CWE 199.452.1
C/o Smith Consulting Architects
12220 El Camino Real, Suite 200
San Diego, California San Diego 92130
Attention: Jon Oils on
SUBJECT: REPORT OF GEOTECHNICAL INVESTIGATION, PROPOSED
RESEARCH AND DEVELOPMENT BUILDING, LOT 54 CARLSBAD
RESEARCH CENTER, DARWIN COURT, CARLSBAD, CALIFORNIA.
Ladies and Gentlemen:
In accordance with your request and our Proposal dated August 12, 1999, we have completed a
geotechnical investigation for the subject project. The findings and recommendations of our study
are presented herewith.
In general, the findings of this study indicate that the site is suitable for the proposed development.
The most significant geotechnical conditions affecting the proposed development consist of presence
the moderately expansive soils and relatively deep fill materials. The expansive nature of the on-site
soils will require special design considerations for structures, pavements, or any other movements-
sensitive improvements.
If you have any questions after reviewing the findings and recommendations contained in the
attached report, please do not hesitate to contact this office; This opportunity to be of professional
service is sincerely appreciated.
Respectfully submitted,
CHRISTIAN WHEELER ENGINEERING, INC.
I Charles H. Christian, R.G.E. #00215 Curtis R. Burdett, C.E.G. #1090
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TABLE OF CONTENTS
PAGE
Introduction and Project Description ..............................................................................................................I I ProjectScope ........................................................................................................................................................ I
Findings.................................................................................................................................................................2
I Site Description .............................................................................................................................................
SiteDevelopment History ............................................................................................................................
2
3
General Geology and Subsurface Conditions .......................................................................................... 3
I Geologic Setting and Soil Description..................................................................................................3
TectonicSetting........................................................................................................................................4
GeologicHazards .......................................................................... ............................................................... 5
General.......................................................................................................................................................5
I Ground Shaking ....................................................................................................................................... 5
SeismicDesign Parameters ...................................................................................................................... 5
Liquefaction............................................................................................................................................... 6
Tsunamis ....................................................................................................................................................6 I Seiches........................................................................................................................................................6
Seismic Settlement and Differential Compaction ..................... . .......... . ............................................... 6
I Ground Cracking and Surface Rupture................................................................................................6
SlopeStability ............................................................................................................................................ 6
Groundwater................. ...................................................................................... ........................................ 7
I Conclusions ............................................................................................................................................................
General.......................................................................................................................................................
7
7
Recommendations................................................................................................................................................7
I Observation
Grading............................................................................................................................................................
of Grading ...........................................................................................................................
7
7
SitePreparation ........................................................................................................................................7
SurfaceDrainage ...................................................................................................................................... 8
. Earthwork .................................................................................................................................................... 8 I Foundations........................................................................ ........................................................... .... ............8
General....................................................................................................................................................... 8
I Reinforcement ................................................................................................ . ..........................................
SettlementCharacteristics.......................................................................................................................9
9
Expansive Characteristics.......................................................................................................................9
I Foundation Plan Review ......................................................... ................................................................
Foundation Excavation Observation ..................................... ................................................................
9
9
On-Grade Slabs ............................................................................................................................................9
I Exterior
Interior On-Grade Floor Slabs ......................................................................................... ............. . .......
Slabs On-Grade ......................................................................................................................10
9
EarthRetaining Walls ................................................................................................................................10
PassivePressure......................................................................................................................................10
I Active Pressure ....................................................................................................................................... 10
Backfill..................................................................................................................................................... 10
Factorof Safety ...................................... ................................................................................................•11
I Preliminary Pavement Recommendations..............................................................................................11
Limitations..........................................................................................................................................................12
FieldExplorations .............................................................................................................................................. 12
LaboratoryTesting .............................................................................................................................................. 13
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ATTACHMENTS
TABLES
Table I Maximum Bedrock Accelerations, Page 5
FIGURES
Figure 1 Site Vicinity Map, Follows Page 1
PLATES
Plate 1 Site Plan
Plates 2-7 Boring Logs
Plate 8 Laboratory Test Results
APPENDICES
Appendix A Recommended Grading Specifications and Special Provisions
Appendix B References
GEOTECHNICAL INVESTIGATION
PROPOSED RESEARCH AND DEVELOPMENT BUILDING
LOT 54 CARLSBAD RESEARCH CENTER
DARWIN COURT
CARLSBAD, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of our geotechnical investigation for a proposed research and
development building to be constructed on Lot 54 of the Carlsbad Research Center, in the City of
Carlsbad, California. The location of the site, which is on Darwin Court, is illustrated in the vicinity
map presented on the following Figure Number 1.
We understand that the subject property is to be developed by the construction of a concrete tilt-up
I building with conventional shallow foundations and an on-grade concrete floor slab. The structure
will be a high-bay structure with a mezzanine floor. The footprint of the building will cover 30,227
I square feet. The mezzanine floor will have an area of 9,321 square feet. Asphalt concrete driveways
and parking will surround the building on three sides. Two truck docks are proposed on the rear side
I of the building. Precise grading to develop the property is expected to consist of cuts and fills of less
than about five feet from existing grades.
To assist in the preparation of this report, we were provided with a site plan prepared by Smith
Consulting Architects, dated August 6, 1999. A copy of this site plan was used as the base for our
Site Plan and is included herewith as Plate Number 1. In addition, we have reviewed the following
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documents:
a) As-Built Grading Plans for Carlsbad Tract No. 85-24, Carlsbad Research Center, Unit 3
& 4, prepared by Rick Engineering Company, as-built date January 10, 1991.
PROJECT SCOPE
The investigation consisted of: surface reconnaissance, subsurface explorations, obtaining
representative disturbed and undisturbed samples, laboratory testing, analysis of the field and
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C.W.E. 199.452.1 October 11, 1999 Page 2
laboratory data, research of available geologic literature pertaining to the site, and preparation of this
report. More specifically, the intent of this analysis was to:
Explore the subsurface conditions to the depths influenced by the proposed
construction.
Evaluate, by laboratory tests, the pertinent engineering properties of the various
strata which may influence the proposed construction, including bearing capacities,
expansive characteristics, and settlement potential.
Describe the general geology at the site including possible geologic hazards that
could have an effect on the site development.
Address potential construction difficulties that may be encountered due to soil
conditions, groundwater, or geologic hazards, and provide preliminary
recommendations concerning these problems.
Develop soil engineering criteria for site preparation and grading, which includes
recommendations to lime-treat the soils in the building pads and pavement subgrade
to mitigate the expansive soil conditions.
Provide preliminary asphalt concrete pavement and Portland Cement concrete
pavement design recommendations.
Recommend an appropriate foundation system for the type of structures anticipated
and develop soil engineering design criteria for the recommended foundation
design.
FINDINGS
SITE DESCRIPTION
The subject property consists of an undeveloped, roughly rectangular parcel of land approximately
2.1.2 acres in area. The vacant lot is located east of the Darwin Court cul-de-sac and is identified as
Lot 54 of Carlsbad Reach Center. The property is bounded on the north, east and south by
C.W.E. 199452.1 October 11, 1999 Page 3
developed research and development property. Topographically, the lot is relatively level and was
sheet-graded to slope towards the west and Darwin Court. Fill slopes up to about 30 feet high and at
inclinations of about 2:1 (horizontal to vertical) descend from the north and east sides of the lot. In
addition, a fill slope up to about four feet high with an inclination of about 2:1 ascends to the
adjacent lot to the south. An existing water main is located in an easement that is just off-site and
adjacent to the south property line of the subject property. Vegetation on the pad consists of a
relatively sparse cover of natural grasses and weeds. The slopes have been planted with ground
cover. These areas appear to be routinely irrigated.
SITE DEVELOPMENT HISTORY
Prior to the development of the Carlsbad Research Center subdivision, the subject property and
surrounding area was open undeveloped land or land used for agricultural purposes. A review of the
pre-development 200-scale topographic maps indicates that the topography of the subject site proper
was characterized by a moderately steep, easterly-facing hillside that descended to a northerly-
trending drainage channel near the eastern property line. The original elevations ranged from
approximately 300 feet in the area of Darwin Court down to approximately 260 feet near the
northeastern corner of the lot. The mass grading for the tract was apparently performed under the
testing and observation services of San Diego Soils Engineering, Inc. in approximately 1982. We
were unable to locate a copy of the report for the grading operations at the City of Carlsbad.
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located near the
boundary between the Foothills Physiographic Province and the Coastal Plains Physiographic
Province of San Diego County and is underlain byjurassic/Cretaceous-age metavolcanic rock,
Cretaceous(?)-age sedimentary deposits, original surficial soils, and artificial fill.
The fill material was noted to be moderately-well compacted, and is believed to be documented fill
that was placed during the mass grading for Units 3 and 4 of the Carlsbad Research Center
subdivision. The fill material was encountered in all three of our subsurface explorations and was
found to extend to a maximum depth of about 42 feet at Boring No. B-I and to a depth of 11 feet at
Boring No. B-3. The fill material basically consists of moist, medium stiff, silty clay to clayey silt with
moderate to high plasticity. This material is classified as a CCCL4JJJ by the Unified Soil Classification
System and was found to have a moderate potential for expansion, as determined by UBC test
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C.W.E.199.452.1 October 11, 1999 Page 4
Method 29-2. This material was found to have moderate strength parameters for determining the
soil bearing capacity and to have low strength parameters for determining structural pavement
sections.
Boring No. B-3 encountered approximately one foot of "B" horizon topsoil below the fill material
that was humid to moist, medium dense to dense, silty sand to sandy silt (SM-ML). Approximately
one foot of subsoil was exposed below the topsoil that consisted of moist, stiff, sandy clay (SC).
Normally, these materials are removed prior to placing structural fill material. However, the topsoil
and subsoil exposed appeared to be competent and capable of supporting settlement-sensitive
structures and improvements. The topsoil and subsoil were absent in Borings B-i and B-3.
Material tentatively identified as part of the Cretaceous-age Rosario Group was exposed below the fill
material in Boring No. B-2. This material consisted of humid, very dense, silty sand to sandy gravel
(SM-GM) that appears to be locally derived from the underlying bedrock source. It is anticipated that
this material is relatively thin and is underlain by metavolcanic rock.
The Santiago Peak Volcanics exposed below the fill material in Borings B-I and B-3 was found to
consist of weathered rock that was classified as a moist, very dense, silty sands to sandy gravel (SM-
GM). This material has low to moderately expansive potential and has relatively high strength
parameters when determining soil bearing capacity.
TECTONIC SETTING: Much of Southern California, including San Diego County, is
characterized by a series of Quaternary-age fault zones which typically consist of several individual,
en echelon faults that generally strike in a northerly to northwesterly direction. Some of these fault
zones (and the individual faults within the zone) are classified as active while others are classified as
only potentially active according to the criteria of the California Division of Mines and Geology.
Active fault zones are those which have shown conclusive evidence of faulting during the Holocene
Epoch (the most recent 11,000 years) while potentially active fault zones have demonstrated
movement during the Pleistocene Epoch (11,000 to 1.6 million years before the present) but no
movement during Holocene time.
A review of available geologic maps indicates that the Rose Canyon Fault Zone is located
approximately 6 miles west of the site. Other active fault zones in the region that could possibly
affect the site include the Coronado Bank and San Clemente Fault Zones to the west, the Elsinore
and San Jacinto Fault Zones to the northeast, and the Agua Blanca and San Miguel Fault Zones to
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the south. Some minor inactive faults have been previously mapped in the general vicinity of the
subject site; these small faults should be of only nominal consequence to the proposed project.
GEOLOGIC HAZARDS
GENERAL: The site is located in an area that is relatively free of significant geologic hazards.
There are no hazards of sufficient magnitude to preclude development of the site as presently
proposed.
GROUND SHAKING: A likely geologic hazard to affect the site is ground shaking as result of
movement along one of the major active fault zones mentioned above. The maximum bedrock
accelerations that would be attributed to a maximum probable earthquake occurring along the nearest
fault segments of selected fault zones that could affect the site are summarized in the following Table I.
TABLE I
Fault Zone Distance MaximumProbable
Earthquake
Maximum Bedrock
Acceleration
Rose Canyon 6 miles 6.5 magnitude 0.30 g
Elsinore 23 miles 7.3 magnitude 0.16 g
Coronado Bank 22 miles 7.0 magnitude 0.14 g
San jacinto 47 miles 7.8 magnitude 0.13 g
Probable ground shaking levels at the site could range from slight to moderate, depending on such
factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site
will experience the effects of at least one moderate to large earthquake during the life of the proposed
structures.
SEISMIC DESIGN PARAMETERS: In accordance with the evaluations provided above, the
Maximum Bedrock Acceleration at the site is 0.30 g (based upon a Maximum Probable Seismic Event of
6.5 Magnitude along the Rose Canyon Fault Zone). For structural design purposes, a damping ratio not
greater than 5 percent of critical dampening, and Soil Profile Type S0 are recommended (UBC Table 16-
J). Based upon the location of the site of approximately 10 kilometers (6¼ miles) from the Rose Canyon
Fault (Type B Fault), Near Source Factors Na equal to 1.0 and N equal to 1.0 are also applicable.
C.W.E. 199.452.1 October 11, 1999 Page 6
Additional seismically related design parameters are recommended to be obtained from the Uniform
Building Code (UBC) 1997 edition, Volume II, Chapter 16, utilizing a Seismic Zone 4.
LIQUEFACTION: The materials at the site are not subject to liquefaction due to such factors as
soil density, grain-size distribution, and lack of shallow groundwater.
TSUNAMIS: Tsunamis are great sea waves produced by a submarine earthquake or volcanic
eruption. Due to the site's location, it is not subject to tsunamis.
SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays, or
reservoirs. No such large bodies of standing water are located in an area that could possibly affect
the subject site.
SEISMIC SETTLEMENT AND DIFFERENTIAL COMPACTION: The formational
materials and the compacted fills at the site are all medium dense/medium stiff to stiff and very
stiff/very dense and are not subject to seismic settlement or differential compaction.
GROUND CRACKING AND SURFACE RUPTURE: No active faults are known to traverse
the site, so the site is not considered subject to surface rupture from on-site faulting. Ground
cracking caused by shaking from distant seismic sources is considered to be highly unlikely.
SLOPE STABILITY: The site is identified as being in Relative Landslide Susceptibility Area 3-I
according to the Landslide Susceptibility Map prepared by the California Division of Mines and
Geology. Area 3 is considered to be a generally susceptible area and includes areas that are
considered to be at or near their stability limits due to a combination of weak materials and steep
slopes. A review of the pre-development aerial photographs revealed the presence of several
topographic features in the vicinity of the project site that may suggest previous slope failures and
some landslides were identified during the geotechnical investigation for the subdivision. Based on
our site-specific study and the information available to date, it is our opinion that the previous mass
grading operation has satisfactorily mitigated the presence of landslides and that the likelihood of
deep-seated slope instability phenomena at the subject site proper can be considered to be low.
Potential shallow, surficial problems can be mitigated by the use of appropriate landscaping and
slope maintenance practices.
Page 7 C.W.E. 199.452.1 October 11, 1999
I GROUNDWATER: We do not anticipate any major groundwater related problems, either during
or after construction. However, it should be recognized that minor groundwater seepage problems
I might occur after development of a site even where none were present before development. These
are usually minor phenomena and are often the result of an alteration of the permeability
I characteristics of the soil, an alteration in drainage patterns and an increase in irrigation water. Based
on the proposed development scheme, it is our opinion that the likelihood of future seepage
I phenomena should be considered to be low. It is further our opinion that these problems can be
most effectively corrected on an individual basis is and when they develop.
CONCLUSIONS
GENERAL: In general, no geotechnical conditions were encountered which would preclude the
I development of the site as presently proposed provided the recommendations presented herein are
followed. The development the geotechnical conditions encountered that will most affect the of site
is the presence of moderately expansive soils that will require special design for foundations and on-
grade concrete slabs, and that will require relatively thick structural pavement sections. The fill
material was found to be moderately well compacted. However, the upper foot of fill material was
I found to have loosened over the years as a result of wetting and drying and the expansion
characteristics of the soil. This material should be removed and replaced as uniformly compacted fill.
I No other soil or geologic conditions were found that would significantly affect the development of
the property as proposed.
RECOMMENDATIONS
GRADING
I OBSERVATION OF GRADING: Continuous observation by Christian Wheeler Engineering is
essential during the grading operation to construct the building pads and paved areas in order to
I confirm the conditions anticipated by our investigation, to allow adjustments in design criteria to reflect
the actual field conditions exposed, and to determine that the grading proceeds in general accordance
I with the recommendations contained herein.
I SITE PREPARATION: Site preparation should begin with the removal of any existing vegetation
and deleterious matter from the areas of the site to be graded and/or that will support new
I improvements. It is recommended that the upper twelve inches (12) inches of the existing fill
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materials where not removed by the planned grading, be removed and be replaced as uniformly
compacted fill. The minimum horizontal removal limits of this operation should include all areas
that will support settlement-sensitive improvements, including exterior walkways and paved areas.
All excavations should be approved by the geotechnical engineer or his representation prior to filling.
The soils exposed at the bottom of all excavations should be scarified to a depth of 12 inches,
moisture-conditioned and be recompacted to at least 90 percent as determined in accordance with
ASTM D-1557-91 prior to replacing the excavated fill. All fill should be placed in lifts six to eight
inches is thickness with each lift mechanically compacted to at least 90 percent of maximum dry
density.
SURFACE DRAINAGE: It is recommended that all surface drainage be directed away from the
structure and the top of slopes. Ponding of water should not be allowed adjacent to foundations.
EARTHWORK. All earthwork and grading contemplated for site preparation should be
accomplished in accordance with the attached Recommended Grading Specifications and Special
Provisions. All special site preparation recommendations presented in the sections above will
supersede those in the standard Recommended Grading Specifications. All embankments, structural
fill and fill should be compacted to at least 90 percent relative compaction at or slightly over
optimum moisture content. Utility trench backfill within five feet of the proposed structures and
beneath all pavements should be compacted to a minimum of 90 percent of its maximum dry
density. The upper twelve inches of subgrade beneath paved areas should be compacted to 90
percent of it maximum dry density. This compaction should be obtained by the paving contractor
just prior to placing the aggregate base material and should not be part of the mass grading
requirements. The maximum dry density of each soil type should be determined in accordance with
ASTM Test D-1557-91.
FOUNDATIONS
GENERAL: Shallow foundations may be utilized for the support of the proposed structure. The
concrete tilt-up panels should be supported on continuous grade-beam style footings. All footings
should be embedded a minimum depth of 24 inches below lowest adjacent finish pad grade. A
minimum width of 18 inches and 24 inches is recommended for continuous and isolated footings,
respectively. A bearing capacity of 2,500 pounds per square foot may be assumed for said footings.
This bearing capacity may be increased by one-third when considering wind and/or seismic forces.
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I REINFORCEMENT: Footing reinforcement should be specified by the project structural
engineer. However, as a minimum we recommend that both exterior and interior continuous
I footings be reinforced with at least two No. 5 bars positioned near the bottom of the footing and
two No. 5 bars positioned near the top of the footing. This reinforcement is based on soil
characteristics and is not intended to be in lieu of reinforcement necessary to satisfy structural
considerations.
SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential settlements for
I the proposed structure will be less than one inch, provided the recommendations presented in this
report are followed. It should be recognized that minor cracks normally occur in concrete slabs and
I foundations due to shrinkage during curing or redistribution of stresses and some cracks may be
anticipated. Such cracks are not necessarily an indication of excessive vertical movements.
I EXPANSIVE CHARACTERISTICS: The anticipated foundation soils were found to vary from
moderately expansive. The recommendations presented in this report reflect a highly expansive soil
I condition.
I FOUNDATION PLAN REVIEW: It is recommended that the foundation plans be submitted to
this office for review in order to verify that the recommendations presented in this report are
I incorporated in the structural plans.
I FOUNDATION EXCAVATION OBSERVATION: We recommend that all footing excavations
be observed by the geotechnical engineer to verify that the footing excavations comply with our
I minimum recommendations and the structural plans, and that the soil conditions are as anticipated in
the preparation of this report.
I ON-GRADE SLABS
I INTERIOR ON-GRADE FLOOR SLABS: The thickness, reinforcing and compressive strength
of the interior slabs should be specified by the structural engineer. However, as a minimum, we
I recommend that the interior concrete on-grade floor slabs have a actual thickness of at least six
inches in warehouse areas and five inches is office areas. The interior concrete slabs should be
I reinforced with at least No. 3 reinforcing bars placed at least at 18 inches on-center each way. The
floor slab reinforcing should be supported on chairs such that they will be positioned mid-height in
I the slab.
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four Interior floor slabs should be underlain by a -inch blanket of clean, poorly graded, coarse sand.
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The sand should have less than ten percent passing the #100 sieve and five percent passing the #200
Where floor barrier be in sieve. moisture-sensitive coverings are planned, a visqueen should placed
the center of the sand layer.
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EXTERIOR SLABS ON-GRADE: Exterior slabs (excluding driveways) should have a minimum
I thickness of five inches. Walks or slabs five feet in width should be reinforced with at least No. 3
bars at 18 inches on center each way and provided with weakened plane joints. Any slabs between
I five and ten feet should be provided with longitudinal weakened plane joints at the centerlines. Slabs
exceeding ten feet in width should be provided with a weakened plane joint in accordance with
American Concrete Institute Standards.
EARTH RETAINING WALLS
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PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be considered to
be 300 foot foot depth. This be increased for pounds per square per of pressure may one-third seismic
loading. The coefficient of friction for concrete to soil may be assumed to be 0.30 for the resistance to
I lateral movement. When combining frictional and passive resistance, the friction should be reduced by
one-third. The upper 12 inches of exterior retaining wall footings should not be included in passive
I pressure calculations where abutted by landscaped areas.
I ACTIVE PRESSURE: The active soil pressure for the design of unrestrained earth retaining
structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 40
I pounds per cubic foot. An additional 15 pounds per cubic foot should be added to this value for
restrained retaining walls. These pressures do not consider any other surcharge. If any are anticipated,
I this office should be contacted for the necessary increase in soil pressure. These values assume a
drained backfill condition. Waterproofing details should be provided by the project architect. A
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suggested wall subdrain detail is provided on the attached Plate Number 10. We recommend that the
Geotechnical Consultant be retained to observe all retaining wall subdrains to verify proper
construction.
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BACKFILL: All backfill soils should be compacted to at least 90 percent relative compaction.
I Expansive or clayey soils should not be used for backfill material. The wall should not be backfllled
until the masonry has reached an adequate strength.
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C.W.E. 199.452.1 October 11, 1999 Page 11
FACTOR OF SAFETY: The above values, with the exception of the allowable soil friction
coefficient, do not include a factor-of-safety. Appropriate factors-of-safety should be incorporated into
the design to prevent the walls from overturning and sliding.
PRELIMINARY PAVEMENT RECOMMENDATIONS
The recommended preliminary pavement section presented below is based on a subgrade soil R-
Value of 12, as determined by California Test Method 301. In addition, since the use of the property
will be for research and development with a relatively low volume of truck traffic, a traffic index of
5.5 was assumed for the design of the structural pavement section for areas subject to truck traffic.
A Traffic index of 4.5 was assumed for general automobile parking areas. If heavy truck traffic is
expected, the pavement section recommendations presented below should be modified to reflect the
anticipated traffic loads. The structural section should be verified after "R" value tests of the actual
subgrade soils are performed. All paving methods and materials should conform with good
engineering practices and with the requirements of the City of Carlsbad.
Truck Traffic Areas:
4.0 inches of asphalt concrete pavement, on
8.5 inches of crushed aggregate base
General Automobile Parking Areas:
4.0 inches of asphalt concrete pavement, on
5.0 inches of crushed aggregate base
The aggregate base material should conform with the Standard Specifications for Public Works
Construction (Green Book), Section 200-2.2.2, and should be compacted to at least 95 percent
relative compaction. The asphalt concrete should conform to Section 203-6.2.1 for the asphalt and
Section 203-6.2.2 for the aggregate. The subgrade soils should be compacted to at least 90 percent
relative compaction just prior to placing base material. Therefore, this compaction should be
accomplished by the paving contractor.
Portland (emcnt Concrete (PcC) pavement should have a numnmm thickness of 5.5 inchh and
should be underlain by at least 4.0 inches of crushed aggregate base material compacted to at least 95
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C.W.E. 199.452.1 October 11, 1999 Page 12
percent relative compaction. The subgrade should be processed as recommended above for asphalt
concrete sections. PCC should conform with Section 201 of the Green Book.
The compaction of the subgrade and base material and the asphalt concrete lay down should be
observed and tested by the geotechnical consultant. All paving and construction methods should
comply with good engineering practices, the Green Book and with the requirements of the City of
Carlsbad.
LIMITATIONS
The recommendations and opinions expressed in this report reflect our best estimate of the project
requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface
exploration locations and the assumption that the soil conditions do not deviate appreciably from
those encountered. It should be recognized that the performance of the foundations may be
influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the
I intermediate and unexplored areas. Any unusual conditions not covered in this report that may be
encountered during site development should be brought to the attention of the soils engineer so that
he may make modifications if necessary. In addition, this office should be advised of any changes in
I the project scope or proposed site grading so that it may be determined if the recommendations
contained herein are appropriate. This should be verified in writing or modified by a written
I addendum.
FIELD EXPLORATIONS
I Five subsurface explorations were made at the locations indicated on the attached Plate Number 1
on September 16, 1999. These explorations consisted of borings made with a 24-inch-diameter
bucket-type drill rig. The fieldwork was conducted under the observation of our engineering geology
I personnel.
I The explorations were carefully logged when made. These logs are presented on the following Plates
Number 2 through 7. The soils are described in accordance with the Unified Soils Classification. In
I addition, a verbal textural description, the wet color, the apparent moisture and the density or
consistency are provided. The density of granular soils is given as either very loose, loose, medium
I dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium
stiff, stiff, very stiff, or hard.
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C.W.E. 199.452.1 October 11, 1999 Page 13
Disturbed and "undisturbed" samples of typical and representative soils were obtained and returned
to the laboratory for testing. Representative undisturbed core samples were obtained by means of a
split tube sampler driven into the soils by means of the kelly bar on the drill rig free-falling a distance
of 12. The number of blows required to drive the sampler one foot is indicated on the boring logs
as "sample penetration resistance".
LABORATORY TESTING
Laboratory tests were performed in accordance with the generally accepted American Society for
Testing and Materials (ASTM) test methods or suggested procedures. A brief description of the tests
performed is presented below:
CLASSIFICATION: Field classifications were verified in the laboratory by visual
examination. The final soil classifications are in accordance with the Unified Soil
Classification System.
MOISTURE-DENSITY: In-place moisture contents and dry densities were
determined for representative soil samples. This information was an aid to
classification and permitted recognition of variations in material consistency with
depth. The dry unit weight is determined in pounds per cubic foot, and the in-place
moisture content is determined as a percentage of the soil's dry weight. The results
are summarized in the boring logs.
GRAIN SIZE DISTRIBUTION: The grain size distribution was determined for
representative samples of native soils in accordance with ASTM D422. The results
of these tests are presented on Plate Number 8.
EXPANSION INDEX TEST: Expansion index tests on remolded samples were
performed on representative samples of soils likely to be present at finish grade.
The tests were performed on the portion of the samples passing the #4 standard
sieve. The samples were brought to optimum moisture content and then dried back
to a constant moisture content for 12 hours at 230 +1- 9 degrees Fahrenheit. The
specimen were then compacted in a 4-inch-diameter mold in two equal layers by
means of a tamper, then trimmed to a final height of 1 inch, and brought to a
saturation of approximately 50 percent. The specimen were placed in a
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I C.W.E. 199.452.1 October 11, 1999 Page 14
consolidometer with porous stones at the top and bottom, a total normal load of
12.63 pounds was placed (144.7 psf), and the sample was allowed to consolidate for
a period of 10 minutes. The samples were allowed to become saturated, and the
change in vertical movement was recorded until the rate of expansion became
nominal. The expansion indexes are reported on the attached Plate Number 8 as
the total vertical displacement time the fraction of the samples passing the #4 sieve
times 1000.
CLASSIFICATION OF EXPANSIVE SOIL
EXPANSION INDEX POTENTIAL EXPANSION
1-20 very low
21-50 low
51-90 medium
91-130 high
Above 131 very high
DIRECT SHEAR TESTS: Direct shear tests were performed to determine the
failure envelope based on yield shear strength. The shear box was designed to
accommodate a sample having a diameter of 2.375 inches or 2.50 inches and a
height of 1.0 inch. Samples were tested at different vertical loads and a saturated
moisture content. The shear stress was applied at a constant rate of strain of
approximately 0.05 inch per minute. The results of these tests are presented on the
attached Plate Number 8.
RESISTANCE VALUE TEST (R-VALUE): The Resistance value of a
representative sample of the subgrade soil was determined in accordance with
California Teat Method 301. The resuots of this test is presented on Plate No. 9.
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1 PROPOSED RESEARCH & DEVELOPMENT BUILDING
Darwin Court, Carlsbad H
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Christian Wheeler Engineering
Job Number: 199.452
Date: September 1999
Plate Number: 1
LEGEND
Approximate In-Place Density Test Location
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U I - [7 •
\VI l_----.--- T-
R&6BLMkthg
....----.
- B3
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. \ \ . ( I!5L1&bE 91$.
aidAauE3a2V 01 :n •
— \• . I'll
c •/ \
S .
• f ;• •'
: • • S
° ' 11I './•,., ...-......- ®•, ./ f • / / • / • -- No Scale .••...... •
- - --
. - - :'
M2 peeL1 *'ioe
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LOG OF TEST BORING NUMBER B-i
Date Excavated: 9/16/99 Logged by: CRB
Equipment: Larive Drilling Project Manager. CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer: N/A
0•
SUMMARY OF SUBSURFACE CONDITIONS
P.
SAMPLES
ZOE
(I)
- 2
- 4
-
-6
-8
-10
-12
-14
-16
- 18
20
FILL (Oaf):
Gray brown, dark yellow brown to medium brown, moist,
medium stiff to stiff, CLAYEY SILT/SILTY CLAY
(ML/CL).
CK
US
CK
US
Push
Push
1E DS
18.2
19.8
21.6
21.5
100.8
102.1
97
101.1
MD
SA
- - - - -
Continues on Plate Number 3.
PROPOSED RESEARCH & DEVELOPMENT BUILDING
Darwin Court, Carlsbad
CHRJSflAN WHEELER- BY: CRB DATE: Sep-99
ENGINEERING JOB NO.: 199.452 PLATE NO.: 2
LOG OF TEST BORING NUMBER B-i (Continued)
Date Excavated: 9/16/99 Logged by: CRB
Equipment Larive Drilling Project Manager: CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer: N/A
CD
SUMMARY OF SUBSURFACE CONDITIONS
SAMPLES
z
ci)
-22
-24
-26
-28
-30
-32
-34
-36
-.38
FILL (Oaf):
Gray brown, moist, medium stiff to stiff, CLAYEY SILT!
SILTY CLAY (ML/CL).
40 — — — — — —
CK
US
CK
US
US
jJ
Push
Push
Push
21.5
22.0
24.3
24.4
21.9
105.1
98.8
93.8
94.2
100.4
Continues on Plate Number 4.
CHPJS11AN WHEELER
E NGINEEPLING
PROPOSED RESEARCH & DEVELOPMENT BUILDING
Darwin Court, Carlsbad
BY: CRB DATE: Sep-99
JOB NO.: 199.452 JPLATE NO.: 3
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LOG OF TEST BORING NUMBER B-i (Continued)
Date Excavated: 9/16/99 Logged by: CRB
Equipment: Larive Drilling Project Manager: CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer: N/A
- SAMPLES
-21
SUMMARY OF SUBSURFACE CONDITIONS CIO
; ZO-
CIO P,
k,_I
FILL (Oaf):
-42 H' Gray brown, moist, medium stiff, CLAYEY SILT to
• cY ......................................................................................-.....
CK 198 1012
JjjjjjJJjJ\ FILL (Oaf): Possibly Qal left in place.
-
- \ Dark gray, moist, stiff, SANDY CLAY (CL),
-
\slight organic odor.
WEATHERED SANTIAGO PEAK VOLCANICS
(Jsp): Dark yellow brown, moist, stiff to very stiff,
- 46
STY SILT ...................................../
SANTIAGO PEAK VOLCANICS (Jsp): Yellow brown, -48
humid very dense, SILTY SAND/SANDY GRAVEL
50 (SM/GM) Material is fractured, but very dense
- - - - - -
Bottom of boring at 50 feet.
PROPOSED RESEARCH & DEVELOPMENT BUILDING
21 Darwin Court, Carlsbad
CHRISTIAN WHEELER. BY: CRB DATE: Sep-99
ENGINEERING FOB 199.452 IPLATE NO.:
LOG OF TEST BORING NUMBER B-2
Date Excavated: 9/16/99 Logged by: CRB
Equipment Larive Drilling Project Manager: CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer: N/A
SAMPLES
'-I U
SUMMARY OF SUBSURFACE CONDITIONS ,
ZOE-'
FILL (Oaf):
Gray brown, moist, medium stiff, CLAYEY SILT! WV
- 2
SILTY CLAY (ML/CL). us 1111] Push 19.7 100.1
US Push 21.6 101.1
-6
-8
CK Push 20.8 99.9
- 10
us
- 12
-14
us Push 21.0 98.2
-16
-18
20 - - - - - -
Continues on Plate Number 6.
- PROPOSED RESEARCH & DEVELOPMENT BUILDING a Darwin Court, Carlsbad
CHRISTIAN WHEELER BY: CRB DATE: Sep-99
EN G IN E E P. ING JOB NO.: 199.452 PLATE NO.: 5
LOG OF TEST BORING NUMBER B-2 (Continued)
Date Excavated: 9/16/99 Logged by: CRB
Equipment: Larive Drilling Project Manager: CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer N/A
SAMPLES
o
SUMMARY OF SUBSURFACE CONDITIONS E
O z - oO
zO
c/)
FILL (Oaf): US Push
-22 Gray brown, moist, medium stiff, SILTY CLAY!
CLAYEY SILT (CL/ML).
- 24
US Push -26
-28
-30 FILL (Oaf): Dark gray with medium
brown and yellow brown, moist, stiff, SANDY CLAY (CL). CK 18.7 105.1
-32
34 WEATHERED POINT LOMA FORMATION (Kp)
Dark yellow brown, humid, very dense, SILTY SAND!
-36 SANDY GRAVEL (SM/GM).
-38 --
140
Bottom of boring at 38 feet.
-
PROPOSED RESEARCH & DEVELOPMENT BUILDING
Darwin Court, Carlsbad
CHRISTIAN WHEELER BY: CRB DATE: Sep-99 E N G I N E E P. I N G
JOB NO.: 199.452 PLATE NO.: 6
LOG OF TEST BORING NUMBER B-3
Date Excavated: 9/16/99 Logged by. CRB
Equipment: Larive Drilling Project Manager: CRB
Surface Elevation (ft) N/A Depth to Water (ft): N/A
Hammer Weight: 3500# to 27', 2400# 27-55', 1300# below 55' Drop of Hammer: N/A
SAMPLES
L)
E'
SUMMARY OF OF SUBSURFACE CONDITIONS
ZOF-
FILL (Qaf):
2N Gray brown, moist, medium stiff, SILTY CLAY/CLAYEY
SILT (CL/ML).
US I I Push I 14.9 I 109.2
4
US I I Push I 24.0 I 101.4
[]
"B" HORIZON TOPSOIL: Dark red brown, humid toI 10
moist, medium dense to dense, SILTY SAND/SANDY SILT US Push 16.4100
12
SUBSOIL: Light red brown, moist, stiff, SANDY CLAY
WEATHERED SANTIAGO PEAK VOLCANICS
16 iiriit \
(Jsp): Dark yellow brown, humid, dense to very dense,
____ \ SILTY SAND (SM).
18 SANTIAGO PEAK VOLCANICS (Isp): Gray brown,
humid, very dense, SILTY SAND/SANDY GRAVEL
20
Bottom of boring at 17 feet.
PROPOSED RESEARCH & DEVELOPMENT BUILDING
Darwin Court, Carlsbad
CHRISTIAN WHEELER BY: CRB DATE: Sep-99
ENGINEEPLING JOB NO.: 199.452 PLATE NO.: 7
LABORATORY TEST RESULTS
LOT 54, CARLSBAD RESEARCH CENTER
MAXIMUM DENSITY! OPTIMUM MOISTURE CONTENT
Sample Number Boring No. 1 @ 4 '- 5'
Description Silty Clay - Clayey Silt(CL - ML)
Maximum Density 110.0 Pounds Per Cubic Foot
Optimum Moisture Content 15.1 Percent
DIRECT SHEAR TEST
Sample Number Boring No. 1 @ 4'- 5'
Condition Remolded to 90 Percent
Angle of Friction 28 Degrees
Apparent Cohesion 250 Pounds Per Square Foot
EXPANSION INDEX TEST
Sample Number Boring No. 1 @4' —5'
Initial Moisture Content 14.1 Percent
Initial Dry Density 96.8 Pounds Per Cubic Foot
Finial Moisture Content 31.0 Percent
Expansion Index 78
Classification Moderate
GRAIN SIZE DISTRIBUTION
Sample Number Boring I @ 4 '- 5'
Sieve Size Percent Passing
#4 100
#8 100
#15 98
#30 97
#50 95
#100 92
#200 86
0.05 mm 85
0.005 mm 43
0.001 mm 22
CWE 199.452 October 11, 1999 Plate No. 8
CWE 199.452 October 11, 1999 Appendix A, Page Al
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
PROPOSED RESEARCH AND DEVELOPMENT BUILDING
LOT 54, CARLSBAD RESEARCH CENTER
DARWIN COURT
CARLSBAD, CALIFORNIA
GENERAL INTENT
The intent of these specifications is to establish procedures for clearing, compacting natural ground,
preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the
accepted plans. The recommendations contained in the preliminary geotechnical investigation report
and/or the attached Special Provisions are a part of the Recommended Grading Specifications and
shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall
only be used in conjunction with the geotechnical report for which they are a part. No deviation
from these specifications will be allowed, except where specified in the geotechnical report or in
other written communication signed by the Geotechnical Engineer.
OBSERVATION AND TESTING
Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the
earthwork in accordance with these specifications. It will be necessary that the Geotechnical
Engineer or his representative provide adequate observation so that he may provide his opinion as to
whether or not the work was accomplished as specified. It shall be the responsibility of the
contractor to assist the Geotechnical Engineer and to keep him appraised of work schedules, changes
and new information and data so that he may provide these opinions. In the event that any unusual
conditions not covered by the special provisions or preliminary geotechnical report are encountered
during the grading operations, the Geotechnical Engineer shall be contacted for further
recommendations.
If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as
questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse
weather, etc., construction should be stopped until the conditions are remedied or corrected or he
shall recommend rejection of this work.
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I October 11, 1999 Appendix A, Page A2 CWE 199.452
Tests used to determine the degree of compaction should be performed in accordance with the
following American Society for Testing and Materials test methods:
Maximum Density & Optimum Moisture Content— ASTM D-1557-91
Density of Soil In-Place - ASTM D-1556-90 or ASTM D-2922
All densities shall be expressed in terms of Relative Compaction as determined by the foregoing
ASTM testing procedures.
PREPARATION OF AREAS TO RECEIVE FILL
All vegetation, brush and debris derived from clearing operations shall be removed, and legally
disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free
from unsightly debris.
After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 12
inches, brought to the proper moisture content, compacted and tested for the specified minimum
degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural
ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its
maximum dry density.
When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1
vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm
competent formational soil. The lower bench shall be at least 10 feet wide or 1'/2 times the
equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not
less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of
each bench shall be compacted prior to receiving fill as specified herein for compacted natural
ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the
Geotechnical Engineer.
Any abandoned buried structures encountered during grading operations must be totally removed.
All underground utilities to be abandoned beneath any proposed structure should be removed from
within 10 feet of the structure and properly capped off. The resulting depressions from the above
described procedure should be backfilled with acceptable soil that is compacted to the requirements
of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer
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CWE 199.452 October 11, 1999 Appendix A, Page A3
lines or leach lines, storm drains and water lines. Any buried structures or utilities not to be
abandoned should be brought to the attention of the Geotechnical Engineer so that he may
determine if any special recommendation will be necessary.
FILL MATERIAL
Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of
organic matter and other deleterious substances. Granular soil shall contain sufficient fine material
to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils
are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation,
or soils with low strength characteristics may be thoroughly mixed with other soils to provide
satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import
material shall be approved by the Geotechnical Engineer before being brought to the site.
PLACING AND COMPACTION OF FILL
Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches
in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow
the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each
layer shall be uniformly compacted to the specified minimum degree of compaction with equipment
of adequate size to economically compact the layer. Compaction equipment should either be
specifically designed for soil compaction or of proven reliability. The minimum degree of
compaction to be achieved is specified in either the Special Provisions or the recommendations
contained in the preliminary geotechnical investigation report.
When the structural fill material includes rock, no rocks will be allowed to nest and all voids must be
carefully filled with soil such that the minimum degree of compaction recommended in the Special
Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in
non-structural fills is discussed in the geotechnical report, when applicable.
Field observation and compaction tests to estimate the degree of compaction of the fill will be taken
by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be
at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer
is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the
Geotechnical engineer and until the desired relative compaction has been obtained.
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CWE 199.452 October 11, 1999 Appendix A, Page A4
Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment.
Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In
addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled.
Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been
constructed. Slope compaction operations shall result in all fill material six or more inches inward
from the finished face of the slope having a relative compaction of at least 90 percent of maximum
dry density or the degree of compaction specified in the Special Provisions section of this
specification. The compaction operation on the slopes shall be continued until the Geotechnical
engineer is of the opinion that the slopes will be surficially stable.
Density tests in the slopes will be made by the Geotechnical Engineer during construction of the
slopes to determine if the required compaction is being achieved. Where failing tests occur or other
field problems arise, the Contractor will be notified that day of such conditions by written
communication from the Geotechnical Engineer or his representative in the form of a daily field
report.
If the method of achieving the required slope compaction selected by the Contractor fails to produce
the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of
compaction is obtained, at no cost to the Owner or Geotechnical Engineer.
CUT SLOPES
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The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material
during the grading operations at intervals determined at his discretion. If any conditions not
anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a
potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during
grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer
to determine if mitigation measures are necessary.
Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or
steeper than that allowed by the ordinances of the controlling governmental agency.
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CWE 199.452 October 11, 1999 Appendix A, Page A5
ENGINEERING OBSERVATION
Field observation by the Geotechnical Engineer or his representative shall be made during the filling
and compaction operations so that he can express his opinion regarding the conformance of the
grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or
his representative or the observation and testing shall release the Grading Contractor from his duty
to compact all fill material to the specified degree of compaction.
SEASON LIMITS
Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy
rain, filling operations shall not be resumed until the proper moisture content and density of the fill
materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be
repaired before acceptance of work.
RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS
RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted
natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and
parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative
compaction.
EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion
index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-C.
OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of
soil over 6 inches in diameter. Oversized materials should not be placed in fill unless
recommendations of placement of such material are provided by the Geotechnical Engineer. At least
40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building
pad, the cut portion should be undercut a minimum of 18 inches below the base of the proposed
footings and recompacted as structural backfill. In certain cases that would be addressed in the
geotechnical report, special footing reinforcement or a combination of special footing reinforcement
and undercutting may be required.
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I CWE 199.452 October 11, 1999 Appendix B, Page B1
REFERENCES
I Anderson, J.G.; Rockwell, R.K. and Agnew, D.C., 1989, 'Past and Possible Future Earthquakes of
Significance to the San Diego Region," Earthquake Spectra, Volume 5, No. 2, 1989.
Geologic Maps of the Northwestern Partof San Diego County, Geologic Maps of the Oceanside,
San Luis Rey, and San Marcos 7.5' Quadrangles, 1996, California Division of Mines and
Geology, Open-File Report No. 96-02, scale 1:24,000.
I Geotechnical Investigation Callaway Golf Distribution Building Carlsbad Research Center -Lot 12 Carlsbad, California, 1994, prepared by Woodward-Clyde Consultants, Project No.
9451092K-SIO1, dated August 8,: 1994.
'Preliminary Jennings, C.W., 1992, Fault Activity Map of California," California Division of
Mines and Geology, Open-File No. 92-3.
I
Mualchin, L., Jones, A.L., 1992, Peak Accelerations from Maximum Credible Earthquakes in
California (Rock and Stiff-Soil Sites), California Department of Conservation, DMG Open- I File Report 92.1
I San Diego County General Plan, Seismic Safety Element, Part V Adopted-January 9, 1975, Amended April 24, 1991.
Tan, Siang S., and Giffen, Desmond G., 1995, Landslide Hazards in the Northwestern Part of the
San Diego Metropolitan Area, San Diego County, California, Oceanside and San Luis Rey
I Quadrangles, California Division of Mines and Geology, Open-File Report No. 95-04, scale
1:24,000.
I Weber, F.H. Jr., 1963, Geology and Mineral Resources of San Diego County, California,
California Division of Mines and Geology, County Report 3.
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