HomeMy WebLinkAboutMS 13-02; King Property; Minor Subdivision (MS) (4)RECEIVED
MAR 2 1 2013
CITY OF CARLSBAD
PLANNING DIVISION
UPDATE GEOTECHNIC.4L EVALUATION
FOR
PROPOSED PARCEL SUBDIVISION
BLT:NA VISTA DRIVE AND JAMES DRIM:
CARLSBAD, CALIFORMA
PREPARED FOR
WALTERS LAND SURVEYLNG
606 CASSIDY STREET, SUITE B
OCEANSIDE, CALIFORNL\ 92054
PREPARED BY
GEOTEK, INC.
1384 POINSETTU A\TNL1E
VISTA, CALrF0RNL\ 92081
PRO.rECTN0.:2643SD3 NOVEMBER 19, 2004
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^ 1384 Poinsetta Ave., Suite A
' Vista, CA 92081-8505
(760) 599-0509 FAX (760) 599-0593
Walters Land Surveying
606 Cassidy Street, Suite B
Oceanside, Califomia 92054
Attention: Mr. John Walters
Geotechnical
Environmental
Materials
November 19,2004
ProjectNo.: 2643SD3
Subject: Update Geotechnical Evaluation
Proposed Parcel Subdivision
Buena Vista Drive and James Drive
Carlsbad, Califomia
As requested and authorized, GeoTek, Inc. (GeoTek) is pleased to provide herewith an
updated geotechnical report for the parcel located northwest of the intersection of Buena Vista
Drive and James Drive, in the City of Carlsbad, Califomia. This report presents the results of
our investigation, discussion of our findings, and provides geotechnical recommendations
for foundation design and constmction. In our opinion, the proposed development ofthe site
appears feasible from a geotechnical viewpoint provided that the recommendations included
herein are incorporated into the design and constmction phases of the project. Our previous
reports regarding the same subject may be considered superseded and are no longer referenced
or considered to be required for review.
The opportunity to be of service is sincerely appreciated. If you should have any questions,
please do not hesitate to call our office.
Respectfully submitted.
GeoTek, Inc.
Jeffrey P. Blake,
tEG 2248, Exp. 10/31/
Project Manager
Sinion I. Saiid,
GE 2641, Exp. 9/30/05
Senior Engineer
(4) Addressee
G:\Projects\Projects 2000 to 2999\Projeas 2600 to 2649\2643 Walters Land Surveys\Updte'Georpt.doc
ARIZONA CAUFORNIA IDAHO NEVADA
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WALTERS LAND SURVEYING Project No.: 2643SD3
Update Geotechnical Evaluation November 19,2004
Proposed Parcel Subdivision Page i
TABLE OF CONTENTS
1. INTENT 1
2. PURPOSE AND SCOPE OF SERVICES 1
3. SITE DESCRIPTION AND PROPOSED DEITILOPMENT 2
3.1 SITE DESCRIPTION 2
3.2 PROPOSED DEVELOPMENT 2
4. FIELD EXPLORATION AND LABORATORY TESTING 2
4.1 FIELD EXPLORATION 2
4.2 L'VBORATORY TESTING 3
5. GEOLOGIC AND SOILS CONDITIONS 3
5.1 GENERAL 3
5.1.1 Slopewash 3
5.1.2 Terrace Deposits 3
5.2 SURFACE .A.ND GROLTS'D WATER 3
5.3 F.AULTING AND SEISMICITY 4
5.4 OTHER SEISMIC H.A.Z.\RDS 4
6. CONCLUSIONS AND RECOIVIMENDATIONS 6
6.1 E.A.RTHWORK CONSIDERATIONS : : 6
6.1.1 General Grading Guidelines 6
6.2 DESIGN RECOMMENDATIONS 7
6.2.1 Foundation Design Criteria.. 7
6.2.2 Foundaiion Set Bach 8
6.2.3 Slab-On-Grade 9
6.3 CONCRETE CONSTRUCTION 9
6.3.1 General 9
6.3.2 Cement Type '. 9
6.3.3 Concreie Flatwork 9
6.3.4 Concreie Cracking 9
6.4 RET.ILINING W.^LL DESIGN AND CONSTRUCTION l o
6.4.1 General Design Criteria 10
6.5 POST CONSTRUCTION CONSIDERATIONS 11
6.5.1 Landscape .Maintenance and Planting 11
6.5.2 Drainage 12
6.6 PLAN REVIEW .AND CONSTRUCTION OBSERVATIONS 12
7. LIMITATIONS 13
8. SELECTED REFERENCES 14
ENCLOSURES
Figure 1 - Site Location Map
Figure 2 - Trench Location Plan
Appendix A - Logs of Explorator>' Borings
•Appendix B - Results of Laboratory Testing
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WALTERS LAND SURVEYING Project No.: 2643SD3
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Proposed Parcel Subdivision Page 1
1. INTENT
It is the intent of this report to aid in the design and constmction of the proposed
development. Implementation ofthe advice presented in Section 6 of this report is intended
to reduce risk associated with constmction projects. The professional opinions and
geotechnical advice contained in this report are not intended to imply total performance of
the project or guarantee that unusual or variable conditions will not be discovered during or
after constmction.
The scope of our evaluation is limited to the area explored that is shown on the Boring
Location Plan (Figure 2). This evaluation does not and should in no way be constmed to
encompass any areas beyond the specific area of the proposed constmction as indicated to us
by the chent. Further, no evaluation of any existing site improvements is included. The scope
is based on our understanding of the project and the client's needs, and geotechnical
engineering standards normally used on similar projects in this region.
2. PUTUPOSE AND SCOPE OF SERVICES
The purpose of this study was to provide a geotechnical evaluation based on current site
conditions and an updated site plan. Our previous report dated August 2, 2004 regarding the
same parcel should be considered superseded and no longer required for review with the
governing authorities on this project. Our e^'aluation for this site consisted of the following:
> Research and review of available published data regarding geologic and soil conditions at
the site.
> Site exploration consisting of the excavation, logging, and sampling of 4 exploratory'
borings.
> Review and evaluation of site seismicity, and
> Compilation of this report, which presents our findings, conclusions, and
recommendations for site development.
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Proposed Parcel Subdivision Page 2
3. SITE DESCRIPTION AND PROPOSED DEVELOPIVIENT
3.1 SITE DESCRIPTION
The subject site is located to the northwest of the intersection of Buena Vista Drive and
James Drive, in the City of Carlsbad, San Diego County, California. An existing single-
family residence currently occupies the westem portion ofthe site. This evaluation is specific
to the eastem portion of the site planned for the development. The project area is mostly
vacant land that measures approximately one acre. Access to the site is readily available off
of Buena Vista Drive. The site topography gently slopes to the east. Site vegetation is
relatively sparse with a few large frees.
3.2 PROPOSED DE\T:L0PMENT .
It is our understanding that the site is proposed for three new single-family residences as part
of a four parcel developments. Grading plans provided by Walters Land Sun'eying (Figure
2), untitled and undated were provided for this update report. Cuts and fills depths of up to 12
feet uill be requfred to achieve finish grades. Cut and fill slopes up to 15 feet in height are
planned. It is assumed that the proposed residences will be one or two-story wooden frame
stmctures with conventional slab on grade type foundations.
4. FIELD EXPLORATION AND LABORATORY TESTING
4.1 FIELD EXPLORATION
The field exploration was conducted on July 16, 2004. The four exploratory borings were
excavated with a limited access drill rig to a maximum depth of 11.5 feet and terminared
primarily due to encountering dense formational materials. A geologist from our firm logged
the excavations and collected representative soil samples for fuxthex laboratory testing. The
logs of the exploratory borings are included in Appendix A. The locations of the exploratory
borings are shown on Fieure 2.
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WALTERS LAND SURVEYING Project No.: 2643SD3
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Proposed Parcel Subdivision Page 3
4.2 LABORATORY TESTING
Laboratory testing was performed on selected'disturbed and relatively undisturbed samples
collected during our field investigation. The purpose of the laboratory testing was to confirm
the field classification of the soil materials encountered and to evaluate thefr physical
properties for use m the engineering design and analysis. The results ofthe laboratory-testing
program along with a brief description and relevant information regarding testing procedures
are included m Appendix B.
5. GEOLOGIC AND SOILS CONDITIONS
5.1 GENERAL
A brief description of the earth materials encountered is presented in the following sections
of this report. A more detailed description of these materials is provided on the exploratory
borings mcluded in Appendix A.
5.1.1 Slopewash
The slopewash layer constimtes up to 2 feet of the surficial materials. The slopewash is
described as brown silty sand. Based on our experience and testing on similar soils, these
materials posses a very low expansion potential (EI<21) in accordance with Table 18-I-B of
the 2001 Cahfomia Building Code (CBC).
5.1.2 Terrace Deposits
The Pleistocene aged Terrace Deposits underhe the surficial materials at this site. These
sedimentary materials were encountered to the maximum depths explored of 11.5 feet below
existing grade and consisted primarily of reddish-brown silty sand. Based on our experience
and laboratory testing, these materials posses a very low expansion potential (EI<21).
5.2 SURFACE AND GROUND WATER
No surface \^'ater or ponding was observed at the time of the field investigation. Overall site
drainage is generally to the east. All site drainage should be reviewed and designed by the
project civil engineer.
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WALTERS LAND SURVEYING
Update Geotechnical Evaluation
Proposed Parcel Subdivision
ProjectNo.: 2643SD3
November 19,2004
Page 4
Groundwater was not encountered in our exploratory excavation. No natural groundwater
condition is known to be present which would impact site development. However,
groundwater or localized seepage can occur due to variations in rainfall, irrigation practices,
and other factors not evident at the time of this investigation.
5.3 FAULTING AND SEISMICITY
The site is in a seismically active region. No active or potentially active fault is known to exist
at this site nor is it simated within an Alquist-Priolo Earthquake Fault Zone (Special Studies
Zone). The Newport-Inglewood (offshore) Fault is the nearest known active fault located
approximately 5.6 miles west of the site.
The computer program EQFAULT, version 3.00 (Blake 1989, updated 2000) was used to
determine the distance to known faults and estimate peak ground accelerations. The
Newport-Inglewood (offshore) Fault is considered to represent the highest risk to generate
ground shaking. A maximum seismic event of magnitude 6.9 is posmlated based on a
deterministic analysis. The estimated peak site acceleration is 0.42g.
Seismically resistant stmctural design in accordance with local building ordinances should be
followed during die design of all stiiictures. Building Codes have been developed to
minimize stmctural damage. However, some level of damage as the result of ground shaking
generated by nearby earthquakes is considered likely in this general area.
For the purpose of seismic design a Type B seismic source at a distance of 9.0 km from the
site may be used. Shown in Table 5.3.1 below are seismic design factors in keeping with the
criteria presented in the 2001 Califomia Building Code (CBC), Division IV & V, Chapter 16.
TABLE 5.3.1 - SEISMIC DESIGN PARAMETERS
Parameters
Soil Profile
Type Nv Seismic
Source Type
Source Table 16J 16Q 16R 163 16T 16U
Value Sc 0.40 0.56 1.0 1.1 1 B
5.4 OTHER SEISMIC HAZARDS
The hquefaction potential on the site is considered to be very low due to the dense nature of
the subsurface soils and lack of a shallow groundwater.
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The potential for secondary seismic hazards such as seiche and tsimami are considered to be
I neghgible due site elevation and distance from an open body of water.
Evidence of ancient landshdes or slope instabihties at this site was not observed during our
I investigation. A.ccordingly, the potential for landslides is considered low.
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6. CONCLUSIONS AND RECOIVEVIENDATIONS
The proposed development of the site appears feasible from a geotechnical \aewpoint
provided that the following recommendations are incorporated into the design and
constmction phases of development.
6.1 EARTHWORK CONSIDERATIONS
6.1.1 General Grading Guidelines
6.1.1.1 Grading and earthwork should be perfonned in accordance with the local grading
ordinances, appHcable provisions ofthe 2001 Cahfomia Building Code (CBC), aud
our recommendations presented herein.
6.1.1.2 Prior to site grading, a preconstmction conference should be held at the site to
discuss earthwork considerations and comphance with the recommendations
presented herein. At a mimmum, the owTier, grading confractor, civil engineer and
geotechnical engineer should be in attendance.
6.1.1.3 The grading confractor should take all precautions deemed necessary during site
grading to maintain adequate safety measures and working conditions. All
apphcable safety requfrements of CAL-OSHA should be met during constmction.
6.1.1.4 Site preparation should start with the removal of deleterious materials and vegetation
and disposed properly off site.
6.1.1.5 Temporary excavations within the onsite formational materials should be stable at
1H:1V friclinations for short durations during constmction, and where cuts do not
exceed 10 feet in height.
6.1.1.6 The top 2 to 3 feet of alluvial materials are relatively dry and potentially
compressible, thus they should be removed and recompacted beneath all settlement-
sensitive structures. Depending on actual field conditions encountered during
grading, locally deeper areas of removal may be necessary. The lateral extent of
removal beyond the outside edge of all settlement-sensitive stmctures/foundations
should be equivalent to that vertically removed. Similarly, all compacted fill should
extend laterally from die outside edge of foundations to a distance equal to the depth
of fillina.
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Proposed Parcel Subdivision Page 7
6.1.1.7 Excavations in the on site materials within the depth explored of 11.5 feet should be
generally accompUshed with heavy-duty earthmoving or excavating equipment.
6.1.1.8 The on-site materials are considered suitable for reuse as compacted fill provided
they are free from vegetation, roots, and cobbles and boulders greater than 6 inches
in diameter. The earthwork confractor should ensure that all proposed excavated
materials to be used for backfiUfrig at this project are approved by the soils engineer.
6.1.1.9 .Any undercut areas should be brought to final grade elevations with fill compacted in
layers no thicker than 8 niches compacted to at least 90 percent of maximum dry
density at near optimum moisture content, as detennined in accordance with ASTM
Test Method D1557-00. Prior to receiving fill, the bottom of excavation should be
scarified to a depth of 6 inches; moisture conditioned, and recompacted to at least 90
percent of maximum dry density.
6.1.1.10 Where fill is being placed on slopes steeper than 5:1, the fill should be property
benched into the existing slopes and a sufficient size keyway shall be constmcted in
accordance with the recommendations of the soils engineer.
6.1.1.11 Proposed cut and fill slopes on the site are designed to a maximum height of
approximately 15 feet. Based on 2:1 gradients or flatter, these slopes should exhibit a
mmimum factor of safety of 1.5:1 for an overall gross stability. All cut slopes or
backcut excavations should be geologically mapped during grading to check for the
presence of potentially adverse geologic conditions.
6.2 DESIGN RECOiVEVIENT) ATIONS
6.2.1 Foundation Design Criteria
Foundation design criteria for conventional slab-on-grade system in conformance with the
2001 CBC are presented in Table 6.3.1, below. These are typical design criteria and are not
intended to supersede the design by the stmctural engineer.
The majority of the onsite materials are classified as very low expansion soils. Laboratory
testing of soils near finish grade should be performed at the completion of site grading to
verify the actual conditions. We anticipate that the compacted fill soils will tvpically possess
very low (0<EI<21) and Plastic Index (PI) of less than 15. Thus, we recommend that
drawings be prepared for the soil conditions presented m the Table 6.3.1 below. Actual as
graded conditions will detemiine the apphcable foundation design criteria.
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November 19,2004
Pages
TABLE 6.3.1 - MEVEVIUM DESIGN CRITERLA
DESIGN PARAMETER E.I. < 20
P.L<15
Foundation Depth or Perimeter Beam depth
(inches below lowest adjacent grade)
One Story - 12
Two story -18
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Foundation Width (Inches)
One Story - 12
Two story -15
Maximum Beam Spacing (feet) NA
(Cantilevered length as soil function) NA
Minimimi Slab Thickness (inches) 4
Presaturation of subgrade soil (% of
OptimumTDepth in inches) Subgrade to be well wetted before pouring concrete
An allowable bearing capacity of 2500 pounds per square foot (psf), including both dead and
live loads, may be used if footings are designed in accordance with the above criteria. The
allowable bearing value may be increased by one-third when considering short-term live
• loads (e.g. seismic and wind loads).
The passive earth pressure may be computed as an equivalent fluid having a density of 150
psf per foot of depth, to a maximum earth pressure of 2000 psf A coefficient of friction
between soil and concrete of 0.30 may be used with dead load forces. When combining
passive pressure and fiictional resistance, the passive pressure component should be reduced
fay one-thfrd.
6.2.2 Foundation Set Backs
"WTiere applicable, the followmg foundation setbacks should apply to all foimdations. Any
improvements not conforming to these setbacks may be subject to lateral movements and/or
differential settlements:
6.2.2.1 The outside bottom edge of all footings should be set back a minimum of H3 (where
H is the slope height) from the face of any descending slope. The setback should be
at least 7 feet and need not exceed 20 feet.
6.2.2.2 The bottom of all footings for stmctures near retaining walls should be deepened so
as to extend below a 1:1 projection upward from die bottom inside edge of the wall
stem.
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6.2.2.3 The bottom of any existing foundations for stmctures should be deepened so as to
extend below a 1:1 projection upward from the bottom ofthe nearest excavation.
6.2.3 Slab-On-Grade
Where appUcable, concrete slabs should be a mmimum of 4 inches thick and reinforced with
No. 3 steel bars placed at 24 inches on center, both ways. The slab reinforcement should be
positioned at mid-height within the concrete slab. Control joints should be provided to help
minimize random cracking. Where moisture condensation is undesirable, all slabs should be
underlain with a minimum 10 mil polyvinyl chloride membrane, sandwiched between two
layers of clean sand, S.E. 30 or greater, each being at least two inches thick. Care should be
taken to adequately seal all seams and not puncture or tear the membrane. The sand should be
proof rolled.
6.3 CONCRETE CONSTRUCTION
6.3.1 General
Concrete constmction should follow the CBC and ACI guidelines regarding design, mix
placement and curing of the concrete. If desired, we could provide quality confrol testing of
the concrete during constmction.
6.3.2 Cement Type
Laboratory testing indicates that the sulfate content of the soil tested is less than 0.10%,
which is considered to be neghgible in accordance with Table 19-A-4 of the CBC. Cement
T}'pe n or equivalent may be used.
6.3.3 Concrete Flatvvork
Exterior concrete flatwork (patios, walkways, driveways, etc.) is often some of the most
visible aspects of site development. They are typically given the least level of quaUt}' control,
bemg considered "non-stmctural" components. Cracking of these features is fairly common
due to various factors. "WTiile cracking is not usually detrimental, it is unsightly. We suggest
that the same standards of care be applied to these features as to the stmcture itself
6.3.4 Concrete Cracking
Concrete cracks should be expected. These cracks can vary from sizes that are essentially
uimoticed to more than 1/8 inch in width'. Most cracks in concrete while unsightly do not
significantly impact long-term performance. While it is possible to take measures (proper
concrete mix, placement, curing, confrol jomts, etc.) to reduce the extent and size of cracks
WALTERS LAND SURVEYING Project No.: 2643SD3
Update Geotechnical Evaluation November 19, 2004
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that occur, some cracking will occur despite the best efforts to minimize it. Concrete
undergoes chemical processes that are dependent on a wide range of variables, which are
difficult, at best, to control. Concrete, while seemingly a stable material, also is subject to
intemal expansion and confraction due to extemal changes over time.
One of the simplest means to confrol cracking is to provide weakened joints for cracking to
occur along. These do not prevent cracks from developing; they simply provide a reUef point
for the stresses that develop. These joints are widely accepted means to confrol cracks but are
not always effective.
Control joints are more effective the more closely spaced. We would suggest that confrol
joints be placed in two dfrections spaced the mmieric equivalent of two times thickness of the
slab in niches changed to feet (e.g. a 4 mch slab would have confrol joints at 8 feet centers).
As a practical matter, this is not always possible nor is it a widely appUed standard.
6.4 RET.AINING WALL DESIGN AND CONSTRUCTION
6.4.1 General Design Criteria
Recommendations below may be applied to typical masonry or concrete vertical retaining
waUs to a maximum height of 10 feet. Additional review and recommendations should be
requested for higher walls. - ~
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6.4.1.1 Recommendations were developed assuming that wall backfill placed within a 1 to 1
projection behind any wall is comprised of onsite soils with a very low expansion
potential. The backfill materials should be placed in hfts no greater than 8-inches m
thickness and compacted at 90% relative compaction at optimum moisture content or
higher. Backfill soil should be properly dramed to prevent buildup of hydrostatic
pressures.
6.4.1.2 Retaining walls embedded a minimum of 18 inches into compacted fill or
formational materials should be designed using a net aUowable bearing capacity of
2,500 psf. An increase of one-thfrd may be apphed when considering short-term live
loads (e.g. seismic and wind loads).
6.4.1.3 The passive earth pressure may be computed as an equivalent fluid having a density
of 250 psf per foot of depth, to a maximum earth pressure of 3,000 psf A coefficient
of fiiction between soil and concrete of 0.40 may be used with dead load forces.
When combining passive pressure and fiictional resistance, the passive pressure
component should be reduced by one-thfrd.
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November 19, 2004
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6.4.1.3 The passive earth pressure may be computed as an equivalent fluid having a density
of 250 psf per foot of depth, to a maximum earth pressure of 3,000 psf A coefficient
of fiiction between soil and concrete of 0.40 may be used with dead load forces.
When combining passive pressure and fiictional resistance, the passive pressure
component should be reduced by one-thfrd.
6.4.1.4 An equivalent fluid pressure approach may be used to compute the horizontal active
pressure against the wall. The appropriate fluid unit weights are given in Table 6.5.1
below for specific slope gradients of retained materials.
TABLE 6.5.1 - ACTIVE EARTH PRESSLliES
Surface Slope of Retained Materials
(H:V)
Equivalent Fluid Pressure
(PCF)
Level 33
2:1 45
The above equivalent fluid weights do not include other superimposed loading
conditions such as expansive soil, vehicular fraffic, stmctures, seismic conditions or
adverse geologic conditions.
6.5 POST CONSTRUCTION CONSIDERATIONS
6.5.1 Landscape Maintenance and Planting
s
Water has been shown to weaken the inherent strength of soil, and slope stability is
significantly reduced by overly wet conditions. Positive surface drainage away from graded
slopes should be maintained and only the amount of irrigation necessary to sustain plant life
should be provided for planted slopes. ConfroUing surface drainage and runoff, and
maintaining a suitable vegetation cover can minimize erosion. Plants selected for landscaping
should be hghtweight, deep-rooted types that require little water and are capable of surviving
the prevailing climate.
Over watering should be avoided. The soils should be maintained in a soUd to semi-soUd
state as defined by the materials Atterberg Limits. Care should be taken when adding soil
amendments to avoid excessive watering. Leaching as a method of soil preparation prior to
planting is not recommended.
An abatement program to confrol ground-burrowing rodents should be implemented and
maintained. This is critical as burrowing rodents can decreased the long-term perfonnance of
slopes.
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It is common for planting to be placed adjacent to stmctures m planter or lawn areas. This
will result m the infroduction of water into the ground adjacent to the foundation. This type
of landscaping should be avoided. If used, then exfreme care should be exercised witii regard
to the irrigation and drainage in these areas. Waterproofing of the foundation and'or
subdrains may be warranted and advisable. We could discuss these issues, if desfred, when
plans are made available.
6.5.2 Drainage
The need to maintain proper surface drainage and subsiu-face systems cannot be overly
emphasized. Positive site drainage should be maintained at all tunes. Drainage should not
flow unconfroUed dovm any descending slope. Water should be dfrected away from
foundations and not allowed to pond or seep into the ground. Pad drainage should be dfrected
toward approved area(s). Positive drainage should not be blocked by other improvements.
Even apparently minor changes or modifications can cause problems. '
6.6 PLAN RE\TEW AND CONSTRUCTION OBSERVATIONS
We recommend that site graduig, specifications, and foundation plans be reviewed by this
office prior to constmction to check for conformance with the recoinmendations of this
report. We also recommend that GeoTek representatives be present during site grading and
foundation constmction to check for proper implementation of the geotechnical
recommendations. These representatives should perform at least the following duties:
• Observe site clearing and gmbbing operations for proper removal of all unsuitable
materials.
• Obser\'e bottom of removals prior to fiU placement.
• Evaluate die suitability of on-site and unport materials for fiU placement, and collect soil
samples for laboratory testing where necessary.
• Obser\'e tlie fill for uniformity during placement includmg utility frenches. Also, test the
fill for field density and relative compaction.
• Observe and probe foimdation materials to confirm suitability of bearing materials and
proper footing dimensions.
If requested, GeoTek will provide a constmction observation and compaction report to
comply witii the requirements of the govemmental agencies having jurisdiction over the
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I project. We recommend that these agencies be notified prior to commencement of
constmction so that necessary grading permits can be obtauied.
7. LIMITATIONS
The materials observed on the project site appear to be representative of the area; however,
soil and bedrock materials vary in character between excavations and natural outcrops or
conditions exposed during site constmction. Site conditions may vary due to seasonal
changes or other factors. GeoTek, Inc. assumes no responsibility or liability for work, testing
or recommendations performed or provided by others.
Since our recommendations are based the site conditions obsen'ed and encountered, and
laboratory testing, our conclusion and recommendations are professional opinions that are
limited to the extent of the available data. Observations during constmction are important to
allow for any change in recommendations found to be warranted. These opinions have been
derived in accordance with current standards of practice and no warranty is expressed or
impUed. Standards of practice are subject to change with tune.
I WALTERS LAND SURVEYING Project Na: 2643SD3
November 19,2004
8. SELECTED REFERENCES
Update Geotechnical Evaluation
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1. ASTM, 200, "Soil and Rock: American Society for Testmg and Materials," vol. 4.08 for
I ASTM test metiiods D-420 to D-4914, 153 standards, 1,026 pages; and vol. 4.09 for
ASTM test method D-4943 to highest number.
] 2. Blake, T., 1989, "EQFAULT, version 3.00, updated 2000", a Computer Program for
Deterministic Estimation of Maximum Earthquake Event and Peak Ground Acceleration.
I 3. Califomia Code of Regulations, Titie 24,1998 "Califomia Building Code," 3 volumes.
4. Califomia Division of Mines and Geology (CDMG), 1997, "Guideluies for Evaluating
I and Mitigating Seismic Hazards m Califomia," Special PubHcation 117.
5. Cahfomia Division of Mines and Geology (CDMG), 1998, Maps of Known Active Fauh
I Near-Source Zones m CaHfomia and Adjacent Portions of'Nevada: Intemational
Conference of Buildmg Officials.-^
• ^ 6. Califomia Division of Mines and Geology (CDMG), 1996, Geologic Maps of die
I w Northwestem Part of San Diego County, Califomia, Plate 1-Oceanside, San Luis Rey,
and San Marcos 7.5 Quadrangles, Plate 2-Encuiitas and Rancho Santa Fe 7.5
I Quadrangles
7. GeoTek, Inc., In-house proprietary information.
I 8. Seed, H.B., and Tokimatsu, K, Harder, L.F., and Chung, R.M., 1985, "frifluence of SPT
Procedures in Soil Liquefaction Resistance Evaluations," Joumal of tiie Geotechnical
(Engineering Division, American Society of Civil Engineers, vol. Ill, no. GT12, pp.l425-
1445.
I 9. Youd, T. LesUe and Idriss, Izzmat M., 1997, Proceeding of tiie NCEER Workshop on
I Evaluation of Liquefaction Resistance of Soils, National Center for Earthquake
Enc^ineering Research. Technical Report NCEER-97-0022.
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Walters Land Surveying
Proposed Residential Project
Buena Vista Drive and James Drive
Carlsbad Califomia 92008
GeoTek :siimber: 2643-SD3
N
Figure 1
Site
Location
V Map
.EK, INC.
1384 Poinsettia Avenue, Suite A
Vista. CaHfomia 92081-8505
Source: Walters Land Su^ve^^n2 •Approximate location of exploraton' boring
Walters Land Surveying
Proposed Residential Project
Buena Vista Drive and James Drive
Carlsbad, Califomia 92008
GeoTek Number: 2643SD3
Exploratory
Boring Location
Plan
O
.EK, INC.
1384 Poinsettia Avenue, Suite A
Vista, Califomia 92081-8505
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APPENDIX A
LOGS OF EXPLORATORY BORLNGS
Proposed Parcel Subdivision
Carlsbad, California
Project No.: 2643SD3
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WALTERS LAND SURVEYING APPENDIX A
Update Geotechnical Evaluation November 19, 2004
Proposed Parcel Subdivision ] Page A-l
A - HELD TESTING AND SAMPLING PROCEDURES
The Standard Penetration Test ("SPT)
The SPT is performed in accordance with ASTM Test Method D 1586-99. The SPT sampler is
typically driven into the ground 12 or 18 inches with a 140-pound hammer free falling from a height
of 30 inches. Blow coimts are recorded for every 6 inches of penetration as indicated on the log of
boring. The split-barrel sampler has an extemal diameter of 2 inches and an unlined intemal diameter
of 1-3/8 inches. The samples of earth materials collected in the sampler are t\'pically classified in the
field, bagged, sealed and transported to the laboratory for further testing.
The Modified Split-Barrel Sampler (Ring)
The Ring sampler is driven into the ground in accordance with ASTM Test Method D 3550-84. The
sampler, with an extemal diameter of 3.0 inches, is lined with 1-inch long, thin brass rings with inside
diameters of approximately 2.4 inches. The sampler is typically driven into the ground 12 or 18
inches with a 140-pound hammer free falling from a height of 30 inches. Blow counts are recorded
for ever}' 6 inches of penetration as indicated on the log of boring. The samples are removed from the
sample barrel in the brass rings, sealed, and transported to the laboratory for testing.
Large Bulk Samples
Bulk samples are normally bags of representative earth materials over 20 pounds in weight collected
from the field by means of hand digging or exploratory cuttings.
Small Bulk Samples
Plastic bags samples are nonnally airtight and contain less than 5 pounds in weight of representative
earth materials collected from the field by means of hand digging or exploratory cuttings. These
samples are primarily used for determining natural moisture content and classification indices.
B - BORING LOG LEGEND
The following abbreviations and s>Tnbols often appear in the classification and description of soil and
rock on the logs of borings:
SOILS
USCS Unified Soil Classification System
f-c Fine to coarse
f-m Fine to medium
GEOLOGIC
B: Attitudes Bedding: strike/dip
J: .A.tritudes Joint: strike,-dip
C: Contact line
Dashed line denotes approximate USCS material change
Solid Line denotes approximate unit / formational change
Thick solid line denotes approximate end of boring
(Additional denotations and sjmbols are provided on the logs of borings)
bkK
GeoTek, Inc.
LOG OF EXPLORATORY BORING
CLIENT:
PROJECT NAME:_
PROJECTNO.:
LOCATION:
Walters Land Surveys
Buena Visla/James Drive
2643SD3
DRILLER:
DRILL METHOD
HAMMER:
SouthCoast Drilling
6* Solid Stem Auger
140 Ibw/30" drop
See Site Plan
LOGGED BY:_
OPERATOR:]
RIG TYPE:"
DATE:'
TCS
Roser
Limited Access w/catnead
SAMPLES
to n u
BORING NO.: B-1
MATERIAL DESCRIPTION AND COMMENTS
Laboratory Testing
01 u
a a £• O
SM
Slopewash
Brown, dry, loose to medium dense, silty fine SAND; abundant gopher
holes
16
22
27
18
27
32
10 17
25
31
SM
B1-1
B1-2
B1-3
Terrace Deposits
Reddish-brown, dry to moist, medium dense, silty f-m SAND; orange
mottling, manganese staining, weakly cemented
! 5.5 feet becomes dense; moist
6.2
8.3
113
112
SHEAR
6.2 115
15 -
20
25 -
Sample tvoe:
HOLE TERMINATED AT 11.5 FEET
- No groundwater observed
- Hole backfilled with soil cuttings
—Ring -SPT 0-•Small Bulk -Large Bulk • -No Recovery -Water Taole
Lab testina: AL = Atterberg Limits
SR = Sulfate/Resistivity TesI
El = Expansion Index
SH = Shear Test
SA - Sieve Analysis
CO = Consolidation test
RV= R-Value Test
MD 2 Maximum Density
GeoTek, Inc.
LOG OF EXPLORATORY BORING
CLIENT:
PROJECT NAME:]
PROJECTNO.: ]
LOCATION:
Walters Land Surveys
Buena Visla/James Drive
2643SD3
DRILLER:
DRILL METHOD
HAMMER:
SouthCoast Drilling
6* Solid Stem Auger
140 Ibw/30'drop
See Sile Plan
LOGGED BY;
OPERATOR:
RIG TYPE
DATE:
TCS
Roger
Limited Access w/cathead
7/16/04
SAMPLES
E E
(0 3
0) z
BORING NO.: B-2
MATERIAL DESCRIPTION AND COMMENTS
a 6
> c
Laboratory Testing
12
B2-1
SM
Slopewash
Brown, dry, loose to medium dense, silty fine SAND; abundant gopher
holes Terrace Deposits
Reddish-brown, dry, very dense, silty fine SAND
@ 3.5 feet - difficult drilling
5-S
27
50-4"
30
42
B2-2
B2-3
SM 2.9 117
10
15 -
20
25 -
HOLE TERMINATED AT 5.5 FEET
No groundwater observed
Hole backfilled with soil cuttings
Sample type: WSi -Ring y —SPT —Small Bulk -Large Bulk • -No Recovery Water Table
Lab testing: AL = Atterberg Limits
SR = Sulfate/Resistivity Test
El = Expansion Index
SH = Shear Test
SA = Sieve Analysis
CO s Consolidation test
RV= R-Value Test
MD = Maximum Density
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GeoTek, Inc.
LOG OF EXPLORATORY BORING
CLIENT:
PROJECT NAME:]
PROJECTNO.: ]
LOCATION:
Walters Land Survevs
Buena Vista/James Drive
2643SD3
DRILLER:
DRILL METHOD
HAMMER
SouthCoast Drilling
6* Solid Stem Auger
140lbv</30'droD
See Sile Plan
LOGGED BY:
OPERATOR:
RIG TYPE:
DATE
TCS
Roger
Limited Access w/cathead
7/15/04
SAMPLES
II
14
18
22
34
15
20
25
14
18
22
B3-1
B3-2
B3-3
B3-4
SM
SM
BORING NO.: B-3
MATERIAL DESCRIPTION AND COMMENTS
Laboratory Testinq
C C"
S "
Slopewash
Brown, dry, loose to medium dense, silty fine SAND; abundant gopher
holes
Terrace Deposits
Reddish-brown, dry to moist, dense, silty f-m SAND; orange mottling,
manganese staining, weakly cemented
HOLE TERMINATED AT 11.5 FEET
No groundwater observed
Hole backfilled with soil cuttings
3..5
8.8
114
117
EI. Sulfate
Sample tvoe: —Ring -SPT —Small Bulk -Large Bulk • -No Recovery Water Table
Lab testing: AL = Atterberg Umits
SR = Sulfaie/Resistivity Test
El = Expansion Index
SH = Shear Test
SA = Sieve Analysis
CO = Consolidation test
RV= R-Value Test
MD = Maximum Density
GeoTek, Inc.
LOG OF EXPLORATORY BORING
CLIENT:
PROJECT NAME:]
PROJECTNO.: ]
LOCATION:
Walters Land Surveys
Buena VIsta/James Drive
2643SD3
DRILLER:
DRILL METHOD:
HAMMER:
SouthCoast Drilling
6' Solid Stem Auger
140 Ibw/30" drop
See Site Plan
LOGGED BY:
OPERATOR:
RIG TYPE
DATE:
TCS
Roger
Umited Access w/cathead
7/1S/W
SAMPLES
E E eo u
15
BORING NO.: B-4
MATERIAL DESCRIPTION AND COMMENTS
m 5
Laboratory Testing
c c
a; o
a u. £-a
-i
Slopewash
Brown, dry, medium dense, silty fine SAND; abundant gopher holes
Terrace Deposits
Reddish-brown, dry to moist, medium dense, silty f-m SAND; orange
mottling, manganese staining, weakly cemented
10
B4-1
7
13
14 B4-2
18
26
37 B4-3
10 feet - becomes very dense
SA
15
20
25 -
Sample tvoe:
HOLE TERMINATED AT 11.5 FEET
' No groundwater obsen/ed
Hole backfilled with soil cuttings
-Ring -SPT —Small Buik -Large Bulk No Recovery ater Table
Lab testing: AL = Atterberg Limits
SR = Sulfale/Resistivily Test
Ei = Expansion Index
SH = Shear Test
SA = Sieve Analysts
CO = Consolidation test
RV= R-Value Test
MD = Maximum Density
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APPENDIX B
LABOR.A.TORY TESTING RESULTS
Proposed Parcel Subdivision
Carlsbad, California
Project .No.: 2643SD3
EQ
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WALTERS LAND SURVEYING APPENT)IX B
Update Geotechnical Evaluation November 19, 2004
Proposed Parcel Subdivision Page B-1
SU]\L\LARY OF LABORATORY TESTING
Classification
Soils were classified visually according to the Unified Soil Classification System (ASTM Test
Method D2487). The soil classifications are shown on the logs of exploratory trenches in
Appendix A.
Gram size distribution (particle size analysis) was performed on a selected sample in
accordance with ASTM D422. Results of gram size analysis are shown included herein.
Expansion Index
Expansion fridex testing was performed on a representative soil sample. Testing was
performed m general accordance with ASTM Test Method D4829. Results are mcluded
herein.
Direct Shear
Shear testing was performed m a direct shear machine of the strain-confrol type m general
accordance with ASTM Test Method D3080. The rate of deformation is approximately 0.03
inches per minute. The samples were sheared under varying confimng loads m order to
determine the coulomb shear sfrength parameters, angle of intemal friction and cohesion. The
tests were performed on ring samples collected during our subsurface exploration. The shear
test results are mcluded herein.
Sulfate Content
The water-soluble sulfate content is measured in accordance with Cahfomia Test No. 417.
The results indicate a sulfate content less than 0.1, which is considered neghgible as per Table
19-A-4 of tiie CBC.
In Situ Moisture and Unit Weight
The field moisture content was measured ui the laboratory' on selected samples collected
during die field investigation. The field moisture content is determuied as a percentage of the
dry unit weight. Results of these tests are presented on the logs of explorator}' borings in
Appendix A. The dry density was measured in the laboraton.' on selected ring samples. The
resuhs are shown on the logs of exploratory borings in Appendix A.
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Particle Size Distribution Report
•= T — S CJ S CM — — n r>
ooo
100
90
80
70
LLl 50
Z
u.
2 50
111 o a: m 40
30
20
10
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! !;
! !
i!M: i I • 1^
500 100 10
GRAIN SIZE- mm
0.01
SIEVE PERCENT SPEC* PASS?
SIZE FINER PERCENT (X=NO)
#16 100.0
#30 95.6
#40 79.7
#50 55.8
#100 31.4
#200 24.7
0.001
% COBBLES 1 % GRAVEL % SAND % SILT 1 % CLAY
0.0 1 0.0 75.3 24.7
(no specification provided)
Sample Nc:
, Location: B4-2 @ 6.5'
Soil Descriotion
Reddish brown silt}^ medium to fine S.AND
PL=
Atterberq Limits
LL= Pl=
•85= 0.468
•30= 0.137
Coefficients
D60= 0.320 D5o= 0.272
Di5= Dio=
USCS= SM
Classification
MSHTO= A-2-4(0)
Remarks
Source of Sample: B4-2 @ 6.5' Date: 07/23/04
Eiev./Depth:
GeoTek, Inc.
Client: Walters Land Sur^'eys
Project: Buena Vista
ProjectNo: 2643-SD3 Plate SA-1
EXPANSION INDEX TEST
(ASTM D4829)
Project Name:
Project Number:
Project Location:
Buena Visla
2643-SD3
Ring Id Ring Dia. ,4:; Ringl_r
Loading weight: 5516. grams
DENSITY DETERMINATION
A Weight of compacted sample & ring 803.63
B Weight of ring 369.87
C Net v/eight of sample 433.76
D Wet Density, Ib / ft3 (C*0.3016) 130.8
E Drv Density, Ib / fl3 (D/1.F) 120.8
SATURATION DETERMINATION
F Moisture Content, % 8.3
G (E*F) 998.2
H (E/167.232) 0.72
1 (1.-H) 0.28
J (62.4*1) 17.3
K (G/J)=L % Saturation 57.7
Tested/ Checked By:
Date Tested:
Sample Source:
Sample Description:
DC Lab No 1354
READINGS
DATE TIME READING
7/22/2004 8:27 0.161
7/22/2004 8:37 0.161
7/22/2004 8:38 0.160
7/22/2004 8:43 0.160
7/23/2004 7:24 0.158
7/22/2004
B3-2 @ 2.5'
Reddish brown silty medium to fine SAND
Initial
10 min/Dry
1 min/Wet
5 min/Wet
Random
Final
FINAL MOISTURE
Weight ot wet sample
& tare
Weight ot dry sample
& (are Tare % Moisture
179.57 166.49 8.14 8.3%
Initial Moisture
Wet Wgt _25a99_
Dry Wgt 252.25
Tare 8.30
1.9%
EXPANSION INDEX =
^ "^^If , , 1,111
Tested DC Reviewed By DC
PLATE El -1
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1384 Poinsettia Ave., Suite A, Vista, CA 92083
(760) 599-0509 FAX (760) 599-0593
SOIL SULFATE TEST
(California Test 417)
Project Name:
Project Number:
Project Location:
Buena Vista
2643-SD3
Tested/ Checked By:
Date Tested:
Sample Source:
Sample Description:
DC Lab No 1354
7/20/2004
B3-2 @ 2.5'
Reddish brown silty medium to fine SAND
Blank
Reatiinq
A
B
C
D
Sample
Reading
Corrected
Turbidity
Turbidity of standard equal to 0 mg 804 0.1 0.15 0.1 NTUs Blank = 1.56
Turbidity of standard equal to 1 mg 804 0.23 8.74 8.5 NTUs w/ BaCI = 2.34
Turbidity of standard equal to 2 mg 804 0.22 23.55 23.3 NTUs Actuai = 0.78
Turbidity of standard equal to 3 mg 804 0.38 57 56.6 NTUs
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E Sample size (ml) -before diluting to lOOmL & adding regents
F mg of 804 present in sample (from calibration curve)
Sample Graph
20
0.09
0 0.78
3 0.78
Water Soluble Sufate = 0.001%
Calibration Curve
(A
I-
•a
• Callibrafion 1
•Test Sample I
0.1
mg of S04
Plate SL-1
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DIRECT SHEAR TEST
Project Name:
Project Number:
Buena Vista
2643-SD3
Sample Source:
Date Tested:
B1-1 @ 5'
07/23/04
Lt reddish brown silty medium
Soil Description: to fine SAND
cn (0 Ul ce I-
(0
s
0.5 1.5 2.5 3 3.5
NORMAL STRESS (ksfl
4.5 5.5
Shear Strength: O = 39.7 ° , C = 1.35 ksf
Water Content Dry Density
Test No. Load (ksf) (%) (pcf)
1 1.4 6 107
2 2.8 6 107
3 5.6 6 107
Notes: l - The soil specimen used in the shear box were "ring" samples collected during the field investigation.
2 - Shear strength calculated at maximum load.
3 - The tests were ran at a shear rale of 0.05 in/min.
PLATE SH-1