HomeMy WebLinkAboutSDP 00-16; PIRINEOS POINTE; GEOTECHNICAL INVESTIGATION AND FOUNDATION RECOMMENDATIONS; 2000-11-10ENGINEERING
DESIGN GROUP
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2121 Montiel Road, San Marcos, California 92069 . (760) 839-7302 • Fax: (760) 480-7477 • E-mail: ENGDG@aol.com
GEOTECHNICAL INVESTIGATION AND FOUNDATION RECOMMENDATIONS
PROPOSED NEW MULTI-UNIT DEVELOPMENT,
LOCATED ON THE NORTH SIDE OF PIRINEOS WAY,
A.P.N. 216-200-2400
CITY OF CARLSBAD, CALIFORNIA
Project No. 002425-1
November 10, 2000
PREPARED FOR:
Darryl Clubb RECEIVED
COAST CONTRACTING
7909 Silverton Avenue, Suite 213 NOV 282001
San Diego, CA 92126
ENGINEERING
DEPARTMENT S
TABLE OF CONTENTS 0
Page
SCOPE . ..........................................................1
SITE AND PROJECT DESCRIPTION ....................................I
FIELD INVESTIGATION ................................................1
SUBSOIL CONDITIONS ...............................................1
GROUNDWATER ....................................................2
LIQUEFACTION......................................................2
CONCLUSIONS AND RECOMMENDATIONS ...............................4
GENERAL......................................................4
EARTHWORK ..................................................4
FOUNDATIONS ..................................................6
CONCRETE SLABS ON GRADE ...................................7
RETAINING WALLS .............................................9
SURFACE DRAINAGE ..........................................10
CONSTRUCTION OBSERVATION AND TESTING ..........................II
MISCELLANEOUS...................................................12
ATTACHMENTS
Site Vicinity Map .............................................Figure No. I
Site Location Map ............................................Figure No. 2
Site Plan/Location of Exploratory Trenches ........................Figure No. 3
Logs of Exploratory Trenches .................................Figures No. 4-8
References ..................................................Appendix A
General Earthwork and Grading Specifications ......................Appendix B
Testing Procedures ...........................................Appendix C
SCOPE
This report gives the results of our geotechnical investigation for the vacant parcel of land
located on the north side of Pirineos Way, legally identified as APN 216-200-2400 in the
City of Carlsbad, California. (See Figure No. 1, "Site Vicinity Map", and Figure No. 2, "Site
Location Map"). The scope of our work, conducted on-site to date, has included a visual
reconnaissance of the property and neighboring properties, a limited subsurface
investigation of the property, field analysis and preparation of this report presenting our
findings, conclusions, and recommendations.
SITE AND PROJECT DESCRIPTION
The subject property consists of a vacant lot located at the north of Pirineos Way in the City
of Carlsbad. The site is bordered to the north, west, and east by multi unit residential
developments, and to the south by Pirineos Way. The overall topography of the site area
consists of moderately sloping hillside terrain. The subject site consists of a previously
graded pad, bounded along the rear portion of the lot by a 11/2 :1 cut slope.
Based on our conversations with the project developer, and our review of the preliminary
project site plan, it is anticipated that the proposed site improvement will consist of four
separate structures, each containing four residential units. In addition, each building will
contain partially subterranean garages.
FIELD INVESTIGATION
Our field investigation of the property, conducted September 22, 2000 and October 10,
2000, consisted of a site reconnaissance, site field measurements, observation of existing
conditions on-site and on adjacent sites, and a limited subsurface investigation of soil
conditions. Our subsurface investigation consisted of visual observation of five exploratory
trenches, logging of soil types encountered, and sampling of soils. The locations of the
Trenches are given in Figure No. 3, "Site Plan/Location of Exploratory Trenches". Logs
of the exploratory trench excavations are presented in Figures No. 4-8, "Trench
Excavations".
SUBSOIL CONDITIONS
Materials consisting of slightly silty/clayey sand and sandy silts to sandy clay topsoil/fill
CLUBB DEVELOPMENT Page No. 1
APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL. CIVIL. STRUCTURAL A ARCHITECTURAL CONSULTANTS
underlain by siltstone were encountered during our subsurface investigation of the site.
Soil types within our test pit excavations are described as follows:
Fill:
Weathered fill materials were found to extended to depths of 4-5 feet
below adjacent grade. Fill materials consist of brown to light brown,
slightly moist to moist, medium dense, silty sand to sandy silts. Old Fill
materials are not considered suitable for the support of structural
improvements. These materials are suitable for use as compacted
fill during grading. Fill Materials classify as SM-ML according to the
Unified Classification System, and based on visual observation and our
experience, possess expansion potentials in the medium range.
Siltstone
Formational siltstone was found to underlie fill material within the test pit
excavations. Siltstone materials consisted of mottlied tan to dark brown
moist, dense, siltstone. Siltstone materials are considered suitable
for the support of structures and structural improvements, provided
the recommendations of this report are followed. Siltstone materials
classify as SM-ML according to the Unified Classification System, and
based on visual observation and our experience, possess expansion
potentials in the medium range.
For detailed logs of soil types encountered in our trenches excavations, as well as a
depiction of our trench locations, please see Figure No. 3, "Site Plan/Location of
Exploratory Trenches", and Figures No. 4-8, "Trench Excavations".
GROUNDWATER
Groundwater was not encountered during our subsurface investigation of the site. Ground
water is not anticipated to be a significant concern to the project provided the
recommendations of this report are followed.
LIQUEFACTION
It is our opinion that the site could be subjected to moderate to severe ground shaking in
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ENGINEERING DESIGN GROUP
GEOTECHNICAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
the event of a major earthquake along any of the faults in the Southern California region.
However, the seismic risk at this site is not significantly greaterthan that of the surrounding
developed area.
Liquefaction of cohesionless soils can be caused by strong vibratory motion due to
earthquakes. Research and historical data indicate that loose, granular soils underlain by
a near-surface ground water table are most susceptible to liquefaction, while the stability
of most silty clays and clays is not adversely affected by vibratory motion. Because of the
dense nature of the soil materials underlying the site and the lack of near surface
water, the potential for liquefaction or seismically-induced dynamic settlement at the
site is considered low. The effects of seismic shaking can be reduced by adhering to the
most recent edition of the Uniform Building Code and current design parameters of the
Structural Engineers Association of California.
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ENGINEERING DESIGN GROUP
GEOTECIIMCAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
CONCLUSIONS AND RECOMMENDATIONS
GENERAL
In general, it is our opinion that the proposed construction, as described herein, is feasible
from a geotechnical standpoint, provided that the recommendations of this report and
generally accepted construction practices are followed.
The following recommendations should be considered as minimum design parameters, and
shall be incorporated within the project plans and utilized during construction, as
applicable.
EARTHWORK
Where structural and cosmetically sensitive improvement are proposed onsite, existing fill
material will require removal and re-compaction during grading. Based on our
investigation, removal depths are anticipated to range from 4-5 feet below existing site
grade. Where removals can not be made as described above, the non-conforming
condition should be brought to the attention of the Engineering Design Group in writing so
modified recommendations may be provided.
Site Preparation
Prior to any grading, areas of proposed improvement should be cleared of surface
and subsurface organic debris (including topsoil). Removed debris should be
properly disposed of off-site prior to the commencement of any fill operations.
Holes resulting from the removal of debris, existing structures, or other
improvements which extend below the undercut depths noted, should be filled and
compacted using on-site material or a non-expansive import material.
Removals
Fill soils found to mantle the site in our exploratory trenches (i.e., upper
approximately 4-5 feet), are not suitable for the structural support of buildings or
improvements in their present state, and will require removal and re-compaction
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
in areas of proposed slab on grade floors or other settlement sensitive locations.
In general, grading should consist of the removal of fill profiles, scarification of
removal bottom, and re-compaction of fill materials to 90 percent relative
compaction per ASTM 1557-91 (See Appendix B for grading detailing).
Excavated fill materials are suitable for re-use as fill material during grading,
provided they are cleaned of debris and oversize material in excess of 6 inches
in diameter (oversized material is not anticipated to be of significant concern) and
are free of contamination.
Removals and undercuts should extend a minimum of 5 feet beyond the
footprint of the proposed structures and settlement sensitive improvements.
Where this condition cannot be met, it should be reviewed by the
Engineering Design Group on a case by case basis. Removal depths should
be visually verified by a representative of our firm prior to the placement of
fill.
3. Fills
Areas to receive fill and/or structural improvements should be scarified to a
minimum depth of 12 inches, brought to near optimum moisture content, and re-
compacted to at least 90 percent relative compaction (based on ASTM 131 557-91).
Compacted fills should be cleaned of loose debris, oversize material in excess of
6 inches in diameter, brought to near optimum moisture content, and re-
compacted to at least 90% relative compaction (based on ASTM D1557-91).
Surf,cial, loose or soft soils exposed or encountered during grading (such as any
undocumented or loose fill materials) should be removed to competent formational
material and properly compacted prior to additional fill placement.
Fills should generally be placed in lifts not exceeding 8 inches in thickness. If the
import of soil is planned, soils should be non-expansive and free of debris and
organic matter. Prior to importing, soils should be visually observed, sampled and
tested at the borrow pit area to evaluate soil suitability as fill.
After completion of grading, the geotechnical consultant shall confirm the
"medium" expansion potential assumed herein.
Cut\fill shall be mitigated per the details provided in Appendix B of this report.
All excavations shall be made in accordance with OSHA, City and Industry
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHMCAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
accepted standards. Onsite safety is the sole responsibility of the project
contractor.
FOUNDATIONS
In deriving foundation recommendations for this site the subsoil conditions were
evaluated. We anticipate that the proposed foundation system for the structure will
utilize slab on grade and perimeter footing foundation system.
1. Footings bearing in competent fill or formational materials may be designed
utilizing maximum allowable soils pressure of 2,000 psf.
Seismic Design Parameters:
Seismic Zone Factor 4
Soil Profile Type Sd
(Table 16-J) .
Near Source 15.0 km
Distance. Rose Canyon
(Distance to Closest
Active Fault)
Seismic Source Type B
(Table 16-U)
Bearing values may be increased by 33% when considering wind, seismic, or
other short duration loadings.
The following parameters should be used as a minimum, for designing footing width
and depth below lowest adjacent grade:
No. of Floors
Supported
Minimum Footing Width *Minimum Footing Depth
Below Lowest Adjacent Grath
1 15 inches 18 inches
2 15 inches 18 inches
3 18 inches T 24 inches
Medium expansion potential
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL. CIVIL. STRUCTURAL & ARCI-WIECTURAI. CONSULTANTS
All footings should be reinforced with a minimum of two #4 bars at the top and two
#4 bars at the bottom (3 inches above the ground). For footings over 30 inches in
depth, additional reinforcement, and possibly a stemwall system will be necessary.
This detail should be reviewed on a case by case basis by our office prior to
construction.
All isolated spread footings should be designed utilizing the above given bearing
values and footing depths, and be reinforced with a minimum of #4 bars at 12
inches o.c. in each direction (3 inches above the ground). Isolated spread footings
should have a minimum width of 24 inches.
For footings (including site\retaining wall footings) and all other cosmetically
sensitive improvements adjacent to slopes, a minimum 10 feet horizontal setback
in formational material or properly compacted fill should be maintained. A setback
measurement should be taken at the horizontal distance from the bottom of the
footing to slope daylight. Where this condition can not be met it should be brought
to the attention of the Engineering Design Group for review.
All excavations should be performed in general accordance with the contents of
this report, applicable codes, OSHA requirements and applicable city and/or
county standards.
All foundation subgrade soils and footings shall be pre-moistened a minimum of
18 inches in depth prior to the pouring of concrete.
CONCRETE SLABS ON GRADE
Concrete slabs on grade should use the following as the minimum design parameters:
1. Concrete slabs on grade of the garage should have a minimum thickness of 4
inches (5 inches at garage and driveway locations) and should be reinforced with
#4 bars at 18 inches o.c. placed at the midpoint of the slab.
All concrete shall be poured per the following:
Slump: Between 3 and 4 inches maximum
Aggregate Size: 3/4 - 1 inch
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APIJ 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
Air Content: 5 to 8 percent
Moisture retarding additive in concrete at moisture sensitive areas.
Water to cement Ratio - 0.5 maximum
All required fills used to support slabs, should be placed in accordance with the
grading section of this report and the attached Appendix B, and compacted to 90
percent Modified Proctor Density, ASTM D-1557.
A uniform layer of 4 inches of clean sand is recommended under the slab in order
to more uniformly support the slab, help distribute loads to the soils beneath the
slab, and act as a capillary break. In addition, a visqueen layer (10 mil) should be
placed mid-height in the sand bed to act as a vapor retarder.
Adequate control joints should be installed to control the unavoidable cracking of
concrete that takes place when undergoing its natural shrinkage during curing. The
control joints should be well located to direct unavoidable slab cracking to areas that
are desirable by the designer.
All subgrade soils to receive concrete flatwork are to be pre-soaked to 3 percent
over optimum moisture content to a depth of 24 inches.
6 Brittle floor finishes placed directly on slab on grade floors may crack if concrete is
not adequately cured prior to installing the finish or if there is minor slab movement.
To minimize potential damage to movement sensitive flooring, we recommend the
use of slip sheeting techniques (linoleum type) which allows for foundation and slab
movement without transmitting this movement to the floor finishes.
7. Exterior concrete flatwork and driveway slabs, due to the nature of concrete
hydration and minor subgrade soil movement, are subject to normal minor concrete
cracking. To minimize expected concrete cracking, the following may be
implemented:
Concrete slump should not exceed 4 inches.
Concrete should be poured during "cool" (40 - 65 degrees) weather if
possible. If concrete is poured in hotter weather, a set retarding additive
should be included in the mix, and the slump kept to a minimum.
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECIINICAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
Concrete subgrade should be pre-soaked prior tothe pouring of concrete.
The level of pre-soaking should be a minimum of 4% over optimum moisture
to a depth of 24 inches.
Concrete may be poured with a 10 inch deep thickened edge.
Concrete should be constructed with tooled joints or sawcuts (1 inch deep)
creating concrete sections no larger than 225 square feet. For sidewalks,
the maximum run between joints should not exceed 5 feet. For rectangular
shapes of concrete, the ratio of length to width should generally not exceed
0.6 (i.e., 5 ft. long by 3 ft. wide). Joints should be cut at expected points of
concrete shrinkage (such as male corners), with diagonal reinforcement
placed in accordance with industry standards.
Drainage adjacent to concrete flatwork should direct water away from the
improvement. Concrete subgrade should be sloped and directed to the
collective drainage system, such that water is not trapped below the flatwork.
The recommendations set forth herein are intended to reduce cosmetic
nuisance cracking but will not prevent concrete cracking. The owner
should be aware all concrete, because of it's cementitious nature, will to
some degree shrink and crack. The amount, location and impact on the
cosmetic finish, of cracking can be reduced by design philosophy and
construction. The project concrete contractor is ultimately responsible for
concrete quality and performance, and should pursue a cost-benefit analysis
of these recommendations with the owner & general contractor, and other
options available in the industry, prior to the pouring of concrete.
Additionally, the project owner should be made fully aware of expected
performance of concrete finishes, so as to avoid follow up calls regarding
minor concrete cracking.
RETAINING WALLS
Retaining walls up to 10 feet may be designed and constructed in accordance with the
following recommendations and minimum design parameters:
Retaining wall footings should be designed in accordance with the allowable bearing
criteria given in the "Foundations" section of this report, and should maintain
minimum footing depths outlined in uFoundationn section of this report.
Unrestrained cantilever retaining walls should be designed using an active
equivalent fluid pressure of 35 pcf. This assumes that granular, free draining
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL, CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
material will be used for backfill, and that the backfill surface will be level. For
sloping backfill, the following parameters may be utilized:
Condition 2:1 Slope 1.5:1 Slope
Active 50 65
Any other surcharge loadings shall be analyzed in addition to the above values.
If the tops of retaining walls are restrained from movement, they should be
designed for an additional uniform soil pressure of 7XH psf, where H is the height
of the wall in feet.
Passive soil resistance may be calculated using an equivalent fluid pressure of
350 pcf. This value assumes that the soil being utilized to resist passive pressures,
extends horizontally 2.5 times the height of the passive pressure wedge of the soil.
Where the horizontal distance of the available passive pressure wedge is less than
2.5 times the height of the soil, the passive pressure value must be reduced by the
percent reduction in available horizontal length.
A coefficient of friction of 0.35 between the soil and concrete footings may be
utilized to resist lateral loads in addition to the passive earth pressures above.
Retaining walls should be braced and monitored during compaction. If this cannot
be accomplished, the compactive effort should be included as a surcharge load
when designing the wall.
All walls shall be provided with adequate back drainage to relieve hydrostatic
pressure, and be designed in accordance with the minimum standards contained
in the "Retaining Wall Drainage Detail", Appendix B. Area drains should not be
connected to French Drain System behind retaining wall.
Retaining wall backfill should be placed and compacted in accordance with the
"Earthwork" section of this report. Backfill shall consist of a non-expansive
granular, free draining material.
SURFACE DRAINAGE
Adequate drainage precautions at this site are imperative and will play a critical role on the
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHMCAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
future performance of the dwelling and improvements. Under no circumstances should
water be allowed to pond against or adjacent to foundation walls, or tops of slopes. The
ground surface surrounding proposed improvements should be relatively impervious in
nature, and slope to drain away from the structure in all directions, with a minimum slope
of 2% for a horizontal distance of 7 feet (where possible). Area drains or surface swales
should then be provided to accommodate runoff and avoid any ponding of water. Roof
gutters and downspouts shall be installed on the new and existing structures and tightlined
to the area drain system. All drains should be kept clean and unclogged, including gutters
and downspouts. Area drains should be kept free of debris to allow for proper drainage,
and remain separate from any wall back drain systems.
During periods of heavy rain, the performance of all drainage systems should be inspected.
Problems such as gullying or ponding should be corrected as soon as possible. Any
leakage from sources such as water lines should also be repaired as soon as possible.
In addition, irrigation of planter areas, lawns, or other vegetation, located adjacent to the
foundation or exterior flat work improvements, should be strictly controlled or avoided.
CONSTRUCTION OBSERVATION AND TESTING
The recommendations provided in this report are based on subsurface conditions disclosed
by our investigation of the project area. Interpolated subsurface conditions should be
ferified in the field during construction. The following items shall be conducted prior/during
construction by a representative of Engineering Design Group in orderto verify compliance
with the geotechnical and civil engineering recommendations provided herein, as
applicable. The project structural and geotechnical engineers may upgrade any condition
as deemed necessary during the development of the proposed improvement(s).
Attendance of a pre-construction meeting prior to the start of work
Review of final approved structural plans prior to the start of work, for compliance with
geotechnical recommendations.
Observation of the removal bottom.
Testing of any fill placed, including retaining wall backfill and utility trenches.
Observation of footing excavations prior to steel placement.
Field observation of any "field change" condition involving soils.
Walk through of final drainage detailing prior to final approval.
The project soils engineer may at their discretion deepen footings or locally recommend
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHNICAL. CIVIL. STRUCTURAL & ARCHITECTURAL CONSULTANTS
additional steel reinforcement to upgrade any condition as deemed necessary during site
observations.
Engineering Design Group shall, prior to the issuance of the certificate of occupancy, issue
in writing that the above inspections have been conducted by representative of their firm,
and the design considerations of the project soils report have been met. The field
inspection protocol specified herein is considered the minimum necessary for Engineering
Design Group to have exercised "due diligence" in the soils engineering design aspect of
this building. Engineering Design Group assumes no liability for structures constructed
utilizing this report not meeting this protocol.
Before commencement of grading the Engineering Design Group will require a separate
contract for quality control observation and testing. Engineering Design Group requires
a minimum of 48 hours notice to mobilize onsite for field observation and testing.
MISCELLANEOUS
It must be noted that no structure or slab should be expected to remain totally free of
cracks and minor signs of cosmetic distress. The flexible nature of wood and steel
structures allows them to respond to movements resulting from minor unavoidable
settlement of fill or natural soils, the swelling of clay soils, or the motions induced from
seismic activity. All of the above can induce movement that frequently results in cosmetic
cracking of brittle wall surfaces, such as stucco or interior plaster or interior brittle slab
finishes.
Data for this report was derived from surface observations at the site, knowledge of local
conditions, and a visual observation of the soils exposed in the exploratory trenches. The
recommendations in this report are based on our experience in conjunction with the limited
soils exposed at this site and neighboring sites. We believe that this information gives an
acceptable degree of reliability for anticipating the behavior of the proposed structure;
however, our recommendations are professional opinions and cannot control nature, nor
can they assure the soils profiles beneath or adjacent to those observed. Therefore, no
warranties of the accuracy of these recommendations, beyond the limits of the obtained
data, is herein expressed or implied. This report is based on the investigation at the
described site and on the specific anticipated construction as stated herein. If either of
these conditions is changed, the results would also most likely change.
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECIIMCAL. CIVIL STRUCTURAL & ARCHITECTURAL CONSULTANTS
Man-made or natural changes in the conditions of a property can occur over a period of
time. In addition, changes in requirements due to state of the art knowledge and/or
legislation, are rapidly occurring. As a result, the findings of this report may become invalid
due to these changes. Therefore, this report for the specific site, is subject to review and
not considered valid after a period of one year, or if conditions as stated above are altered.
It is the responsibility of the owner or his representative to ensure that the information in
this report be incorporated into the plans and/or specifications and construction of the
project. It is advisable that a contractor familiar with construction details typically used to
deal with the local subsoil and seismic conditions, be retained to build the structure.
If you have any questions regarding this report, or if we can be of further service, please
do not hesitate to contact us. We hope the report provides you with necessary information
to continue with the development of the project.
Sincerely,
INEE{NG DESIGN GROUP
California RCE #47672
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APN 216-200-2400, PIRINEOS WAY, CARLSBAD, CA Job No. 002425-1
ENGINEERING DESIGN GROUP
GEOTECHMCAL. CML. STRUCTURAL & ARCHITECTURAL CONSULTANTS
APPENDIX A
APPENDIX A
California Department of Conservation, Division of Mines and Geology, Fault-Rupture
Zones in California, Special Publication 42, RevIsed 1990.
Greensfelder, R.W., 1974, Maximum Credible Rock Acceleration from Earthquakes in
California: California Division of Mines and Geology, Map Sheet 23.
Hart, Michael, June 17. 1994, Geologic Investigation, 7505 Hillside Drive, La Jolla, CA,
File No: 153-94.
Engineering Design Group, Unpublished In-House Data.
Ptoessel, M.R., and Slosson, J.E., 1974, Repeatable High Ground Acceleration from
Earthquakes: California Geology, Vol. 27, No. 9, P. 195-199.
State of California, Fault Map of California, Map No: 1, Dated: 1975.
State of California, Geologic Map of California, Map No: 2, Dated 1977.
APPENDIX - B
These specifications are presented as general procedures and recommendations for
grading and earthwork to be utilized in conjunction with the approved grading plans.
These general earthwork and grading specifications are a part of the
recommendations contained in the geotechnical report and shall be superseded by
the recommendations in the geotechnical report in the case of conflict. Evaluations
performed by the consultant during the course of grading may result in new
recommendations which could supersede these specifications or the
recommendations of the geotechnical report. It shall be the responsibility of the
contractor to read and understand these specifications, as well as the geotechnical
report and approved grading plans.
2.0 Earthwork Observation and Testing
Prior to the commencement of grading, a qualified geotechnical consultant should be
employed for the purpose of observing earthwork procedures and testing the fills for
conformance with the recommendations of the geotechnical report and these
specifications. It shall be the responsibility of the contractor to assist the consultant
and keep him apprised of work schedules and changes, at feast 24 hours in advance,
so that he may schedule his personnel accordingly. No grading operations should be
performed without the knowledge of the geotechnical consultant. The contractor shall
not assume that the geotechnical consultant is aware of all grading operations.
It shall be the sole responsibility of the contractor to provide adequate equipment and
methods to accomplish the work in accordance with applicable grading codes and
agency ordinances, recommendations in the geotechnical report, and the approved
grading plans not withstanding the testing and observation of the geotechnical
consultant. If, in the opinion of the consultant, unsatisfactory conditions, such as
unsuitable soil, poor moisture condition, inadequate compaction, adverse weather,
etc., are resulting in a quality of work less than recommended in the geotechnical
report and the specifications, the consultant will be empowered to reject the work and
recommend that construction be stopped until the conditions are rectified.
Maximum dry density tests used to evaluate the degree of compaction should be
performed in general accordance with the latest version of the American Society for
Testing and Materials test method ASTM 01557.
t
-1-
3.1 Clearing and Grubbing: Sufficient brush, vegetation, roots and all other
deleterious material should be removed or properly disposed of in a method
acceptable to the owner, design engineer, governing agencies and the
geotechnical consultant.
The geotechnical consultant should evaluate the extent of these removals
depending on specific site conditions. In general, no more than 1 percent (by
volume) of the fill material should consist of these materials and nesting of
these materials should not be allowed.
3.2 Processing: The existing ground which has been evaluated by the
geotechnical consultant to be satisfactory for support of fill, should be scarified
to a minimum depth of 6 inches. Existing ground which is not satisfactory
should be overexcavated as specified in the following section. Scarification
should continue until the soils are broken down and free of large clay lumps or
clods and until the working surface is reasonably uniform, flat, and free of
uneven features which would inhibit uniform compaction.
3.3 Overexcavation: Soft, dry, organic-rich, spongy, highly fractured, or otherwise
unsuitable ground, extending to such a depth that surface processing cannot
adequately improve the condition, should be overexcavated down to
competent ground, as evaluated, by the geotechnical consultant. For purposes
of determining quantities of materials overexcavated, a licensed land
surveyor/civil engineer should be utilized.
3.4 Moisture Conditioning: Overexcavated and processed soils should be watered,
dried-back, blended, and/or mixed, as necessary to attain a uniform moisture
content near optimum.
3.5 Recompaction: Overexcavated and processed soils which have been properly
mixed, screened of deleterious material, and moisture-conditioned should be
recompacted to a minimum relative compaction of 90 percent or as otherwise
recommended by the geotechnical consultant.
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3.6 Benching: Where fills are to be placed on ground with slopes steeper than 5:1
(horizontal to vertical), the ground should be stepped or benched. The lowest
bench should be a minimum of 15 feet wide, at least 2 feet into competent
material as evaluated by the geotechnical consultant. Other benches should
be excavated into competent material as evaluated by the geotechnical
consultant. Ground sloping flatter than 5:1 should be benched or otherwise
overexcavated when recommended by the geotechnical consultant.
3.7 Evaluation of Fill Areas: All areas to receive fill, including processed areas,
removal areas, and toe-of-fill benches, should be evaluated by the
geotechnical consultant prior to fill placement.
4.0 Fill Material
4.1 General: Material to be placed as fill should be sufficiently free of organic
matter and other deleterious substances, and should be evaluated by the
geotechnical consultant prior too placement. Soils of poor gradation,
expansion, or strength characteristics should be placed as recommended by
the geotechnical consultant or mixed with other soils to achieve satisfactory fill
material.
4.2 Oversize: Oversize material, defined as rock or other irreducible material with
a maximum dimension greater than 6 inches, should not be buried or placed
in fills, unless the location, materials, and disposal methods are specifically
recommended by the geotechnical consultant. Oversize disposal operations
should be such that nesting of oversize material does not occur, and such that
the oversize material is completely surrounded by compacted or densified fill.
Oversize material should not be placed within 10 feet vertically of finish grade,
within 2 feet of future utilities or underground construction, or within 15 feet
horizontally of slope faces, in accordance with the attached detail.
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4.3 Import: If importing of fill material is required for grading, the import material
should meet the requirements of Section 4.1. Sufficient time should be given
to allow the geotechnical consultant to observe (and test, if necessary) the
proposed import materials.
J• 1l I .M1iitii1i't [I.J tit.t71
5.1 Fill Lifts: Fill material should be placed in areas prepared and previously
evaluated to receive fill, in near-horizontal layers approximately 6 inches in
compacted thickness. Each layer should be spread evenly and thoroughly
mixed to attain uniformity of material and moisture throughout.
5.2 Moisture Conditioning: Fill soils should be watered, dried-back, blended,
and/or mixed, as necessary to attain a uniform moisture content near optimum.
5.3 Compaction of Fill: After each layer has been evenly spread, moisture-
conditioned, and mixed, it should be uniformly compacted to not less than 90
percent of maximum dry density (unless otherwise specified). Compaction
equipment should be adequately sized and be either specifically designed for
soil compaction or of proven reliability, to efficiently achieve the specified
degree and uniformity of compaction.
5.4 Fill Slopes: Compacting of slopes should be accomplished, in addition to
normal compacting procedures, by backrolling of slopes with sheepsfoot rollers
at increments of 3 to 4 feet in fill elevation gain, or by other methods producing
satisfactory results. At the completion of grading, the relative compaction of
the fill out to the slope face would be at least 90 percent.
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5.5 Compaction Testing: Field tests of the moisture content and degree of
compaction of the fill soils should be performed at the consultant's discretion
based on field conditions encountered. In general, the tests should be taken
at approximate intervals of 2 feet in vertical rise and/or 1,000 cubic yards of
compacted fill soils. In addition, on slope faces, as a guideline approximately
one test should be taken for each 5,000 square feet of slope face and/or each
10 feet of vertical height of slope.
xs irirnii
Subdrain systems, if recommended, should beinstalled in areas previously evaluated
for suitability by the geotechnical consultant, to conform to the approximate alignment
and details shown on the plans or herein. The subdrain location or materials should
not be changed or modified unless recommended by the geotechnical consultant.
The consultant, however, may recommend changes in subdrain line or grade
depending on conditions encountered. All subdrains should be surveyed by a
licensed land surveyor/civil engineer for line and grade after installation. Sufficient
time shall be allowed for the survey, prior to commencement of filling over the
subdrains.
7.0 Excavation
Excavations and cut slopes should be evaluated by a representative of the
geotechnical consultant (as necessary) during grading. If directed by the geotechnical
consultant, further excavation, overexcavation, and refilling of cut areas and/or
remedial grading of cut slopes (i.e., stability fills or slope buttresses) may be
recommended.
8.0 Quantity Determination
For purposes of determining quantities of materials excavated during grading and/or
determining the limits of overexcavation, a licensed land surveyor/civil engineer
should be utilized.
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APPENDIX - C
LABORATORY TESTING PROCEDURES
Direct Shear Test Direct shear tests are performed on remolded and/or relatively undisturbed
samples which are soaked for a minimum of 24 hours prior to testing. After transferring the
sample to the shearbox, and reloading, pore pressures are allowed to dissipated for a period of
approximately 1 hour prior to application of shearing force. The samples are sheared in a motor-
driven, strain controlled, direct-shear testing apparatus. After a travel of approximately 1/4 inch,
the motor is stopped and the sample is allowed to "relax" for approximately 15 minutes. Where
applicable, the "relaxed" and "peak" shear values are recorded. It is anticipated that, in a majority
of samples tested, the 15 minutes relaxing of the sample is sufficient to allow dissipation of pore
pressures set up due to application of the shearing force. The relaxed values are therefore
judged to be good estimations of effective strength parameters.
Expansion Index Tests: The expansion potential of representative samples is evaluated by the
Expansion Index Test, U.B.C. Standard No. 29-2. Specimens are molded under a given
compactive energy to approximately the optimum moisture content and approximately 50 percent
saturation. The prepared 1-inch thick by 4-inch diameter specimens are loaded to an equivalent
144 psf surcharge and are inundated with tap water for 24 hours or until volumetric equilibrium
is reached.
Classification Tests: Typical materials are subjected to mechanical grain-size analysis by wet
sieving from U.S. Standard brass screens (ASTM D422-65). Hydrometer analyses are performed
where appreciable quantities of fines are encountered. Data is evaluated to determine the
classification of the materials. The grain-size distribution curves are presented in the test data
and the Unified Soil Classification is presented in both the test data and the boring logs.