HomeMy WebLinkAboutSDP 16-25; LEGOLAND WP17 PROJECT; GEOTECHNICAL UPDATE REPORT; 2016-08-26ECHNICAL UPDATE REPORT
PROPOSED WPI7 PROJECT
LEGOLAND THEME PARK
CARLSBAD, CALIFORNIA
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Prepared for:
MERLIN ENTERTAINMENT GROUP!
US HOLDING, INC.
One Lego Drive
Carlsbad, California 92008
Project No. 10075.016
August 26, 2016
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NOV 15 2016
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LAND DEVELOPMENT
WOW . ENGINEERING
Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY çl)p iC4,-oS
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Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY
August 26, 2016
Project No. 10075.016
To: Merlin Entertainment Group/US Holding, Inc.
do LEGOLAND California, LLC
One Lego Drive
Carlsbad, California 92008
Attention: Mr. Chris Brzezicki
Subject: Geotechnical Update Report, Proposed WPI7 Project, LEGOLAND Theme
Park, Carlsbad, California
In accordance with your request and authorization, Leighton and Associates, Inc.
(Leighton) has conducted a geotechnical update for the proposed WP1 7 project that is
planned for the LEGOLAND Theme Park in Carlsbad, California (Figure 1). This report
presents the results of our review of pertinent geotechnical documents, previous
laboratory testing, limited geotechnical analyses, and provides our conclusions and
recommendations for the proposed redevelopment area.
Based on the result of our current geotechnical study, the proposed redevelopment
project is considered feasible from a geotechnical standpoint provided our
recommendations are implemented in the design and construction of the project. If you
have any questions regarding our report, please do not hesitate to contact this office.
We appreciate this opportunity to be of service. 00AL Q 0. b 145' t.D.4,
Respectfully submitted, 0 NO. a457 %
LEIGHTON AND ASSOCIATES, INC.
UP A/ALa at
William D. Olson, RCE 45289 *
Associate Engineer
Distribution: (4) Addressee
GEOLOGIST •
OF C
2.
Mike D. Jensen, CEG 2457
Senior Project Geologist
3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425
858.292.8030 • Fax 858.292.0771 • www.leightongroup.com
10075.016
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION ...................................................................................................... I
1.1 PURPOSEANDSCOPE ............................................................................................. I
1.2 SITE LOCATION AND DESCRIPTION ............................................................................ I
1.3 PROPOSED DEVELOPMENT ......................................................................................2
2.0 SUMMARY OF GEOTECHNICAL CONDITIONS....................................................3
2.1 GEOLOGIC SETTING ................................................................................................3
2.2 SITE-SPECIFIC GEOLOGY ........................................................................................3
2.2.1 Undocumented Artificial Fill (Not Mapped) ....................................................4
2.2.2 Artificial Fill Documented (Map Symbol - Af) ................................................4
2.2.3 Quaternary-Aged Terrace Deposits (Map Symbol - Qt) ................................4
2.2.4 Santiago Formation (Map Symbol - Tsa)......................................................4
2.3 GROUND WATER ..................................................................................................... 5
2.4 LANDSLIDES ...........................................................................................................5
2.5 SLOPES..................................................................................................................6
2.6 ENGINEERING CHARACTERISTICS OF ON-SITE SOIL ...................................................6
2.6.1 Soil Compressibility and Collapse Potential ..................................................6
2.6.2 Expansive Soils.............................................................................................7
2.6.3 Soil Corrosivity ..............................................................................................7
2.6.4 Excavation Characteristics .............................................................................7
2.6.5 Infiltration Characteristics ..............................................................................7
3.0 FAULTING AND SEISMICITY.................................................................................9
3.1 FAULTING ...............................................................................................................9
3.2 SEISMIC DESIGN PARAMETERS ................................................................................9
3.3 SITE-SPECIFIC GROUND MOTION ANALYSIS ............................................................10
3.4 SECONDARY SEISMIC HAZARDS .............................................................................10
3.4.1 Shallow Ground Rupture .............................................................................11
3.4.2 Liquefaction .................................................................................................11
3.4.3 Tsunamis and Seiches ................................................................................11
4.0 CONCLUSIONS.....................................................................................................12
5.0 RECOMMENDATIONS..........................................................................................14
5.1 EARTHWORK ........................................................................................................14
5.1.1 Site Preparation...........................................................................................14
5.1.2 Excavations and Oversize Material .............................................................15
5.1.3 Cut/Fill Transitions.......................................................................................15
5.2 FOUNDATION DESIGN CONSIDERATIONS .................................................................16
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TABLE OF CONTENTS (Continued)
Section S Page
5.2.1 Conventional Foundations...........................................................................16
5.2.2 Drilled Pile Foundations ................. . .............................................................. 17
5.2.3 Mat Slab......................................................................................................18
5.3 FLOOR SLAB CONSIDERATIONS ............................................................................... 18
5.4 RETAINING WALL DESIGN ......................................................................................19
5.5 SURFACE DRAINAGE AND EROSION ........................................................................20
5.6 CONCRETE FLATWORK ..........................................................................................20
5.7 PLAN REVIEW .......................................................................................................21
5.8 CONSTRUCTION OBSERVATION ..............................................................................21
6.0 LIMITATIONS .................................................................................................22
Tables
Table 1 -2013 Mapped Spectral Accelerations Parameters - Page 10
Table 2 - Shaft Model Parameters - Page 18
Table 3 - Static Equivalent Fluid Weight (pcf) - Page 19
Figure
Figure 1 - Site Location Map - Rear of Text
Figure 2 - Geotechnical Map - Rear of Text
Figure 3 - Proposed Improvements - Rear of Text
Appendices
Appendix A - References
Appendix B - CIDH Pile Capacity Curves
Appendix C - General Earthwork and Grading Specifications
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1.0 INTRODUCTION
We recommend that all individuals utilizing this report read the proceeding information
sheet prepared by GBC (the Geotechnical Business Council of the Geoprofessional
Business Council) and the Limitations, Section 6.0, located at the end of this report.
1.1 Purpose and Scope
This report presents the results of our updated geotechnical study for the
proposed WP17 project that is to be constructed in the northern portion of
LEGOLAND Theme Park in Carlsbad, California (Figure 1). The purpose of our
update report was to identify and evaluate the existing geotechnical conditions
present at the site and to provide conclusions and recommendations relative to
the proposed development. Our scope of services included:
. Review of pertinent documents regarding the geotechnical conditions at the
site (Appendix A).
. A site reconnaissance to observe existing site conditions.
. Limited geotechnical evaluation and analysis of existing data.
Preparation of this report presenting our findings, conclusions, and
geotechnical recommendations with respect to the proposed geotechnical
design, site grading and general construction considerations.
It should be noted that percolation testing to evaluate site infiltration characteristics
was not part of our scope for this study.
1.2 Site Location and Description
The LEGOLAND Theme Park is located north of Palomar Airport Road and west
of College Boulevard in Carlsbad, California (Figure 1). The location of the
proposed WPI7 project is in the northern portion of the LEGOLAND Park. The
conceptual site plan prepared by Commercial Development Resources (CDR,
2016) was utilized as the base map for the Geotechnical Map (Figure 2).
Currently, the site is occupied by an existing attraction with small support
structures, and landscaping. Topographically, the site grades slope to the
towards the south with elevations ranging from approximately 166 feet above
mean sea level (msl) at the northern perimeter of the site to approximately 161
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feet at the southern perimeter. There is also an earthen knoll/berm area along
the northwestern perimeter of the site, which is about 6 to 10 feet higher than the
surrounding grades.
As background, Leighton performed the initial geotechnical investigation for the
LEGOLAND Theme Park in 1995. Subsequently, the site was mass graded
between 1996 and 1998 under the direct observation and testing of Leighton. As
a result of the mass grading operations for the development of the LEGOLAND
Theme Park, the subject site was generally a cut area which is overlain by the a
fill to create the earthen knoll/berm area (see Figure 2).
Site Latitude and Longitude
I33.12900 N
-117.31290 W
1.3 Proposed Development
It is our understanding that the proposed attraction will consist of a wading pool,
a restroom building, a raised attraction, retaining walls, and a retail/support
building (see Figure 3). In addition, pavement surfaces and shade structures will
be constructed around the pools. We anticipate the site earthwork will consist of
general grading (i.e., cuts and
fills) to reach the proposed site finish grades. We anticipate the foundation
system for the proposed buildings will be shallow conventional footings or mat-
type foundations and potentially some shallow isolated pole foundations.
Preliminary grading and foundation plans or structural loads were not available
prior to the preparation of this report.
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2.0 SUMMARY OF GEOTECHNICAL CONDITIONS
2.1 Geologic Selling
The site is located in the coastal section of the Peninsular Range Province, a
geomorphic province with a long and active geologic history throughout Southern
California. Throughout the last 54 million years, the area known as "San Diego
Embayment" has undergone several episodes of marine inundation and
subsequent marine regression, resulting in the deposition of a thick sequence of
marine and nonmarine sedimentary rocks on the basement rock of the Southern
California batholith.
Gradual emergence of the region from the sea occurred in Pleistocene time, and
numerous wave-cut platforms, most of which were covered by relatively thin
marine and nonmarine terrace deposits, formed as the sea receded from the
land. Accelerated fluvial erosion during periods of heavy rainfall, coupled with the
lowering of the' base sea level during Quaternary times, resulted in the rolling
hills, mesas, and deeply-incised canyons which characterize the landforms we
see in the general site area today.
2.2 Site-Specific Geology
Based on our previous subsurface exploration, geologic mapping during previous
grading operations (Leighton, 1998), and review of pertinent geologic literature
and maps, the geologic units underlying the site consist of documented artificial
fill soils, Quaternary-aged Terrace Deposits and Tertiary-aged Santiago
Formation. Specifically, the site of the proposed WP 17 project site is overlain by
2 to 10 feet of documented Artificial Fill (Af).
A brief description of the geologic units present on the site is presented in the
following sections. The approximate aerial distributions of those units are shown
on the Geotechnical Map (Figure 2).
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2.2.1 Undocumented Artificial Fill (Not Mapped)
Areas of undocumented fill up to approximately 3 feet in thickness may be
encountered in planters and landscape areas. The fill was derived from on-
site excavations that were placed following the rough grading operations
which occurred in the late 1990's. The existing slopes along the northern
and western perimeters should be evaluated during site grading for
adverse geological conditions and for competency of fill soil.
2.2.2 Artificial Fill Documented (Map Symbol - Af)
The artificial fill consists of moist, red-brown, dense, silty sands. The fill
was derived from on-site excavations that was placed -and compacted
during the rough grading operations in the late 1990's. The fill soils were
compacted to at least 90 percent relative compaction based on ASTM Test
Method D1557 (Leighton, 1998). The upper I to 2 feet of previously placed
documented fill is weathered or disturbed by existing improvements and
should be removed and reprocessed prior to the placement of additional
fills or construction of new improvements.
2.2.3 Quaternary-Aged Terrace Deposits (Map Symbol - Qt)
Quaternary Terrace Deposits are present in the eastern portion of the site
beneath the artificial fill. These Terrace Deposits consist of brown to
reddish brown, dry to moist, medium dense to very dense, silty fine- to
medium-grained sandstone. It should be noted that the top 3 to 5 feet of
Terrace Deposits that were weathered and/or disturbed by previous
agricultural use were removed and replaced by compacted fill during
grading operations (Leighton, 1998). Sand lenses within the Terrace
Deposits are known to contain layers that transmit water seepage. If cut
slopes are planned they should be evaluated by the geotechnical
consultant.
2.2.4 Santiago Formation (Map Symbol - Tsa)
Santiago Formation is present in the western portion of the site beneath
the artificial fill. Santiago Formation consists of gray-brown to off-white
damp, very dense, silty fine to medium sandstone. We do not anticipate
that Santiago Formation will be encountered during site grading with the
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exception of deep foundation (drilled pile) associated with the proposed
improvements, if any.
2.3 Ground Water
No indication of surface water or evidence of surface ponding was observed
during our site reconnaissance. However, surface water may drain as sheet flow
across the site during rainy periods. Ground water was not observed in the
original exploration borings or during the site grading (Leighton, 1998). Perched
ground water levels may develop and fluctuate during periods of precipitation.
Based on our experience and given the approximate elevation of the site, we
* anticipate the ground water to be at a depth of 75 feet or more. However, it
should be noted that previous nearby investigations have encountered perched
ground water accumulated on the geologic contact between the Santiago
Formation and the Terrace Deposits observed at the site. These conditions will
need to be evaluated on a case-by-case basis during site grading and within
sandy layers in the Terrace Deposits. Therefore, based on the above information,
we do not anticipate ground water will be a constraint to the construction of the
project.
2.4 Landslides
Landslides are deep-seated ground failures (several tens to hundreds of feet
deep) in which a large arcuate shaped section of a slope detaches and slides
downhill. Landslides are not to be confused with minor slope failures (slumps),
which are usually limited to the topsoil zone and can occur on slopes composed
of almost any geologic material. Landslides can cause damage to structures both
above and below the slide mass. Structures above the slide area are typically
damaged by undermining of foundations. Areas below a slide mass can be
damaged by being overridden and crushed by the failed slope material.
Several formations within the San Diego region are particularly prone to
landsliding. These formations generally have high clay content and mobilize
when they become saturated with water. Other factors, such as steeply dipping
bedding that project out of the face of the slope and/or the presence of fracture
planes, will also increase the potential for landsliding. Based on our site
reconnaissance and geologic mapping, the materials on site are generally
massive with no distinctive structure.
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No active landslides or indications of deep-seated landsliding were noted at the
site during our field reconnaissance, site grading, or our review of available
geologic literature, topographic maps, and stereoscopic aerial photographs.
Furthermore, our field reconnaissance and the local geologic maps indicate the
site is underlain by favorable oriented geologic structure, and no nearby slopes.
Therefore, the potential for significant landslides or large-scale slope instability at
the site is considered low.
2.5 Slopes
If grading of the site includes the construction of new slopes, we recommend that
permanent slopes be inclined no steeper than 2:1 (horizontal to vertical). Fills over
sloping ground should be benched to produce a level area to receive fill. Benches
should be wide enough to provide complete coverage by the compaction
equipment during fill placement. If cut slopes are proposed to reach site grades,
they should be evaluated by the geotechnical consultant during grading plan
review and grading.
All slopes may be susceptible to surficial slope instability and erosion given
substantial wetting of the slope face. Surficial slope stability may be enhanced by
providing proper site drainage. The site should be graded so that water from the
surrounding areas is not able to flow over the top of slopes. Diversion structures
should be provided where necessary.
2.6 Engineering Characteristics of On-Site Soil
Based on the results of our previous geotechnical investigations and our
professional experience on adjacent sites with similar soils, the engineering
characteristics of the on-site soils are discussed below.
2.6.1 Soil Compressibility and Collapse Potential
Based on the dense nature of the on-site documented fill, Terrace
Deposits and Santiago Formation, it is our opinion that the potential for
settlement and collapse at the site is low. Existing undocumented fills and
disturbed soils that are present are considered compressible but are
expected to be removed by planned grading and/or remedial grading.
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2.6.2 Expansive Soils
Laboratory tests carried out on selected soil samples collected during our
previous explorations and grading activities (Appendix A) indicate the soils
at the site possess a very low to low expansion potential. Locally, soils
may have a low to medium potential expansion. Soils generated from
excavations in the Terrace Deposits are also expected to possess a very
low to low expansion potential. Laboratory testing upon completion of
remedial and fine grading operations for the proposed building and ride
pads are recommended to determine actual expansion potential of finish
grade soil at the site.
2.6.3 Soil Corrosivity
Laboratory tests carried out on selected soil samples collected during our
previous explorations and grading activities (Appendix A) indicate the soils
possess a low soluble sulfate content, neutral pH, low soluble chloride
content, and low electrical resistivity.
These findings indicate that the corrosive effects to buried ferrous metal
are expected to be moderate to severe. Affects to properly designed and
placed concrete are considered low. Laboratory testing upon completion of
remedial and fine grading operations for the proposed building. pad is
recommended to determine actual soluble sulfate content of finish grade
soil at the site.
2.6.4 Excavation Characteristics
It is anticipated the on-site soils can be excavated with conventional
heavy-duty construction equipment. Localized loose soil zones and friable
sands, if encountered, may require special excavation techniques to
prevent collapsing of the excavation.
2.6.5 Infiltration Characteristics
Based on our experience, we anticipate that the underlying documented
fill consisting of a mixture of soils and the underlying formation will have
permeable and impermeable layers can transmit and perched ground
water in unpredictable ways. Therefore, Low Impact Development (LID)
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measures may impact down gradient improvements and the use of some
unlined LID measures may not be appropriate for this project. All
Infiltration and Bioretention Stormwater Systems design should be
reviewed by geotechnical consultant.
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3.0 FAULTING AND SEISMICITY
3.1 Faulting
Our discussion of faults on the site is prefaced with a discussion of California
legislation and policies concerning the classification and land-use criteria
associated with faults. By definition of the California Geological Survey, an active
fault is a fault which has had surface displacement within Holocene time (about the
last 11,000 years). The state geologist has defined a Dotehtially active fault as any
fault considered to have been active during Quaternary time (last 1,600,000
years). This definition is used in delineating Earthquake Fault Zones as mandated
by the Alquist-Priolo Geologic Hazards Zones Act of 1972 and most recently
revised in 2007 (Bryant and Hart, 2007). The intent of this act is to assure that
unwise urban development and certain habitable structures do not occur across
the traces of active faults. The subject site is not included within any Earthquake
Fault Zones as created by the Alquist-Priolo Act.
Our review of available geologic literature (Appendix A) indicates that there are
no known major or active faults on or in the immediate vicinity of the site. The
nearest active regional fault is the offshore segment of the Rose Canyon Fault
Zone located approximately 4.6 miles (7.4 kilometers) west of the site.
3.2 Seismic Design Parameters
The site can be considered to lie within a seismically active region, as can all of
Southern California. The effect of seismic shaking may be mitigated by adhering
to the California Building Code and state-of-the-art seismic design practices of
the Structural Engineers Association of California. Provided below in the Table I
are the risk-targeted spectral acceleration parameters for the project determined
in accordance with the 2013 California Building Code (CBSC, 2013) and the
USGS Worldwide Seismic Design Values tool (Version 3.1.0).
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Table 1
2013 CBC Mapped Spectral Acceleration Parameters
Site Class D
Site Coefficients Fa 1.049
FV = 1.567
Mapped MCER Spectral Ss = 1.126g
Accelerations S1 = 0.433g
Site Modified MCER Spectral SMS = 1.182g
Accelerations SMI = 0.679g
Design Spectral Accelerations SDS = 0.788g
SD1 = 0.453g
Utilizing ASCE Standard 7-10, in accordance with Section 11.8.3, the following
additional parameters for the peak horizontal ground acceleration are associated
with the Geometric Mean Maximum Considered Earthquake (MCEG). The
mapped MCEG peak ground acceleration (PGA) is 0.446g for the site. For a Site
Class D, the FPGA is 1.054 and the mapped peak ground acceleration adjusted
for Site Class effects (PGAM) is 0.47g for the site.
3.3 Site-Specific Ground Motion Analysis
The site is not located in a Seismic Hazard Zone, an Alquist-Priolo Earthquake
Fault Zone or in a moderate or high hazard zone designation in the City of
Carlsbad Geotechnical Hazards Analysis and Mapping Study (1992). In addition
the site is not assigned to a Seismic Design Category E or F. Therefore, per
Section 4-317(e) of the California Administrative Code the development of a site-
specific ground motion analysis is not required per Section 1616A.1.3 of the 2013
CBC.
3.4 Secondary Seismic Hazards
Secondary effects that can be associated with severe ground shaking following a
relatively large earthquake include shallow ground rupture, soil liquefaction and
dynamic settlement, lateral spreading, seiches and tsunamis. These secondary
effects of seismic shaking are discussed in the following sections.
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3.4.1 Shallow Ground Rupture
No active faults are mapped crossing the site, and the site is not located
within a mapped Alquist-Priolo Earthquake Fault Zone (Bryant and Hart,
2007). Shallow ground rupture due to shaking from distant seismic events
is not considered a significant hazard, although it is a possibility at any
site.
3.4.2 Liquefaction
Liquefaction and dynamic settlement of 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 clayey
material are not adversely affected by vibratory motion. Liquefaction is
characterized by a loss of shear strength in the affected soil layer, thereby
causing the soil to behave as a viscous liquid. This effect may be
manifested at the ground surface by settlement and, possibly, sand boils
where insufficient confining overburden is present over liquefied layers.
Where sloping ground conditions are present, liquefaction-induced
instability can result.
Based on the results of our previous studies, reports (Appendix A), and
geotechnical analysis it is our professional opinion that the site is not
considered susceptible to liquefaction resulting from ground shaking at the
design ground motion.
3.4.3 Tsunamis and Seiches
Based on the distance between the site and large, open bodies of water,
and the elevation of the site with respect to sea level, the possibility of
seiches and/or tsunamis is considered to be very low.
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4.0 CONCLUSIONS
Based on the results of our geotechnical review of the site, it is our opinion that the
proposed development is feasible from a geotechnical viewpoint, provided the following
conclusions and recommendations are incorporated into the project plans and
specifications. The following is a summary of the significant geotechnical factors that we
expect may affect development of the site.
The location of the proposed improvements is within an area underlain by existing
documented fill placed as part of the original mass grading of the park and by
Quaternary-aged Terrace Deposits and Tertiary-aged Santiago Formation.
Areas of undocumented fill and disturbed soils up to approximately 3 feet in
thickness may be located in areas of existing improvements and landscape areas.
These materials, if encountered, should be removed prior to the placement of
additional fills or construction of improvements.
The upper I to 2 feet of previously placed documented fill is weathered and - ----.--.----. - --
should be removed and reprocessed prior to the placement of additional' fills or
-aZ_ ---
construction of improvements. Additional overexcavat!on or undercutting may be
needed, if cut to fill transitions are encountered during site grading
Existing underground utilities and construction debris (i.e., existing footings) should
be anticipated during future grading and construction. The depths and location of
these utilities are unknown at this time. It should be noted that backfill associated
with utility trenches should be evaluated on a case-by-case basis and may require
complete removal prior to placement of additional fill or construction of
foundations.
We anticipate that the soils present on the site will be generally rippable with
conventional heavy-duty earthwork equipment.
Although foundation plans have not been finalized and building loads were not
provided at the time this report was drafted, we anticipate that a lightly loaded
conventional foundation system, consisting of continuous and spread footings
with slab-on-grade flooring supported by competent documented fill materials or
Terrace Deposits, will be utilized for the site structures. Additionally we
understand that some of the structures may utilize drilled piles, and/or mat
foundations to compensate for overturning forces.
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Based on previous laboratory testing, the soils on the site generally possess a
very low to low expansion potential. Nevertheless, there may be localized areas
across the site and between our exploration locations having a higher expansion
potential.
Based on previous laboratory testing, the soils present on the site have a
negligible potential for sulfate attack on normal concrete, and are moderately to
severely corrosive to buried ferrous metals. These tests should be confirmed
upon completion of the grading activities where appropriate. A corrosion
consultant should be consulted.
The existing onsite soils are suitable material for fill construction provided they
are relatively free of organic material, debris, and cobbles or rock fragments
larger than 8 inches in maximum dimension.
Ground water was not encountered during the site investigation or grading.
Therefore, ground water is not considered a constraint on the proposed project
development. However, perched ground water and seepage may develop within
sandy layers and along the less permeable clay and silt layers within the Terrace
Deposits and along the fill and Terrace Deposit contact during periods of
precipitation or increased landscape irrigation.
Active faults are not known to exist on or in the immediate vicinity or project
toward the site. However, the proposed project is located in the seismically active
region of southern California and can expect to be subjected to seismic shaking
during its design life.
Our review of the geologic literature (Appendix A) along with the results of our
study, indicate that the probability of geologic hazards including, tsunamis and
seiche, landsliding, liquefaction, and seismic induced settlement are considered
low for the site.
Low Impact Development (LID) measures may impact down gradient
improvements and the use of some unlined LID measures may not be
appropriate for this project.
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5.0 RECOMMENDATIONS
The conclusions and recommendations in this report are based in part upon data that
were obtained from a limited number of observations, site visits, excavations, samples,
and tests. Such information is by necessity incomplete. The nature of many sites is such
that differing geotechnical or geological conditions can occur within small distances and
under varying climatic conditions. Changes in subsurface conditions can and do occur
over time. Therefore, the findings, conclusions, and recommendations presented in this
report can be relied upon only if Leighton has the opportunity to observe the subsurface
conditions during earthwork operations and construction of the project, in 'order to
confirm that our preliminary findings are representative for the site. A review of the
grading and foundation plans should be performed prior to construction.
5.1 Earthwork
We anticipate that earthwork at the site will consist of remedial grading of the
undocumented fill and disturbed documented fill for new site improvements; utility
construction; subgrade preparation in flatwork and pavement areas; foundation
excavation; and retaining wall construction and backfill operations. We
recommend that earthwork on the site be performed in accordance with the
following recommendations and the General Earthwork and Grading
Specifications for Rough Grading included in Appendix C. In case of conflict, the
following recommendations shall supersede those in Appendix C.
5.1.1 Site Preparation
The areas to receive structural fill, engineered structures, or hardscape
should be cleared of surface and subsurface obstructions, including any
existing debris and undocumented or loose weathered fill soils, and
stripped of vegetation. Removals beneath the proposed building and/or
structures should extend at least 2 feet below the proposed footing
bottoms into the competent documented fill soils and laterally
approximately 5 feet beyond the building/structure footprint. Removals
beneath the proposed surface pavements should extend at least 2 feet
below existing site grade or the proposed subgrade elevation whichever is
deeper into the competent fill soils.
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Removed vegetation and debris should be properly disposed off site.
Holes resulting from the removal of buried obstructions which extend
below finish site grades should be replaced with suitable compacted fill
material. All areas to receive fill and/or other surface improvements should
be scarified to a minimum depth of 8 inches, brought to above optimum
moisture conditions, and recompacted to at least 90 percent relative
compaction based on ASTM Test Method D1557. If clayey soils that are
more expansive (El>70) are encountered, increased moisture and revised
recommendations may be needed.
5.1.2 Excavations and Oversize Material
Shallow excavations of the onsite materials may generally be
accomplished with conventional heavy-duty earthwork equipment.
Localized heavy ripping may be required if cemented and concretionary
lenses are encountered in deeper excavations.
Shallow, temporary excavations, such as utility trenches with vertical
sides, in the engineered fill and formational materials should remain stable
for the period required to construct the utility, provided they are free of
adverse geologic conditions or seeps. In accordance with OSHA
requirements, excavations deeper than 5 feet should be shored or be laid
back to if workers are to enter such excavations. Temporary sloping
gradients should be determined in the field by a "competent person" as
defined by OSHA. For preliminary planning, sloping of surficial soils at 1:1
(horizontal to vertical) may be assumed. Excavations greater than 20 feet
in height will require an alternative sloping plan or shoring plan prepared
by a California registered civil engineer.
5.1.3 Cut/Fill Transitions
In order to minimize potential differential settlement, we recommend that
proposed buildings and settlement sensitive structures are entirely
underlain by a layer of properly compacted fill. Cut portions of areas
planned for structures should be overexcavated to a minimum depth of 2
feet below lowest footing bottom elevation and replaced with properly
compacted fill. The overexcavated areas should be graded with a 1
percent gradient sloping toward the deeper fill areas, if possible.
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Leighton
10075.016
5.2 Foundation Design Considerations
As discussed in the preceding section, we anticipate that the proposed
improvements will be supported on conventional footings, drilled piles (CIDH),
and/or mat slabs. The following sections address the recommendations for these
types of foundation systems.
5.2.1 Conventional Foundations
Footings should extend at least 18-inches beneath the lowest adjacent
finish grade. At these depths, footings founded in properly compacted fill
soil or formational material may be designed for a maximum allowable
bearing pressure of 2,000 psf. The allowable pressures may be increased
by one-third when considering loads of short duration such as wind or
seismic forces. The minimum recommended width of footings is 15 inches
for continuous footings and 18 inches for square or round footings.
Continuous footings should have a minimum reinforcement of four No. 5
reinforcing bars (two top and two bottom). Footings should be designed in
accordance with the structural engineer's requirements.
The recommended allowable bearing capacity for spread footings is based
on a maximum allowable total and differential settlements of 1-inch and
3/4-inch. Since settlements are functions of footing size and contact
bearing pressures, some differential settlement can be expected between
adjacent columns, where large differential loading conditions exist. With
increased footing depth to width ratios, differential settlement should be
less.
We recommend a horizontal setback distance from the face of slopes and
retaining wall for all structural footings and settlement-sensitive structures.
The distance is measured from the outside edge of the footing,
horizontally to the slope face (or to the face of a retaining wall) and should
be a minimum of H/2 and need not be greater than 15 feet. Utility trenches
that parallel or nearly parallel structural footings should not encroach
within a 1:1 plane extending downward from the outside edge of footing.
Please note that the soil within the structural setback area possess poor
lateral stability, and improvements (such as retaining walls, sidewalks,
fences, pavements, etc.) constructed within this setback area may be
40
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10075.016
subject to lateral movement, and/or differential settlement. Potential
distress to such improvements may be mitigated by providing a deepened
footing or a pier and grade beam foundation system to support the
improvement. Deepened footings should meet the setback as described
above.
5.2.2 Drilled Pile Foundations
For the analysis and development of the various vertical capacities of
CIDH piles, the computer program SHAFT (Version 2012) produced by
Ensoft, Inc. was used. As shown in Appendix B, the Shaft capacity curves
were developed for 24- to 48-inch diameter piles penetrating into dense fill
and formational material. Uplift capacity curves are also presented in
Appendix B. Pile settlement is anticipated to be less than 1/4 inch under
design loads and normal service conditions. The design curves are based
on center to center pile spacings of at least 3 pile diameters for the CIDH
piles less than or equal to 3 foot diameter, and at least 5 pile diameters for
the CIDH piles greater than 3 foot diameter. Where piles are spaced more
closely, reduction in pile capacity is necessary. Construction of piles
should be sequenced such that the concrete of constructed piles are
allowed to setup prior to construction of piles within 5 diameters.
Design of free standing poles as columns embedded in the earth (i.e.,
CIDH foundations) to resist lateral loads can be designed in accordance
with Section 1807.3 of the 2013 CBC. For level ground conditions, we
recommend lateral soil bearing pressures of 300 psf per foot of depth
below the finish grade be used for determination of parameters SI and
S3, in the Non-constrained and Constrained design criteria, respectively.
These values should be reduced by 50 percent to account for 2 to I
downward sloping ground conditions, if applicable.
In addition, we recommend that no subsurface existing or proposed
improvement be constructed within at least five (5) pile diameters of the
proposed CIDH foundations.
If alternative methods of lateral analysis are preferable, we recommend
analysis methods such as p-y of strain wedge models that consider the
boundary conditions at the ground surface. The following Table 2 presents
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10075.016
idealized soil profile models for use in Shaft analysis, or similar lateral pile
analysis software.
Table 2
Shaft Model Parameters
Layer Depth Effective Unit Friction k
Top Bottom Soil Model Weight Angle (p ci) (ft) (ft) WO) (4)
0 20 Sand 127 32 225
20 80 Sand 125 32 225
5.2.3 Mat Slab
A soil modulus of 200 pounds per cubic inch is recommended for design
of structural slab foundations. Structural foundations should be designed
by the project structural engineer utilizing an allowable bearing pressure of
1,500 psf.
5.3 Floor Slab Considerations
Slab-on-grade floors should be at least 5 inches thick and be reinforced with No.
4 rebars 18 inches on center each way (minimum) placed at mid-height in the
slab. We recommend control joints be provided across the slab at appropriate
intervals as designed by the project architect. Where moisture-sensitive finishes
are planned, underslab moisture protection should be designed by the project
architect in accordance with Section 4.505 of the 2013 California Green Building
Standards Code (CBSC, 2013).
Prior to placement of the sand layer, the upper 6-inches of slab subgrade should
be moisture conditioned to at or above the laboratory optimum moisture content.
The potential for slab cracking may be reduced by careful control of
water/cement ratios. The contractor should take appropriate curing precautions
during the pouring of concrete in hot weather to minimize cracking of the slabs.
We recommend that a slipsheet (or equivalent) be utilized if grouted tile, marble
tile, or other crack-sensitive floor covering is planned directly on concrete slabs.
All slabs should be designed in accordance with structural considerations. If
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10075.016
heavy vehicle or equipment loading is proposed for the slabs, greater thickness
and increased reinforcing may be required.
5.4 Retaining Wall Design
For design purposes, the following lateral earth pressure values in Table 3 for
level or sloping backfill are recommended for walls backfilled with very low to low
expansion potential (Expansion Index less than 50).
Table 3
Static Equivalent Fluid Weight (pcf)
Conditions Level 2:1 Slope
Active 35 55
At-Rest 55 85
Passive 3 00
(maximum of 3 ksf)
150 (sloping down)
Active earth pressures are considered are considered appropriate for walls that
are allowed to rotate an amount equal to 0.002H at the top of the wall, where H is
equal to the wall height. Where walls are not allowed to rotate that minimum
amount, at-rest pressures are considered appropriate.
Retaining structures should be provided with a drainage system, as illustrated in
Appendix C, to prevent buildup of hydrostatic pressure behind the wall. For
sliding resistance, a friction coefficient of 0.35 maybe used at the soil-concrete
interface. The lateral passive resistance can be taken into account only if it is
ensured that the soil against embedded structures will remain intact with time.
Retaining wall footings should have a minimum embedment of 12 inches below
the adjacent lowest grade unless deeper footings are needed for other reasons.
To account for potential redistribution of forces during a seismic event, retaining
walls providing lateral support where exterior grades on opposites sides differ by
more than 6 feet fall under the requirements of 2013 CBC Section 1616A.1.11
and/or ASCE 7-10 Section 12.7.2 and should also be analyzed for seismic
loading. For that analysis, an additional lateral seismic force of 8H2 pounds per
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10075.016
foot acting at 0.6 of the wall height needs to be considered for the design of the
retaining walls, where H is the height of the wall. A surcharge load for a
restrained or unrestrained wall resulting from automobile traffic may be assumed
to be equivalent to a uniform lateral pressure of 75 psf, which is in addition to the
equivalent fluid pressure given above. For other uniform surcharge loads, a
uniform lateral pressure equal to 0.35q should be applied to the wall (where q is
the surcharge pressure in psf).
If segmental walls are planned, a friction angle of 28 degrees and a unit weight of
120 to 125 pcf are considered appropriate for the onsite materials. The design
should be performed in accordance with NCMA methodology (NCMA, 2009) and
design requirements of the wall system.
5.5 Surface Drainage and Erosion
Surface drainage should be controlled at all times. The proposed structures
should have appropriate drainage systems to collect runoff. Positive surface
drainage should be provided to direct surface water away from the structure
toward suitable drainage facilities. In general, ponding of water should be
avoided adjacent to the structure or pavements. Over-watering of the site should
be avoided. Protective measures to mitigate excessive site erosion during
construction should also be implemented in accordance with the latest City of
Carlsbad grading ordinances.
5.6 Concrete Flatwork
Concrete sidewalks and other flatwork (including construction joints) should be
designed by the project civil engineer and should have a minimum thickness of 4
inches. For all concrete flatwork, the upper 12 inches of subgrade soils should be
moisture conditioned to at least 2 percent above optimum moisture content and
compacted to at least 90 percent relative compaction based on ASTM Test
Method D1557 prior to the concrete placement. These recommendations are
assuming low expansive materials are present within the upper 2 feet below
su bgrade.
Control joints should be provided at a distance equal to 24 times the slab
thickness in inches, 'not to exceed 12 feet. Expansion joints should be
incorporated where paving abuts a vertical surface, where paving changes
direction and at 30 feet maximum spacing, joints should be laid out so as to
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10075.016
create square or nearly square areas. Sidewalks should be reinforced with 6x6-
6/6, or heavier, welded wire mesh slip dowels should be provided across control
joints along ADA walkways, curbs, and at doorways.
5.7 Plan Review
Foundation and grading plans should be reviewed by Leighton to confirm that the
recommendations in this report are incorporated in project plans.
5.8 Construction Observation
The recommendations provided in this report are based on preliminary design
information, our experience during rough grading, and subsurface conditions
disclosed by widely spaced excavations. The interpolated subsurface conditions
should be checked in the field during construction. Construction observation of all
onsite excavations and should be performed by a representative of this office so
that construction is in accordance with the recommendations of this report. All
footing excavations should be reviewed by this office prior to steel placement.
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10075.016
6.0 LIMITATIONS
The conclusions and recommendations in this report are based in part upon field
reconnaissance and our previous geotechnical study with widely spaced subsurface
explorations. Such information is by necessity incomplete. The nature of many sites is
such that differing geotechnical or geological conditions can occur within small
distances and under varying climatic conditions. Changes in subsurface conditions can
and do occur over time. Therefore, the findings, conclusions, and recommendations
presented in this report can be relied upon only if Leighton has the opportunity to
observe the subsurface conditions during grading and construction of the project, in
order to confirm that our preliminary findings are representative for the site.
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Figures
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Approximate
Site Location
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LOCATION MAP
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Base Map. ESRI AitGlS Online 2016 Carlsbad, California Thematic Information: Leighton
Author: (mreurphy)
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APPENDIX A
References
I
10075.016
APPENDIX A
References
American Concrete Institute (Ad), 2006, Guide for Concrete Slabs that Receive
Moisture-Sensitive Flooring Materials.
Bryant, W. A. and Hart, E. W., 2007, Fault Rupture Hazard Zones in California, Alquist-
Priolo Special Studies Zones Act of 1972 with Index to Special Study Zone Maps,
Department.of Conservation, Division of Mines and Geology, Special Publication
42, dated 1997 with 2007 Interim Revision.
California Building and Safety Commission (CBSC), 2013, California Building Code.
Kennedy, M.P., and Tan, S.S., 2007, Geologic Map of the Oceanside 30'x60'
Quadrangle, California, California Geologic Survey, 1:100,000 scale.
Leighton and Associates, Inc., 1995, Preliminary Geotechnical Investigation, Lego
Family Park and Pointe Resorts, Lots 17 and 18 of the Carlsbad Ranch,
Carlsbad, California, Project No. 950294-001, dated October 5, 1995.
1996, Supplemental Geotechnical Investigation, Lego Family Park,
Carlsbad Ranch, Carlsbad, California, Project No. 960151-001, dated July 23.
1998, Final As-Graded Report of Rough-Grading, LEGOLAND, Carlsbad,
California, Project No. 4960151-003, dated February 10.
2009, Geotechnical Investigation, Proposed Waterworks Cluster,
LEGOLAND Theme Park, Carlsbad, California, Project No. 960151-031, dated
September 30.
2011, Geotechnical Investigation, Proposed Pirate Island Attraction,
LEGOLAND Theme Park, Carlsbad, California, Project No. 960151-035, dated
September 30.
A-i
10075.016
APPENDIX A (Continued)
-, 2013, Geotechnical Update Report, Proposed Water Park Activity Pool,
LEGOLAND Theme Park, Carlsbad, California, Project No. 10075.002, dated July
24.
NCMA, 2009, Design Manual for Segmental Retaining Walls, 3Id Edition
Tan, S. S. and Kennedy; M. P., 1996, Geologic Maps of the Northwestern Part of San
Diego County, California, Division of Mines and Geology (DMG) Open-File
Report 96-02, San Luis Rey and San Marcos Quadrangles.
Treiman, J.A., 1993, The Rose Canyon Fault Zone, Southern California: California
Division of Mines and Geology, Open-File Report 93-02, 45 p.
United States Geologic Survey (USGS), 2010, Ground Motion Parameter Calculator,
Version 5.1.0.
A-2
APPENDIX B
CIDH Pile Capacity Curves
Total ResistancelF.S. (tons)
o io 20 30 40 50 60 70 80 90 100 110 120 130 140
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APPENDIX C
General Earthwork and Grading Specifications
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
1.0 General
1.1 Intent
These General Earthwork and Grading Specifications are for the grading
and earthwork shown on the approved grading plan(s) and/or indicated in
the geotechnical report(s). These Specifications are a part of the
recommendations contained in the geotechnical report(s). In case of
conflict, the specific recommendations in the geotechnical report shall
supersede these more general Specifications. Observations of the
earthwork by the project Geotechnical Consultant during the course of
grading may result in new or revised recommendations that could
supersede these specifications or the recommendations in the
geotechnical report(s).
1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner-shall employ the Geotechnical
Consultant of Record (Geotechnical Consultant). The Geotechnical
Consultants shall be responsible for reviewing the approved geotechnical
report(s) and accepting the adequacy of the preliminary geotechnical
findings, conclusions, and recommendations prior to the commencement
of the grading.
Prior to commencement of grading, the Geotechnical Consultant shall
review the "work plan" prepared by the Earthwork Contractor (Contractor)
and schedule sufficient personnel to perform the appropriate level of
observation, mapping, and compaction testing.
During the grading and earthwork operations, the Geotechnical Consultant
shall observe, map, and document the subsurface exposures to verify the
geotechnical design assumptions. If the observed conditions are found to
be significantly different than the interpreted assumptions during the
design phase, the Geotechnical Consultant shall inform the owner,
recommend appropriate changes in design to accommodate the observed
conditions, and notify the review agency where required. Subsurface
areas to be geotechnically observed, mapped, elevations recorded, and/or
tested include natural ground after it has been cleared for receiving fill but
before fill is placed, bottoms of all "remedial removal" areas, all key
bottoms, and benches made on sloping ground to receive fill.
The Geotechnical Consultant shall observe the moisture-conditioning and
processing of the subgrade and fill materials and perform relative
compaction testing of fill to determine the attained level of compaction.
The Geotechnical Consultant shall provide the test results to the owner
and the Contractor on a routine and frequent basis.
-1-
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced,
and knowledgeable in earthwork logistics, preparation and processing of
ground to receive fill, moisture-conditioning and processing of fill, and
compacting fill. The Contractor shall review and accept the plans,
geotechnical report(s), and these Specifications prior to commencement of
grading. The Contractor shall be solely responsible for performing the
grading in accordance with the plans and specifications.
The Contractor shall prepare and submit to the owner and the
Geotechnical Consultant a work plan that indicates the sequence of
earthwork grading, the number of "spreads" of work and the estimated
quantities of daily earthwork contemplated for the site prior to
commencement of grading. The Contractor shall inform the owner and
the Geotechnical Consultant of changes in work schedules and updates to
the work plan at least 24 hours in advance of such changes so that
appropriate observations and tests can be planned and accomplished.
The Contractor shall not assume that the Geotechnical Consultant is
aware of all grading operations.
The Contractor shall have the sole responsibility to provide adequate
equipment and methods to accomplish the earthwork in accordance with
the applicable grading codes and agency ordinances, these
Specifications, and the recommendations in the approved geotechnical
report(s) and grading plan(s). If, in the opinion of the Geotechnical
Consultant, unsatisfactory conditions, such as unsuitable soil, improper
moisture condition, inadequate compaction, insufficient buttress key size,
adverse weather, etc., are resulting in a quality of work less than required
in these specifications, the Geotechnical Consultant shall reject the work
and may recommend to the owner that construction be stopped until the
conditions are rectified.
2.0 Preparation of Areas to be Filled
2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material
shall be sufficiently removed and properly disposed of in a method
acceptable to the owner, governing agencies, and the Geotechnical
Consultant.
-2-
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
The Geotechnical Consultant shall evaluate the extent of these removals
depending on specific site conditions. Earth fill material shall not contain
more than 1 percent of organic materials (by volume). No fill lift shall
contain more than 5 percent of organic matter. Nesting of the organic
materials shall not be allowed.
If potentially hazardous materials are encountered, the Contractor shall
stop work in the affected area, and a hazardous material specialist shall
be informed immediately for proper evaluation and handling of these
materials prior to continuing to work in that area.
As presently defined by the State of California, most refined petroleum
products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have
chemibal constituents that are considered to be hazardous waste. As
such, the indiscriminate dumping or spillage of these fluids onto the
ground may constitute a misdemeanor, punishable by fines and/or
imprisonment, and shall not be allowed.
2.2 Processing
Existing ground that has been declared satisfactory for support of fill by
the Geotechnical Consultant shall be scarified to a minimum depth of
6 inches. Existing ground that is not satisfactory shall be overexcavated
as specified in the following section. Scarification shall continue until soils
are broken down and free of large clay lumps or clods and the working
surface is reasonably uniform, flat, and free of uneven features that would
inhibit uniform compaction.
2.3 Overexcavation
In addition to removals and overexcavations recommended in the
approved geotechnical report(s) and the grading plan, soft, loose, dry,
saturated, spongy, organic-rich, highly fractured or otherwise unsuitable
ground shall be overexcavated to competent ground as evaluated by the
Geotechnical Consultant during grading.
2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1
(horizontal to vertical units), the ground shall be stepped or benched.
Please see the Standard Details for a graphic illustration. The lowest
bench or key shall be a minimum of 15 feet wide and at least 2 feet deep,
into competent material as evaluated by the Geotechnical Consultant.
Other benches shall be excavated a minimum height of 4 feet into
competent material or as otherwise recommended by the Geotechnical
-3-
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
Consultant. Fill placed on ground sloping flatter than 5:1 shall also be
benched or otherwise overexcavated to provide a flat subgrade for the fill.
2.5 Eva luation/AcceQtance of Fill Areas
All areas to receive fill, including removal and processed areas, key
bottoms, and benches, shall be observed, mapped, elevations recorded,
and/or tested prior to being accepted by the Geotechnical Consultant as
suitable to receive fill. The Contractor shall obtain a written acceptance
from the Geotechnical Consultant prior to fill placement. A licensed
surveyor shall provide the survey control for determining elevations of
processed areas, keys, and benches.
3.0 Fill Material
3.1 General
Material to be used as fill shall be essentially free of organic matter and
other deleterious substances evaluated and accepted by the Geotechnical
Consultant prior to placement. Soils of poor quality, such as those with
unacceptable gradation, high expansion potential, or low strength shall be
placed in areas acceptable to the Geotechnical Consultant or mixed with
other soils to achieve satisfactory fill material.
3.2 Oversize
Oversize material defined as rock, or other irreducible material with a
maximum dimension greater than 8 inches, shall not be buried or placed
in fill unless location, materials, and placement methods are specifically
accepted by the Geotechnical Consultant. Placement operations shall be
such that nesting of oversized material does not occur and such that
oversize material is completely surrounded by compacted or densified fill.
Oversize material shall not be placed within 10 vertical feet of finish grade
or within 2 feet of future utilities or underground construction.
3.3 Import
If importing of fill material is required for grading, proposed import material
shall meet the requirements of Section 3.1. The potential import source
shall be given to the Geotechnical Consultant at least 48 hours (2 working
days) before importing begins so that its suitability can be determined and
appropriate tests performed.
-4-
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
4.0 Fill Placement and Compaction
4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per
Section 3.0) in near-horizontal layers not exceeding 8 inches in loose
thickness. The Geotechnical Consultant may accept thicker layers if
testing indicates the grading procedures can adequately compact the
thicker layers. Each layer shall be spread evenly and mixed thoroughly to
attain relative uniformity of material and moisture throughout.
4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as
necessary to attain a relatively uniform moisture content at or slightly over
optimum. Maximum density and optimum soil moisture content tests shall
be performed in accordance with the American Society of Testing and
Materials (ASTM Test Method D1557).
4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly
spread, it shall be uniformly compacted to not less than 90 percent of
maximum dry density (ASTM Test Method D1557). Compaction
equipment shall be adequately sized and be either specifically designed
for soil compaction or of proven reliability to efficiently achieve the
specified level of compaction with uniformity.
4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction
of slopes shall be accomplished by backrolling of slopes with sheepsfoot
rollers at increments of 3 to 4 feet in fill elevation, or by other methods
producing satisfactory results acceptable to the Geotechnical Consultant.
Upon completion of grading, relative compaction of the fill, out to the slope
face, shall be at least 90 percent of maximum density per ASTM Test
Method D1557.
4.5 Compaction Testing
Field-tests for moisture content and relative compaction of the fill soils
shall be performed by the Geotechnical Consultant. Location and
frequency of tests shall be at the Consultant's discretion based on field
conditions encountered. Compaction test locations will not necessarily be
selected on a random basis. Test locations shall be selected to verify
adequacy of compaction levels in areas that are judged to be prone to
-5-
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
inadequate compaction (such as close to slope faces and at the
fill/bedrock benches).
4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or
1,000 cubic yards of compacted fill soils embankment. In addition, as a
guideline, at least one test shall be taken on slope faces for each
5,000 square feet of slope face and/or each 10 feet of vertical height of
slope. The Contractor shall assure that fill construction is such that the
testing schedule can be accomplished by the Geotechnical Consultant.
The Contractor shall stop or slow down the earthwork construction if these
minimum standards are not met.
4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation
and horizontal coordinates of each test location. The Contractor shall
coordinate with the project surveyor to assure that sufficient grade stakes
are established so that the Geotechnical Consultant can determine the
test locations with sufficient accuracy. At a minimum, two grade stakes
within a horizontal distance of 100 feet and vertically less than 5 feet apart
from potential test locations shall be provided.
5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved
geotechnical report(s), the grading plan, and the Standard Details. The
Geotechnical Consultant may recommend additional subdrains and/or changes in
subdrain extent, location, grade, or material depending on conditions
encountered during grading. All subdrains shall be surveyed by a land
surveyor/civil engineer for line and grade after installation and prior to burial.
Sufficient time should be allowed by the Contractor for these surveys.
6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be
evaluated by the Geotechnical Consultant during grading. Remedial removal
depths shown on geotechnical plans are estimates only. The actual extent of
removal shall be determined by the Geotechnical Consultant based on the field
evaluation of exposed conditions during grading. Where fill-over-cut slopes are
to be graded, the cut portion of the slope shall be made, evaluated, and accepted
by the Geotechnical Consultant prior to placement of materials for construction of
the fill portion of the slope, unless otherwise recommended by the Geotechnical
Consultant.
19
LEIGHTON AND ASSOCIATES, INC.
General Earthwork and Grading Specifications
7.0 Trench Backfills
7.1 Safety
The Contractor shall follow all OSHA and Cal/OSHA requirements for
safety of trench excavations.
7.2 Bedding and Backfill
All bedding and backfill of utility trenches shall be performed in
accordance with the applicable provisions of Standard Specifications of
Public Works Construction. Bedding material shall have a Sand
Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot
over the top of the conduit and densified. Backfill shall be placed and
densified to a minimum of 90 percent of relative compaction from 1 foot
above the top of the conduit to the surface.
The Geotechnical Consultant shall test the trench backfill for relative
compaction. At least one test should be made for every 300 feet of trench
and 2 feet of fill.
7.3 Lift Thickness
Lift thickness of trench backfill shall not exceed those allowed in the
Standard Specifications of Public Works Construction unless the
Contractor can demonstrate to the Geotechnical Consultant that the fill lift
can be compacted to the minimum relative compaction by his alternative
equipment and method.
7.4 Observation and Testing
The densification of the bedding around the conduits shall be observed by
the Geotechnical Consultant.
-7-
FILL SLOPE
PROJECTED PLANE 1: 1-
(HORIZONTAL: VERTICAL)
MAXIMUM FROM TOE
OF SLOPE TO
APPROVED GROUND
f "REMOVE
EXISTiNG ----_- --- UNSUITABLE
GROUND SURFACE\ - -:-:--:-: I BENCH MATERIAL F:- :----c-x-:-- 1 • RFN(H HFIHT
(4 FEET TYPICAL)
2 FEET MIN LOWEST
KEY DEPTH BENCH (KEY)
FILL-OVER-CUT SLOPE
EXISTING
GROUND SURFACE
/
I - -:--:-: -BENCH
1-15 FEET MIN.
LOWEST
2 FEET BENCH (KEY)
MIN. KEY
DEPTH
BENCH HEIGHT
(4 FEET TYPICAL)
REMOVE
UNSUITABLE
MATERIAL
CUT-OVER-FLL SLOPE
CUT FACE
SHALL BE CONSTRUCTED PRIOR TO /
FILL PLACEMENT TO ALLOW VIEWiNG /,'
OF GEOLOGIC CONDITIONS
EXISTING-------,/
GROUND
SURFACE ---..-- -
CUT FACE SHALL BE
CONSTRUCTED PRIOR
TO FILL PLACEMENT
OVERBUILD AN
TRIM BACK
DESIGN SLOPE--76 PROJECTED PLANE -•
1 TO 1 MAXIMUM
FROM TOE OF SLOPE
TO APPROVED GROUND
-:-:-2? .M1N-:-:-:
1I 15 FEET MIN.
2 FEET MIN. LOWEST
KEY DEPTH BENCH (KEY)
REMOVE
UNSUITABLE
MATERIAL
BENCH HEIGHT
(4 FEET TYPICAL)
BENCHING SHALL BE DONE WHEN SLOPE'S
ANGLE IS EQUAL TO OR GREATER THAN 5:1.
MINIMUM BENCH HEIGHT SHALL BE 4 FEET
AND MINIMUM FILL WIDTH SHALL BE 9 FEET.
KEYING AND BENCHING
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL A 4
NISH GRADE
SLOPE FACE
---------------
------ ~`
OVERSIZE WINDROW
OVERSIZE ROCK IS LARGER THAN
8 INCHES IN LARGEST DIMENSION.
* EXCAVATE A TRENCH IN THE COMPACTED
FILL DEEP ENOUGH TO BURY ALL THE
ROCK.
' BACKFILL WITH GRANULAR SOIL JETTED
OR FLOODED IN PLACE TO FILL ALL THE
VOIDS.
* DO NOT BURY ROCK WITHIN 10 FEET OF
FINISH GRADE.
WINDROW OF BURIED ROCK SHALL BE
PARALLEL TO THE FINISHED SLOPE.
b
GRANULAR MATERIAL TO BE' DETAIL DENSIFIED IN PLACE BY
FLOODING OR JETTING.
-JETTED OR FLOODED
GRANULAR MATERIAL
TYPICAL PROFILE ALONG WINDROW
OVERSIZE ROCK
DISPOSAL
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL B
B
,
/
/
/
MOVE
SUITABLE
TERIAL
TRENCH
SEE DETAIL BELOW
FILTER FABRIC
(MIRAFI 140N OR APPROVED
EOUIVA•LENT)
CALTRANS CLASS 2 PERMEABLE 6" MIN.
OR #2 ROCK (9FT3/FT) WRAPPED COVER
IN FILTER FABRIC
4" MIN. BEDDING
COLLECTOR PIPE SHALL
BE MINIMUM 6" DIAMETER
SCHEDULE 40 PVC PERFORATED
PIPE. SEE STANDARD DETAIL 0
SUBDRAIN DETAIL
FOR PIPE SPECIFICATIONS
DESIGN FINISH
GRADE
MIN. FILTER FABRIC
I
BACKFILL / (MIRAFI 140N OR APPROVED
/ EQUIVALENT)
.... . 'S . • ..-CALTRANS CLASS 2 PERMEABLE
-. " OR #2 ROCK (9FT'3/FT) WRAPPED II • . • . . . IN FILTER FABRIC
20 MIN. "IS MIN. PERFORATED
NONPERFORATED 6"0 MIN. 6" ØMIN. PIPE
DETAIL OF CANYON SUBDRAIN OUTLET
CANYON SUBDRAINS GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL C
* 15' MIN. -
OUTLET PIPES
4' 0 NONPERFORATED PIPE,
100' MAX. O.C. HORIZONTALLY,
30' MAX O.C. VERTICALLY
!BAcK CUT
OR FLATTER
BENCH
SEE SUBDRAIN TRENCH
DETAIL
LOWEST SUBDRAIN SHOULD
BE SITUATED AS LOW AS
POSSIBLE TO ALLOW
SUITABLE OUTLET
KEY WIDTH
KEY DEPTH
NOTED ON GRADING PLANS' 12" MIN. OVERLAP—, TH (15' MIN.)
(2' MIN.) FROM THE TOP HOG I
6 FEET 1-CONNECTION
FOR COLLECTOR
RING TIED EVERY
CALTRANS CLASS II PIPE TO OUTLET PIPE
-
ROCK (3 FT-3/FT)
PERMEABLE OR #2
WRAPPED IN FILTER 6" MIN.
FABRIC COVER
PERFORATED
4" 0 4" 0
,ON-PERFORATED
J.... PIPE OUTLET PIPE -
- -
4" MIN.
BEDDING
PROVIDE POSITIVE FILTER FABRIC
SEAL AT THE ENVELOPE (MIRAFI
JOINT 140 OR APPROVED
EQUIVALENT)
SUBDRAIN TRENCH DETAIL
SUBDRAIN INSTALLATION - subdroin collector pipe sholl be installed with perforation down or,
unless otherwise designated by the geotechnicol consultant. Outlet pipes shall be non-perforoted
pipe. The subdroin pipe sholl have at least 8 perforations uniformly spaced per foot. Perforation
sholl be 1/4" to 1/2 if drill holes ore used. All subdroin pipes shall have o grodieAt of at
least 2Z towards the outlet.
SUBDRAIN PIPE - Subdroin pipe sholl be ASTM D2751, SDR 23.5 or ASTM D1527, Schedule 40. or
ASTM 03034, SDR 23.5. Schedule 40 Polyvinyl Chloride Plastic (PVC) pipe.
All outlet pipe shall be placed in 0 trench no wider than twice the subdroin pipe.
BUTTRESS OR GENERAL EARTHWORK AND -4011,
REPLACEMENT GRADING SPECIFICATIONS
FILL SUBDRAINS STANDARD DETAIL
CUT-FILL TRANSITION LOT OVEREXCAVATION
REMOVE UNSUITABLE
-
I- GROUND-\
- -r - -
- -1-' 5 - IMIN. I
________---------'f
------------__-- ------- XX)/O(\X/O.X\X)?cJ 5' MIN --COMPACTEDFIL+----.—
-_-_--_-_-_--_----_---_ K\/' ----------------
OVEREXCAVATE
_.... AND RECOMPACT
- - - - - - - -...TYPICAL
- - - BENCHING
- - UNWEATHERED BEDROCK OR MATERIAL APPROVED
\ .\\ BY THE GEOTECHNICAL CONSULTANT
TRANSITION LOT FILLS
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL E
SOIL BACKFILL COMPACTED TO
90 PERCENT RELATIVE COMPACTION
BASED ON ASTM 01557
--:------:-----:-}]2
RETAINING WALL WALI--.. ------------- -----------
F-7-7-
6 ' MIN.
WALL WATERPROOFING -.
OVERLAP I:.c:: FILTER FABRIC ENVELOPE
PER ARCHITECT'S • • (MIRAFI 140N OR APPROVED
SPECIFICATIONS
-. I
• " EQUIVALENT)
oo : MIN0
l
.1 ::::: /TO 1-1/2° CLEAN GRAVEL lo 34
FINISH GRADE 0 • 4 (MIN.) DIAMETER PERFORATED
/ 1' ° PVC PIPE (SCHEDULE 40 OR
7 I • ° . I-:-:-:-: EQUIVALENT) WITH PERFORATIONS
ORIENTED DOWN AS DEPICTED ° MINIMUM 1 PERCENT GRADIENT
4o -_ TO SUITABLE OUTLET -------------------------------- -----------
3" MIN.
WAIL FOOTING
COMPETENT BEDROCK OR MATERIAL
AS EVALUATED BY THE GEOTECHNICAL
CONSULTANT
NOTE: UPON REVIEW BY THE GEOTECHNICAL CONSULTANT,
COMPOSITE DRAINAGE PRODUCTS SUCH AS MIRADRAIN OR
J—DRAIN MAY BE USED AS AN ALTERNATIVE TO GRAVEL OR
CLASS 2 PERMEABLE MATERIAL. INSTALLATION SHOULD BE
PERFORMED IN ACCORDANCE WITH MANUFACTURER'S
SPECIFICATIONS.
RETAINING WALL
DRAINAGE
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL F
ACTIVE
ZONE
-FILTER FABRIC
L__JS-------------------_____ /
e -4 REINFORCED RETAINED
ZONE ZONE / /
/ "L BACKDRAIN
/ 1070%OF
..' / WALL HEIGHT
I
-- /
4 FTER FABRIC /
GRAVEL • .'
DRAINAGE FILL —WALL SUBDRAIN \ MIN 6" BELOW WALL REAR SUBDRAIN:
MIN 12" BEHIND UNITS 4" (MIN) DIAMETER PERFORATED PVC PIPE
I FOUNDATION SOILSI (SCHEDULE 40 OR EQUIVALENT) WITH
PERFORATIONS DOWN. SURROUNDED BY
1 CU. FT/FT OF 3/4" GRAVEL WRAPPED IN
FILTER FABRIC (MIRAFI 140N OR EQUIVALENT)
OUTLET SUBDRAINS EVERY 100 FEET, OR CLOSER, NOTES: BY TIGHTLINE TO SUITABLE PROTECTED OUTLET
MATERIAL GRADATION AND PLASTICITY
REINFORCED ZONE: GRAVEL DRAINAGEEILL
SIEVE SIZE % PASSING SIEVE SIZE %_PASSING
1 INCH 100 1 INCH 100
NO. 4 20-100 3/4 INCH 75-100
NO. 40 0-60 NO.4 0-60
NO. 200 0-35 NO. 40 0-50
FOR WALL HEIGHT < 10 FEET, PLASTICITY INDEX <20 NO. 200 0-5
FOR WALL HEIGHT 10 TO 20 FEET, PLASTICITY INDEX < 10
FOR TIERED WALLS, USE COMBINED WALL HEIGHTS
WALL DESIGNER TO REQUEST SITE-SPECIFIC CRITERIA FOR WALL HEIGHT >20 FEET
CONTRACTOR TO USE SOILS WITHIN THE RETAINED AND REINFORCED ZONES THAT MEET THE STRENGTH REQUIREMENTS OF WALL DESIGN.
GEOGRID REINFORCEMENT TO BE DESIGNED BY WALL DESIGNER CONSIDERING INTERNAL, EXTERNAL, AND COMPOUND STABILITY.
3) GEOGRID TO BE PRETENSIONED DURING INSTALLATION.
IMPROVEMENTS WITHIN THE ACTIVE ZONE ARE SUSCEPTIBLE TO POST-CONSTRUCTION SETTLEMENT. ANGLE a -45+0/2, WHERE 4 IS THE
FRICTION ANGLE OF THE MATERIAL IN THE RETAINED ZONE.
BACKDRAIN SHOULD CONSIST OF J-DRAIN 302 (OR EQUIVALENT) OR 6-INCH THICK DRAINAGE FILL WRAPPED IN FILTER FABRIC. PERCENT
COVERAGE OF BACKDRAIN TO BE PER GEOTECHNICAL REVIEW.
SEGMENTAL I GENERAL EARTHWORK AND At
GRADING SPECIFICATIONS RETAINING WALLS STANDARD DETAIL G I Mw