HomeMy WebLinkAboutGeotechnical Report Rough Grading
. ~INLAND, INC.
. Geotechnical Consulting
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GEOTECHNICAL REPORT OF ROUGH GRADING
TENTATIVE TRACTS 23513 (Il LOTS)
AND 29466 (4 LOTS)
CITY OF TEMECULA, RIVERSIDE COUNTY
CALIFORNIA
Project No. 104721-30
Dated: August 19,2005
Prepared For:
Mr. David R. Meade
GALLERY DEVELOPMENT
31618-1 Railroad Canyon Road
Canyon Lake, California
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41531 Date Street - Murrieta, CA- (951) 461-1919 - Fax1951) 461-7677
· 1m INLAND, INC.
. Geotechnical Consulting
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August 19,2005
Project No, I04721-30
Mr. David R. Meade
GALLERY DEVELOPMENT
31618-1 Railroad Canyon Road
Canyon Lake, California 92587
Subject:
Geotechnical Report of Rough Grading, Tentative Tracts 23513 (Illots) and 29466 (4 lots),
City of Temecula, Riverside County, California
This report presents a summary of the observation and testing services provided by LGC Inland, Inc., (LGC)
during rough grading operations to develop the subject site in the City of Temecula, Riverside County,
California. Conclusions and recommendations pertaining to the suitability of the grading for the proposed
residential construction are provided herein, as well as foundation-design recommendations based on the as-
graded soil conditions.
The purpose of grading was to develop 15 lots for construction of single family residences, as well as to provide
appurtenant infrastructure facilities. The proposed residential structures will be one- and two-story structures
with wood or steel-framed construction. Grading on the subject pads began during March of 2005 and was
completed during June of2005.
1.0
REGULATORY COMPLIANCE
Removal and re-compaction of low-density surface soils, processing of the exposed bottom surfaces or
placement of compacted fill under the purview of this report have been completed under the observation and
with selective testing by LGC. Earthwork and grading operations were performed in general accordance with
the recommendations presented in the referenced reports (see References) and the grading code of the City of
Temecula, California. The completed earthwork has been reviewed and is considered adequate for the
construction now planned. On the basis of our observations and field and laboratory testing, the
recommendations presented in this report were prepared in conformance with generally accepted professional
engineering practices and no further warranty is expressed or implied.
2.0
ENGINEERING GEOLOGY
2,1
General
Geologic conditions exposed during the process of grading were frequently observed and mapped by
LGC's geologic/technical staff.
2.2
Geolordc Units
Earth materials within the site included alluvial silty sands, clayey sand, and Pauba Formation
sandstones.
2.3
Groundwater
During over-excavations, no free groundwater was encountered.
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41531 Date Street - Murrieta, CA - (951) 461-1919 - Fax (951) 461-7677
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2.4 Faultinf!
No faults were observed during grading operations on the site.
3.0 SUMMARY OF EARTHWORK OBSERVA TIONS AND DENSITY TESTING
3.1 Site Clearinf! and Grubbinf!
Prior to grading, all grasses and weeds were stripped and removed from the site.
3.2 Ground Preparation
The purpose of this grading operation was to provide either a compacted fill mat or native bedrock
material under each of the individual building sites. In proposed areas where fills and/or shallow cuts
less than 3 feet below original ground surface were planned, overexcavation of existing ground surfaces
extended into the underlying Pauba Formation bedrock to remove the existing alluvium and/or
colluvium. All cut/fill transitions were eliminated by overexcavating the cut areas and constructing a
compacted fill with a minimum thickness of 4 feet. Removals throughout most the of subject site
varied from approximately 4 to 12 feet below original grades, with locally deeper removals, up to 14
feet, in some areas.
In cut areas greater than 3 feet below original ground surface, the exposed cuts were observed and
additional overexcavation and re-compaction with depths ranging from 4 to 10 feet below finish grade
were applied in these areas in order to provide a uniform, compacted fill mat below the proposed
structures (shown on Plate I).
Prior to placing fill, the exposed bottom surfaces were scarified to depths of 6 to 8 inches, watered or
air-dried as necessary to achieve at or slightly above optimum moisture content and then re-compacted
in-place to a minimum relative compaction of90 percent.
3.3 Disposal of Oversize Rock
Oversize rock (rock generally greater than I-foot in maximum dimension) was not encountered during
the removal operations.
3,4 Fill Placement and Testinf!
Fill materials consist of onsite soils. All fills were placed in lifts restricted to approximately 6 to 8
inches in maximum thickness, watered or air-dried as necessary to achieve near optimum moisture
conditions, then compacted in-place to a minimum relative compaction of 90 percent by rolling with an
834 rubber-tired bulldozer or loaded scrapers. The maximum vertical depth of fill placed within the
subject pads as a result of grading is approximately 15 feet.
Field density and moisture content tests were performed in accordance with ASTM Test Methods D2922
and D3017 (nuclear gauge). Test results are presented on Table 11 (attached) and test locations are
shown on the enclosed As - Graded Geotechnical Map (Figure I).
Field density tests were taken at vertical intervals of approximately I to 2 feet and the compacted fills
were tested at the time of placement to verify that the specified moisture content and minimum required
relative compaction of 90 percent had been achieved. At least one in-place density test was taken for
each 1,000 cubic yards of fill placed and/or for each 2 feet in vertical height of compacted fill. The
actual number of tests taken per day varied with the project conditions, such as the number of ~
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earthmovers (scrapers) and availability of support equipment. When field density tests produced results
less than the required minimum relative compaction of 90 percent, the approximate limits of the
substandard fill were established. The substandard area was then reworked, moisture conditioned, re-
compacted, and retested until the minimum relative density was achieved.
Visual classification of earth materials in the field was the basis for determining which maximum dry
density value, summarized in Appendix B, was applicable for a given density test. One-point checks
were periodically performed to supplement visual classification.
3.5 Slopes
Slopes constructed within the subject site consist oflow-height 2: I horizontal to vertical (h:v) cut slopes
and low to moderate height fill slopes varying to a maximum height of:!: 70 feet.
The factors of safety of the slopes with heights greater than 30 feet, which were deemed critical from a
geotechnical perspective, were determined during our analysis. A two-dimensional (2D) cross section
was prepared for the fill slope on Lot 9 that exceeded 30 feet in height, see Cross Section A-A' and
which was deemed typical for the project. In general, 2D cross sections depict the slope height, slope
ratio, and relevant geologic information. Based on laboratory test results and/or previous experience
with similar materials, the geotechnical engineering properties of each geologic unit were assigned. The
main properties utilized in our analyses are the unit weight and shear strength (friction angle and
cohesion) of each material.
Each cross section was digitized and entered into the computer program GSTABLE7. GSTABLE7 is a
dynamic limit equilibrium slope stability program, which utilizes the Modified Bishop Method,
Sirnplified Janbu Method, and Spencer's Method to determine the factor of safety for the slopes. The
factor of safety was calculated based on the principles of soil mechanics and is defined as the quotient of
the ratio of the sum of the forces tending to resist failure divided by the sum of the forces tending to
cause failure. The computer program allows the critical failure surface to be composed of circles, planes
or other shapes considered to yield the minimum factor of safety. The actual shape of the failure surface
is primarily driven by the geologic structure of the units shown on the cross-sections.
The factor of safety of the slope was evaluated under both static and pseudo static loading conditions.
Per local code requirements, the minimum acceptable factor of safety was taken as 1.5 for static loading
and 1.1 for pseudostatic loading. Pseudostatic analysis included the effects of static loads combined
with a horizontal inertial force acting out of slope and through the center of gravity of the potential
sliding mass. A minimum pseudostatic horizontal force equal to 0.15 times gravity was applied to the
same critical surface as determined during static analysis.
To evaluate the stability of the near surface soils, the factor of safety with regard to surficial failure can
be calculated. To perform this calculation, the geotechnical engineering properties of the near surface
soils, including unit weight and shear strength characteristics, are assigned. The surficial stability of the
slope face can be calculated using an infinite slope with seepage occurring parallel to the slope face. In
the analysis, the vertical depth of the soil saturation is taken as a minimum of 4 feet. Per local code
requirements, the minimum acceptable factor of safety for surficial stability is 1.5 for static loading.
Our calculations indicate that uniform compacted fill slopes are surficially stable with a factor of safety
greater than 1.5, see Surficial Stability - Calculation Sheet No. I, enclosed herein.
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Our review of the grading plan indicates that a fill slope is planned below the proposed project (Cross
Section A-A', Plate) approximately 70 feet high at a 2:1 (h:v) slope orientation. Our static and
pseudostatic analyses indicate that the proposed compacted fill, cut, and native slopes exceed the
minimum required factors of safety. A tabulation of the slope stability results is presented below in
Table!.
TABLE 1
FACTORS OF SAFETY
;SLOPE TyPE .... HEIGHT r{t} .. STATIC .. PSE1)JJOSTAtIC . . SURFICIAL.
2:1 Compacted Fill @ :1:70 1.86 1.32 1.60
Lot 9, typical
4.0 LABORATORY TESTING
4.1 Maximum Drv Densitv
Maximum dry density and optimum moisture content for the major soil types observed during grading
were determined in our laboratory in accordance with ASTM Test Method DI557-00. Pertinent test
values are summarized in Appendix B.
4.2 Expansion Index Tests
Expansion index tests were performed on representative samples of soil existing at or near finish-pad
grade within the subject building pads. These tests were performed in accordance with ASTM D4829-
03. Test results are summarized in Appendix B.
4.3 Soluble Sulfate Analvses
Water-soluble sulfate contents were also determined for representative samples of soil existing at or near
pad grade of the subject pads in accordance with California Test Method No. 417. These tests resulted
in negligible sulfate contents ofless than 0.1 percent. Test results are summarized in Appendix B.
5.0 POST GRADING CONSIDERATIONS
5.1 Landscapinf! and Maintenance of Graded Slopes
The fill slopes within the subject tract areas vary up to a maximum height of approximately 70 feet.
Unless long term mitigation measures are taken, the slopes may be subject to a low to moderate degree
of surficial erosion or degradation during periods of heavy rainfall. Therefore, it is recommended that
fill slopes be landscaped with a deep-rooted, drought-resistant, woody plant species. To provide
temporary slope protection while the woody materials mature, the slopes should be planted with an
herbaceous plant species that will mature in one season or provided with some other protection, such as
jute matting or polymer covering. The temporary protection should be maintained until the woody
material has become fully mature. A landscape architect should be consulted to determine the most
suitable plant materials and irrigation requirements.
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To mitigate future surficial erosion and slumping, a permanent slope-maintenance program should be
initiated. Proper slope rnaintenance must include regular care of drainage- and erosion-control
provisions, rodent control, prompt repair of leaking irrigation systems and replacement of dying or dead
plant materials. The irrigation systern should be designed and maintained to provide constant moisture
content in the soils. Over-watering, as well as over-drying, of the soils can lead to surficial erosion
and/or slope deterioration.
The owners should be advised of the potential problems that can develop when drainage on their pads
and adjacent slopes is altered in any way. Drainage can be adversely altered due to the placement of fill
and construction of garden walls, retaining walls, walkways, patios, swimming pools and planters.
5.2 Pad Drainafle
Drainage on the pads should be designed to carry surface water away from all graded slopes and
structures. Pad drainage should be designed for a minimum gradient as requires by the UBC with
drainage directed to the adjacent drainage facilities or other location approved by the building official.
Ground adjacent to foundations shall be graded so that it is sloped away from the building at least 12:1
(h:v) (4.8") for a minimum distance of 6 feet, or another alternative approved way shall be found to
divert water from the foundation. After dwellings are constructed, positive drainage away from the
structures and slopes should be provided on the lots by rneans of earth swales, sloped concrete flatwork
and area drains.
5.3 Uti/itv Trenches
All utility-trench backfill within street right-of-ways, utility easements, under sidewalks, driveways and
building floor slabs and within or in proximity to slopes, should be compacted to a minimum relative
compaction of 90 percent. Where onsite soils are utilized as backfill, mechanical compaction will be
required. Density testing, along with probing, should be performed by a LGC representative to verify
adequate compaction. Excavations for trenches that exceed 4 feet in depth should be laid-back at a
maximum gradient of I: I (h:v).
For deep trenches with vertical walls, backfills should be placed in lifts no greater than 6 - to 8 - inches
in thickness and then mechanically compacted with a hydra-hammer, pneumatic tampers or similar
equipment. For deep trenches with sloped walls, backfill materials should be placed in lifts no greater
than 8 inches and then compacted by rolling with a sheepsfoot tamper or sirnilar equipment.
Where utility trenches are proposed parallel to any building footing (interior and/or exterior trenches),
the bottom of the trench should not be located within a I: I (h:v) plane projected downward from the
outside bottom edge of the adjacent footing.
6.0 FOUNDATION DESIGN RECOMMENDATIONS
6.1 General
Conventional shallow foundations are considered feasible for support of the proposed residential
structures. Foundation recommendations are provided below.
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6.2 Allowable Bearinf! Values
An allowable bearing value of 1,500 pounds per square foot (pst) is recommended for design of 24-inch-
square pad footings and 12-inch-wide continuous footings founded at a minimum depth of 12-inches
below the lowest adjacent final grade. This value may be increased by 20 percent for each additional I
foot of width and/or depth to a maximum value of 2,500 pounds per square foot. Recommended
allowable-bearing values include both dead and live loads and may be increased by one-third when
designing for short-duration wind and seismic forces.
6.3 Settlement
Based on the general settlement characteristics of the soil types that underlie the building sites and the
anticipated loading, it has been estimated that the maximum total settlement of conventional footings
will be less than approximately %-inch. Differential settlement is expected to be about Yz-inch over a
horizontal distance of approximately 20 feet, for an angular distortion ratio of 1 :480. It is anticipated
that the majority of the settlement will occur during construction or shortly thereafter as building loads
are applied.
The above settlement estimates are based on the assumption that the grading was performed in
accordance with the grading recommendations presented in this report and that the project geotechnical
consultant will observe or test the soil conditions in the footing excavations.
6.4 Lateral Resistance
A passive earth pressure of 250 psf per foot of depth to a maximum value of 2,500 psf may be used to
determine lateral-bearing resistance for footings. Where structures are planned in or near descending
slopes, the passive earth pressure should be reduced to 150 psf per foot of depth to a maximum value of
1,500 psf. In addition, a coefficient of friction of 0.40 times the dead-load forces may be used between
concrete and the supporting soils to determine lateral sliding resistance. The above values may be
increased by one-third when designing for short-duration wind or seismic forces.
The above values are based on footings placed directly against compacted fill. In the case where footing
sides are formed, all backfill placed against the footings should be compacted to a minimum of 90
percent of maximum dry density.
6.5 Footinf! Observations
All foundation excavations should be observed by the project geotechnical engineer to verify that they
have been excavated into competent bearing materials. The foundation excavations should be observed
prior to the placement of forms, reinforcement or concrete. The excavations should be trimmed neat,
level and square. All loose, sloughed or moisture softened soil should be removed prior to concrete
placement.
Excavated materials from footing excavations should not be placed in slab-on-grade areas unless the
soils are compacted to a minimum 90 percent of maximum dry density.
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6.6 Expansive Soil Considerations
6.6.1 Verv Low Expansion Potential (Expansion Index 0(20 or Less)
Results of our laboratory tests indicate onsite soils exhibit a VERY LOW expansion potential as
classified in accordance with Table IS-I-B of the 1997 Uniform Building Code (UBC). Since
the onsite soils exhibit expansion indices of 20 or less, the design of slab-on-ground foundations
is exempt from the procedures outlined in Section ISI5. Based on the above soil conditions, it is
recommended that footings and floors be constructed and reinforced in accordance with the
following minimum criteria. However, additional slab thickness, footing sizes and/or
reinforcement should be provided as required by the project architect or structural engineer.
6.6.1.1 Footinfls
. Exterior continuous footings may be founded at the minimum depths indicated in UBC
Table IS-I-C (i.e. l2-inch minimum depth for one-story and IS-inch minimum depth for
two-story construction). Interior continuous footings for both one- and two-story
construction may be founded at a minimum depth of 12 inches below the lowest adjacent
grade. All continuous footings should have a minimum width of 12 and IS inches, for
one-story and two-story buildings, respectively, and should be reinforced with two No.4
bars, one top and one bottom.
. Exterior pad footings intended for the support of roof overhangs, such as second story
decks, patio covers and similar construction should be a minimum of 24 inches square
and founded at a minimum depth of IS inches below the lowest adjacent final grade. No
special reinforcement of the pad footings will be required.
6.6.1.2 Bui/dinfl Floor Slabs
. Concrete floor slabs should be 4 inches thick and reinforced with either 6-inch by 6-inch,
No.6 by No.6 welded wire mesh (6x6-W2.9xW2.9); or with No.3 bars spaced a
maximum of 24 inches on center, both ways. All slab reinforcement should be supported
on concrete chairs or bricks to ensure the desired placement near mid-depth.
. Interior floor slabs with moisture sensitive floor coverings should be underlain by a 15-
mil thick moisture/vapor barrier to help reduce the upward migration of moisture from
the underlying sub grade soils. The moisture/vapor barrier product used should meet the
performance standards of an ASTM E 1745 Class A material, and be properly installed in
accordance with ACI publication 302. It is the responsibility of the contractor to ensure
that the rnoisture/vapor barrier systems are placed in accordance with the project plans
and specifications, and that the moisture/vapor retarder materials are free of tears and
punctures prior to concrete placement. Additional moisture reduction and/or prevention
measures may be needed, depending on the performance requirements of future interior
floor coverings.
Recommendations are traditionally included with geotechnical foundation
recommendations or sand layers placed below slabs and above/below vapor barriers and
retarders for the purpose of protecting the barrier/retarder and to assist in concrete curing.
Sand layer requirements are the purview of the foundation engineer/structural engineer,
and should be provided in accordance with ACI Publication 302 "Guide for Concrete
Floor and Slab Construction". We have provided recommendations in Table I that we
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consider to be a minimum from a geotechnical perspective. These recommendations must
be confirmed (and/or altered) by the foundation engineer, based upon the performance
expectations of the foundation. Ultimately, the design of the moisture retarder system and
recommendations for concrete placement and curing are the purview of the foundation
engineer, in consideration of the project requirements provided by the architect and
developer.
. Garage area floor slabs should be 4 inches thick and should be reinforced in a similar
manner as living-area floor slabs. Garage area floor slabs should also be placed
separately from adjacent wall footings with a positive separation maintained with 3/S-
inch-minimum felt expansion-joint materials and quartered with weakened-plane joints.
A 12-inch-wide grade beam founded at the same depth as adjacent footings should be
provided across garage entrances. The grade beam should be reinforced with a minimum
oftwo No.4 bars, one top and one bottom.
. Prior to placing concrete, the subgrade soils below all living-area and garage area floor
slabs should be pre-watered to promote uniform curing of the concrete and minimize the
development of shrinkage cracks.
6.7 Post Tensioned Slab/Foundation Desifln Recommendations
In lieu of the proceeding recommendations for conventional footing and floor slabs, post tensioned slabs
may be utilized for the support of the proposed structures. We recommend that the foundation engineer
design the foundation system using the geotechnical parameters provided below in Table I. These
parameters have been determined in general accordance with Chapter IS Section ISI6 of the Uniform
Building Code (UBC), 1997 edition. Alternate designs are allowed per 1997 UBC Section IS06.2 that
addresses the effects of expansive soils when present. In utilizing these parameters, the foundation
engineer should design the foundation system in accordance with the allowable deflection criteria of
applicable codes and the requirements ofthe structural engineer/architect.
Please note that the post tensioned design methodology reflected in UBC Chapter IS is in part based on
the assumption that soil moisture changes around and beneath the post-tensioned slabs are influenced
only by climatological conditions. Soil moisture change below slabs is the major factor in foundation
damages relating to expansive soil. The UBC design methodology has no consideration for
presaturation, owner irrigation, or other nonclimate related influences on the moisture content of
subgrade soils. In recognition of these factors, we have modified the geotechnical parameters obtained
from this methodology to account for reasonable irrigation practices and proper homeowner
maintenance. In addition, we recommend that prior to foundation construction, slab sub grades be
presoaked to 12 inches prior to trenching and maintained at above optimum moisture up to concrete
construction. We further recommend that the moisture content of the soil around the immediate
perimeter of the slab be maintained near optimum moisture content (or above) during construction and
up to occupancy.
The following geotechnical parameters provided in the Table below assume that if the areas adjacent to
the foundation are planted and irrigated, these areas will be designed with proper drainage so ponding,
which causes significant moisture change below the foundation, does not occur. Our recommendations
do not account for excessive irrigation and/or incorrect landscape design. Sunken planters placed
adjacent to the foundation, should either be designed with an efficient drainage system or liners to
prevent moisture infiltration below the foundation. Some lifting of the perimeter foundation beam
should be expected even with properly constructed planters. Based on the design parameters we have
provided, and our experience with monitoring similar sites on these types of soils, we anticipate that if
a
Project No. 104721-30 Page 8 August 19.2005 0
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the soils become saturated below the perimeter of the foundations due to incorrect landscaping irrigation
or maintenance, then up to approximately ~-inch of uplift could occur at the perimeter of the foundation
relative to the central portion of the slab.
Future owners should be informed and educated regarding the importance of maintaining a consistent
level of soil moisture. The owners should be made aware of the potential negative consequences of both
excessive watering, as well as allowing expansive soils to become too dry. The soil will undergo
shrinkage as it dries up, followed by swelling during the rainy winter season, or when irrigation is
resumed. This will result in distress to site improvements and structures.
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Preliminarv Geotechnical Parameters for Post Tensioned Foundation Slab Desifln
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PARAMETER ' .. VALUE "
Expansion Index Very Low'
Percent that is Finer than 0.002 mm in the Fraction Passing the No. < 20 percent (assumed)
200 Sieve.
Clay Mineral Tvoe Montmorillonite (assumed)
Thornthwaite Moisture Index -20
Depth to Constant Soil Suction (estimated as the depth to constant 7 feet
moisture content over time, but within UBC limits)
Constant Soil Suction P.F.3.6
Moisture Velocitv 0.7 inches/month
Center Lift Edge moisture variation distance, em 5.5 feet
Center lift, yon
1.5 inches
Edge Lift Edge moisture variation distance, em 2.5 feet
Edge lift, yon
0.4 inches
Soluble Sulfate Content for Design of Concrete Mixtures in
Contact with Site Soils in Accordance with 1997 UBC Table 19-A- Negligible
4
Modulus of Subgrade Reaction, k (assuming presaturation as 200 pci
indicated below)
Minimum Perimeter Foundation Embedment 12
Perimeter foundation reinforcement NaneL
Minimum slab thickness 6 inches
Under slab moisture retarder and sand layer 15-mil thick moisture retardant (or equivalent) in conformance
with an ASTM E 1745 Class A material overlain by I-inch of
sand3
1. Assumed for design purposes or obtained by laboratory testing.
2. Recommendations for foundation reinforcement are ultimately the purview of the foundation/structural engineer based upon the
geotechnical criteria presented in this report, and structural engineering considerations.
3. Recommendations for sand below slabs are traditionally included with the geotechnical foundation recommendations, although
they are not the purview of the geotechnical consultant. The sand layer requirements are the purview of the foundation
engineer/structural engineer and should be provided in accordance with ACI Publication 302, Guide for Concrete Floor and Slab
Construction.
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6.8 Corrosivitv to Concrete
The National Association of Corrosion Engineers (NACE) defines corrosion as "a deterioration of a
substance or its properties because of a reaction with its enviromnent." From a geotechnical viewpoint,
the "enviromnent" is the prevailing foundation soils and the "substances" are the reinforced concrete
foundations or various buried metallic elements such as rebar, piles, pipes, etc., which are in direct
contact with or within close vicinity of the foundation soil.
In general, soil environments that are detrimental to concrete have high concentrations of soluble
sulfates and/or pH values of less than 5.5. Table 19-A-4 of the U.B.C., 1997, provides specific
guidelines for the concrete mix design when the soluble sulfate content of the soils exceeds 0.1 percent
by weight or 1,000 ppm.
Based on testing performed within the project area, the onsite soils are classified as having a negligible
sulfate exposure condition in accordance with Table 19-A-4 ofU.B.C., 1997. Therefore, in accordance
with Table 19-A-4 structural concrete in contact with earth materials should have cement of Type 1 or II.
Despite the minimum recommendation above, LGC is not a corrosion engineer, therefore, we
recommend that you consult with a competent corrosion engineer and conduct additional testing (if
required) to evaluate the actual corrosion potential of the site and provide recommendations to mitigate
the corrosion potential with respect to the proposed improvements. The recommendations of the
corrosion engineer may supercede the above requirements.
6.9 Structural Setbacks
Structural setbacks in addition to those required in the UBC, are not required due to geologic or
geotechnical conditions within the site. Building setbacks from slopes, property lines, etc. should
conform to 1997 UBC requirements.
7.0 RETAINING WALLS
7.1 Active and At-Rest Earth Pressures
An active earth-pressure represented by an equivalent fluid having a density of 35 pounds per cubic foot
(pcf) should tentatively be used for design of retaining walls up to 10 feet high retaining a drained level
backfill. Where the wall backfill slopes upward at 2: I (h:v), the above value should be increased to 52
pcf. All retaining walls should be designed to resist any surcharge loads imposed by other nearby walls
or structures in addition to the above active earth pressures.
For design of retaining walls up to 10 feet high that are restrained at the top, an at-rest earth pressure
equivalent to a fluid having a density of 53 pcf should tentatively be used for walls supporting a level
backfill. This value should be increased to 78 pcffor ascending 2:1 (h:v) backfill.
7.2 Drainafle
Weep holes or open vertical masonry joints should be provided in retaining walls to prevent entrapment
of water in the backfill. Weep holes, if used, should be 3 inches in minimum diameter and provided at
minimum intervals of 6 feet along the wall. Open vertical masonry joints, if used, should be provided at
32-inch-minimum intervals. A continuous gravel fill, 12 inches by 12 inches, should be placed behind
the weep holes or open masonry joints. The gravel should be wrapped in filter fabric to prevent
infiltration of fines and subsequent clogging. Filter fabric may consist of Mirafi 140N or equivalent.
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In lieu of weep holes or open joints, a perforated pipe-and-gravel subdrain may be used. Perforated pipe
should consist of 4-inch-minimum diameter PVC Schedule 40 or ABS SDR-35, with the perforations
laid down. The pipe should be embedded in 1.5 cubic feet per foot of 0.75- or 1.5-inch open-graded
gravel wrapped in filter fabric. Filter fabric may consist of Mirafi 140N or equivalent.
The backfilled side of the retaining wall supporting backfill should be coated with an approved
waterproofing compound to inhibit infiltration of moisture through the walls.
7.3 Temoorarv Excavations
All excavations should be made in accordance with OSHA requirements. LGC is not responsible for job
site safety.
7.4 Wall Backfill
All retaining-wall backfill should be placed in 6-inch to 8-inch maximum lifts, watered or air dried as
necessary to achieve near optimum moisture conditions and compacted in place to a minimum relative
compaction of 90 percent.
8.0 MASONRY GARDEN WALLS
Footings for masonry garden walls should also be reinforced with a minimum of four No.4 bars, two top and
two bottom. In order to mitigate the potential for unsightly cracking, positive separations should also be
provided in the garden walls at a maximum horizontal spacing of 20 feet. These separations should be provided
in the blocks only and not extend through the footing. The footing should be placed monolithically with
continuous rebars to serve as an effective "grade beam" below the wall.
In areas where garden walls may be proposed on or near the tops of descending slopes, the footings should be
deepened such that a minimum horizontal clearance of 5 feet is maintained between the outside bottom edges of
the footings and the face of the slope.
9.0 CONCRETE FLATWORK
9.1 Thickness and Joint Spacinfl
To reduce the potential of unsightly cracking, concrete sidewalks and patio-type slabs should be at least
3Y, inches thick and provided with construction or expansion joints every 6 feet or less. Any concrete
driveway slabs should be at least 4 inches thick and provided with construction or expansion joints every
10 feet or less.
9.2 Subflrade Preoaration
As a further measure to minimize cracking of concrete flatwork, the subgrade soils underlying concrete
flatwork should first be compacted to a minimum relative compaction of90 percent and then thoroughly
wetted to achieve a moisture content that is at least equal to or slightly greater than optimum moisture
content. This moisture should extend to a depth of 12 inches below sub grade and be maintained in the
soils during the placement of concrete. Pre-watering of the soils will promote uniform curing of the
concrete and minimize the development of shrinkage cracks. A representative of the project geotechnical
engineer should observe and verify the density and moisture content of the soils and the depth of
moisture penetration prior to placing concrete.
Project No. 104721-30
Page 11
August 19,2005 ,\
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9.3 Drainafle
Drainage from patios and other flatwork areas should be directed to local area drains and/or graded-earth
swales designed to carry runoff water to the adjacent streets or other approved drainage structure. The
concrete flatwork should also be sloped at a minimum gradient of I percent away from building
foundations, retaining walls, masonry garden walls and slopes.
9.4 Tree Wells
Tree wells are not recommended in concrete-flatwork areas since they can introduce excessive water
into the subgrade soils or allow for root invasion, both of which can result in uplift of the flatwork.
10.0 PLANTERS AND PLANTER WALLS AND LANDSCAPING
10.1 Planters
Planters that are located within 5 feet of building foundations, retaining walls, masonry-garden walls and
slope areas should be provided with either sealed bottoms or bottom drains to prevent infiltration of
water into the adjacent foundation soils. The surface of the ground in these areas should also be
maintained at a minimum gradient of2 percent and direct drainage to area drains or earth swales.
Planters adjacent to a building or structure should be avoided wherever possible or be properly designed
(e.g., lined with a membrane), to reduce the penetration of water into the adjacent footing subgrades and
thereby reduce moisture related damage to the foundation. Planting areas at grade should be provided
with appropriate positive drainage. Wherever possible, exposed soil areas should be above adjacent
paved grades to facilitate drainage. Planters should not be depressed below adjacent paved grades unless
provisions for drainage, such as multiple depressed area drains are constructed. Adequate drainage
gradients, devices, and curbing should be provided to prevent runoff from adjacent pavement or walks
into planting areas. Irrigation methods should promote uniformity of moisture in planters and beneath
adjacent concrete flatwork. Over-watering and under-watering oflandscape areas must be avoided.
10.2 Planter Walls
Low height planter walls should be supported by continuous concrete footings constructed in accordance
with the recommendations presented for masonry block wall footings.
10.3 Landscapinfl
In recognition that the future homeowners will add either soft-scape or hard-scape after precise grading,
the following recommendations may be used as a guide. It is paramount that future homeowners consult
with a professional engineer to ensure that the construction of future landscaping improvements will not
cause obstruction of existing drainage patterns or does not cause surface water to collect adjacent to the
foundation, creating saturated soils adjacent to the foundation.
Area drains should be maintained and kept clear of debris in order to properly function. Homeowners
should also be made aware that excessive irrigation of neighboring properties can cause seepage and
moisture conditions on adjacent lots. Homeowners should be furnished with these recommendations
communicating the importance of maintaining positive drainage away from structures towards streets
when they design their improvements.
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The impact of heavy irrigation or inadequate runoff gradients can create perched water conditions. This
may result in seepage or shallow groundwater conditions where previously none existed. Maintaining
adequate surface drainage and controlled irrigation will significantly reduce the potential for nuisance-
type moisture problems. To reduce differential earth movements such as heaving and shrinkage due to
the change in moisture content of foundation soils, which may cause distress to a residential structure
and associated improvements, moisture content of the soils surrounding the structure should be kept as
relatively constant as possible.
10.4 Swimminl! Pools and Spas
No pools or spas are shown on the plans. In general, due to the presence of soils with very low
expansion potential, LGC does not recommend pools or spas be located within 15 feet of the top of2:l
(h:v) slopes without special foundation design considerations. While expansive soil-related cracking of
concrete flatwork and garden walls may only be cosmetic in nature, and thus tolerable, such cracking in
pools and/or spas cannot be tolerated. Soil expansion forces should be taken into account for design and
construction of a swimming pool and/or spa.
For soils having a very low expansion potential, we recommend a lateral earth pressure of 60 pcf be
used for design of pools/spa shells.
To avoid localized saturation of soils, landscaping of the backyard should not be planned with unlined
planter boxes in the immediate vicinity of the pool/spa shell.
The excavated material from the pool/spa area is often used to build elevated planter boxes and/or other
structures adjacent to the pool area. This practice imposes significant loads at the location of these
structures and induces differential settlements. This practice could jeopardize the integrity of the
pool/spa and possibly other improvements. Pool decking should also receive special design
considerations, since the pool is founded generally 5 to 6 feet below grade. If pool decking is not
correctly designed for expansive soils, differential movement between the flatwork and pool will occur.
A geotechnical consultant should be retained to evaluate the impact of planned improvements and
provide proper recommendations for design. Whether the pool/spa shell is in the zone of influence of the
building or wall footing, the need for shoring or support for the building or wall footing should also be
taken into consideration.
11.0 POST GRADING OBSERVA TIONS AND TESTING
LGC should be notified at the appropriate times in order to provide the following observation and testing
services during the various phases of post grading construction.
11.1 Bui/dinll Construction
. Observe all footings when first excavated to verify adequate depth and competent soil bearing
conditions.
. Re-observe all footings, if necessary, if trenches are found to be excavated to inadequate depth
and/or found to contain significant slough, saturated or compressible soils.
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11.2 Retaininf! Wall Construction
. Observe all foundations when first excavated to verify adequate depth and competent soil bearing
conditions.
. Re-observe all foundations, if necessary, if excavations are found to be at an inadequate depth and/or
found to contain significant slough, saturated or compressible soils.
. Observe and verify proper installation of subdrain systems prior to placing wall backfill.
. Observe and test placement of all wall backfill.
11.3 Masonrv Garden Walls
. Observe all footing trenches when first excavated to verify adequate depth and competent soil
bearing conditions.
. Re-observe all footing trenches following removal of any slough and/or saturated soils and re-
excavate to proper depth.
11.4 Exterior Concrete Flatwork Construction
. Observe and test sub grade soils below all concrete flatwork areas to verify adequate compaction and
moisture content.
11.5 Uti/itv- Trench Backfill
. Observe and test placement of all utility trench backfill.
11.6 Re-Gradinf!
. Observe and test placement of any fill to be placed above or beyond the finish grades shown on the
grading plans.
12.0 LIMITATIONS
Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances,
by reputable engineers and geologists practicing in this or similar localities. No other warranty, expressed or
implied, is made as to the conclusions and professional advice included in this report.
This report is issued with the understanding that it is the responsibility of the owner, or of his /her representative,
to ensure that the information and recommendations contained herein are brought to the attention of the
architect and/or project engineer and incorporated into the plans, and the necessary steps are taken to see that
the contractor and/or subcontractor properly implements the recommendations in the field. The contractor
and/or subcontractor should notify the owner if they consider any of the recommendations presented herein to
be unsafe.
The findings of this report are valid as ofthe present date. However, changes in the conditions of a property can
and do occur with the passage of time, whether they be due to natural processes or the works of man on this or
adjacent properties.
Project No. 104721-30
Page 14
August 19,2005
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1~.4t
I ~ti~e ;;e~d;~ole
Principal Engineer, GE 692
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In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or
the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by
changes outside our control. Therefore, this report is subject to review and modification, and should not be
relied upon after a period of 3 years.
This opportunity to be of service is sincerely appreciated. Please call if you have any questions pertaining to
this report.
LGC INLAND, INC.
Respectfully submitted,
Chad Welke
Associate Engineer/Geologist, RCE 83712, CEG 2378
GEU/SMP/CW/ts/mn
Attachments:
Table 11- Summary ofField Density Tests (Rear of Text)
Appendix A - References (Rear of Text)
Appendix B - Laboratory Test Criteria/Laboratory Test Data (Rear of Text)
Appendix C - Slope Stability Analysis (Rear of Text)
Plate I - As-Graded Geotechnical Map (In Pocket)
Distribution: (6) Addressee
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APPENDIX A
REFERENCES
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APPENDIX A
REFERENCES
Blake, T.F., 2000, "FRISKSP, Version 4.0, A Computer Program for the Probabilistic Estimation of
Peak Acceleration and uniform Hazard Spectra Using 3.D Faults as Earthquake Sources."
, 1998/1998, "UBCSEIS, Version 1.30, A Computer Program for the Estimation of Uniform
Building Code Coefficients Using 3-D Fault Sources.
International Conference of Building Officials, 1997, Uniform Building Code, Structural Engineering
Design Provisions.
Leighton and Associates, 1999, Preliminary Geotechnical Evaluation, Grading Plan Review, Tract
23513 and Adjacent Parcel 4, P.N. 11900246-003, dated July 19.
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APPENDIX B
LABORATORY TESTING PROCEDURES AND TEST DATA
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APPENDIX B
Laboratorv Testinf! Procedures and Test Results
The laboratory testing program was directed towards providing quantitative data relating to the relevant
engineering properties of the soils. Samples considered representative of site conditions were tested in general
accordance with American Society for Testing and Materials (ASTM) procedure and/or California Test Methods
(CTM), where applicable. The following summary is a brief outline of the test type and tables summarizing the
test results.
Expansion Index: The expansion potential of selected samples was evaluated by the Expansion Index Test,
ASTM D4829. Specimens are molded under a given compactive energy to approximately the optimum moisture
content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared
I-inch thick by 4-inch diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with
tap water until volumetric equilibrium is reached.
SAMPLJi . " 'SAMPLE, COMPACTElJ DRY . 'EXPANSION EXPANSION
, NUMBER ' :LOCATION DENSITY (pc}) ,INDEX POTENTIAL *
El Lot I 115.7 0 Very Low
E2 Lot 2 114.9 0 Very Low
E3 Lot 3 115.5 0 Very Low
E4 Lot 4 115.0 0 Very Low
E5 lotS 114.3 4 Very Low
E6 Lot 6 112.9 3 Very Low
E7 Lot 7 115.1 0 Very Low
E8 Lot 8 117.9 0 Very Low
E9 Lot 9 113.4 I Very Low
ElO Lot 10 113.1 3 Very Low
Ell Lot II 110.2 0 Very Low
EI2 Parcel I 115.5 0 Very Low
EI3 Parcel 2 115.6 0 Very Low
El4 Parcel 3 115.6 14 Very Low
EI5 Parcel 4 113.4 0 Very Low
. Per Table 18-I-B of 1997 UBe.
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Maximum Densitv Tests: The maximum dry density and optimum moisture content of typical materials were
determined in accordance with ASTM Dl557.
,SAMPLE, , .:'$!JY1:~ .. MAlf!MpM DRY OPTJMijMM01STURE ..,
. l'(lJMBER .DESCRlPT10N I)ENS1TY(pcj) CONTENT ,0/0) ,
I Red-brown Sand 131.0 8.5
2 Olive-brown silty Sand 130.0 9.0
with traces of gravel
3 Olive silty Sand with 118.5 10.5
traces of sand
4 Olive-brown clayey Sand 129.0 9.0
with traces of gravel
Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical
methods (CTM 417). The soluble sulfate content is used to determine the appropriate cement type and maximum
water-cement ratios. The test results are presented in the table below:
'., ',' , SULFATE
SAMPLE .' . " ,.' S#fPLE SULFATE,
. .JlicfMIJ.ER . CONTENT . EXPOSURE* ,
,.LOCATION
" (% by WI.) * .
El Lot I 0.001 Negligible
E3 Lot 3 0.001 Negligible
E5 LotS 0.003 Negligible
E7 Lot? 0 Negligible
E9 Lot 9 0.001 Negligible
Ell Lot II 0.002 Negligible
E13 Parcel 2 0 Negligible
EI5 Parcel 4 0 Negligible
* Based on the 1997 edition of the Uniform Building Code (U.s. C.), Table No. 19-A-4, prepared by the International Conference of
Building Officials (lCBO, 1997).
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Project No. /04721-30
Page 2
August 19.2005
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APPENDIX C
SLOPE STABILITY
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C:\STEDWIN\-NEWFILE.OUT Page 1
I
*** GSTABL7 ***
** GSTABL7 by Garry H. Gregory, P.E. **
** Original Version 1.0, January 1996; Current Version 2.002, December 2001 **
(All Rights Reserved-Unauthorized Use Prohibited)
*********************************************************************************
I
SLOPE STABILITY ANALYSIS SYSTEM
Modified Bishop, Simplified Janbu, or GLE Method of Slices.
(Includes Spencer & Morgenstern-Price Type Analysis)
Including Pier/Pile, Reinforcement, Soil Nail, Tieback,
Nonlinear Undrained Shear Strength, Curved Phi Envelope,
Anisotropic Soil, Fiber-Reinforced Soil, Boundary Loads, Water
Surfaces, Pseudo-Static Earthquake, and Applied Force Options.
*********************************************************************************
Analysis Run Date: 7/20/2005
Time of Run: 1:46PM
Run By: GUecker
Input Data Filename: C:-NEWFILE.
Output Filename: C:-NEWFILE.OUT
Unit System: English
Plotted Output Filename: C:-NEWFILE.PLT
PROBLEM DESCRIPTION: Gallery Dev - PNI04721-30
2:1 Fill Slope, Lot 9, Static
BOUNDARY COORDINATES
7 Top Boundaries
12 Total Boundaries
Boundary X-Left Y-Left
No. (ft) (ft)
1 0.00 67.00
2 21.00 70.00
3 64.00 90.00
4 70.00 90.00
5 128.00 118.00
6 138.00 118.00
7 180.00 140.00
8 21.00 70.00
9 25.00 60.00
10 50.00 60.00
11 185.00 130.00
12 0.00 0.00
Default Y-Origin = O.OO(ft)
ISOTROPIC SOIL PARAMETERS
2 Type(s) of Soil
Soil Total Saturated Cohesion Friction Pore
Type Unit Wt. Unit Wt. Intercept Angle Pressure
No. (pcf) (pef) (psf) (deg) Paramo
1 118.0 145.0 250.0 31.0 0.00
2 118.0 145.0 200.0 30.0 0.00
A Critical Failure Surface Searching Method, Using A
Technique For Generating Circular Surfaces, Has Been
10000 Trial Surfaces Have Been Generated.
100 Surface{s) Initiate{s) From Each Of 100 Points Equally Spaced
Along The Ground Surface Between X 10.00{ft)
and X 40.00(ft)
Each Surface Terminates Between X 150.00(ft)
and X 225.00(ftl
Unless Further Limitations Were Imposed, The Minimum Elevation
At Which A Surface Extends Is Y = O.OO(ft)
25.0Q(ft) Line Segments Define Each Trial Failure Surface.
Following Are Displayed The Ten Most Critical Of The Trial
Failure Surfaces Evaluated. They Are
Ordered - Most Critical First.
* * Safety Factors Are Calculated By The Modified Bishop Method * *
Total Number of Trial Surfaces Evaluated = 10000
Number of Trial Failure Surfaces is Greater Than 5000.
Statistical Data on FS Values are Not Generated.
To Generate Stastical Data, Reduce Number of Trial
Failure Surfaces to 5000 or less.
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X-Right
(ft)
21. 00
64.00
70.00
128.00
138.00
180.00
270.00
25.00
50.00
185.00
269.00
0.00
Y-Right
(ft)
70.00
90.00
90.00
118.00
118.00
140.00
140.00
60.00
60.00
130.00
130.00
0.00
Soil Type
Below Bnd
1
2
2
2
2
2
2
1
1
1
1
o
Piez.
Surface
No.
o
o
Pressure
Constant
(psf)
0.0
0.0
Random
Specified.
-zl\
-----------
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I Slice
No.
1
2
I 3
4
5
6
I 7
8
9
10
I 11
12
13
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Failure
Point
No.
1
2
3
4
5
6
7
8
9
Circle
Surface Specified By 9
X-Surf Y-Surf
1ft) (ft)
21.21 70.10
46.01 73.28
70.44 78.57
94.34 85.93
117.52 95.29
139.82 106.59
161.07 119.76
181.12 134.69
187.11 140.00
Center At X = -3.68
Factor of Safety
*** 1.863 ***
Individual data on the
Water Water
Force Force
Width Weight Top Bot
(ft) 11bs) 11bs) 11bs)
24.8 12212.0 0.0 0.0
18.0 22470.3 0.0 0.0
6.0 8617.9 0.0 0.0
0.4 605.5 0.0 0.0
23.9 38717.9 0.0 0.0
23.2 45779.9 0.0 0.0
10.5 21674.6 0.0 0.0
10.0 17535.5 0.0 0.0
1.8 2643.2 0.0 0.0
21.3 28435.3 0.0 0.0
18.9 18391.2 0.0 0.0
1.1 756.4 0.0 0.0
6.0 1875.5 0.0 0.0
Failure Surface Specified By 9
Point X-Surf Y-Surf
No. 1ft) 1ft)
1 21.21 70.10
2 45.99 73.39
3 70.42 78.72
4 94.33 86.04
5 117.55 95.30
6 139.92 106.45
7 161.31 119.40
8 181.55 134.07
9 188.45 140.00
Circle Center At X = -6.27
Factor of Safety
*** 1.873 ***
Failure Surface Specified By 9
Point X-Surf Y-Surf
No. 1ft) 1ft)
1 23.64 71.23
2 48.47 74.14
3 72.91 79.40
4 96.74 86.95
5 119.75 96.72
6 141.73 108.64
7 162.48 122.58
8 181.81 138.43
9 183.39 140.00
Circle Center At X = 5.38; Y
Factor of Safety
*** 1.887 ***
Failure Surface Specified By 9
Point X-Surf Y-Surf
No. (ft) (ft)
1 22.12 70.52
Coordinate Points
y
361. 96
13 slices
Tie Tie
Force Force
Norm Tan
11bs) (lbs)
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
O. O.
Coordinate Points
y
371.89
Coordinate Points
333.94
Coordinate Points
C:\STEDWIN\-NEWFILE.OUT Page 2
and Radius
292.92
Earthquake
Force Surcharge
Hor Ver Load
11bs) (lbs) 11bs)
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
and Radius
303.04
and Radius
263.35
?Jt'
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I
2 46.86 74.16
I 3 71.21 79.79
4 95.04 87.36
5 118.18 96.83
6 140.47 108.14
I 7 161. 78 121. 22
8 181.96 135.97
9 186.63 14 0.00
Circle Center At X = -10.50
I Factor of Safety
H' 1. 887 H'
Failure Surface Specified By 9
Point X-Surf Y-Surf
I No. 1ft) 1ft)
1 23.03 70.94
2 47.87 73.75
3 72.34 78.86
4 96.24 86.22
I 5 119.34 95.78
6 141.45 107.44
7 162.39 121.10
8 181.96 136.65
I 9 185.45 140.00
Circle Center At X = 5.30 ;
Factor of Safety
'H 1.892 'H
I Failure Surface Specified By 9
Point X-Surf Y-Surf
No. 1ft) (ft)
1 26.36 72.49
I 2 51. 05 76.44
3 75.40 82.13
4 99.27 89.54
5 122.56 98.63
I 6 145.14 109.36
7 166.90 121. 67
8 187.73 135.50
9 193.56 140.00
Circle Center At X = -16.55
I Factor of Safety
H' 1. 893 .*'
Failure Surface Specified By 9
Point X-Surf Y-$urf
I No. 1ft) (ft)
1 21. 52 70.24
2 46.33 73.26
3 70.81 78.34
I 4 94.78 85.46
5 118.06 94.56
6 140.50 105.57
7 161. 95 118.43
I 8 182.24 133.03
9 190.38 140.00
Circle Center At X = -2.08
Factor of Safety
.*' 1. 895 H'
I Failure Surface Specified By 9
Point X-Surf Y-Surf
No. 1ft) 1ft)
1 23.33 71.09
I 2 48.03 74.96
3 72.36 80.71
4 96.17 88.32
5 119.33 97.74
I 6 141. 70 108.91
7 163.14 121. 76
8 183.54 136.22
I
y
378.09
Coordinate Points
y
338.89
Coordinate Points
y
420.55
Coordinate Points
y
367.71
Coordinate Points
C:\STEDWIN\-NEWFILE.DUT Page 3
and Radius
and Radius
and Radius
and Radius
309.29
268.54
350.69
298.41
1,,-~
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C:\STEDWIN\-NEWFILE.OUT Page 4
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9 188.08 140.00
Circle Center At X = -14.65 Y 394.09 and Radius
Factor of Safety
*** 1.895 ***
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. 1ft} 1ft)
1 21.52 70.24
2 46.17 74.40
3 70.46 80.30
4 94.28 87.89
5 117.50 97.14
6 140.02 108.02
7 161.70 120.45
8 182.46 134.39
9 189.67 140.00
Circle Center At X = -25.05 Y 421.05 and Radius
Factor of Safety
*** 1.896 ***
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. 1ft) 1ft)
1 24.55 71.65
2 49.36 74.67
3 73.82 79.83
4 97.74 87.10
5 120.94 96.42
6 143.24 107.72
7 164.48 120.91
8 184.48 135.90
9 189.06 140.00
Circle Center At X = 2.29 ; Y 358.23 and Radius
Factor of Safety
*** 1.896 ***
**** END OF GSTABL7 OUTPUT ****
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C:\STEOWIN\-NEWFILE.OUT Page 1
I
*** GSTABL7 ***
** GSTABL7 by Garry H. Gregory, P.E. **
** Original Version 1.0, January 1996; Current Version 2.002, December 2001 **
(All Rights Reserved-Unauthorized Use Prohibited)
*********************************************************************************
I
SLOPE STABILITY ANALYSIS SYSTEM
Modified Bishop, Simplified Janbu, or GLE Method of Slices.
(Includes Spencer & Morgenstern-Price Type Analysis)
Including Pier/Pile, Reinforcement, Soil Nail, Tieback,
Nonlinear Undrained Shear Strength, Curved Phi Envelope,
Anisotropic Soil, Fiber-Reinforced Soil, Boundary Loads, Water
Surfaces, Pseudo-Static Earthquake, and Applied Force Options.
*********************************************************************************
Analysis Run Date: 7/20/2005
Time of Run: 3:57PM
Run By: GUecker
Input Data Filename: C:-NEWFILE.
Output Filename: C:-NEWFILE.OUT
Unit System: English
Plotted Output Filename: C:-NEWFILE.PLT
PROBLEM DESCRIPTION: Gallery Oev - PNI04721-30
2:1 Fill Slope, Lot 9, Seismic
BOUNDARY COORDINATES
7 Top Boundaries
12 Total Boundaries
Boundary X-Left Y-Left
No. 1ft) 1ft)
1 0.00 67.00
2 21.00 70.00
3 64.00 90.00
4 70.00 90.00
5 128.00 118.00
6 138.00 118.00
7 180.00 140.00
8 21.00 70.00
9 25.00 60.00
10 50.00 60.00
11 185.00 130.00
12 0.00 0.00
Default Y-Origin ~ O.OOlft)
ISOTROPIC SOIL PARAMETERS
2 Typels) of Soil
Soil Total Saturated Cohesion
Type Unit Wt. Unit Wt. Intercept
No. Ipcf) (pcf) (psf)
1 118.0 145.0 250.0
2 118.0 145.0 200.0
A Horizontal Earthquake Loading
Of 0.150 Has Been Assigned
A Vertical Earthquake Loading Coefficient
Of 0.000 Has Been Assigned
Cavitation Pressure = O.O(psf)
A Critical Failure Surface Searching Method, Using A Random
Technique For Generating Circular Surfaces, Has Been Specified.
10000 Trial Surfaces Have Been Generated.
100 Surface(s) Initiate(s) From Each Of 100 Points Equally Spaced
Along The Ground Surface Between X 10.OO(ftJ
and X 40.00Ift)
Each Surface Terminates Between X 150.00(ftl
and X 225.00Ift)
Unless Further Limitations Were Imposed, The Minimum Elevation
At Which A Surface Extends Is Y = O.OO(ft)
25.00(ft) Line Segments Define Each Trial Failure Surface.
Following Are Displayed The Ten Most Critical Of The Trial
Failure Surfaces Evaluated. They Are
Ordered - Most Critical First.
* * Safety Factors Are Calculated By The Modified Bishop Method * *
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X-Right
1ft)
21. 00
64.00
70.00
128.00
138.00
180.00
270.00
25.00
50.00
185.00
269.00
0.00
Y-Right
(ft)
70.00
90.00
90.00
118.00
118.00
140.00
140.00
60.00
60.00
130.00
130.00
0.00
Friction Pore
Angle Pressure
(deg) Paramo
31.0 0.00
30.0 0.00
Coefficient
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Soil Type
Below Bnd
1
2
2
2
2
2
2
1
1
1
1
o
Pressure
Constant
(psf)
0.0
0.0
Piez.
Surface
No.
o
o
,?/Cp
-------- --------------
I
I C:\STEDWIN\-NEWFILE.OUT Page 2
Total Number of Trial Surfaces Evaluated = 10000
I Number of Trial Failure Surfaces is Greater Than 5000.
Statistical Data on FS Values are Not Generated.
To Generate Stastical D~ta, Reduce Number of Trial
Failure Surfaces to 5000 or less.
I Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 21. 21 70.10
I 2 46.01 73.28
3 70.44 78.57
4 94.34 85.93
5 11 7.52 95.29
I 6 139.82 106.59
7 161.07 119.76
8 181.12 134.69
9 187.11 140.00
I Circle Center At X = -3.68 y 361. 96 and Radius 292.92
Factor of Safety
H* 1.316 H'
Individual data on the 13 slices
Water Water Tie Tie Earthquake
I Force Force Force Force Force Surcharge
Slice Width Weight Top Bot Norm Tan Hor Ver Load
No. (ft) (lbs) (lbs) Ilbs) (lbs) (lbs) 11bs) (lbs) (lbs)
1 24.8 12212.0 0.0 0.0 O. O. 1831.8 0.0 0.0
I 2 18.0 22470.3 0.0 0.0 o. O. 3370.5 0.0 0.0
3 6.0 8617.9 0.0 0.0 O. O. 1292.7 0.0 0.0
4 0.4 605.5 0.0 0.0 o. O. 90.8 0.0 0.0
5 23.9 38717.9 0.0 0.0 O. O. 5807.7 0.0 0.0
I 6 23.2 45779.9 0.0 0.0 O. O. 6867.0 0.0 0.0
7 10.5 21674.6 0.0 0.0 O. O. 3251. 2 0.0 0.0
8 10.0 17535.5 0.0 0.0 o. O. 2630.3 0.0 0.0
9 1.8 2643.2 0.0 0.0 O. O. 396.5 0.0 0.0
I 10 21. 3 28435.3 0.0 0.0 o. O. 4265.3 0.0 0.0
11 18.9 18391. 2 0.0 0.0 O. O. 2758.7 0.0 0.0
12 1.1 756.4 0.0 0.0 O. O. 113.5 0.0 0.0
13 6.0 1875.5 0.0 0.0 O. O. 281. 3 0.0 0.0
Failure Surface Specified By 9 Coordinate Points
I Point X-Surf Y-Surf
No. (ft) 1ft)
1 21.21 70.10
2 45.99 73.39
I 3 70.42 78.72
4 94.33 86.04
5 11 7.55 95.30
6 139.92 106.45
I 7 161.31 119.40
8 181. 55 134.07
9 188.45 140.00
Circle Center At X = -6.27 y 371. 89 and Radius 303.04
I Factor of Safety
H* 1.322 H'
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
I No. (ft) 1ft)
1 26.36 72.49
2 51. 05 76.44
3 75.40 82.13
4 99.27 89.54
I 5 122.56 98.63
6 145.14 109.36
7 166.90 121. 67
8 187.73 135.50
I 9 193.56 140.00
Circle Center At X = -16.55 Y 420.55 and Radius 350.69
Factor of Safety
I 1--'\
I
I C:\STEDWIN\-NEWFILE.OUT Page 3
*H 1. 332 H*
I Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 22.12 70.52
I 2 46.86 74.16
3 71.21 79.79
4 95.04 87.36
5 118.18 96.83
I 6 140.47 108.14
7 161. 78 121.22
8 181.96 135.97
9 186.63 140.00
I Circle Center At X "" -10.50 y 378.09 and Radius 309.29
Factor of Safety
H* 1. 334 H*
Failure Surface Specified By 9 Coordinate Points
I Point X-Surf Y-Surf
No. (ft) (ft)
1 23.64 71.23
2 48.47 74.14
3 72.91 79.40
I 4 96.74 86.95
5 119.75 96.72
6 141. 73 108.64
7 162.48 122.58
I 8 181. 81 138.43
9 183.39 140.00
Circle Center At X = 5.38 ; y 333.94 and Radius 263.35
Factor of Safety
I H* 1. 334 H*
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) 1ft)
I 1 21. 52 70.24
2 46.33 73.26
3 70.81 78.34
4 94.78 85.46
5 118.06 94.56
I 6 14 0.50 105.57
7 161. 95 118.43
8 182.24 133.03
9 190.38 140.00
I Circle Center At X = -2.08 y 367.71 and Radius 298.41
Factor of Safety
H* 1. 336 H*
Failure Surface Specified By 9 Coordinate Points
I Point X-Surf Y-Surt
No. 1ft) 1ft}
1 23.03 70.94
2 47.87 73.75
I 3 72.34 78.86
4 96.24 86.22
5 119.34 95.78
6 141. 45 107.44
7 162.39 121.10
I 8 181.96 136.65
9 185.45 140.00
Circle Center At X = 5.30 ; Y 338.89 and Radius 268.54
Factor of Safety
I H* 1. 337 *H
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
I 1 21. 52 70.24
2 46.17 74.40
3 70.46 80.30
I ~
------------
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C:\STEDWIN\-NEWFILE.OUT Page 4
94.28 87.89
117.50 97.14
140.02 108.02
161.70 120.45
182.46 134.39
189.67 140.00
Center At X = -25.05
Factor of Safety
*** 1.338 ***
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 24.55 71.65
2 49.36 74.67
3 73.82 79.83
4 97.74 87.10
5 120.94 96.42
6 143.24 107.72
7 164.48 120.91
8 184.48 135.90
9 189.06 140.00
Circle Center At X = 2.29 ; Y
Factor of Safety
*** 1.338 ***
Failure Surface Specified By 9 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 20.00 69.86
2 44.97 71.02
3 69.71 74.67
4 93.95 80.78
5 117.46 89.28
6 140.00 100.09
7 161.35 113.10
8 181.28 128.19
9 194.02 140.00
Circle Center At X = 20.92
Factor of Safety
*** 1.339 ***
**** END OF GSTABL7 OUTPUT ****
4
5
6
7
8
9
Circle
421.05
and Radius
y
358.23
and Radius
y
319.47
and Radius
353.88
287.44
249.61
1/0...
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LGC
SURFICIAL STABILITY
IN:
CLIENT:
104721-30 CONSULT: GEU
Gallerv DeveloDment
CALCULATION SHEET # 1
CALCULATE THE SURFICIAL STABILITY OF THE EARTH MATERIAL USING THE INFINITE SLOPE ANALYSIS
WITH PARALLEL SEEPAGE. THIS METHOD WAS RECOMMENDED BY THE ASCE AND THE BUILDING AND
SAFETY ADVISORY COMMITTEE (8/16/78). MODIFIED FROM SKEMPTON & DeLORY. 1957.
CALCULATION PARAMETERS
EARTH MATERIAL:
COHESION:
PHI ANGLE:
DENSITY:
Compacted Fill
200 pst
30 degrees
118 pct
SHEAR DIAGRAM:
SLOPE ANGLE:
SATURATION DEPTH (t):
Direct Shear Plot
26.6 degrees
4.0 teet
GraundSurface
FS=
c+ (y..il-~ -t-cos28tan4>
'Yooil - t - cos<J>sin 4>
SAFETY FACTOR = 1.60
CONCLUSIONS:
THE CALCULATION INDICATES THAT COMPACTED FILL SLOPES ARE
SURFICIALLY STABLE.
~