HomeMy WebLinkAboutGPA 05-06; AURA CIRCLE; PRELIMINARY GEOTECHNICAL EVALUATION; 2004-12-08RECEIVED
AUG O 7 2003
CITY OF CARLSBAD
PLANNING DEPT.
PRELIMINARY GEOTECHNICAL EVALUATION
AURA CIRCLE, PROPOSED 13 LOT SUBDIVISION,
CARLSBAD, CALIFORNIA
FOR
MSK DEVELOPMENT
• 5142 AVENI DA ENCINAS
CARLSBAD, CALIFORNIA 92008
W.O. 3008-A-SC MARCH 5, 2001
Lot Coveraae
Lot Plan Type Lot Size Building
Footnrint
1 2A 10450 2865
2 1 A 8002 1925
3 2A 9145 2865
4 3A 9992 3670
5 3A 9766 3670
6 1 A 9362 1925
7 2A 8080 2865
8 1 A 9115 1925
9 2 AR 11173 2865
1st floor Garage 2nd floor
Plan 1 1422 503 1860
Plan 2 1653 1212 1725
Plan 3 3065 605
¾of
Coverage
27.4%
24.1%
31.3%
36.7%
37.6%
20.6%
35.5%
21.1%
25.6%
Building
Coverane
1925
2865
3670
MSK Development
Aura Circle
Lot Widths Front Yard Required
/min 20'J Rear Yard
68 20 1'6
71 20 14.2
70 20 14
70 20 14
69 20 13 8
72 20 14.4
77 20 15.4
69 20 13.8
35 20 7
Total Livable Total SF
3282 3785
3378 4590
3065 3670
Setback Reauirements
Required Left Side Right Side Combined Rear Yard Side Yard Yam Yam Side Yard
27.5 68 5 14 19
30 7.1 8 15 23
43 7 5 13 18
37 7 5 12 17
36.5 6.9 5 11 16
53 7.2 8 13 21
17 77 5 10.4 15.4
45 6.9 8 13 21
23.2 3.5 5 30 35
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TABLE OF CONTENTS
SCOPE OF SERVICES ................................................... 1
SITE DESCRIPTION ..................................................... 1
PROPOSED DEVELOPMENT .............................................. 3
FIELD STUDIES ......................................................... 3
REGIONAL GEOLOGY ................................................... 3
EARTH MATERIALS ...................................................... 4
Artificial Fill • Undocumented (Map Symbol • Afu) ........................ 4
Colluvium/Alluvium (Map Symbol -Qcol/Oal)) ........................... 4
Santiago Peak Volcanics (Map Symbol -Tsa) ........................... 4
FAULTING AND REGIONAL SEISMICITY ..................................... 4
Faulting ........... , .............................................. 4
S • • ·ty e1sm1c1 ........................................................ s
Seismic Shaking Parameters ......................................... 7
GROUNDWATER ........................................................ 7
MASS WASTING ........................................................ 8
SEISMIC HAZARDS ...................................................... 8
LABORATORY TESTING .................................................. 8
General .......................................................... 8
Moisture-Density ................................................... 8
Laboratory Standard ............................................... 9
Shear Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Expansion Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 O
Atterberg Limits .................................................. 1 o
Consolidation Testing ............................................. 1 O
Corrosion/Sulfate Testing ........................................... 10
SLOPE STABILITY ANALYSIS ............................................. 10
Fill Slope Stability Analysis .......................................... 1 O
Gross Stability .............................................. 11
Surficial Stability ............................................ 11
CONCLUSIONS AND RECOMMENDATIONS ................................ 11
Earthwork Construction Recommendations ............................ 11
Site Preparation .................................................. 12
Removals (Unsuitable Surficial Materials) .............................. 12
GeoSoils, Jne.
PROPOSED DEVELOPMENT
Based on a review of the tentative map for the project (i.e. Plate 1), prepared by O'Day
Consultants (OC), dated January, 2000, it is our understanding that the proposed
development would consist of a 13 single family residential homes, with associated
roadways and underground utility improvements. We further understand that the proposed
buildings would consist of one-or two-story structures, with slabs-on-grade, and
continuous footings, or post tensioned foundations, utilizing wood-frame and/or masonry
block construction. Building loads are assumed to be typical for this type of relatively light
construction. The maximum thickness of planned cuts and fills are proposed at about 25
to 30 feet, excluding remedial removals in fill areas. Various areas will have side yard
slopes and portions of the extension of Aura Circle will require retaining walls. Sewage
disposal is understood to be accommodated by tying into the regional municipal system.
FIELD STUDIES
Field work conducted during our evaluation of the property consisted of excavating nine
test pits (with a rubber tire backhoe) and five large diameter borings within the site to
evaluate near surface soil and geologic conditions. Test pits were logged by a geologist
from our firm. Representative bulk and in-place samples were taken for appropriate
laboratory testing. Logs of the test pits and borings are presented in Appendix 8. The
approximate locations of test pits and borings are shown on Plate 1, which utilizes the 40-
scale tentative map prepared by OC (2000) as a base map.
REGIONAL GEOLOGY
The subject property is located within a prominent natural geomorphic province in
southwestern California known as the Peninsular Ranges. It is characterized by steep,
elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are
underlain by basement rocks consisting of-pre-Cretaceous metasedimentary rocks,
Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California
batholith.
In the San Diego region, deposition occurred during the Cretaceous period and Cenozoic
era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age
plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep,
coastal plain and continental margin of the basin. These rocks have been uplifted, eroded
and deeply incised. During early Pleistocene time, a broad coastal plain was developed
from the deposition of marine terrace deposits. During mid to late Pleistocene time, this
plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys,
and young marine sediments are currently being deposited/eroded within coastal and
beach areas.
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EARTH MATERIALS
Earth materials encountered during our subsurface investigation and site reconnaissance
included artificial fill, colluvium/alluvium, as well as sedimentary bedrock belonging to the
Santiago Formation. Earth materials are generally described below from youngest to
oldest. Limits, of the earth. materials based on the available data, are indicated on Plate 1.
Geologic cross sections were developed from the available data and are presented as
Figures 3 through 6.
Artlflclal Fill -Undocumented {Map Symbol -Alu)
The artificial fill generally consists of a light brown to olive brown, damp to moist, very loose
to soft, silty sand to sandy clay. Thickness of the material appears to vary up to
approximately 13 feet. Artificial fill at the subject site is considered potentially compressible
in its present state. Accordingly, these soils are considered unsuitable for support of
additional fill and/or settlement sensitive improvements in there existing state.
Colluvlum/Alluvlum {Map Symbol -Qcol/Qal)
Undifferentiated colluvium/alluvium materials encountered onsite generally consists of a
yellowish brown to dark brown, moist, loose to stiff, silty sand to sandy clay. Thickness
of the material is approximately 1 ½ to 4 feet on slopes to 25 to 35 feet within canyon
bottoms. Field observations and our laboratory analysis indicate that colluvium/alluvium
at the subject site is potentially compressible, and subject to hydrocollapse in its present
state. Accordingly, these soils are considered unsuitable for support of additional fill
and/or settlement sensitive improvements in there existing state.
Santiago Formation {Map Symbol -Tsa)
The Tertiary-age Santiago Formation underlies the site at depth, and outcrops on the
surface. As encountered, this unit generally consists of light brown to olive brown,
sandstone to clayey sandstone, and is dense to very dense with depth. Due to the
relatively loose and highly weathered condition of the upper ±2 foot, these sediments
should be removed, moisture conditioned, and recompacted and/or processed in place,
should settlement-sensitive improvements be proposed.
FAULTING AND REGIONAL SEISMICITY
Faulting
The site is situated in a region of active as well as potentially-active faults. Our review
indicates that there are no known active faults crossing the site within the areas proposed
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for development (Jennings, 1994), and the site is not within an Earthquake Fault Zone
(Hart and Bryant , 1997).
There are a number of faults in the southern California area that are considered active and
would have an effect on the site in the form of ground shaking, should they be the source
of an earthquake (Figure 2). These faults include-but are not limned to-the San Andreas
fault, the San Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the
Newport-Inglewood -Rose Canyon fault zone. The possibility of ground acceleration or
shaking at the site may be considered as approximately similar to the southern California
region as a whole. •
The following table lists the major faults and fault zones in southern California that could
have a significant effect on the site should they experience significant activity .
• -·
.. . ,_. . . ' _,. ·. , .
ABBREVIATED FAULT NAME APPROXIMATE DISTANCE -MILES IKMl
Coronado Bank-Anua Blanca 22 (35)
Elsinore 23 (38l
La Naci6n 23 (38)
Newoort-lnc lewood-Offshore 9 (151
Rose Canvon 5.5 (8.9)
San Diena Trouah-Bahia Sol. 31 (511
Selsmiclty
The acceleration-attenuation relations of Joyner and Boore (1982), Campbell and
Bozorgnia (1994), and Sadigh and others (1987) have been incorporated into EQFAULT
(Blake, 1997). For this study, peak horizontal ground accelerations anticipated at the site
were determined based on the mean plus 1 sigma attenuation curves developed by Joyner
and Boore (1982), Campbell and Bozorgnia (1994), and Sadigh and others (1989). These
acceleration-attenuation relations have been incorporated in EOFAULT, a computer
program by Thomas F. Blake (1997), which perfonns detenninistic seismic hazard analyses
using up to 150 digitized Cal~omia faults as earthquake sources. The program estimates
the closest distance between each fault and a user-specified file.
If a fault is found to be within a user-selected radius, the program estimates peak horizontal
ground acceleration that may occur at the site from the upper bound C'maximum credible'1
and "maximum probable" earthquakes on that fault
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Site acceleration, as a percentage of the acceleration of gravity (g), is computed by any of
the 14 user-selected acceleration-attenuation relations that are contained in EQFAULT.
Based on the above, peak horizontal ground accelerations from an upper bound
(maximum credible) earthquake may be on the order of 0.57 g to 0.68 g, and maximum
probable event may be on the order of 0.30 g to 0.38 g , assuming upper bound (maximum
credible) and maximum probable event of a magnitude about 6.9, on the Rose Canyon
fault zone, located approximately 5.5 miles from the subject site.
Seismic Shaking Parameters
Based on the site conditions, Chapter 16 of the Uniform Building Code (International
Conference of Building Officials, latest edition), the following seismic parameters are
provided.
Seismic zone (per Figure 16-2*) 4
Seismic Zone Factor (per Table 16-1*) 0.40
Soll Profile Type (per Table 16-J*) s,
Seismic Coefficient c. (per Table 16-Q*) 0.44 N.
Seismic Coefficient Cv (per Table 16-R*) 0.64 NV
Near Source Factor N. (per Table 16-S*) 1.0
Near Source Factor Nv (per Table 16-T*) 1.18
Seismic Source Type (per Table 16-U*) B
Distance to Seismic Source 5.5 ml. (8.9 km)
Upper Bound Earthquake Mw6.9
* Fioure and table references from Chapter 16 of the Uniform Building Code (1ssn.
GROUNDWATER
Groundwater was encountered onsite in boring 8-3 at a depth of ±35 feet and is generally
not anticipated to significantly affect site development, providing that the recommendations
contained in this report are incorporated into final design and construction, and that
prudent surface and subsurface drainage practices are incorporated into the construction
plans. Perched groundwater conditions along zones of contrasting permeabillties should
not be precluded from occurring in the future Q.e. post grading) due to site irrigation, poor
drainage conditions, or damaged utilities. Should perched groundwater conditions
develop, this office could assess the affected area(s) and provide the appropriate
recommendations to mitigate the observed groundwater conditions.
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MASS WASTING
Field mapping did not indicate the presence of any existing mass wasting features onsite.
Indications of deep seated landsliding were not noted during our review of available
documents (Appendix A).
SEISMIC HAZARDS
The following list includes other seismic related hazards that have been considered during
our evaluation of the site. The hazards listed are considered negligible and/or completely
mitigated as a result of site location, soil characteristics and typical site development
procedures:
• Liquefaction
• Tsunami
• Dynamic Settlement
• Surface Fault Rupture
• Ground Lurching or Shallow Ground Rupture
It is important to keep in perspective that in the event of a maximum probable or credible
earthquake occurring on any of the nearby major faults, strong ground shaking would
occur in the subject site's general area. Potential damage to any structure(s) would likely
be greatest from the vibrations and impelling force caused by the inertia of a structure's
mass, than from those induced by the hazards considered above. This potential would be
no greater than that for other existing structures and improvements in the immediate
vicinity.
LABORATORY TESTING
General
Laboratory tests were performed on representative samples of the onslte earth materials
in order to evaluate their physical characteristics. The test procedures used and results
obtained are presented below.
Moisture-Density
The dry unit weight was determined in pounds per cubic foot, and the field moisture
content was determined as a percentage of the dry weight for relatively undisturbed ring
samples obtained from the large diameter borings, in general accordance with ASTM D-
3550. The results of these tests are shown on the logs of the test pits, Appendix B.
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Laboratory Standard
The maximum dry density and optimum moisture content was determined for the major soil
type encountered in the trenches. The laboratory standard used was ASTM D-1557. The
moisture-density relationship obtained for this soil is shown below:
OPTIMUM
TEST PIT ANO MAXIMUM DRY .MOISTURE
SOIL TYPE DEPTH (fl.) DENSITY tnef\ CONTENT 1%l
Sandy Clay, yellowish brown B-2@ 0-4' 122.0 13.0
Clayey Sand, brown TP-3 @3' 117.5 14.0
Sandv Clav, vertowish brown TP-4@ 6' 105.0 20.5
Shear Testing
Shear testing was performed on a representative, "undisturbed" and "remolded" samples
of site soil. Testing was in general accordance with ASTM test method D-3080 in a Direct
Shear Machine of the strain control type. Shear test results are presented as Plate C-1
through C-6 in Appendix C, and as follows:
... · ,• . .. Primary ,;'_ •· . . '--c-·
Sample
Location. Cohesion (psi) • Friction Angle-... ,, . (Degrees) • '
B-2@ 2tr 701
TP-3 @3' 2517
TP-3 @3' 286 (remolde.-f\
TP-4@ 6' 350
TP-8 @5' 705
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34
32
28
26
31
.. -----. Resld~I-.-. . __ -,.
"/. ' -"', ·;<· .
Cohesion (psi) , . .
549
553
279
357
733
. •.· .. .
Frl~lon Angl~ ., '.'
--IDeareesl--'
43
29
28
25
30
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March 5, 2001
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GeoSoils, lne.
Expansion Potential
Expansion testing was performed on representative samples of site soil in accordance with
UBC Standard 18-2. The results of expansion testing are presented in the following table.
LOCATION EXPANSION INDEX EXPANSION
POTENTIAL
TP-3@3' 20 Very Low
B-2 @0-4' 55 Medium
TP-4@ 6' 53 Medium
B-2@ 15-17' 94 High
Atterberg Limits
Atterberg Limits were determined in general accordance with ASTM test method D-4318.
Test results are presented as Plate C-7 in Appendix C.
Consolidation Testing
Consolidation tests were performed on selected undisturbed samples in general
accordance with ASTM test method D-2435. Test results are presented as Plates C-8
through C-15 in Appendix C.
Corrosion/Sulfate Testing
Su~ate testing indicates that site soils have a negligible exposure to concrete per Table 19-
A-4 of the 1997 UBC (sample = 0.012 percent by weight). Corrosion testing (pH,
resistivity) indicates that the soils are essentially neutral (pH=7.0), but severely corrosive
to ferrous metals (saturated resistivity= 91 0 ohms-cm). Alternative methods and additional
comments should be obtained by a qualified corrosion engineer.
SLOPE STABILITY ANALYSIS
FIii Slope Stability Analysis
Analyses were performed utilizing the two dimensional slope stability computer program
"XST ABL." The program calculates the factor of safety for specified circles or searches for
a circular, block, or irregular slip surface having the minimum factor of safety using the
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modified Bishop Method, Jan bu or general limit equilibrium (Spencer). Additional
information regarding the methodology utilized in these programs are included in
Appendix D. Computer print-outs of calculations and shear strength parameters used are
provided in Appendix C. Our slope stability analysis was performed with respect to static
conditions, and when subject to seismic shaking (pseudo-static or seismic) conditions.
Gross Stability
Based on the available data, the constraints outlined above, and our stability calculations
shown in Appendix D, a calculated factor-of-safety greater than 1.5 (static) and 1.15
(pseudo-static or seismic) has been obtained for proposed fill and cut slopes, with the
exception of the retaining wall, as will be explained later in this report. Factors of safety of
1.5 (static case) and 1.15 (seismic case) are the currently accepted minimum safety factors
applied to slope stability analysis for the construction industry and used by local governing
agencies. Our analysis assumes that the slopes are designed and constructed in
accordance with guidelines provided by the City of Carlsbad, the Uniform Building Code
and recommendations provided by this office. While cut slopes appear to be stable based
on our current analysis, the inability to obtain site specific structural data in some areas
may not preclude the need for stabilization/buttress fill during site construction due to
unforseen adverse conditions exposed during site grading. Furthermore, while slope
stability appears favorable in the vicinity of a proposed retaining wall along the south side
of Aura Circle, the gross stability in this area will be dependant on the precise nature of
materials used in embankment construction. At this time, it is assumed that fills used to
construct this embankment will consist of silty to sandy, relatively granular material derived
from excavations made in the vicinity of Lots 8 and 9.
Surtlcial Stability
An analysis ofsurficial stability was performed for graded slopes constructed of compacted
fills and/or bedrock material. Our analysis, quantified in Appendix D, indicates that slopes
exhibit an adequate factor of safety against surficial failure (i.e. > 1.5) provided that the
slopes are properly constructed and maintained.
CONCLUSIONS AND RECOMMENDATIONS
Based upon our site reconnaissance and test results, it is our opinion that the subject site
appears suitable for the proposed residential development. The following
recommendations should be incorporated into the construction details.
Earthwork Construction Recommendations
All grading should conform to the guidelines presented in Appendix Chapter A33 of the
Uniform Building Code Qatest edition), the requirements of the City of Carlsbad and/or the
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County of San Diego, and the Grading Guidelines presented in Appendix E, except where
specifically superseded in the text of this report. Prior to grading, a GSI representative
should be present at the preconstruction meeting to provide additional grading guidelines,
if needed, and review the earthwork schedule.
During earthwork construction all site preparation and the general grading procedures of
the contractor should be observed and the fill selectively tested by a representative(s) of
GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed
by this office and if warranted, modified and/or additional recommendations will be offered.
All applicable requirements of local and national construction and general industry safety
orders, the Occupational Safety and Health Act, and the Construction Safety Act should
be met.
Site Preparation
Debris, vegetation and other deleterious material should be removed from the building
area prior to the start of grading. Sloping areas to receive fill should be properly benched
in accordance with current industry standards of practice and guidelines specified in the
Uniform Building Code.
Removals (Unsuitable Surficial Materials}
Due to the relatively loose/soft condition (and the potential for hydrocollapse) of
colluvium/alluvium, these materials should be removed and recompacted in areas
proposed for settlement sensitive structures, or in areas to receive compacted fill. At this
time, removal depths on the order of 25 to 35 feet should be anticipated in the canyons,
and 1 ½ to 4 feet within existing slopes and other areas; however, locally deeper removals
may be necessary. Removals should be completed below a 1 :1 projection down and away
from the edge of any settlement sensitive structure and/or limits of proposed fill. Due to
property line restrictions along the southern property line, removals should remain above
a 1: 1 projection down and away from the property line. Once removals are completed, the
exposed bottom should be reprocessed and compacted .. Fill slopes in areas where
removals are limited by property lines may be subject to settlement; however, the tops of
slopes would not be affected, based on the available data.
Overexcavatlon/Transitlons
In order to provide for the uniform support of the structure, a minimum 3-foot thick fill
blanket is recommended for lots containing plan transitions. Any cut portion of the pad for
the residence should be over excavated a minimum 3 feet below finish pad grade. Areas
with planned fills less than 3 feet should be over excavated in order to provide the
minimum fill thickness. Maximum to minimum fill thickness within a given lot should not
exceed ratio of 3:1, if conventional foundations are desired. Overexcavation is also
recommended for cut lots exposing claystones and/or heterogenous material types (i.e.,
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sand/clay). Overexcavation depths will be determined in the field based on site conditions,
and may vary from 3 to 7 feet.
Fill Placement
Subsequent to ground preparation, onsite soils may be placed in thin (B±inch) lifts,
cleaned of vegetation and debris, brought to a least optimum moisture content, and
compacted to achieve a minimum relative compaction of 90 percent. If soil importation is
lanned, a sample of the soil import should be evaluated by this office prior to importing, in
order to assure compatibility with the onstte stte soils and the recommendations presented
in this report. Import soils (ff any) for a fill cap should be low expansive (E.1. less than 50).
The use of subdrains at the bottom of the fill cap may be necessary, and subsequently
recommended based on compatibility wtth onstte soils and potential for groundwater.
FOUNDATION RECOMMENDATIONS
General
In the event that information concerning the proposed development plan is not correct, or
any changes in the design, location or loading conditions of the proposed structure are
made, the conclusions and recommendations contained in this report shall not be
considered valid unless the changes are reviewed and conclusions of this report are
modified or approved in writing by this office.
RECOMMENDATIONS -CONVENTIONAL FOUNDATIONS
General
The foundation design and construction recommendations are based on laboratory testing
and engineering analysis of onsite earth materials by GSI. Recommendations for
conventional foundation systems are provided in the following sections for bedrock. or fill
on bedrock areas. The foundation systems may be used to support the proposed
structures, provided they are founded in competent bearing material. Foundations should
be founded entirely in compacted fill of rippable bedrock, with no exposed transitions.
The information and recommendations presented in this section are not meant to
supersede design by the project structural engineer. Upon request, GSI could provide
additional inpuVconsultation regarding soil parameters, as related to foundation design.
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Preliminary Foundation Design
Our review, field work, and laboratory testing indicates that onsite soils have a very low to
high expansion potential. Preliminary recommendations for foundation design and
construction are presented below. Final foundation recommendations should be provided
at the conclusion of grading, and based on laboratory testing of fill materials exposed at
finish grade.
Bearing Value
1. The foundation systems should be designed and constructed in accordance with
guidelines presented in the latest edition of the Uniform Building Code.
2. An allowable bearing value of 1500 pounds per square foot may be used for the
design of continuous footings at least 12 inches wide and 12 inches deep, and
column footings at least 24 inches square and 24 inches deep, connected by a
grade beam in at least one direction. This value may be increased by 20 percent
for each additional 12 inches in depth to a maximum of 2500 pounds per square
foot. No increase in bearing value is recommended for increased footing width ..
The allowable bearing pressure may be increased by % under the effects of
temporary loading, such as seismic or wind loads.
Lateral Pressure
1. For lateral sliding resistance, a 0.30 coefficient of friction may be utilized for a
concrete to soil contact when multiplied by the dead load.
2. Passive earth pressure may be computed as an equivalent fluid having a density of
250 pounds per cubic foot with a maximum earth pressure of 2500 pounds per
square foot.
3. When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
Construction
The following foundation construction recommendations are presented as a minimum
criteria from a soils engineering standpoint. The onsite soils expansion potentials are
generally in the very low to low (expansion index Oto 50), to potentially high (expansion
index 91 to 130) range. During grading of the site, we recommend that expansive material
should not be placed within 3 feet of finish grade, if feasible. Therefore, it is anticipated
that the finish grade materials will have a low (or medium) expansion potential.
Conventional foundation systems are not recommended for high to very highly expansive
soil conditions. Post-tension slab foundations are recommended for these conditions.
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Recommendations by the project's design-structural engineer or architect, which may
exceed the soils engineers recommendations, should take precedence over the following
minimum requirements. Final foundation design will be provided based on the expansion
potential of the near surface soils encountered during grading.
Very Low to Low Expansive Soils (Expansion Index o to SO)
1. Exterior and interior footings should be founded at minimum depths of 12 and 18
inches for one or two-story loads, respectively, below the lowest adjacent surface.
Isolated column and panel pads or wall footings should be founded at a minimum
depth of 24 inches and connected in one direction by a grade beam. All footings
should be reinforced with a minimum of two No. 4 reinforcing bars, one placed near
the top and one placed near the bottom of the footing, and in accordance with the
recommendations width per UBC.
2. A grade beam, reinforced as above, and at least 12 inches wide should be provided
across large (e.g., garage or parking area) entrances. The base of the grade beam
should be at the same elevation as the bottom of adjoining footings.
3. Concrete slabs should be underlain by a minimum of 2 inches of washed sand.
Where moisture condensation is undesirable, concrete slabs should be underlain
with a vapor barrier consisting of a minim.um 10 mil, polyvinyl-chloride or equivalent
membrane, with all laps sealed. This membrane should be placed on acceptable
pad grade materials and a minimum 2 inch thickness of sand should be placed over
the visqueen to aid in uniform curing of the concrete.
4. Concrete slabs, including garage areas, should be minimally reinforced with No. 3
reinforcement bars placed on 18-inch centers, each way. All slab reinforcement
should be supported and positioned near the vertical midpoint of the slab.
"Hooking• of reinforcement is not an acceptable method of positioning the
reinforcement.
5. Garage slabs should be poured separately from adjacent footings and be quartered
with expansion joints or saw cuts. A positive separation from the footings should
be maintained with expansion joint material to permit relative movement.
6. A minimum slab thickness of 4 inches is recommended. The design engineer
should determine the actual thickness of the slabs based on loadings and use.
7. Premoistening is recommended for these soils conditions, with the moisture content
of the subgrade soils equal to or greater than the optimum moisture content to a
depth of 12 or 18 inches, for one-or two-story loads, respectively, prior to pouring
slabs and prior to placing visqueen or reinforcement.
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8. In design of any additional concrete, flatwork, pools or walls, the potential for
differential settlement of the soils should be considered.
9. As an alternative, a post tension foundation system may be utilized.
Medium Expansive Solis (Expansion Index 51 to 90)
1. Exterior footings for one-and two-story floor loads should be founded at a minimum
depth of 18 inches below the lowest adjacent ground surface. Interior footings may
be founded at a minimum depth of 12 or 18 inches below the lowest adjacent
ground surface for one-or two-story loads, respectively, and in accordance with the
Uniform Building Code floor loading requirements. All footings should be reinforced
with a minimum of one No. 4 reinforcing bar at the top and one No. 4 reinforcing bar
at the bottom. Footings should have a minimum width of 12 inches, or as
determined by the UBC. Isolated interior and/or exterior piers/columns are not
recommended.
2. A grade beam, reinforced as above and at least 12 inches square, should be utilized
across any garage area entrance and between piers/columns. The base of this
reinforced grade beam should be at the same elevation as the bottom of the
adjoining footings.
3. Concrete slabs in residential or moisture sensitive areas should be underlain with
a total of 4 inches of washed sand or crushed rock. In addition, a vapor barrier
consisting of a minimum of 10-mil, visqueen membrane with all laps sealed should
be provided. Two inches of the sand should be placed over the membrane to aid
in uniform curing of the concrete.
4. Concrete slabs, including garage areas, should be reinforced with No. 3 rebar at 18-
inches on center, each way. All slab reinforcement should be supported to ensure
proper mid-slab positioning during placement of concrete. "Hooking" of
reinforcement is not an acceptable method of positioning the reinforcement.
5. Garage slabs should be poured separately from adjacent footings and be quartered
with expansion joints or saw cuts. A positive separation from the footings should
be maintained with expansion joint material to permit relative movement.
6. A minimum slab thickness of 4 inches is recommended. The design engineer
should determine the actual thickness of the slabs based on loadings and use.
7. Presaturation of slab areas is recommended for these soil conditions. The moisture
content of each slab area should be 120 percent or greater above optimum and
verified by this office to a depth of 18 inches below adjacent ground grade in the
slab areas, within 72 hours of the visqueen placement.
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8. In design of any additional concrete, flatwork, pools or walls, the expansive nature
of the soils should be considered, as should the potential for differential settlement.
9. As an alternative, a post tension foundation system may be utilized.
POST TENSIONED SLAB DESIGN
Post-tensioned slab foundation systems may be used to support the proposed buildings.
Based on the potential differential settlement within areas of the site underlain by alluvium,
post-tensioned slab foundations are recommended exclusively.
General
The information and recommendations presented in this section are not meant to
supersede design by a registered structural engineer or civil engineer familiar with post-
tensioned slab design or corrosion engineering consultant. Upon request, GSI could
provide addltional data/consultation regarding soil parameters as related to post-tensioned
slab design during grading. The post-tensioned slabs should be designed in accordance
with the Post-Tensioning Institute (PTI) Method. Alternatives to the PTI method may be
used if equivalent systems can be proposed which accommodate the angular distortions,
expansion potential and settlement noted for this site.
Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to
non-uniform swell and shrinkage of subgrade soils. The differential movement can occur
at the comer, edge, or center of slab. The potential for differential uplift can be evaluated
using the 1997 Uniform Building Code Section 1816, based on design specifications of the
Post-Tensioning Institute. The following table presents suggested minimum coefficients
to be used in the Post-Tensioning Institute design method.
Thomthwaita Moisture Index -20 inches/year
Correction Factor for Irrigation 20 inches/year
Depth to Constant Soil Suction Sfeet
Constant Soil Suction 3.6
The coefficients are considered minimums and may not be adequate to represent worst
case conditions such as adverse drainage and/or improper landscaping and maintenance.
The above parameters are applicable provided structures have gutters and downspouts
and positive drainage is maintained away from structures. Therefore, it is important that
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information regarding drainage, site maintenance, settlements, and effects of expansive
soils be passed on to Mure owners.
Based on the above parameters, design values were obtained from figures or tables of the
1997 Uniform Building Code Section 1816 and presented in Table 1. These values may
not be appropriate to account for possible differential settlement of the slab due to other
factors O.e. fill settlement). If a stiffer slab is desired, higher values of ym may be warranted.
TABLE 1
POST TENSION FOUNDATIONS
Expansion Potential Very LowPI to Medium Highly
Low Expansive Expansive Expansive
. /El = 0-501 /El= 51-901 /El =91-120)
em center lift 5.0 feet 5.5 feet 5.5 feet
em edge lift 2.5 feet 2.7 feet 3.0 feet
Ym center lift 1.1 inch 2.0 inch 2.5 inch
Ym edge lift 0.35 inch 0.55 inch 0.75 inch
Bearing Value 11) 1000 psf 1000 psf 1000 psf
Lateral Pressure 225 psi 225 psi 225 psf
Subgrade Modulus (k) 1 00 pci/inch 85 pci/lnch 70 pcVinch
Perimeter footing 12 inches 18 inches 24inches
embedment 00
<1l Internal bearing values within the perimeter of the posHension slab may be
increased TO 1500 psf for a minimum embedment of 12 inches, then by 20
percent for each additional foot of embedment to a maximum of 2,500 psf.
(2> As measured below the lowest adjacent compacted subgrade surface.
(3! FoundatiOns for very loW' expansive soil conditions may use the California
Method (soanabilitv method)
Subgrade Preparation
The subgrade material should be compacted to a minimum 90 percent of the maximum
laboratory dry density. Prior to placement of concrete, the subgrade soils should be well
moistened to at least optimum moisture content and verified by our field representative.
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Perimeter Footings and Pre-Wetting
From a soil expansion/shrinkage standpoint, a fairly common contributing factor to distress
of structures using post-tensioned slabs is a significant fluctuation in the moisture content
of soils underlying the perimeter of the slab, compared to the center, causing a "dishing"
or "arching" of the slabs. To mitigate this possible phenomenon, a combination of soil pre-
wetting and construction of a perimeter cut-off wall grade beam should be employed.
Deepened footings/edges around the slab perimeter must be used to minimize non-
uniform surface moisture migration (from an outside source) beneath the slab.
Embedment depths are presented in Table 1 for various soil expansion conditions. The
bottom of the deepened footing/edge should be designed to resist tension, using cable
or reinforcement per the structural engineer. Other applicable recommendations presented
under conventional foundation recommendations in the referenced report should be
adhered to during the design and construction phase of the project.
Floor slab subgrade should be at, or above the soils optimum moisture content to a depth
of 24 inches prior to pouring concrete, for existing soil conditions. Pre-wetting of the slab
subgrade soil prior to placement of steel and concrete will likely be recommended and
necessary, in order to achieve optimum moisture conditions. Soil moisture contents
should be verified at least 72 hours prior to pouring concrete.
Underslab Moisture Barrier
A visqueen vapor barrier, a minimum 6 mils thick, should be placed underneath the slab
in accordance with recommendations presented in the conventional foundation section of
this report. This vapor barrier should be lapped adequately to provide a continuous
waterproof barrier under the entire slab. Moisture barrier placement beneath the garage
slab is optional. However, future uses of the garage slab area (room conversion, storage
of moisture sensitive material) should be considered.
Footing Setbacks
All footings should maintain a minimum horizontal setback of H/3 (H=slope height) from
the base of the footing to the descending slope face should be no less than 7 feet, nor
need not be greater than 40 feet. This distance is measured from the footing face at the
bearing elevation. Footings adjacent to unlined drainage swales should be deepened to
a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for
structures adjacent to retaining walls should be deepened so as to extend below a 1 :1
projection from the heel of the wall. Alternatively, walls may be designed to accommodate
structural loads from buildings or appurtenances as described in the retaining wall section
of this report.
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SETTLEMENT
In addition to designing slab systems (PT or other) for the soil expansion conditions
described herein, the estimated total and differential settlement values that an individual
structure could be subject to should be evaluated by a structural engineer, and utilized in
the foundation design. The levels of angular distortion may be evaluated on a 40-loot
length assumed as minimum dimension of buildings; ii, from a structural standpoint, a
decreased or increased length over which the differential is assumed to occur is justified,
this change should be incorporated into the design. Based on the nature of removals and
the underlying bedrock geometry, fills on the order of 20 to 60 feet in depth may be
anticipated within Lots 1 through 7 and 13. The structures within these lots should be
evaluated and designed for the combination of the soil parameters presented above and
the estimated differential settlements and angular distortions provided as 1 ½ to 2½ inches
in 40 feet post construction settlement. Total settlement may range from 1 to 3½ inches
across the lots onsite, assuming that the recommendations of this report are utilized.
RETAINING WALL RECOMMENDATIONS
General
The following parameters are provided for conventional retaining walls only. Design
parameters for special walls o.e., crib, geogrid, Loffelstein, etc.) will be provided based on
site specific conditions. The equivalent fluid pressure parameters provide for the use of
low expansive select granular backfill to be utilized behind the proposed walls. The low
expansive granular backfill, should be provided behind the wall at a 1 :1 (h:v) projection
from the heel of the foundation system. Low expansive fill is Class 3 aggregate base rock
or Class 2 permeable rock. Wall backfilling should be performed with relatively light
equipment within the same 1 :1 projection (i.e., hand tampers, walk behind compactors).
Highly expansive soils should not be used to backfill any proposed walls. During
construction, materials should not be stockpiled behind nor in front of walls for a distance
of 2H where H is the height of the wall.
Foundation systems for any proposed retaining walls should be designed in accordance
with the recommendations presented in the Foundation Design section of this report.
There should be no increase in bearing for footing width. Building walls, below grade,
should be water-proofed or damp-proofed, depending on the degree of moisture
protection desired. All walls should be properly designed in accordance with the
recommendations presented below and seismically resistant per the USC (1997).
Some movement of the walls constructed should be anticipated as soil strength
parameters are mobilized. This movement could cause some cracking depending upon
the materials used to construct the wall. To reduce the potential for wail cracking, walls
should be Internally grouted and reinforced with steel. To mitigate this effect, the use of
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vertical crack control joints and expansion joints, spaced at 20 feet or less along the walls
should be employed.
Vertical expansion control joints should be infilled with a flexible grout. Wall footings
should be keyed or doweled across vertical expansion joints. Walls should be internally
grouted and reinforced with steel.
Restrained Walls
Any retaining walls that will be restrained prior to placing and compacting backfill material
or that have re-entrant or male comers, should be designed for an at-rest equivalent fluid
pressures (EFP) of 65 pcf, plus any applicable surcharge loading. This restrained-wall,
earth pressure value is for select backfill material only. For areas of male or re-entrant
corners, the restrained wall design should extend a minimum distance of twice the height
of the wall laterally from the corner.
Building walls below grade or greater than 2 feet in height should be water-proofed or
damp-proofed, depending on the degree of moisture protection desired. The wall should
be drained as indicated in the following section. A seismic increment of 1 OH (uniform
pressure) should be oonsidered on walls for level backfill, and 20H for sloping backfill of
2:1, where H is defined as the height of retained material behind the wall. For structural
footing loads within the 1 :1 zone of influence behind wall backfill, refer to the following .
section.
Cant/levered Walls
These recommendations are for cantilevered retaining walls up to 15 feet high. Active
earth pressure may be used for retaining wall design, provided the top of the wall is not
restrained from minor deflections. An empirical equivalent fluid pressure approach may
be used to oompute the horizontal pressure against the wall. Appropriate fluid unit weights
are provided for specific slope gradients of the retained material. These do not include
other superimposed loading conditions such as traffic, structures, seismic events,
expansive soils, or adverse geologic oonditions .
.
SURFACE SLOPE OF RETAINED EQUIVALENT FLUID WEIGHT FOR SELECT
MATERIAL lhorlzonlal lo vertical) "'e"'" low to low e anslvel NATIVE SOIL*
I Level** I 45 I 2 to 1 60
*To be increased by traffic, structural surcharge and seismic loading as needed.
**Level walls are those where Qrades behind the wall are level for a distance of 2H.
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Wall Backfill and Drainage
All retaining walls should be provided with an adequate backdrain and outlet system
(a minimum two outlets per wall and no greater than 100 feet apart), to prevent buildup of
hydrostatic pressures and be designed in accordance with minimum standards presented
herein. The very low expansive granular backfill should be provided behind the wall at a
1 :1 (h:v) projection from the heel of the foundation element. Drain pipe should consist of
4-inch diameter perforated schedule 40 PVC pipe embedded in gravel. Gravel used in the
backdrain systems should be a minimum of 3 cubic feet per lineal foot of %-to 1-inch clean
crushed rock wrapped in filter fabric (Mirafi 140 or equivalent) and 12 inches thick behind
the wall. Where the void to be fitted is constrained by lot lines or property boundaries, the
use of panel drains (Miradrain 5000 or equivalent) may be considered with the approval
of the project geotechnicai engineer. The surface of the backfill should be sealed by
pavement or the top 1 B inches compacted to 90 percent relative compaction with native
soil. Proper surface drainage should also be provided. Weeping of the walls in lieu of a
backdrain is not recommended for walls greater than 2 feet in height. For walls 2 feet or
less in height, weepholes should be no greater than 6 feet on center in the bottom coarse
of block and above the landscape zone.
A paved drainage channel (v-ditch or substitute), either concrete or asphaitic concrete,
behind the top of the walls with sloping backfill should be considered to reduce the
potential for surface water penetration. For level backfill, the grade should be sloped such
that drainage is toward a suitable outlet at 1 to 2 percent.
Retaining Wall Footing Transitions
Site walls are anticipated to be founded on footings designed in accordance with the
recommendations in this report. Wall footings may transition from formational bedrock to
select fill. If this condition is present the civil designer may specify either:
a) If transitions from native soil to fill transect the wall footing alignment at an angle of
less than 45 degrees (plan view), then the designer should perform a minimum 3-
foot overexcavation for a distance of two times the height of the wall and increase
overexcavation until such transition is between 45 and 90 degrees to the wall
alignment.
b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints
or crack control joints) such that an angular distortion of 1 /360 for a distance of 2H
(where H=wall height in feet) on either side of the transtlion may be
accommodated. Expansion joints should be sealed with a flexible, non-shrink
grout.
c) Embed the footings entirely into a homogeneous fill.
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Top-of-Slope Walls
The geotechnical parameters previously provided may be utilized for top-of-slope sound
walls, if planned, which are founded in either competent bedrock or compacted fill
materials.
The strength of the concrete and grout should be evaluated by the structural engineer of
record. The proper ASTM tests for the concrete and mortar should be provided along with
the slump quantities. Additional design recommendations by the corrosion specialist
should be followed.
The placing of joints (expansion and crack control} should be incorporated into the wall
layout. These expansion joints should be placed no greater than 20 feet on-center and
should be reviewed by the civil engineer and structural engineer of record. GSI anticipates
distortions on the order of ½ to 1 ± inch in 50 feet for these walls located at the tops of low
to medium expansive fill/cut slopes. To reduce this potential, the footings may be
deepened and/or the use of piers may be employed.
DEVELOPMENT CRITERIA
Landscape Maintenance and Planting
Water has been shown to weaken the inherent strength of soil and slope stability is
significantly reducad by overly wet condmons. Positive surfaca drainage away from graded
slopes should be maintained and only the amount of irrigation necessary to sustain plant
life should be provided for planted slopes. Overwatering should be avoided.
Graded slopes constructed within and utilizing onslte materiais would be erosive. Eroded
debris may be minimized and surficial slope stability enhanced by establishing and
maintaining a suitable vegetation cover soon after construction. Plants selected for
landscaping should be light weight, deep rooted types which require little water and are
capable of surviving the prevailing climate. Compaction to the face of fill slopes would
tend to minimize short term erosion until vegetation is established. In order to minimize
erosion on a slope face, an erosion control fabric (i.e. jute matting} should be considered.
From a geotechnical standpoint leaching is not recommended for establishing
landscaping. tt the surface soils area processed for the purpose of adding amendments
they should be recompacted to 90 percent relative compaction.
Addltlonal Site Improvements
Recommendations for additional grading, exterior concrete flatwork design and
construction, including driveways, can be provided upon request. If in the Mure, any
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additional improvements are planned for the site, recommendations concerning the
geological or geotechnical aspects of design and construction of said improvements cculd
be provided upon request.
Trenching
All footing trench excavations for structures and walls should be observed and approved
by a representative of this office prior to placing reinforcement. Footing trench spoil and
any excess soils generated from utility trench excavations should be compacted to a
minimum relative compaction of 90 percent if not removed from the site. 'All excavations
should be observed by one of our representatives and conform to CAL-OSHA and local
safety codes. GSI does not consult in the area of safety engineers.
In addition, the potential for encountering hard spots during footing and utility trench
excavations should be anticipated. · If these concretions are encountered within the
proposed footing trench, they should be removed, which could produce larger excavated
areas within the footing or utility trenches.
Drainage
Positive site drainage should be maintained at all times. Drainage should not flow
uncontrolled down any descending slope. Water should be directed away from
foundations and not allowed to pond and/or seep into the ground. Pad drainage should
be directed toward the street or other approved area. Roof gutters and down spouts
should be considered to control roof drainage. Down spouts should outlet a minimum of
5 feet from the proposed structure or into a subsurface drainage system. We would
reccmmend that any proposed open bottom planters adjacent to proposed structures be
eliminated for a minimum distance of 1 O feet. As an alternative, closed bottom type
planters could be utilized. An outlet placed in the bottom of the planter, could be installed
to direct drainage away from structures or any exterior concrete flatwork.
Utlllty Trench Backfill
1. All utility trench backfill in structural areas, slopes, and beneath hardscape features
should be brought to near optimum moisture ccntent and then ccmpacted to obtain
a minimum relative compaction of 90 percent of the laboratory standard.
Flooding/jetting is not recommended for the site soil materials. As an alternative,
imported sandy material with an S.E. of 30 or greater, may be flooded/jetted in
shallow (12±inch or less) under-slab interior trenches, only.
2. Sand backfill, unless trench excavation material, should not be allowed in exterior
trenches adjacent to and within an area extending below a 1 : 1 plane projected from
the outside bottom edge of the footing.
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3. All trench excavations should minimally conform to CAL-OSHA and local safety
codes.
4. Soils generated from utility trench excavations to be used onsite should be
compacted to 90 percent minimum relative compaction. This material must not alter
positive drainage patterns that direct drainage away from the structural area and
towards the street.
PLAN REVIEW
Final site development and foundation plans should be submitted to this office for review
and comment, as the plans become available, for the purpose of minimizing any
misunderstandings between the plans and recommendations presented herein. In
addition, foundation excavations and any addltional earthwork construction performed on
the site should be observed and tested by this office. If conditions are found to differ
substantially from those stated, appropriate recommendations would be offered at that
time.
LIMITATIONS
The materials encountered on the project site and utilized in our study are believed
representative of the area; however, soil and bedrock materials vary in character between
excavations and natural outcrops or conditions exposed during mass grading. site
conditions may vary due to seasonal changes or other factors. GS/ assumes no
responsibility or liabillty for work, testing or recommendations performed or provided by
others. The scope of work was performed within the limits of a budget. Inasmuch as our
study is based upon the site materials observed, selective laboratory testing and
engineering analysis, the conclusion and recommendations are professional opinions.
These opinions have been derived in accordance with current standards of practice, and
no warranty is expressed or implied. Standards of practice are subject to change with
time.
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B B' -PL • r
'4 ,__ ® ®
I----1_ Proposed ----
100· B-4 1 __ -.... street I ' .... --.., I .. --
Wall/)
.. ... B-3 ,: --·----,: ..... 0 ~ ;:, 60-Qcol/Qal ....... Existing .. > ...... _ .. house;\ iii --ad -' TD:45' -20-Tsa -~
TD:39'
Tsa
Ns2·w FOR LEGEND SEE PLATE 1
G&;' LOS AHGEJ.£S CO. . RIVERSIDE CO . -ORANGE CO. " SANDIEGOCO.
CROSS SECTION B-B'
filµe4
w.o. 3008-A-SC DATE 2/01 SCALE T:40'
-D D'
Existing
I grade ®
200 I .--200 ---_...._'
I I --__ ,
propsed @ --..... -::... .... -_ " Proposed grade
' I street
Apparent dip of -----· --160----,so bedding plane ' ------,
'-------------..-Af\
' ---... --Apparent dip of -------120-Tsa ------120 bedding plane --'--------------
BO-Tsa -80
N88°E
-> N39°E b
FOR LEGEND SEE PLATE 1
----LOS ANGELES CO. ~I· RIVERSIDE CO.
ORANGE CO.
SAN DIEGO CO.
CROSS SECTION D-D'
Ag,n8
W.0. 3008-A-SC DATE 2/01 SCALE ,r'=40'
APPENDIX A
REFERENCES
APPENDIX A
REFERENCES
Benton Engineering, Inc., 1970, Final Compaction Report, La Costa South Unit 7, August
10, 1970, Project # 69-12-8D.
Blake, Thomas F., 1997, EQFAULT computer program for the deterministic prediction
of horizontal accelerations from digitized California faults.
Campbell, K.W. and Bozorgnia, Y., 1994, Near-source attenuation of peak horizontal
acceleration from worldwide accelrograms recorded from 1957 to 1993;
Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume
Ill, Earthquake Engineering Research Institute, pp 292-293.
Hart, E.W. and Bryant, W.A. 1997, Fault-rupture Hazard Zones in California, Alquist-Priolo
Earthquake Fault Zoning act with Index to Earthquake Fault Maps; California
Division of Mines and Geology Special Publication 42.
International Conference of Building Officials, 1997, Uniform building code: Whittier,
California, vol. 1, 2, and 3.
Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California
Division of Mines and Geology, Map Sheet No. 6, scale 1 :750,000.
Joyner, W.B., and Boore, D.M., 1982, Estimation of response-spectral values as functions
of magnijude, distance and site conditions, in eds., Johnson, J.A., Campbell, K.W.,
and Blake, T.F., AEG short course, seismic hazard analysis, dated June 18, 1994.
Petersen, Mark D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fault parameters
used by the California Division of Mines and Geology to compile the probabilistic
seismic hazard maps of California.
Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported
in Joyner, W.B., and Boore, D.M., 1988, "Measurement, characterization, and
prediction of strong ground motion', in Earthquake Engineering and Soil Dynamics
II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American
Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102.
Tan, S.S., and Kennedy, Michael P., 1996, Geologic maps of the northwestern part of San
Diego County, California: California Division of Mines and Geology, Open File
Report 96-02.
GeoSoils, Jne.
APPENDIX B
BORING AND TEST PIT LOGS
APPENDIXC
LABORATORY DATA
.
4,000
I/
/ / _ 3,000
V
I/ :l.
t
I/ C) z w " ' ti
~ • ::c 2,000 v, V "'
1,000 / /
V •
0 0 1,000 2,000 3,000 4,000
NORMAL PRESSURE, psi
Sample Depth/El. Primary/Residual Shear Sample Type i MC% C q, -• 8-1 25.0 Primary Shear Undisturbed 1132 9.8 701 34
" ■ 8-1 25.0 Residual Shear Undisturbed 113.2 9.8 297 32
C
~ -0 -~ Note: Sample lnnundated prior to testing
•• .
:
' GeoSoils, lnc. DIRECT SHEAR TEST
57 41 Palmer Wa~ Project: MSK DEVELOPMENT
t; est-Cartsbad, CA 92 08 ~ Telephone: S760)438-3155 Number: 3008-A-SC ° Fax: (760) 9 1-0915 Date: February 2001 Figure: C -1 -0
//)/ /v
4,ooof---------+--------i--,,,c::__---+----,L+-------1
f/'/ V
/ . / •
~ 3,000f--~,,.C,,---1------+,/--~L------+------l----__j i 1/ z ~ / ~ iii 2,000f-------vf-----,''----+ ,------1------+-------a
1,000 /
/
0,1,□-----.,b.,----.,,!;;;;-----.-s=------,-,l,.;;----__J 1,000 2,000 3,000 4,000
NORMAL PRESSURE, psf
Sample Depth/El. Primary/Residual Shear Sample Type 'Y4 MC% c
~ • B-2 20.0 Primary Shear Undisturbed 122.6 12.4 2602 32
1-■ B-2 20.0 Residual Shear Undisturbed 122.6 12.4 549 8:n-t-----+---+----------+----------+--+----+--+-----+I 43
5:IH-----,---+------+------+----,--+--+-----11
3,IL,L__ ___ _j_ ___ _i_ _______ __, ________ __i __ _i_ _ __, __ _j_ __ ,, • ..., Note: Sample lnnundated prior to testing
~:1---------------~-~~~~~~=~---1 ~ GeoSoils, Inc. DIRECT SHEAR TEST • es 5741 PalmerWay Project: MSKDEVELOPMENT ~ Cl .. lo1111 ,1!,_ Cartsbad, CA 92008 ~ I" Telephone: (760) 438-3155 Number. 3008-A-SC
Fax: (760) 931--0915 Date: February 2001 Figure: C - 2 3._ _________________ ..., __ ...,;,.;.,;...,;,...,;,.:.;;...,;, _____ ...,;;... ___ ..
V
/
4,000 /
V • / / _ 3,000
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NORMAL PRESSURE, psf
Sample Depth/El, Primary/Residual Shear Sample Type .,. MC% C ~
~ • TP-3 3.0 Primary Shear Undisturbed 120.7 10.3 2517 32
e ■ TP-3 3.0 Residual Shear Undisturbed 120.7 10.3 553 29
C ~
<
-~ Note: Sample lnnundated prior to testing ~ !
~ GeoSoils, Inc. DIRECT SHEAR TEST
• 5741 Palmer Wai Project: MSK DEVELOPMENT ~ &Sf. i Carlsbad, CA 92 08 Number. 3008-A-SC Telephone: ~60) 438-3155
~ Fax: (760) 9 1-0915 Date: February 2001 Figure: C-4
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I GeoSoils, Inc. CONSOLIDATION TEST
es 5741 PalmerWa~ Project: MSK DEVELOPMENT
I Carlsbad, CA 92 8 f-Telephone: ~760) 438-3155 Number: 3008-A-SC
• Fax: (760) 9 1-0915 Dale: February 2001 Figure: C -11
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z i GeoSoils, Inc. es. 5741 Palmer Way
~ -Carlsbad, CA 92008
Initial Initial Final
106.9 7.7 15.1 5800
CONSOLIDATION TEST
Project: MSK DEVELOPMENT
Number. 3008-A-SC
10'
~ Telephone: (760) 438-3155
u Fax: (760) 931-0915 Date: February 2001 Figure: C-12 ~ .... ________________ ....,...;;=;.;....;;;..,;;;;;.:.;;.;.;.;.. ___ ....;;_ ___ _.
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i GeoSoils, Inc. CONSOLIDATION TEST
5741 Palmer Wal Project: MSK DEVELOPMENT
l est-Carlsbad, CA 92 08
Telephone: ~760) 438-3155 Number. 3008-A-SC
u Fax: (760) 9 1-0915 Date: February 2001 Figure: C-14 ' "
1\.1. J, Schiff & Associates, Inc.
Consulting Corrosion Engineers -Since 1959 1308 Monte Vista Avenue, Suite 6
Upland, CA 91786-8224
Phone: 909/931-1360
Table 1 -Laboratory Tests on Soil Samples
Sample ID
Resistivity Units
as-received ohm-cm
saturated ohm-cm
pH
Electrical
Conductivity mS/cm
Chemical Analyses
Cations
calcium Ca2+ mg/kg
magnesium Mg2+ mg/kg
sodium Na1+ mg/kg
Anions
carbonate co~ ' mg/kg
bicarbonate HCO3
1-mg/kg
chloride c11-mg/kg
sulfate S04
2• mg/kg
Other Tests
ammonium NH41+ mg/kg
nitrate N03
1• mg/kg
sulfide s'· qual
Redox mv
Geosoils, Inc.
Your #3008-A-SC, MJS&A #01-0JJILAB
15-Jan-0I
TP-3 TP-4
@3' @6'
2,000 1,300
770 580
7.7 7.3
0.24 0.26
ND 64
46 12
180 217
35 20
101 705
138. 18
237 45
n, na
n, na
n, na
n, na
Electrical conductivity in millisiemens/cm and chemical analysis were made on a I :5 soil-to-water extract.
mg/kg= milligrams per kilogram (parts per million) of dry soil.
Redox = oxidation-reduction potential in millivolts
ND = not detected
na = not analyzed
Page I of 1 Figure C-16
APPENDIX D
SLOPE STABILITY ANALYSIS
APPENDIX D
SLOPE STABILITY ANALYSIS
INTRODUCTION OF XSTABL COMPUTER PROGRAM
Introduction
XSTABL is a fully integrated slope stability analysis program. It permits the engineer to
develop the slope geometry interactively and perform slope analysis from within a single
program. The slope analysis portion of XSTABL uses a modified version of the popular
XSTABL program, originally developed at Purdue University.
XSTABL performs a two dimensional limit equilibrium analysis to compute the factor of
safety for a layered slope using the modified Bishop or Janbu methods. This program can
be used to search for the most critical surface or the factor of safety may be determined
for specific surfaces. XSTABL, Version 5.005, is programmed to handle:
1. Heterogenous soil systems
2. Anisotropic soil strength properties
3. Reinforced slopes
4. Nonlinear Mohr-Coulomb strength envelope
5. Pore water pressures for effective stress analysis using:
a. Phreatic and piezometric surfaces
b. Pore pressure grid
c. R factor
d. Constant pore water pressure
6. Pseudo-static earthquake loading
7. Surcharge boundary loads
8. Automatic generation and analysis of an unlimited number of circular, noncircular
and block-shaped failure surfaces
9. Analysis of right-facing slopes
10. Both SI and Imperial units
General Information
If the reviewer wishes to obtain more information concerning slope stability analysis, the
following publications may be consulted initially:
1.
2.
The Stability of Slopes, by E.N. Bromhead, Surrey University Press, Chapman and
Hall, 411 pages, 2°' edition, ISBN 412 01061 5, 1992.
Rock Slope Engineering, by E. Hoek and J.W. Bray, Inst. of Mining and Metallurgy,
London, England, Third Edition, 358 pages, ISNB 0 900488 573, 1981.
GeoSoils, lne.
3. Landslides Investigation and Mitigation, by A.K. Turner and R.L. Schuster (editors),
Special Report 247, Transportation Research Board, National Research Council,
673 pages, ISBN 0 309 06208-X, National Academy Press, 1996.
XSTABL Features
The present version of XSTABL contains the following features:
1. Allows user to calculate factors of safety for static stability and dynamic stability
situations.
2. Allows user to analyze stability situations with different failure modes.
3. Allows user to edit input for slope geometry and calculate corresponding factor of
safety.-
4. Allows user to readily review on-screen the input slope geometry.
5. Allows user to automatically generate and analyze unlimited number of circular,
non-circular and block-shaped failure sulfaces (i.e., bedding plane, slide plane,
etc.).
Input Data
Input data includes the following items:
t. Unit weight, residual cohesion, residual friction angle, peak cohesion, and peak
friction angle of fill material, bedding plane, and bedrock, respectively. Residual
cohesion and friction angle is used for static stability analysis, whereas peak
cohesion and friction angle is for dynamic stability analysis.
2. Slope geometry and surcharge boundary loads.
3. Apparent dip of bedding plane can be specified in angular range (i.e., from o to 90
degrees.
4. Pseudo-static earthquake loading (an earthquake loading of 0. t 2g was used in the
analysis.
Seismic Discussion
Seismic stability analyses were approximated using a pseudo-static approach. The major
difficulty in the pseudo-static approach arises from the appropriate selection of the seismic
coefficient used in the analysis. The use of a static inertia force equal to this acceleration
during an earthquake (rigid-body response) would be extremely conservative for several
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Appendix D
Page2
reasons including: 1) only low height, stiff/dense embankments or embankments in
confined areas may respond essentially as rigid structures; 2) an earthquake's inertia force
is enacted on a mass for a short time period. Therefore, replacing a transient force by a
pseudo-static force representing the maximum acceleration is considered unrealistic; 3)
Assuming that total pseudo-static loading is applied evenly throughout the embankment
for an extended period of time is an incorrect assumption, as the length of the failure
surface analyzed is usually much greater than the wave length of seismic waves generated
by earthquakes; and 4) the seismic waves would place portions of the mass in
compression and some in tension, resulting in only a limited portion of the failure surface
analyzed moving in a downslope direction, at any one instant of time.
The coefficients usually suggested by regulating agencies, counties and municipalities are
in the range of 0.05g to 0.25g. For example, past regulatory guidelines within the city and
county of Los Angeles indicated that the slope stability pseudostatic coefficient ; 0.15.
Output Information
Outpu1 information includes:
1. All input data.
2. Factors of safety for the ten most critical surfaces for static and pseudo-static
stability situation.
3. High quality plots can be generated. The plots include the slope geometry, the
critical surfaces and the factor of safety.
4. Note, that in the analysis, at least 9000 trial surfaces were analyzed for each section
for either static or pseudo-static analyses.
Results of Slope Stability Calculation
Table D-1 shows parameters used in slope stability calculations. Detailed outpu1
information is presented in Plates D-1 to D-9. A summary of our gross stability analysis is
presented in Table D-2.
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Appendix D
Page3
TABLE D-1
Soll Parameters Used
Material
Unit Weight (pcf) Strength Parameters
. Moist Saturated Cohesion (psf) Friction Angle
Compacted Fill 125 135 250 27
.
Colluvium 120 130 100 25
Santiago 127 135 300 31 Formation
TABLE D-2
Summary of Gross Stability Analysis
Available Factor of Safety .
Location :·. ·,
Section A·A'
Section B·B'
Section 8-8'
(Retaining Wall)
Section C-C'
Section D-D'
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StaUc
2.207
1.527
1.507
1.488
2.086
Seismic
1.587
1.192
1.333
Not Analyzed
1.609
Notes
Assumes the use of select native site soil
during construction. Should be verified in the
field during grading.
Factor of safety for temporary slope during
grading.
Appendix D
Page 4
GeoSoils, lne.
SURFICIAL SLOPE STABILITY ANALYSIS
W.O. 3008-A-SC
Material Type: Compacted Fill, Santiago Formation
Detail Compacted Fill
Depth of Saturation (z) (ft) 4
Slope Angle (i) (for 2: 1 slopes) 26.56
Unrt Weight of Water (Yw) (pcf) 62.4
Saturated Unrt of Soil (y,.,) (pcf) 135
Apparent Angle of Internal Friction (<I>) 27 . ,,,.., '--~ 250
Fs, Static Safety Factor = ~,:-1>.) Cos'(i) Tan (cbl + C
z (OSA,) Sin 0) Cos rn
Factor of Safety
Santiago
Formation
4
26.56
62.4
135
31
300
Depth of Saturation (feet)
',,_ Compacted Fill I Santiago Formation
I 4
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I 1.705
GeoSoils, Jne.
I 2.035 I
Appendix D
Page 5
APPENDIX E
GENERAL EARTHWORK AND GRADING GUIDELINES
GENERAL EARTHWORK AND GRADING GUIDELINES
General
These guidelines present general procedures and requirements for earthwork and grading
as shown on the approved grading plans, including preparation of areas to filled,
placement of fill, installation of subdrains and excavations. The recommendations
contained in the geotechnical report are part of the earthwork and grading guidelines and
would supersede the provisions contained hereafter in the case of conflict. Evaluations
performed by the consultant during the course of grading may 'result in new
recommendations which could supersede these guidelines or the recommendations
contained in the geotechnical report.
The contractor is responsible for the satisfactory completion of all earthwork in accordance
with provisions of the project plans and specifications. The project soil engineer and
engineering geologist (geotechnical consultant) or their representatives should provide
observation and testing services, and geotechnical consultation during the duration of the
project.
EARTHWORK OBSERVATIONS AND TESTING
Geotechnlcal Consultant
Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer
and engineering geologist) should be employed for the purpose of observing earthwork
procedures and testing the fills for conformance with the recommendations of the
geotechnical report, the approved grading plans, and applicable grading codes and
ordinances.
The geotechnical consultant should provide testing and observation so that determination
may be made that the work is being accomplished as specified. Ii is the responsibility of
the contractor to assist the consultants and keep them apprised of anticipated work
schedules and changes, so that they may schedule their personnel accordingly.
All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be
observed and documented by the project engineering geologist and/or soil engineer prior
to placing and fill. It is the contractors's responsibillty to notify the engineering geologist
and soil engineer when such areas are ready for observation. •
Laboratory and Field Tests
Maximum dry density tests to determine the degree of compaction should be performed
in accordance with American Standard Testing Materials test method ASTM designation
D-1557-78. Random field compaction tests should be performed in accordance with test
method ASTM designation D-1556-82, D-2937 or D-2922 and D-3017, at intervals of
approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria
GeoSoils, lne.
would vary depending on the soil conditions and the size of the project. The location and
frequency of testing would be at the discretion of the geotechnical consultant.
Contractor"s Responsibility
All clearing, site preparation, and earthwork performed on the project should be conducted
by the contractor, with observation by geotechnical consultants and staged approval by
the governing agencies, as applicable. It is the contractor's responsibility to prepare the
ground surface to receive the fill, to the satisfaction of the soil engineer, and to place,
spread, moisture condition, mix and compact the fill in accordance with the
recommendations of the soil engineer. The contractor should also remove all major non-
earth material considered unsatisfactory by the soil engineer.
It is the sole responsibility of the contractor to provide adequate equipment and methods
to accomplish the earthwork in accordance with applicable grading guidelines, codes or
agency ordinances, and approved grading plans. Sufficient watering apparatus and
compaction equipment should be provided by the contractor with due consideration for
the fill material, rate of placement, and climatic conditions. If, in the opinion of the
geotechnical consultant, unsatisfactory conditions such as questionable weather,
excessive oversized rock, or deleterious material, insufficient support equipment, etc., are
resulting in a quality of work that is not acceptable, the consultant will inform the
contractor, and the contractor is expected to rectify the conditions, and if necessary, stop
work until conditions are satisfactory.
During construction, the contractor shall properly grade all surfaces to maintain good
drainage and prevent ponding of water. The contractor shall take remedial measures to
control surface water and to prevent erosion of graded areas until such time as permanent
drainage and erosion control measures have been i.nstalled.
SITE PREPARATION
All major vegetation, including brush, trees, thick grasses, organic debris, and other
deleterious material should be removed and disposed of off-site. These removals must be
concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials
determined by the soil engineer or engineering geologist as being unsuitable in-place
should be removed prior to fill placement. Depending upon the soil conditions, these
materials may be reused as compacted fills. Any materials incorporated as part of the
compacted fills should be approved by the soil engineer.
Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic
tanks, wells, pipelines, or other structures not located prior to grading are to be removed
or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly
fractured, or otherwise unsuitable ground extending to such a depth that surface
processing cannot adequately improve the condition should be overexcavated down to
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Appendix E
Page2
firm ground and approved by the soil engineer before compaction and filling operations
continue. Overexcavated and processed soils which have been properly mixed and
moisture conditioned should be re-compacted to the minimum relative compaction as
specified in these guidelines.
Existing ground which is determined to be satisfactory for support of the fills should be
scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the
scarified ground is brought to optimum moisture content or greater and mixed, the
materials should be compacted as specified herein. If the scarified zone is grater that 6
inches in depth, it may be necessary to remove the excess and place the material in lifts
restricted to about 6 inches in compacted thickness.
Existing ground which is not satisfactory to support compacted fill should be
overexcavated as required in the geotechnical report or by the on-site soils engineer
and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of
mixing should continue until the soils are broken down and free of large lumps or clods,
until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or
other uneven features which would inhibit compaction as described previously.
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to verticaQ,
the ground should be stepped or benched. The lowest bench, which will act as a key,
should be a minimum of 15 feet wide and should be at least 2 feet deep into firm material,
and approved by the soil engineer and/or engineering geologist. In fill over cut slope
conditions, the recommended minimum width of the lowest bench or key is also 15 feet
with the key founded on firm material, as designated by the Geotechnical Consultant. As
a general rule, unless specifically recommended otherwise by the Soil Engineer, the
minimum width of fill keys should be approximately equal to ½ the height of the slope.
Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable
material. Benching may be used to remove unsuitable materials, although It is understood
that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered
for unsuitable materials in excess of 4 feet in thickness.
All areas to receive fill, including processed areas, removal areas, and the toe of fill
benches should be observed and approved by the soil engineer and/or engineering
geologist prior to placement of fill. Fills may then be properly placed and compacted until
design grades (elevations) are attained.
COMPACTED FILLS
Any earth materials imported or excavated on the property may be utilized in the fill
provided that each material has been determined to be suitable by the soil engineer.
These materials should be free of roots, tree branches, other organic matter or other
deleterious materials. All unsuitable materials should be removed from the fill as directed
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Appendix E
Page 3
by the soil engineer. Soils of poor gradation, undesirable expansion potential, or
substandard strength characteristics may be designated by the consultant as unsuitable
and may require blending with other soils to serve as a satisfactory fill material.
Fill materials derived from benching operations should be dispersed throughout the fill
area and blended with other bedrock derived material. Benching operations should not
result in the benched material being placed only within a single equipment width away
from the fill/bedrock contact.
Oversized materials defined as rock or other irreducible materials wiih a maximum
dimension greater than 12 inches should not be buried or placed in fills unless the location
of materials and disposal methods are specifically approved by the soil engineer.
Oversized material should be taken off-site or placed in accordance with recommendations
of the soil engineer in areas designated as sultable for rock disposal. Oversized material
should not be placed within 1 o feet vertically of finish grade (elevation) or within 20 feet
horizontally of slope faces.
To facilitate future trenching, rock should not be placed within the range of foundation
excavations, future utilities, or underground construction unless specifically approved by
the soil engineer and/or the developers representative.
If import material is required for grading, representative samples of the materials to be
utilized as compacted fill should be analyzed in the laboratory by the soil engineer to
determine its physical properties. If any material other than that previously tested is
encountered during grading, an appropriate analysis of this material should be conducted
by the soil engineer as soon as possible.
Approved fill material should be placed in areas prepared to receive fill in near horizontal
layers that when compacted should not exceed 6 inches in thickness. The soil engineer
may approve thick lifts tt testing indicates the grading procedures are such that adequate
compaction is being achieved with lifts of greater thickness. Each layer should be spread
evenly and blended to attain unttorrnity of material and moisture suitable for compaction.
Fill layers at a moisture content less than optimum should be watered and mixed, and wet
fill layers should be aerated by scarification or should be blended with drier material.
Moisture condition, blending, and mixing of the fill layer should continue until the fill
materials have a uniform moisture content at or above optimum moisture.
After each layer has been evenly spread, moisture conditioned and mixed, it should be
unttorrnly compacted to a minimum of 90 percent of maximum density as determined by
ASTM test designation, D-1557-78, or as otherwise recommended by the soil engineer.
Compaction equipment should be adequately sized and should be specifically designed
for soil compaction or of proven reliability to efficiently achieve the specified degree of
compaction.
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GeoSoils, lffl!.
Appendix E
Page 4
Where tests indicate that the density of any layer of fill, or portion thereof, is below the
required relative compaction, or improper moisture is in evidence, the particular layer or
portion shall be re-worked until the required density and/or moisture content has been
attained. No additionai fill shall be placed in an area until the last placed lift of fill has been
tested and found to meet the density and moisture requirements, and is approved by the
soil engineer.
Compaction of slopes should be accomplished by over-building a minimum of 3 feet
horizontally, and subsequently trimming back to the design slope configuration. Testing
shall be performed as the fill is elevated to evaluate compaction as the fill core is being
developed. Special efforts may be necessary to attain the specified compaction in the fill
slope zone. Finai slope shaping should be performed by trimming and removing loose
materials with appropriate equipment. A final determination of fill slope compaction should
be based on observation and/or testing of the finished slope face. Where compacted fill
slopes are designed steeper than 2:1 (horizontal to vertical), specific material types, a
higher minimum relative compaction, and special grading procedures, may be
recommended.
If an alternative to over-building and cutting back the compacted fill slopes is selected,
then special effort should be made to achieve the required compaction in the outer 10 feet
of each lift of fill by undertaking the following:
1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot should
be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The
sheepsfoot roller should also be used to roll perpendicular to the slopes, and
extend out over the slope to provide adequate compaction to the face of the slope.
2. Loose fill should not be spilled out over the face of the slope as each lift is
compacted. Any loose fill spilled over a previously completed slope face should be
trimmed off or be subject to re-rolling.
3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope
at appropriate vertical intervals, subsequent to compaction operations.
4. After completion of the slope, the slope face should be shaped with a small tractor
and then re-rolled with a sheepsfoot to achieve compaction to near the slope face.
Subsequent to testing to verify compaction, the slopes should be grid-rolled to
achieve compaction to the slope face. Final testing should be used to confirm
compaction after grid rolling. •
5. Where testing indicates less than adequate compaction, the contractor will be
responsible to rip, water, mix and re-compact the slope material as necessary to
achieve compaction. Addltional testing should be performed to verify compaction.
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GeoSoils, Inc.
Appendix E
Page 5
6. Erosion control and drainage devices should be designed by the project civil
engineer in compliance with ordinances of the controlling governmental agencies,
and/or in accordance with the recommendation of the soil engineer or engineering
geologist.
SUBDRAIN INSTALLATION
Subdrains should be installed in approved ground in accordance with the approximate
alignment and details indicated by the geotechnical consultant. Subdra.in locations or
materials should not be changed or modified without approval of the geotechnical
consultant. The soil engineer and/or engineering geologist may recommend and direct
changes in subdrain line, grade and drain material in the field, pending exposed
conditions. The location of constructed subdrains should be recorded by the project civil
engineer.
EXCAVATIONS
Excavations and cut slopes should be examined during grading by the engineering
geologist. If directed by the engineering geologist, further excavations or overexcavation
and re-filling of cut areas should be performed and/or remedial grading of cut slopes
should be performed. When fill over cut slopes are to be graded, unless otherwise
approved, the cut portion of the slope should be observed by the engineering geologist
prior to placement of materials for construction of the fill portion of the slope.
The engineering geologist should observe all cut slopes and should be notified by the
contractor when cut slopes are started.
If, during the course of grading, unforeseen adverse or potential adverse geologic
conditions are encountered, the engineering geologist and soil engineer should
investigate, evaluate and make recommendations to treat these problems. The need for
cut slope buttressing or stabilizing should be based on in-grading evaiuation by the
engineering geologist, whether anticipated or not.
Unless otherwise specified in soil and geological reports, no cut slopes should be
excavated higher or steeper than that allowed by the ordinances-of controlling
governmental agencies. Additionally, short-term stability of temporary cut slopes is the
contractors responsibility.
Erosion control and drainage devices should be designed by the project civil engineer and
should be constructed in compliance with the ordinances of the controlling governmental
agencies, and/or in accordance with the recommendations of the soil engineer or
engineering geologist.
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GeoSoils, Inc.
Appendix E
Page6
COMPLETION
Observation, testing and consultation by the geotechnical consultant should be conducted
during the grading operations in order to state an opinion that all cut and filled areas are
graded in accordance with the approved project specifications.
After completion of grading and after the soil engineer and engineering geologist have
finished their observations of the work, final reports should be submitted subject to review
by the controlling governmental agencies. No further excavation or filling should be
undertaken without prior notification of the soil engineer and/or engineering geologist.
All finished cut and fill slopes should be protected from erosion and/or be planted in
accordance with the project specifications and/or as recommended by a landscape
architect. Such protection and/or planning should be undertaken as soon as practical after
completion of grading.
JOB SAFETY
General
At GeoSoils, Inc. (GS/) getting the job done safely is of primary concern. The following is
the company's safety considerations for use by all employees on multi-employer
construction sites. On ground personnel are at highest risk of injury and possible fatality
on grading and construction projects. GS/ recognizes that construction activities will vary
on each site and that site safety is the prime responsibility of the contractor; however,
everyone must be safety conscious and responsible at all times. To achieve our goal of
avoiding accidents, cooperation between the client, the contractor and GS/ personnel must
be maintained.
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of field personnel on grading
and construction projects:
Safety Meetings: GS/ field personnel are directed to attend contractors regularly
scheduled and documented safety meetings.
Safety Vests: Safety vests are provided for and are to be worn by GS/ personnel at
all times when they are working in the field.
Safety Flags: Two safety flags are provided to GS/ field technicians; one is to be
affixed to the vehicle when on site, the other is to be placed atop the
spoil pile on all test pits.
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Geo&oil.s, lne,
Appendix E
Page7
Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing
amber beacon, or strobe lights, on the vehicle during all field testing.
While operating a vehicle in the grading area, the emergency flasher
on the vehicle shall be activated.
In the event that the contractor's representative observes any of our personnel not
following the above, we request that it be brought to the attention of our office.
Test Pits Location, Orientation and Clearance
The technician is responsible for selecting test pit locations. A primary concern should be
the technicians's safety. Efforts will be made to coordinate locations with the grading
contractors authorized representative, and to select locations following or behind the
established traffic pattern, preferably outside of current traffic. The contractors authorized
representative (dump man, operator, supervisor, grade checker, etc.) should direct
excavation of the pit and safety during the test period. Of paramount concern should be
the soil technicians safety and obtaining enough tests to represent the fill.
Test pits should be excavated so that the spoil pile is placed away form oncoming traffic,
whenever possible. The technician's vehicle is to be placed next to the test pit, opposite
the spoil pile. This necessitates the fill be maintained in a driveable condition.
Alternatively, the contractor may wish to park a piece of equipment in front of the test
holes, particularly in small fill areas or those with limited access.
A zone of non-encroachment should be established for all test pits. No grading equipment
should enter this zone during the testing procedure. The zone should extend
approximately 50 feet outward from the center of the test pit. This zone is established for
safety and to avoid excessive ground vibration which typically decreased test results.
When taking slope tests the technician should park the vehicle directiy above or below the
test location. If this is not possible, a prominent flag should be placed at the top of the
slope. The contractors representative should effectively keep all equipment at a safe
operation distance (e.g. 50 feet) away from the slope during this testing.
The technician is directed to withdraw from the active portion of the fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in
a highly visible location, well away from the equipment traffic pattern.
The contractor should inform our personnel of all changes to haul roads, cut and fill areas
or other factors that may affect site access and site safety.
In the event that the technicians safety is jeopardized or compromised as a result of the
contractors failure to comply with any of the above, the technician is required, by company
policy, to immediately withdraw and notify his/her supervisor. The grading contractors
representative will eventually be contacted In an effort to effect a solution. However, in the
MSK Development Group
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Appendix E
Page B
interim, no further testing will be performed until the situation is rectified. Any fill place can
be considered unacceptable and subject to reprocessing, recompaction or removal.
In the event that the soil technician does not comply with the above or other established
safety guidelines, we request that the contractor brings this to his/her attention and notify
this office. Effective communication and coordination between the contractors
representative and the soils technician is strongly encouraged in order to implement the
above safety plan.
Trench and Vertical Excavation
It is the contractor's responsibility to provide safe access into trenches where compaction
testing is needed.
Our personnel are directed not to enter any excavation or vertical cut which 1) is 5 feet or
deeper unless shored or laid back, 2) displays any evidence of ins1ability, has any loose
rock or other debris which could fall into the trench, or 3) displays any other evidence of
any unsafe conditions regardless of depth.
All trench excavations or vertical cu1s in excess of 5 feet deep, which any person enters,
should be shored or laid back.
Trench access should be provided in accordance with CAL-OSHA and/or state and local
s1andards. Our personnel are directed not to enter any trench by being lowered or "riding
down" on the equipment.
If the contractor fails to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify his/her supervisor.
The contractors representative will eventually be contacted in an effort to effect a solution.
All backfill not tested due to safety concerns or other reasons could be subject to
reprocessing and/or removal.
If GSI personnel become aware of anyone working beneath an unsafe trench wall or
vertical excavation, we have a legal obligation to put the contractor and owner/developer
on notice to immediately correct the situation. If corrective s1eps are not taken, GSI then
has an obligation to notify CAL-OSHA and/or the proper authorities.
MSK Development Group
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GeoSoih, lne.
Appendix E
Paga 9
TYPICAL SURFACE SETTLEMENT MONUMENT
FlNISH GRADE - --;:::,,=:..:;:-- -.,__ --
3/8" DIAMETER X 6" LENGTH
CARRIAGE BOLT DR EQUIVALENT
~
-
~-DIAMETER X 3 1/2' LENGTH HOLE
-
-3•-s·
-
CONCRETE BACKFILL
--
PLATE EG-15