HomeMy WebLinkAboutCT 2018-0006; LAGUNA DRIVE SUBDIVISION; PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED 12 UNIT RESIDENTIAL STRUCTURES; 2018-04-04RECORD COPY
COAST GEOTECHNICAL
CONSULTING ENGINEERING GEOLOGISTS
Apri14, 2018
RCllYI
Brett Farrow
Brett Farrow Architect
125 Mozart Avenue
Cardiff, CA 92007
JUL 09 222
LAND DEVELOPMENT
ENGfN"t à_. I
RE: PRELIMINARY GEOTECHNICAL INVESTIGATION
Proposed 12 Residential Structures
570-580 Laguna Drive
Carlsbad, CA 92008
Dear Mr. Farrow:
In response to your request and in accordance with our Agreement dated January 16, 2018, we have
performed apreliminary geotechnical investigation on the subject site for the proposed 12 residential
structures. The findings of the investigation, laboratory test results, and recommendations for the
foundation des ign.are presented in this report.
From a geologic and soils engineering point of view, it is our opinion that the site is suitable for the
proposed development, provided the recommendations in this report are implemented during the
design and construction phases. However, certain geotechnical conditions will require special
consideration during the design and construction phases, as indicated by the following:
The existing soil and weathered Paralic Deposits are not suitable for the support of proposed
footings, slabs-on-grade, exterior improvements or proposed fills in their present condition.
Remedial grading is recommended.
P.O. BOX 230163 ENC1NITAS, CALIFORNIA 92023
(858) 755-8622
The rear inland bluff is composed, in part, of friable Paralic Deposits which are susceptible
to surficial failure and bluff retreat. Surface drainage should be directed, as much as
possible, away from the top of slope.
The geologic conditions underlying the rear bluff are such that infiltrated water developing
saturated conditions can adversely affect slope stability. Storniwater infiltration should be
significantly limited and if necessary bioretention basins should be located in the most
southern portion of the site.
If you have ariy questions, please do not hesitate to cOntact us at (858) 755-8622-. This opportunity
to be of service is appreciated.
Respectfully submitted,
COAST GEOTECHNICAL
Wyatt Bartholomew
Project Geologist
MarkBwwell, C.E.G. Vithaya Siñghanet, P.E.
Engineering Geologist Geotechiiical Engineer.
PRELIMINARY GEOTECHNICAL INVESTIGATION
Proposed 12 Residentil Structures
570-580 Laguna.Drive
Carlsbad, CA 92008
Preparedfor
Brett Farrow
Brett Farrow Architect
125 MoaitAveñue
Cardiff, CA 92007
Prepared by:
COAST GEOTECH1TCAL
P.O. Box 230163
Encinitas, CA 92023
April 4,2018
W.O. 686218
TABLE OF CONTENTS
INTRODUCTION...........................................................6
SCOPE OF SERVICES ......................................................6
SITE DESCRIPTION AND PROPOSED DEVELOPMENT .........................7
3.1 Site Description .................................................. ......... 7
3.2 Proposed Development....................................................7
SITE INVESTIGATION AND LABORATORY TESTING ........................... 8
4.1 Site Investigation ................................................. . ........ 8
4.2 Laboratory Testing and Analysis ............................................8
4.3 Infiltration Testing .......................................................9
GEOLOGIC CONDITIONS ................................................... 9
5.1 Regional Geologic Setting .................................................9
5.2 Site Geology ...........................................................10
5.3 Expansive Soil .........................................................11
5.4 Groundwater Conditions .................................................. 11
GEOLOGIC HAZARDS ....................................................11
6.1 Faulting and Seismicity .......................... . ....... . ................. 11
6.2 Landslide Potential ......................................................13
6.3 Liquefaction Potential....................................................14
6.4 Tsunami Potential .................... ................ ................... 15
CONCLUSIONS............................................................15
RECOMMENDATIONS .....................................................16
8.1 Removals and Recompaction ..............................................16
8.2 Temporary Slopes and Excavation Characteristics................................ 17
8.3 Foundations ............................................................... 17
8.4 Sulfate and Chloride Tests .................................................18
8.5 Slabs on Grade (Interior and Exterior) ........................................18
8.6 Lateral Resistance ......................................................19
8.7 Retaining Walls ........................................................... 19
8.8 Dynamic (Seismic) Lateral Earth Pressures ...................................20
8.9 Settlement Characteristics ................................................... 21
8.10 Seismic Considerations....................................................21
8.11 Preliminary Pavement Design ................................... .......... 22
8.12 Permeable Interlocking Concrete Payers (PICP) ..............................23
8.13 Utility Trench ...........................................................24
8.14 Drainage ..............................................................24
8.15 Geotechnical Observations ..................................... .......... ..25
8.16 Plan Review ...........................................................25
LIMITATIONS .......................................................... 25
REFERENCES ................................................................27
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
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APPENDIX A
Figure 1: Location Map
Figure 2: Geotechnical Map
Figure 3:. Cross SectionA-A"
Figure 4 Borehole log N. 1
Figure 5: BOrehole Log NO. 2
Figure 6 Regional Fault Map
Plate A: Typical IsOlation Joints àfld Re-Entrant Corner ReinfOcexnent,
Plae;. Typical.Pàmeable Paver Detail
APPENDIX:B
Laboratory Test Results
Figure 7: Double Ringlnfiliration Test* Data
Figure 8: Infiltration Test Graph.
Seismic Design Parameters
Desi'. Re* sponse Spectrum
APPENDIXC
Slope Stability.Analysis
APPENDIX D
Grading . Gui del ines
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
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INTRODUCTION
This report presents the results of our background review, subsurface investigation, laboratory
testing, geotechnical analyses, conclusions regarding the conditions at 570-580 Laguna Drive, and
recommendations for design and construction. The purpose of this study is to evaluate the nature
and characteristics of the earth materials underlying the property, the engineering properties of the
surficial deposits and their influence on the proposed 12 residential structures.
SCOPE OF SERVICES
The scope of services provided included a review of background data, reconnaissance of the site
geology, and engineering analysis with regard. to the proposed. The performed tasks specifically
included the following:
Reviewing geologic and hazard (seismic, landslide, and tsunami) maps, recently published
regarding the seismic potential of nearby faults, and a site plan for the project. All
background data is listed in the References portion.of this report.
Performing a site reconnaissance, including the observation'of geologic conditions and other
hazards, which may impact the proposed project.
Excavation of exploratory borings consisting of excavating, logging, and sampling of earth
materials to evaluate the subsurface conditions.
Performing geotechnical laboratory testing of recovered soil samples.
Analyzing data obtained from our research, subsurface exploration, and laboratory and
infiltration testing.
9 Preparing this preliminary report.
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W.O. 686218
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3. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
3.1 Site Description
The subject site is a partially developed lot on Laguna Drive in the city of Carlsbad (Figure 1). The
northwest quadrant of the lot is vacant, the southeast quadrant of the lot is developed with a small
building, the northeast and southeast quadrant hosts an existing building and the remainder of the.
lot is paved with asphalt. The property is a polygonal-shaped area that descends gently to the
northwest and is bounded by an inland bluff that descends to Buena Vista Lagoon. The elevation
of the lot ranges from approximately 5.0 to 45 feet.
The subject site includes an existing residence, existing office building, and two existing AC parking
areas. The lot is relatively flat ranging from 40 to 43 feet as you move north to south along the
property. The northern portion of the property is bounded by an inlaiid bluff that descends to the
Buena Vista Lagoon at a gradient approaching 1¼: 1 (horizontal to vertical) for approximately 40
vertical feet. The site is bounded along the north by Buena Vista Lagoon, to the south by Laguna
Drive, and to the east and west by developed residential lots.
Vegetation on the site consists of trees and shrubs. Drainage is generally by sheet flow to the
northwest in the direction of the inland bluff and Buena Vista Lagoon.
3.2 Proposed Development
A topographic plat of the site was prepared by Sampo Engineering. Preliminary architectural plans
for the development of the site were prepared by Brett 'Farrow, Architect. The project is anticipated
to include the demolition of the most southeastern existing building, but not the northeastern
structure, and the construction of 12 residential structures with one car garages (Figure 2). Grading
plans were not available during the assessment of the lot, but due to the relatively flat nature of the
existing lot, we presume grading to be minimal.
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W.O. 686218
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4. SITE INVESTIGATION AND LABORATORY TESTING
4.1 Site Investigation
Site exploration was performed on March 16,2018. It included a visual reconnaissance of the site
and the excavation of two (2) exploratory boreholes (Figures 4-5). The boreholcswere drilled using
a.truck-mounted hollow-stem auger. Samples were obtained tisinga modified California Sampler
and SPT Sampler. All the borings were extended through the underlying top soil, Old Paralic
Deposits and into the underlying Santiago Formation to maximum depths 50 feet in Borehole 1 and
36 feet in Borehole 2. Earth materials encountered were visually classified and logged by our field
project geologist, and sampled for future laboratory testing. Undisturbed, representative samples of
earth materials were obtained at selective intervals by driving a thin-walled steel sampler into the
desired strata with a 140 pound hammer powered by a cathead and rope system. Bulk samples were
also obtained at selected intervals. Samples are retained in waterproof containers and brass rings and
transported to Coast Geotechnical Soils Laboratory for testing and analysis.
The site investigation also included a visual Observation of the surrounding landscape of the project
site. Existing wood retaining walls are in place along the slope into the lagoon.
4.2 Laboratory Testing and Analysis
The laboratory tests were performed in accordance with the generally accepted American Society
for-Testing and Materials (ASTM) test methods or suggested procedures. All lab descriptions and.
results can be found in the Test Results section of Appendix B of this report.
The following tests were preformed:
Classification of Soils
Grain Size Distribution.
Moisture/Density
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
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o Maximum Dry Density and Optimum Moisture Content
Expansion Index Test
Sulfate Ion Content
Chloride Ion Content
pH Test
Field Resistivity Test
Shear Test
Infiltration Test
4.3 Infiltration Testing
Infiltration testing was performed using a Double-Ring Inflitrometer (ASTM D3385). The
infiltration test area is located in the southern portion of the site as indicated on the enclosed
Geotechnical Map. The area was prepared by excavating down to the Paralic Deposits. A level pad
was established for testing. Infiltration results can be found in the .Test Results section of Appendix
B of this report as Figures 7 (Infiltration Test Log) and 8 (Infiltration Test Graph)..
5. GEOLOGIC CONDITIONS
The geologic conditions at the site are based on our field exploration and review of available
geologic and geotechnical. literature.
5.1 Regional Geologic Settings
The subject property is located in the Coastal Plains subdivision of the Peninsular Ranges
geomorphic province of San Diego. The coastal plain area.is characterized by Pleistocene marine
terrace landforms. These surfaces are relatively flat erosional platforms that were shaped by wave
action along the former coastlines. The step-like elevation of the marine terraces was caused by
changes in sea level throughout the Pleistocene and.by seismic activity along the Newport-Inglewood
Fault Zone located 4.5 miles west of the coastline. The Newport-Inglewood Fault Zone is one of
many northwest trending, sub-parallel faults and fault zones that traverse the nearby vicinity. Several
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W.O. 686218
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of these faults, including the Rose Canyon Fault Zone, are considered active faults. Further
discussion of faulting in regards to the site is discussed in the Geologic Hazards section of this
report.
5.2 Site Geology
Previously published geologic maps conducted by Kennedy and Tan (2008) suggest that the subject
property is underlain at depth by the Santiago Formation (Tsa) and Old Paralic Deposits (Qop).
Overlying the rocks is Top Soil (Qs). The Old Paralic Deposits are covered by Top Soil (Qs) along
the surface of the property site as encountered in Boring Nos. I and 2 (B-I and B-2). The general
geologic conditions are depicted on cross-section A-A" enclosed on Figure 3. A brief description
of the earth materials encountered on the site are as follows:
Top Soil (Qs)
In Borehole Nos. 1 and 2 (B-I and B-2), 2.5 to 2 feet Of Top Soil was encountered,
respectively. The Top Soil is a reddish dark brown, fine grained, extremely well sorted,
moderately dense sand and has an organic odor.
Old Paralic Deposits (Qop)
Approximately 17 feet and 18 feet of Paralic sediments were encountered in Borehole Nos.
I and 2 (B-i and B-2) respectively. In Borehole I, from 2.5 feet to 11.5 feet and in Borehole
2, from 2 feet to 11.5 feet, the sediments are* tan reddish brown, fine and medium grained
sandstone, slightly moist and moderately dense. From 11.5 feet to 16 feet in Borehole 1 and
11.5 feet to 15 feet in Borehole 2, the sediments are light brownish tan to red brown fine-
grained sandstone, well sorted, dense, slightly moist and contain rounded gray pebbles. It's
important to note the gravel layer was penetrated in both boreholes at an approximate depth
between 13 to 17 feet. In Borehole 1 from 16 feet to 19 feet and Borehole 2 from 15 feet to
19.5 feet, the sediments encountered were tan to light orange to red brown coarse to fine-
grained sandstone, slightly moist and moderately dense.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
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Santiago Formation (Tsa)
Underlying the Old Paralic Deposits is the Santiago Formation. This formation Of
interbedded sands and clays was encountered at a depth of 19 feet in Borehole 1 and 19.5 feet
in Borehole 2 and extended to the maximum depths of 50 feet and 30 feet in Boreholes 1 and
2, respectively. It consists of gray to pale green to white clayey fine to coarse grained
sandstone and is very dense and slightly moist.
5.3 Expansive Soil
Based on our experience in the area and previous laboratory testing of selected samples, the Paralic
deposits reflect an expansion potential .in the low range.
5.4 Groundwater Conditions
No evidence of perched or high groundwater tables were encountered to the depth explored.
However, the upper Paralic Deposits are pervious and the underlying Santiago Formation is
relatively impervipus suggesting that perched groundwater conditions can develop from infiltration
of water. It should be noted that seepage problems can develop after completion of construction.
These seepage problems most often result from drainage alterations, landscaping, and over-irrigation.
In the event that seepage or saturated ground does occur, it has been our experience that they are
most effectively handled on an individual basis.
6. GEOLOGIC HAZARDS
6.1 Faulting and Seismicity
The subject site is located within the seismically active Southern California region, which is
generally characterized by northwest trending, right-lateral strike-slip faults and fault zones. Several
of these fault segments and zones are classified as active by the California Geologic Survey
(Alquist-Priolo Earthquake Fault Zoning Act.). As a result, ground shaking is a potential hazard
throughout the region.
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Based on a review of published geologic maps, no known active faults traverse the. site (Figure 6).
Thus, ground surface rupture is not likely to occur as a result of an earthquake or seismic event.
The nearest active fault to the site is the Newport Inglewood Fault (offshore), located approximately
4.5 miles West of the site. It should be noted that the Newport Inglewood Fault is one of four-main
fault strands that make up the Newport-Inglewood/Rose Canyon (NIRC) fault system (Treiman,
1984). The four strands form a series of right-stepping en echelon faults situated along the Southern
California coastline. A recent study by Sahakian et al. (2017) concluded that the geometry of the
NIRC fault system may enable rupture along the entire length of the fault zone. The study also
modeled several rupture senaros in light of the newly defined geometry which suggest earthquake
ruptures up to magnitudes (M) of 7.4 are possible along the NIRC system. While the models are
intriguing, the paper recommends further research and modeling on the NIRC fault geometry to
improve our understanding of potential hazards and ground shaking along the Southern California
coast. Therefore, the modeled rupture magnitude of M = 7.4 on the Rose Canyon Fault was not used
for the recommendations for this investigation.
Other nearby faults that may affect the site include the Rose Canyon, Coronado Bahk, Temecula and
Julian FaUlts. The proximity of major. faults to the site, and their estimated maximum earthquake
magnitudes and peak site accelerations are enclosed on Table 1 and were determined by EQFAULT
version 3.00 software (Blake, 2000).
COAST GEOTECHNICAL Brett sParrow.
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Table 1: P!incipai Active Faults
Appjoxmiate Distazfce Ma(rnum!EQ Peak ite
Fault Name
Newport-lnglewood. 4.5 6.9 0.388*
Rose Canyon 4.8 6.9 0.381
EJsinore-Temecul. 20.9. 7.4 .
0.223
Elsinore- Julian. . . 24:1 6.8 0.152
Elsinore- Glen Ivy 24.5 7.1. 0. 1.74
Palos Verdes
.
33.0 6.8 0116
Earthquake Valley. 34.9 7.1. 0.131
Newport-IngIewood' ;44.6 6.5s
: 72
San Jacinto- Anza. . 45.0 6;9, O092
The.Rose Canyon Fä1Alti ôapab1ëOf geherating ä.maitüde àithquákë whiôh would cause-.strong
ground motions at the subject site Further analysis on seismicity and the site specific seismic
parameters. are: discussed.. in the Recommendations chapterofihis r.ep:ort.
2Ijn1sIjde Potential
A landilide is the. displaemettt.. of a mass Of rock, debris, t. down: a slope, caused by
tpographic, geologic al, geotechnical and/or subsurface water cpjitions. Potential laridli4
ha4s:fpr.*he sie'were:a$essedusing th.review of pub1ishd: geologic .andmpographic.:rnaps as
well as substiface. explotation.
According to the Landslide Hazards map, San Luis Ray Quadrangle (Tan and Giffen, 1995), the site
is located within Susceptibility Area 3-I where slopes are generally susceptible MOO sl inopes this
area donot contain landslide deposits, but'.they ëah be subjt to. sirflciàl failür&andbluffretreatas
discussed-below.
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W.O. 686218
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The rear bluff descends at a gradient approaching 11/4: 1 (horizontal to vertical) for approximately 40
vertical feet and is underlain by two (2) major geologic units with different characteristics.
The upper 20 feet of the rear bluff is composed of Pleistocene-age sediments that are weakly
cemented and friable along slope faces. These fine-grained sands are subject to surficial failures and
bluff retreat. Wood bailer boards have been installed in the slope to retard surficial slippage with
limited success.
Underlying the coastal bluff sediments, Eocene-age sedimentary units which have commonly been
correlated with the Santiago Formation are present. The sedimentary rock is primarily composed
of dense to very dense clayey sandstone. Although claystone units within the Santiago Formation
have been associated with landslides, no evidence of deep-seated instability was observed in the
exploratory borings or site topographic expression.
Slope stability analysis utilizing GSTABL7 with STEDwin suggests the most critical failure surface
is primarily within the upper Pleistocene Old Paralic Deposits. Static and Pseudo-static stability
analyses are shown on the enclosed Stability Analysis Appendix C.
6.3 Liquefaction Potential
Liquefactionis a process by which a sand mass loses its shearing strength completely and flows. The
temporary transformation of the material into a fluid mass is often associated with ground motion
resulting from an earthquake, and high groundwater conditions.
The fifty (50) foot deep boring (B- 1)suggests that the Paralic Deposits are in amedium-dense to
dense condition and the underlying sedimentary units of the Santiago Formation are in a very dense
condition. Groundwater was not encountered to a depth of 50 feet below existing ground surface.
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Owing to the moderately dense to very dense nature of the geologic formations and the anticipated
depth to groundwater, the potential for seismically-induced liquefaction and soil instability is
considered low.
6.4 Tsunami Potential
Tsunamis are large sea waves generated by earthquakes, volcanic eruptions, or landslides that
potentially cause the displacement of substantial volumes of water.
The Tsunami Inundation Map for Emergency Planning: San Luis Ray Quadrangle (California
Emergency Management Agency, 2009) suggests that the site is not susceptible to flooding from
tsunamis.
7. CONCLUSIONS
No geologic hazards such as faulting, liquefaction or deep-seated instability which could
preclude development were encountered on the site.
The rear slope is composed of friable Pleistocene sediments which are subject to erosion,
surficial failure and retreat during prolonged rainfall and drainage directed toward the top of
the slope.
Design plans should consider raising the proposed pad grades such that drainage is directed
to the south away from the top Of the bluff.
The geologic conditions underlying the -rear bluff are such that infiltrated water developing
saturated conditions can adversely affect slope, stability. Storm water infiltration should be
significantly limited and, if necessary, bioretention basins should be located inn the most
southern portion of the. site.
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W.O. 686218
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The existing soil and weathered Paralic Deposits are not suitable for the support of proposed
footings, slab-on-grade, exterior improvements or proposed fills in their present condition.
These deposits should be removed and replaced as properly compacted fill.
Disturbed soils resulting from the demolition of structures and utility lines should be
removed and replaced as properly compacted fill.
Prior to the double-ring infiltration test, the area was excavated into the Old Paralic Deposits
about the 42 foot elevation. Testing in the area of the site (IF-1) was conducted in the Paralic
Deposit and reflected a stabilized infiltration rate approaching that of 2.48 inches per hour.
8. RECOMMENDATIONS
8.1 Removals and Recompaction
The existing soil and weathered Old Paralic Deposits in the building pad should be removed and
replace as properly compacted fill. Removals in building pads should extend a minimum of 5.0 feet
beyond the building footprint or the entire building pad depending upon. final design plans. The
depth of removals are anticipated to be on the order of.3.O feet in building pads. Most of the existing
earth deposits are generally suitable for reuse, provided they are cleared of all vegetation, debris, and
thoroughly mixed. Prior to placement of fill, the base of the removal should be observed by a
representative of this firm. Additional overexcavation and recommendations may be necessary at
that time. The exposed bottom should be scarified to a minimum depth of 6.0 inches, moistened as
required, and compacted to a minimum of 90 percent the laboratory maximum dry density. Fill
should be placed in-6.0 to 8.0 inch lifts, moistened to approximately 1.0-2.0 percent above optimum
moisture content and compaction to a minimum of 90 percent the laboratory maximum dry density.
Soil and weathered Paralic Deposits in areas of proposed concrete flatwork, exterior improvements,
and driveways should be removed and replaced as properly compacted fill. Imported fill, if
necessary, should consist of non-expansive granular deposits approved by the geotechnical engineer.
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W.O.686218
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8.2 Temporary Slopes and Excavation Characteristics
Temporary excavation, which expose soil and. weathered Paralic Deposits should be trimmed to a
gradient of 1:1 (horizontal to vertical) or less depending upon conditions encountered during grading.
The Old Paralic Deposits may be excavated to a vertical height of 5.0 feet. The temporary slope
recommendations assume no surcharges are located or will be placed along the top of the slope
within a horizontal distance equal to one half the height of the slope. The Paralic Deposits are dense
below the weathered zone. However, based.on our experience in the area, the Paralic Deposits are
rippable with conventional heavy moving equipment in good working order.
8.3 Foundations
The following design parameters are based on footings founded into non-expansive approved
compacted fill deposits or competent Paralic Deposits. Footings for the proposed structure should
be a minimum of 12 inches and 15 inches wide and founded. a minimum of 12 inches and 18 inches
below the lower most adjacent subgrade at the time offoundation construction for single-story and
two-story structures, respectively. A 12 inch by 12 inch grade beam or footing. should be placed
across the garage opening. Footings should be reinforced with a minimum of four No.4 bars, two
along the top of the footing and two along the base. Where parallel wall footings occur, the upper
footing should be deepened belOw a 45 degree plane projected up from the base of the lower footing,
or the lower wall should be designed for the additional surcharge load from the upper wall. Footing
recommendations provided herein are based upon underlying soil conditions and are not intended
to be in lieu of the project structural engineer's design.
The base of footings should be maintained a minimum horizontal distance of 10 lateral feet to the
face of the nearest slope.
For design purposes, an allowable bearing value of 2000 pounds per square foot and 2400 pounds
per square foot may be used for foundations at the recommended footing depths for single and two
story structures, respectively.
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W.O. 686218
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For .footings deeper than 18 inches, the bearing value may be increased by 250 pounds per square
foot for each additional 6.0 inches of embedment to a maximum of 3000 pounds per square foot.
The bearing value maybe increased by one-third for the short durations of loading, which includes
the effects of wind and seismic forces.
The bearing value indicated above is for the total dead and frequently applied live loads. This value
may be increased by 33 percent for short durations of loading, including the effects of wind and
seismic forces.
8.4 Sulfate and Chloride Tests
The results of our sulfate and chloride tests performed on representative samples are presented on
Tables 8 and 9 in Appendix B. The test results suggest a sulfate content of 0.005 (negligible).
8.5 Slabs on Grade (Interior and Exterior)
Slab on grade should be a minimum of 5.0 inches thick and reinforced in both directions with No.
3 bars placed 18 inches on center in both directions. Exterior slabs on grade should be a minimum
of 4.5 inches thick-and reinforced with No. 3 placed 18 inches on center in both directions. The slab
should be underlain by a minimum 2.0-inch coarse sand blanket (S.E. greater than 30). Where
moisture sensitive floors are used, a minimum 10.0-mil Visqueen, Stego, or equivalent moisture
barrier should be placed over the sand blanket and covered by an additional two inches of sand (S.E.
greater than 30). Utility trenches underlying the slab may be backfilled with on-site materials,
compacted to a minimum of 90 percent of the laboratory maximum dry density. Slabs should be
reinforced as indicated above the provided with saw cuts/expansion joints, as recommended by the
project structural engineer. All slabs should be cast over dense compacted subgrades. At a
minimum, interior slabs should be provided with soficut contraction/control joints consisting of
sawcuts spaced 10 feet on center maximum each way. Cut as soon as the slab will support the
weight of the saw, and operate without disturbing the final finish, which is normally within 2 hours
after final finish at each control joint location or 150 psi to 800 psi. The soficuts should be a
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
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minimum of 3/4 inch in depth, but should not exceed 1 inch deep maximum. Anti-ravel skid plates
should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled
equipment across cuts for at least 24 hours. Provide re-entrant corner (270 degrees corners)
reinforced for all interior slabs consisting of minimum two, 10-feet long No. 3 bars at 12 inches on
center with the first bat placed 3 inches from re-entrant corner (see Plate F). Re-entrant corners will
depend on slab geometry and/or interior column locations. Exterior slabs should be provided with
weakened planejoints at frequent intervals in accordance with the American Concrete Institute (ACI)
guidelines.
Our experience indicates that the use of reinforcement in slabs. and foundations can reduce the
potential for drying and shrinkage cracking. However, some minor cracking is considered normal
and should be expected as the concrete cures. Moisture barriers can retard, but not eliminate
moisture vapor movement from the underlying soils up through the slab.
8.6 Lateral Resistance
Resistance to 1ateral load may be provided by friction acting at the base foundations and by passive
earth pressure. A coefficient of friction of 0.25 may be used with dead-load forces. Design passive
earth resistance may be calculated from a lateral pressure corresponding to an equivalent fluid
density of 300 pounds per cubic foot with a maximum of 2500 pounds per square foot.
8.7 Retaining Walls
Cantilever walls (yielding) retaining nonexpansive granular soils may be designed for an
active-equivalent fluid pressure of 37 pounds per cubic foot for a level surcharge and 45 pounds per
cubic foot for a sloping backfill.. Restrained walls (nonylelding) should be designed for an "at-rest"
equivalent fluid pressure of 60 pounds per cubic foot. Wall footings should be designed in
accordance with the foundation design recommendations. All retaining walls should be provided
with adequate backdrainage system. A geocomposite blanket drain such as Miradrain 6000 or
equivalent is recommended behind walls. The soil parameters assume a level nonexpansive select
granular backfill compacted to a minimum of 90 percent of the laboratory maximum dry density.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 20 of 28
& 8 Dynamic (Seismic) Lateral Earth Pressures
For proposed restrained walls (non-yielding), potential seismic loading should be considered. For
smooth rigid walls, Wood (1973) expressed the dynamic thrust in the following form:
LWe = kh?H2 (nonyielding)
where kh is peak ground acceleration equal to 50 percent of the design spectral response
acceleration coefficient (Sds) divided by 2.5 per C.B.C. (2007), y is. equal to the unit weight of
backfill, and H is equal to the height of the wall.
The pressure diagram for this dynamic component can be approximated as an inverted trapezoid with
stress decreasing with. depth. The point of application of the dynamic thrust is at a height of .0.6
above the base of the wall. The magnitude of the resultant is:
AN = 20.3 H2 (nonyielding)
This dynamic compOnent should be added to. the at-rest static pressure for seismic loading
conditions.
For cantilever walls (yielding), Seed and Whitman (1970) developed the dynamic thrust as:
AN = 3/8 kbyH2(yie1ding)
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 21 of 28
The pressure diagram for this dynamic component can be approximated as an inverted trapezoid with
stress decreasing with depth and the resultant at a height of 0.6 above the base of the wall. The
magnitude of the resultant is:
AN = 7.62 H2 (yielding)
This dynamic component should be added to the static pressure for seismic loading conditions.
8.9 Settlement Characteristics
Estimated total and differential settlement over a horizontal distance of 30 feet is expected to be on
the order of 1.0 inch and 3h inch, respectively. It should also be noted that long term secondary
settlement due to irrigation and loads imposed by structures is anticipated to be /4 inch.
& 10 Seismic Considerations
Although the likelihood of ground rupture on the site is remote, the property will be exposed to
moderate to..high levels- of ground motion resulting from the release of energy should an earthquake
occur along the numerous known and unknown faults in the region.. The Newport-Inglewood
(offshore) Fault Zone located approximately 4.5 miles west of the property is the nearest known
active fault, and is considered the design fault for the site. In addition to the Newport-Inglewood
fault, several other active faults may affect the subject site.
Seismic design parameters were determined as.part of this investigatiOn in accordance with Chapter
16, Section 1.613 of the 2016 California Building Code (CBC) and ASCE 7-10 Standard using the
web-based United States Geological Survey (USGS). Seismic Design Tool. The generated results
for the parameters are presented on Table 2.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 22 of 28
Table 2: Seismic Design Parameters
Factôis
Site Class D
Seismic Design Category 1/11/Ill
Site Coefficient, Fa 1.037
Site Coefficient, F 1.556
Mapped Short Period Spectral Acceleration, S 1.158
Mapped One-Period Spectral Acceleration, S1 0.444
Short Period Spectral Acceleration Adjusted for Site Class, SMS 1.201 g
One-Second Period Spectral Acceleration Adjusted for Site, SMI 0.691 g
Design Short Period Spectral Acceleration, SOS 0.800 g
Design One-Second Period Spectral Acceleration, 5D1 0.461 g
& 11 Preliminary Pavement Design
The following preliminary pavement section is recommended for proposed driveways:
4.0 inches of asphaltic concrete on
6.0 inches of select base (Class 2) on
12 inches of compacted subgrade soils or
5.5 inches of concrete on
12 inches of compacted subgrade soils
Subgrade soils should be compacted to the thickness indicated in the structural section and left in
a condition to receive base materials. Class 2 base materials should have a.minimurn R-value of 78
and a minimum sand equivalent of 30. Subgrade soils and base materials should be compacted to
a minimum of 95 percent of their laboratory maximum dry density. Concrete should be reinforced
with No. 3 bars placed 18 inches on center in both.directions.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 23 of 28
The pavement section should be protected from water sources. Migration.of water into subgrade
deposits and base materials could result in pavement failure.
8.12 Permeable Interlocking Concrete Payers (PICP)
Permeable Interlocking Concrete Payers (PICP), if proposed, should consider several design aspects.
Foundations adjacent to or in close proximity to PICP should be protected by an impervious
membrane extending a minimum of 3.0 lateral feet from the foundation under the pavement section.
The intent is to reduce lateral migration of infiltrated drainage and potential impact on footings.
However, this approach is considered less desirable from a geotechnical viewpoint than lining the
entire section with an impervious liner.
Pavement underdrains are recommended and should be incorporated in the design for proper
collection and disposal of filtrated storm water as indicated on Plate G. If subdrains are not allowed
for storm water infiltration by reviewing agencies, the long term effects of infiltrated water on
structural foundations and slabs cannot be predicted with any degree of certainty,
PICP pavement structural section (Driveways) should consist of 31/e inch .PICP, over a minimum of
2.0 inches of ASTM No. 8. bedding course/choke stone, over a minimum of 8.0 inches ofASTM No.
57 stone base course, over a minimum of 12 inches of 95 percent compacted subgrade. Bedding
course/choke stone and base course stone should also be well compacted, consolidated, and
interlocked. (avoid crushing the underdrain pipes) with heavy construction equipment. ASTM No.
8, No. 9 or No. 89 should be used for joint materials, depending on the joint size and per
manufacturer recommendations. The above stone base section may be reduced from 12 inches to
a minimum of 6.0 inches for walkways and patios, if desired. The gradational requirements are.
summarized on Table 3.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 24 of 28
Table 3: Gradational Requirements for ASMT No. 57, No. 8, No. 89, and No. 9
Sieve
Size
Percent Passing
No. 57 No.-8 No. 89 No. 9
1V2 100 -- -- --
In 95to100 -- -- --
'A" 25 to 60 100 100 --
-- 85 to 100 90 to 100 100
No.4 OtolO 10to30 20to55 85to.100
No.8 0to5 OtolO 5to30 10to40
No. 16 -- 0to5 OtolO O to. lO
No. 50 -- -- 0to5 0to5
8.13 Utility Trench
We recommend that all utilities be bedded in clean sand to at least one foot above the top of the
conduit. The bedding should be flooded in place to fill all the voids around the conduit. Imported
or on-site granular material compacted to at least 90 percent relative compaction may be utilized for
backfill above the bedding.
The invert, of subsurface utility excavations paralleling footings should be located above the zone
of influence of these adjacent footings. This zone of influence is defined as the area below a 45
degree plane projected down from the nearest bottom edge of an adjacent footing. This can be
accomplished by either deepening the footing, raising the invert elevation of the utility, or moving
the utility or the footing away from one another.
8.14 Drainage
Specific drainage patterns should be designated by the project architect or engineer. However, in
general, pad water should be directed away from foundations and around the structure to the street.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 25 of 28
Roof water should be collected and conducted to the. street via non-erodible devices. Pad water
should not be allowed to pond. Vegetation adjacent to foundations should be avoided. If vegetation
in these areas is desired, sealed planter boxes or drought resistant plants should be considered. Other
alternative may be available, however, the intent is to reduce moisture from migrating. into
foundation subsoils. Irrigation should be limited to that amount necessary to sustain plant life. All
drainage systems should be inspected and cleaned annually, prior to winter rains.
& 15 Geotechnical Observations
Structural footing excavations should be observed by a. representative of this firm prior to the
placement of steel and forms. All fill should be placed while a representative of the geotechnical
engineering is presentto observe and test.
8.16 Plan Review
A copy of the final plans should be submitted to this office for review prior to the initiation of
constructions. Additional recommendations may be necessary at that time.
9. LIMITATIONS
This.report is presented with the provision that it is the responsibility of the owner or the owner's
representative to bring the information and recommendations given herein to the attention of the
project's architects and/or engineers so that they may be incorporated into the plans.
If conditions encountered during construction appear to differ from those described in this report,
our office should be notified so that we may consider whether modifications are needed. No
responsibility for construction compliance with design concepts, specifications, or recommendations
given in this report is assumed unless on-site review is performed during the course of construction.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 26 of 28
The subsurface conditions, excavation characteristics, and geologic structure described herein are
based on. individual exploratory excavations made on the subject property. The subsurface
conditions, excavation characteristics, and geologic structures discussed should in no way be
construed to reflect any variations which may occur among the exploratory excavations
Please note that fluctuations in the level of groundwater may occur due. to variations in rainfall,
temperature, and other factors-not evident at the time measurements were made and reported herein.
Coast Geotechnical assumes no responsibility for variations which may occur across the site.
The conclusions and recommendations of this report apply as of the current date. In time, however,
changes can occur on a property whether caused by acts of man or nature on this or adjoining
properties. Additionally, changes in professional standards may be brought about by legislation or
the expansion of knowledge. Consequently, the conclusions and recommendations of this report
may be rendered wholly or partially invalid by event beyond our control. This report is therefore
subject to review and should not be relied upon after the passage of two years.
The professional judgements presented herein are founded partly on our-assessment of the technical
data gathered, partly on our understanding of the proposed construction, and partly on our general
experience in the geotechnical field. However, in no respect do we guarantee the outcome of the
project.
This study has been provided solely for the benefit of the client, and is in no way intended to benefit
or extend any right or interest to any third party. This report is not to be used on other projects or
extensions to this project, except by agreement in writing with Coast Geotechnical.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 27 of 28
REFERENCES
Blake, T. F. (2000). EQFAULT: A Computer Program for the Deterministic Estimation of Peak
Acceleration using Three-Dimensional California Faults as Earthquake Sources, Version 3.0,
Thomas F. Blake Computer Services and Software, Thousand Oaks, CA.
California Building Standards Commission. (January 1, 2016). 2016 California Building Code,
California Code of Regulations.
California Emergency Management Agency, California Geological Survey, and University of
Southern California. (2009). Tsunami Inundation Map for Emergency Planning- San Luis Rey
Quadiangle, California, San Diego County, Scale. 1:24,000.
California Geologic Survey, (1994), Fault Activity Map of California, Map Scale 1=75O,00'.
Gregory Geotechnical Software; GSTABL7 with STEDwhi (1996, 1999). Slope Stability Analysis
System.
Kennedy, M. P., and Tan, S. S. (2008). California Geological Survey, Regional Geologic Map No.
3,.1:100,000 scale.
Sahakian, V., et al. (2017). Seismic Constraints on the Architecture of the Newport-Inglewood/Rose
Canyon Fault: Implications for the Length and Magnitude of Future Earthquake Ruptures. American
Geophysical Union. DO!: 10.1002/2016JB0 13467.
Sampo Engineering Inc. (2018). Topographic Plat: 570-580 Laguna Drive, Carlsbad, California,
Scale I"= 20'.
COAST GEOTECHNICAL Brett Farrow
W.O. 686218
Page 28 of 28
REFERENCES (CONT.).
Seed, H.B., and Whitman, R.V. (1970). Design of earth retaining structures for dynamic loads.
In Proceedings of the ASCE.SpeciaiCorference on Lateral Stresses, Ground Disp1aemnt and Earth
Retaining Structure, Ithaca, N.Y., pp. 103-147.
Tan, S. S., and Giffen, D. G. (1995). Landslide Hazards in the Northern Part of the San Diego
Metropolitan Area, San Diego Countyj California, OFR 95-04, Plate 35D.
Treiman, J. A. (1984). The Rose Canyon Fault Zone: A Review and Analysis, California Division
of Mines and Geology, Fault Evaluation 'Report 216.
Wood, J.H. (1973). Earthquake-induced soil pressures on structures. Ph.D. thesis, the California
Institute of Technology, Pasadena, Calififornia.
USGS, U. S. Seismic. Design Naps, Scale = Variable:
https://earthquake.usgs.gov/dësignmaps/us/application.php
APPENDIX A
COAST GEOTECIINICAL
5931 Sea Lion Place, Suite 109
Carlsbad, CA 92010
570-580 Laguna Drive
Carlsbad, CA 92008 Figure 1
P-686218
APPENDIX B
LABORATORY TESTING AND RESULTS
Earth materials encountered in the exploratory trenches were closely examined and sampled for
laboratory testing. The laboratory tests were performed in accordance with the generally accepted
American Society for Testing and Materials (ASTM) test methods or suggested procedures.
Classification: The field classification was verified through laboratory examination, in accordance
with the Unified Soil Classification System. The final classification is shown on the enclosed
Exploratory Logs provided in Appendix B.
Grain Size Distribution: The grain size distribution of selected soil samples was determined in
accordance with ASTM D6913-04. The test result is presented on Table 4 and is graphically
depicted on the following pages.
TABLE 4
Sieve Size ijil f
3/4 92'r' #' #10 #26 140 1O0 #200
Location Soil Type . Percentage Passing
B1@5' 1 100 100 100 100 199.9 198.8 186.3 139•9 I28.4
Expansion Index Test: An Expansion Test was performed on the selected sample. The test
procedure were conducted in accordance with the Uniform Building Code, Standard No. 29-2 and
AMST D-4829. The classification of expansive soil, based on the expansion index, are as indicated
in Table•29-C of the Uniform Building Code. The test result is presented on Table 5.
Location Soil
Type
Expansion
Reading
Degree of
Saturation
Uncorrected
'Expansion Index (El)
Corrected El for
500/o Saturation
B1@l-5' 1 -0.01 38.6Sm N/A N/A
Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum
moisture content were determined for selected samples of earth materials taken from the site. The
laboratory standard tests were in accordance with AS1'M D- 1557-12. The test result is presented on
Table 6.
TABLE 6
Maximum Dry Optimum Moisture
Location Soil Type
ensity (ym-pcf) Content (copt-%)
Bi @ 11-5' 1 130.0 9.0
Moisture/Density: The field moisture content and dry unit weight were determined for each of the
undisturbed soil samples. Test procedures were conducted in accordance with ASTM D7263-09
(Method A). Thi information is useful in providing, a gross picture of the soil consistency or
variation among exploratory excavation. The field moisture content was determined as a percentage
of the dry unit weight. The dry unit weight was determined in pounds per cubic foot (pcf). The test
results are presented on Table 7.
TABLE 7
Sample
Location
Soil
Type
Field
Moisture
Coiileiit.%)
Field Dry
Density
ydpcf
Max Dry
-Density
yrn-pcf
In-p1ace..Re1ätive
Compaction (%)
Degree of
Saturation
(%)
1@3.5' 1 2.6 117.0 130 90.0 15.3
1@9' 2 2.2 109.7 130 84.4 10.7
1@14' 2 6.5 110.0 130 84.6 31.9
1@19' 3 8.9 122.1 - - -
l@30' 3 9.2 118.6 - - -
1@39' 3 8.3 88.1 - - -
2@4' 1 8.5 126.4 130 97.2 65.2
2@9' 2 6.5 104.2 130 80.2 27.6
2@19' 3 6.7 106.6 - - -
ShearTest: Shear tests were performed in a strain-control type direct shear machine. The laboratory
standard tests were in accordance with ASTM D3080. The rate of deformation was approximately
0.025 inches per minute. Each sample was sheared under varying confining loads in order to
determine the Coulomb shear strength parameters, cohesion, and angle of internal friction. Samples
were tested in a saturated condition. The test results are presented in Table 8.
TABLE 8
Sajnple ID Angle of Internal Friction Apparent Cohesion
B-I @ 9' (ring) 29 degrees 70 psf
B-1 @ 30' (ring) 34 degrees 350 psf
Sulfate and Chloride Tests: A sulfate test was performed on a selected sample in accordance with
California Test Method (CTM) 417, and a chloride test was performed on a selected sample in
accordance with California Test Method (CTM) 422. The test results are presented on Tables 9 and
10.
TABLE 9
Sample ID Sulfate Câñteñt (ppih) Sulfate Content (% by wgt)
B-i @ 1-5 48 0.005
TABLE 10
Sample ID Chloride Content (ppm) Chloride Content (% by wgt)
B-I @ IS 21 0.002
Infiltration Testing: Infiltration tests were performed in accordance to A.STM D3385-09. This test
method is useful for field -measurement of the infiltration rate of soils. A stabilized infiltration rate
of 2.48 inches per hour was established. The results of our testing are graphically shown on Figure
7. The rates indicated above are actual rates measured in the field and do not include asafety factor.
An adequate safety factor as recommended by the project engineer should be incorporated.
Field &Resistivity Test:: Afield resistivity.test wasprfármed on a selected sample inaccordance.with
Califàrnia Test:Method (CTM).6 3.. The fleld reiti.ity test gives an indication of the quantity of
soliible.salts in the SoiLór Wàterto obtain data estimating the service life ofcuiverts. The test resUlts
for pH and field.reals&ity are presented. on .lable'l I
PH: 7.6
- Watcr AdJed tnf) Rcsisti a obn-cm
10 . 13000
5 7800
5 . . 6700
5 . . :• 5600
S.
. . .,
5500
5200.
5 5900
:60-y to perforation of a 16 gauge metal culvert
78 years to perforation of a 14 gauge metal culvert
108 years to pibration of a 12 gauge metal culvert
138 years to perforation of 4. 10 gauge metal culvert.
168 years to perforation of a 8 gauge metal culvert.
Accum. Wt. (gr)
0.1
0.8
6.6
77.4
338.4
403.6
409.5
% Passing
100.0
99.9
98.8
86.3
39.9
28.4
% Retained
0.0
0.1
1.0
12.6
46.3
11.6
1.0
SMS Geotechnical Solutions, Inc. Sieve Analysis
5931 Sea Lion place, Suite 109 ASTM D6913-04
Carlsbad, CA 92010
Sample 1
Project Farrow Job U 686218 I
Supervising Lab Tech SIB Sample Bi @ 1-5' Soil type [ 1
Supervising Lab Manager MS Date Tech F WB
Address I 578 Laguna Drive I
Sample Wet Wt. I 584.6 gr Sample Dry Wt. 1 563.5 gr I Moisture % 3.7 I
Seive
152 mm 6'
75 mm 3"
50 mm 2"
37.5 mm 11/2"
25 mm 1"
19 mm 3/4"
12.5 mm 1/2"
9.5 mm 3/8"
4.75 mm #4
2mm #10
0.85 mm #20
0.6 mm #30
0.425 mm #40
0.15 mm #100
0.075 mm! #200
Pan
Specification
D.G. Class 2
100 100
90-100 100
87-100
50-100 30-65
25-55 5-35
5-18 0-12
DOUBLE RING L\BLTROME1IR TEST DATA
ft~ect Nsme and 'flat Location:
Constents-
Rina
-
Data MarrioteTubes
Lagoon IF-1
AU. .1., Dtb of
I_iquad (in)
Small
Large (cc)
DPI
Factor
EMU RZnE 113.1 6.00' 3,000 cc 104V-S.352cc'
ThtBy juscsciawj - .&m!vhrSpe: 3393 6.25" 10,000 CC lDN&S3ccI
%VatuTabItD~l Inerl -
2.5 OUter 2.5
DteofT 3/19/18IL4%i4J9H2O. I pfl4
e
undThnp(f) atDepd
() Flow Vi1v( Float D ManiotteTub. ( )Other
.Mditiona1Cosfs I Vol cm2x 0.061 =Voc in3
Qf= (DlV) x DIV FACTOR x 0.061= In3
Time
tnter9
lime
(himm)
Di
(itin) &
Tote
lnnerRini Ainni1uj Liqnid
Temp
Infi1traüonRaej
Remadcs
: .
inner
inbr
Outet
ial
I -Stan 12.23 14 0 360 0 310 66.0
4.51 4.06
-
-End 12:37 (14) 360 117.52 3
2 - Start 12:45 15 0 460 0 280
5.31 3.37 End 1:00 (15) 460 150.17 280 2864
3 . Stag 103 15 0 220 0 240
2.54 2.89 End 1:18 (15) 220 71 .JL. 245.26 -
4-Sleet 1:20 iS 0 165 0 _270
1.90 3.25 End 135 -
(15) 165 53.86 ... 275.92
) - Stan 1:38 15 1 0 210 0 225 2.42 2.71 End 153 (15) 210 68.55 225 229.93 555
6- Start 137 15 0 215 0 250
2.48 3.01
-.
End 2:12 (15) 215 70.1 250 255.48
SMt 2:13 15 0 225 0 210 2.59 2.53
214.60 A L 2:28 (15) 25 73.45 210
S-Stan 233 15 0 235 0 250 2.92 3.01 End 2.48 (15) 35 82.59 250 255.48
9-Start -
End
10. Statt
End _______
FAd-
12-Stat
End
13-Start -
End_______
End
Figure 7
ag Design Maps Summary Report
User—Specified Input
Report Title Laguna
Fri March 2, 2018 22:32:56 UTC
Building Code Reference Document ASCE 7-10 Standard
(which utilizes USGS hazard data available in 2008)
Site Coordinates 33.16541°N, 117.35211W
Site Soil Classification Site Class D - "Stiff Soil"
Risk Category 1/11/111
)
Oc"an -.
USGS—Provided Output
Ss = 1.158 g SMS = 1.201 g S's = 0.800 g
S1 = 0.444 g Sm, = 0.691 g S01 = 0.461 g
For information on how the SS and Si values above have been calculated from probabilistic (risk-targeted) and
deterministic ground motions in the direction of maximum horizontal response, please return to the application and
select the "2009 NEHRP" building code reference document.
MCP. Sruc'j'n Des 'co1sc ScYrn
For PGAM, TL, C, and C 1 values, please view th..dti1d reoort.
Although this information is a product of the U.S. Geological Survey, we provide no warranty, expressed or implied, as to the accuracy of
the data contained therein. This tool is not a substitute for technical subject-matter knowledge.
ZUSGS Design Maps Detailed Report
ASCE 7-10 Standard (33.165410N, 117.352°W)
Site Class D - "Stiff Soil'ç Risk Category 1/11/111
Section 11.4.1 - Mapped Acceleration Parameters
Note: Ground motion values provided below are for the direction of maximum horizontal
spectral response acceleration. They h.ae been converted from corresponding geometric
mean ground motions computed by the USGS by applying factors of 1.1 (toobtan S) and
1.3 (to obtain S1). Maps in the 2010 ASCE-7 Standard are provided for Site Class B.
Adjustments for other Site Classes. are made; as needed, in Section 11.4.3.
From Figure 22-4 (1) S5 = 1.158:g
From Figure 22-2 (2) S1 = 0.444
Section 11.4.2 - Site Class
The authority having jurisdiction (not the. USGS), site-specific geotechnical data, and/or
the default has classified the site as Site Class D, based on the site soil properties in
accordance with Chapter 20..
Table 20.3-1 Site Classification
Siti Class, .VS N or Pith su
A. Hard Rock >5,000 ft/s N/A N/A
B._Rock 2,500 to 5,000 ft/s N/A N/A
C.. Very dense soil and soft rock 1,200 to 2,500 ft/s >50 >2,000-psf
.D. Stiff Soil 600th 1,200 ft/s 15 to 50 . 1,000 to 2,000 psf
-
E. SOft clay soil <600 ft/s <15 <1,000 psf
Any profile with more than 10 ft of soil having the
chaacteristics:
Plasticity index P1 20,
Molsture'.cortent w ~_* 40%, and
Undrained shear strength; <5Ô0 psf
F. Soils requiring site response See Section 20.3.1
analysis In accordance with Section
21.1
For SI: Ut/s = 0.3048 rn/s 1ib/ft2 = 60479.kN/m2
Section 11.4.3 - Site Coefficients. and Risk-Targeted Maximum Considered Earthquake(g)
Spectral Response Acceleration Parameters
Table 11.4-1: Site Coefficient F1
Site Class Mapped MCE a Spectral Response Acceleration Parameter at Short Period
S5 :50.25 S5 = 0.50 55 = 0.75 55 = 1.00 S ~:1.25
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
1.1
E E 1.2 E
' E E
F See SectiOn 11.47ofASCE7
Note: Use straight-line interpolation for* intermediate values of S
ForSite Class = D and S5 = 1.158 g, F. = 1.037
Tab!è 11.4-2: Site Coefficient .F,
Site Class Mapped MCE R Spectral Response Acceleration Parameter at 1-s Period
S1 50.10 S1 = 0.20 S = 6.30 S1 =0.40 S1 0.50
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
E
1.5
E. ' E E
F See Section 11.4.7 of ASCE 7
Note: Use straight-line interpolation for intermediae values of S
For Site Class '= D and S = 0.444 g, F. =1.556
Equation (11.4-1): SMS = FaSs = 1.037 X 1.158 = 1.201 g
Equation (11.4-2): SMI = FS1 = 1.556 x 0.444 = 0.691 g
Section 11.4.4 - Design, Spectral Acceleration Parameters
Equation (11.4-3): S0 = % Sms = Wx. 1.201 = 0.800 g
Equation (11.4-4): S01 = =2/3 x ' 0.691 = 0.461 g
Section 11.4.5 - Design Response Spectrum
From Figure 2242131 TL = 8 seconds
Figure 11.4-1: Design Response Spectrum
T 0:SS(O.4+06'T'/T0).
-
To S T:5T8:SS
T5.cT : S= S/T
\ : S. .SmTL I
I: I
I I
-I------------------------
: '
•'
I I
P,o& raa)
r (c)
- 1.2n.
Section 11.4.6 - Risk-Tárgèted Maximum Considered Earthquake (MCER) Response Spectrum
The MCER Response* Spectrum is determined by multiplying the design response spectrum above by
1.5.
Section 11.8.3 - Additional .Geotechnical Investigation Report Requirements for Seismic Design
Categories D through F
From Figure 22-7 PGA = 0.46.0
Equation (11.8-11): PGAM = FPGAPGA = 1.040 x 0.460 = 0.478 g
Table 11.8-1: Site Coefficient FPGA
Site Mapped MCE Geometric Mean Peak Ground Acceleration, PGA
Class
PG S A :5 PGA = . PGA = PGA = PGA ~
0.10 0.20 0.30 0.40 0.50
0.8. 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
1.2
E E
F SeeSection 1.4.7of ASCE 7
Note; Use straight-line interpolation for Intermediate values, of PGA
For Site Class = D and PGA.= 0.460 g,.F. = 1.040
$ection 21.2.1.1 - Method 1 (from Chapter 21 - Site-Specific Ground Motion Procedures for
Seismic Design)
From Figure 22-17 151 CRs.= 0.940
From Figure CR1 0.991
Section 11.6 - Seismic Design Category
Table 11.6-1 Seismic Design Cateaory Based on Short Period Response Acceleration Parameter
VALUE OF SOS
RISK CATEGORY
lorli III IV
S05 < 0.167g A A A
0.167g' 905 < 0.33g B B C
0.33gS05 <0.509 C C D
0.509S0S D D D
For Risk Category' = I and 56s = 0.800 g, Seismic Design Category' D
Table 11.6-2 Seismic Design Category Based on 1-S Period Response Acceleration Parameter
VALUE OF S01
RISK CATEGORY
lorli III IV
SDI < 0.067g A A A
0.0679 S01 < 0.133g B B C
0.1339 S S01 < 0.20g C C D
O.20gSDI D D D
For Risk Category = I and 501 = 0.461 g, Seismic Design Category = D
Note: When S1 Is 'greater than or equal to 0.75g, 'the Seismic Design Category is E for
buildings in Risk Categories I, II, and III, and F for those in Risk Category IV, irrespective
of the above.
Seismic Design Category "the more severe design category in accordance with
Table 11.6-1 or 11.6-2" = D
Note: See Section 11.6 for alternative approaches to calculating Seismic Design Category.
References
Figure 22-1: https ://earthquake.usgs.góv/hazards/deslg nmaps/downlbads/ pdfs/2010_ASCE-7_Flgure_22- 1. pdf
Figure 22-2: https ://earthquake.usgs;gov/hazards/deslgnmaps/downloads/pdfs/20 10_ASCE-7_Figure_22-2. pdf
Figure 22-12: https://earthquake.usgs.gov/hazards/desIgnmaps/downloads/pdfs/2O10_ASCE-
7_Figure_22- 12.pdf
Figure 22-7 https://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figure_227.pdf
Figure 22-17: https://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-
7_Figure_22-17.pdf
Figure 22-18: https ://earthquake.usgs.gov/hazards/deslgnmaps/downloads/pdfs/ 20 10_ASCE-
7_Figure_22- 18.pdf
APPENDIX C
C:\stedwin\p-686218.OUT Page 1
** GSTABL7 ***
** GSTABL7 by Garry H. Gregory, P.S. **
Original Version 1.0, January 1996; Current Version 2.0, September 2001
(All Rights Reserved-Unauthorized Use Prohibited)
SLOPE STABILITY ANALYSIS SYSTEM
Modified Bishop, Simplified Janbu, or GLE Method of Slices.
(Includes Spencer & Morgenstern-Price Type Analysis)
Including Pier/Pile, Reinforcement, Soil Nail, Tieback,
Nonlinear Undrained Shear Strength, Curved Phi Envelope,
Anisotropic Soil, Fiber-Reinforced Soil, Boundary Loads, Water
Surfaces, Pseudo-Static Earthquake, and Applied Force Options.
* * * * * * * * * * * * * * * * * * * * * k * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * + * * * * * * * * * * * ** * * * * *
Analysis Run Date: 4/3/2018
Tine of Run: 6:09PM
Run By: NB/VS
Input Data Filename: C:p-686218.
Output Filename: C:p-686218.OUT
Unit System: English
Plotted Output Filename: C:p-686218.PLT
PROBLEM DESCRIPTION: LAGOON P-686218
BOUNDARY COORDINATES
9 Top Boundaries
9 Total Boundaries
Boundary X-Left Y-Left X-Right Y-Right Soil Type
No. (ft) (ft) (ft) (ft) Below Bnd
1 0.00 25.00 5.00 25.00 2
2 5.00 25.00 11.00 30.00 2
3 11.00 30.00 27.00 40.00 2
1 27.00 40.00 40.00 50.00 1
5 40.00 50.00 57.00 60.00 1
6 57.00 60.00 70.00 62.00 1
7 70.00 62.00 100.00 63.00 1
8 100.60 63.00 136.00 63.00 1
9 136.00 63.00 182.00 64.00 1
ISOTROPIC SOIL PARAMETERS
2 Type(s) of Soil
Soil Total Saturated Cohesion Friction Pore Pressure Piez.
Type Unit Wt. Unit Wt. Intercept Angle Pressure Constant Surface
No. (pcf) (pcf) (psf) (deg) Param. (psf) No.
1 116.0 122.0 70.0 29.0 0.00 0.0 0
2 120.0 128.0 350.0 34.0 0.00 0.0 0
A Critical Failure Surface Searching Method, Using A Random
Technique For Generating Circular Surfaces, Has Been Specified.
1250 Trial Surfaces Have Been Generated.
25 Surfaces Initiate From Each. Of 50 Points Equally Spaced
Along The Ground Surface Between X = 28.00(ft)
and X = 45.00(ft)
Each Surface Terminates Between X = 70.00(ft)
and X = 110.00(ft)
Unless Further Limitations Were Imposed, The Minimum E].évation
At Which A Surface Extends Is Y = D.00(ft)
5.00(ft) Line Segments Define Each Trial Failure Surface.
Following Are Displayed The Ten Most Critical Of The Trial
Failure Surfaces Evaluated. They Are
Ordered - Most Critical First.
* * Safety Factors Are Calculated By The Modified Bishop Method * *
Total Number, of Trial Surfaces Evaluated = 1250
Statistical Data On All Valid FS Values:
FS Max = 8.025 FS Min = 1.513 2'S Ave = 3.582
Standard Deviation = 1.278 Coefficient of Variation. = 35.68
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 29.39 41.84
2 34.14 43.38
C:\stedwin\p-686218.OUT Page 2
3 38.85 45.08
4 43.49 46.94
5 48.06 48.96
6 52.56 51.13
7 56.99 53.46
8 61.34 55.93
9 65.60 58.54
10 69.77 61.30
11 70.78 62.03
Circle Center At X = -13.8 ; Y = 183.0 and Radius, 147.6
Factor of Safety
*** 1.513 ***
Individual data on the 13 slices
Water Water Tie Tie Earthquake.
Force Force Force Force Force Surchatge
Slice Width Weight Top Bot Norm Tan Mor Ver Load
No. (ft) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs)
1 4.8 583.6 0.0 0.0 0.0. 0.0 0.0 0.0 0.0
2 4.7 1675.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0
3 1.2 568.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0
4 3.5 1932.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0
5 4.6 2888.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0
6 4.5 3144.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0
7 4.4 3286.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0
8 0.0 5.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0
9 4.3 2839.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
10 4.3 1858.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0
11 4.2 831.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0
12 0.2 16.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
13 0.8 24.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.00 40.77
2 32.68 42.52
3 37.33 44.38
4 41.93 46.33
5 46.49 48.38
6 51.00 50.54
7 55.47 52.78
8 59.88 55.13
9 64.25 57.57
10 68.56 60.10
11 71.73 62.06
Circle Center At X = -50.8 ; Y = 258.3 and Radius, 231.4
Factor of Safety
*** 1.520
Failure Surface Specified By 12 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.66 41.88
3 38.57 4.2.81
4 43.41 44.07
5 48.15 45.67
6 52.77 47.59
7 57.24 49.83
8 61.54 52.37
9 65.66 .55.21
10 69.57 58.33
11 73.25 61.71
12 73.64 62.12
Circle Center At X = 22.9 ; Y = 112.8 and Radius, 71.7
Factor of Safety
** 1.521
Failure Surface. Specified By 11 Coordinate Points
C:\stedwin\p7686218..OUT Page 3
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.69 41.32
3 38.67 41.83
4 43.57 42.83
5 48.34 44.31
6 52.95 46.26
7 57.34 48.66
8 61.46. 51.48
9 65.29 54.69
10 68.79 58.27
11 71.81 62.06
Circle Center At X 31.0 ; Y = 91.6 and Radius, 50.4.
Factor of Safety
*** 1.525 **
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y- Surf
No. (ft) (ft)
1 28.69 41.30
2 33.46 42.82
3 38.17 44.48
4 42.84 46.28
5 47.45 48.22
6 52.00 50.29
7 56.49 52.49
8 60.91 54.02
9 65.27 57.28
10 69.54 59.87
11 72.99 62.10
Circle Center At X = -20.6 ; Y 204.1 and Radius, 170.1
Factor of Safety
1.535 ***
Failure Surface Specified By 11 Coordinate Points
Point X-Surf '1-Surf
No. (ft) (.ft)
1 29.39 41.84
2 34.39 41.74
3 39.37 42.18
4 44.27 43.15
5.. 49.05 44.64
6 53.63 46.63
57.98 49.09
8 62.04 52.01
9. 65.77 55.35
10 69.11 59.06
11 71.27 62.04
Circle Center At X = 32.8 ; '1 = 88.4 and Radius, 46.7
Factor of Safety.
*** .1.548 ***
Failure Surface Specified By 11 Coordinate Points
Point X-Surf '1-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.39 43.02
3 38.05 44.83
42.67 4.6.75
47.25 48.76
6 51.78 50.88
7 56.26 53.09
8 60.70 55.40
9 65.08 57.80
10 69.41 60.30
11. 72.35 62.08
Circle Center At X = -481 ; '1 = 259.0 and Radius, 230.8
Factor of Safety
C:\stedwin\p-686218.OUT Page 4
** 1.548 *'
Failure Surface Specified By 12 Coordinate Points
Point X-Surf Y- Surf
No. (ft) (ft)
1 28.35 41.04
2 33.34 41.29
3 38.30 41.93
4 43.19 42.96
5 47.99 44.35
6 52.67 46.12
7 57.20 48.24
8 61.55 50.71
9 65.69 53.51
10 69.61 56.61
11 73.28 60.01
12 75.27 62.18
Circle Center AtX = 27.6 ;.Y = 105.3 and Radius, 64.3
Factor of Safety
*** 1.567 ***
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.00 40.77
2 32.59 42.75
3 37.16 44.77
4 41.72 46.84
5 46.25 48.95
6 50.76 .51.10
7 55.26 53.29
8 59.73 55.53
9 64.18 57.80
10 68.61 60.12
11 72.28 62.08
Circle Center At X -183.0 ; Y = 536.1 and Radius, 538.4
Factor of Safety
*** 1.582 ***
Failure. Surface Specified By 12 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1. 29.04 41.57
2 34.04 41.35
3 39.03 41.63
4 43.97 42.42
5 48.80 43.70
6 53.48 45.47
7 57.95 47.70
8 62.18 50.37
9 66.11 53.4.6
10 69.71 56.93
11 72.94: 60.75
12 73.89 62.13
Circle Center At X = 33.8 ; Y = 90.4 and Radius, 49..1
Factor of Safety
1.609 ***
END OF GSTABL7 OUTPUT
C:\stedwin\p-686218.OUT Page 1
*** GSTABL7 ***
** GSTABL7 by Garry H. Gregory, P.E.
Original Version 1.0, January 1996; Current Version 2.0, September 2001 **
(All Rights Reserved-Unauthorized Use Prohibited)
SLOPE STABILITY ANALYSIS SYSTEM
Modified Bishop, Simplified Janbu, or GLE Method of Slices.
(Includes Spencer & Morgenstern-Price Type Analysis)
Including Pier/Pile, Reinforcement, Soil Nail, Tieback,
Nonlinear Undrained Shear Strength, Curved Phi Envelope,
Anisotropic Soil, Fiber-Reinforced Soil, Boundary Loads, Water
Surfaces, Pseudo-Static Earthquake, and Applied Force Options.
Analysis Run Date: 4/3/2018
Time of Run: 6:05PM
Run By: MB/VS
Input Data Filename C:p-686218.
Output Filename: C:p-686218.OUT
Unit System: English
Plotted Output Filename: C:p-686218.PLT
PROBLEM DESCRIPTION: LAGOON P-686218
BOUNDARY COORDINATES
9 Top Boundaries
9 Total Boundaries
Boundary X-Left Y-Left X-Right Y-Right Soil Type
No. (ft) (ft) (ft) (ft) Below End
1 0.00 25.00 5.00 25.00 2
2 5.00 25.00 11.00 30.00 2
3 11.00 30.00 27.00 40.00 2
4 27.00 40.00 40.00 50.00 1
5 40.00 50.00 57.00 60.00 1
6 57.00 60.00 70.00 62.00 1
7 70.00 62.00 100.00 63.00 1
8 100.00 63.00 136.00 63.00 1
9. 136.00 63.00 18.2.00 64.00 1
ISOTROPIC SOIL PARAMETERS
2 Type(s) of Soil
Soil Total Saturated Cohesion Friction Pore Pressure Piez.
Type Unit Wt. Unit Wt. Intercept Angle Pressure Constant Surface
No. (pcf) (pcf) (psf) (deg) Param. (psf) No.
1 116.0 122.0 70.0 29.0 0.00 0.0 0
2 120.0 128.0 350.0 34.0 0.00 0.0 0
A Horizontal Earthquake Loading Coefficient
OfO.160 Has Been. Assigned
A Vertical Earthquake Loading Coefficient
Of0.000 Has Been Assigned
Cavitation Pressure = 0.0(psf)
A Critical Failure Surface Searching Method, Using A Random
Technique For Generating Circular Surfaces, Has Been Specified.
1250 Trial Surfaces Have Been Generated.
25 Surfaces Initiate From Each Of 50 Points Equally Spaced
Along The Ground Surface Between X = 28.00(ft)
and X = 45.00(ft)
Each Surface Terminates Between X = 70.00(ft)
and X = 110.00(ft)
Unless Further Limitations Were Imposed, The Minimum Elevation
At Which A Surface Extends Is Y = 0.00(ft)
5.00(ft) Line Segments Define Each Trial Failure Surface.
Following Are Displayed The Ten Most Critical Of The Trial
Failure Surfaces Evaluated. They Are
Ordered - Most Critical First.
* * Safety Factors Are Calculated By The Modified Bishop Method *
Total Number of Trial Surfaces Evaluated = 1250
Statistical Data On All Valid FS Values:
FS Max 3.436 FS Min = 1.087 FS Ave = 2.097
Standard Deviation = 0.545 Coefficient of Variation = 25.99
C:\stedwin\p-686218.OUT Page 2
Failure Surface Specified By 12 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.66 41.88
3 38.57 42.81
4 43.41 44.07
5 48.15 45.67
6 52.77 47.59
7 57.24 49.83
B 61.54 52.37
9 65.66 55.21
10 69.57 58.33
11 73.25 61.71
12 73.64 62.12
Circle. Center At X = 22.9 ; y = 112.8 and Radius, 71.7
Factor of Safety
*** 1.087 ***
Individual data on the 14 slices
Water Water Tie Tie Earthquake
Force Force Force Force Force Surcharge
Slice Width Weight Top Bot Norm Tan Hor Ver. Load
No. (ft) (ibs) (ibs) (ibs) (ibs) (ibs) (ibs) (ibs) (ibs)
5.0 933.3 0.0 0.0 0.0 0.0 149.3 0.0 0.0
2 4.9 2660.8 0.0 0.0 0.0 0.0 425.7 0.0 0.0
3 1.4 1067.9 0.0 0.0 0.0 0.0 170.9 0.0 0.0
4 3.4 2920.3 0.0 _b.0 0.0 0.0 467.3 0.0 0.0
5 4.7 4688.9 0.0 0.0 0.0 0.0 750.2 0.0 0.0
6 4.6 5098.3 0.0 0.0 0.0 0.0 815.7 04 0.0
7 4.2 4962.5 0.0 0.0 0.0 0.0 794.0 0.0 0.0
8 0.2 281.2 0.0 0.0 0.0 0.0 45.0 0.0 0.0
9 4.3 4626.1 0.0 0.0 0.0 0.0 740.2 0.0 0.0
10 4.1 3448.9 0.0 0.0 0.0 0.0 551.8 0.0 0.0
11 3.9 2205.0 0.0 0.0 0.0 0.0 352.8 0.0 0.0
12 0.4 172.8 0.0 0.0 0.0 0.0 27.6 0.0 0.0
1.3 33 692.0 0.0 0.0 0.0 0.0 110.7 0.0 0.0
14 0.4 9.0 0.0 0.0 0.0 0.0 1.4 0.0 0.0
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No. (.ft) (ft)
1 29.39 41.81
2 34.14 43.38
.3 38.85 45.08
4 43.49 46.94
5 48.06 48.96
6 52.56 51.13
7 56.99 53.46
8 61.34 55.93
9 65.60 58.54-
10 69.77 61.30
11 70.78 62.03
Circle Center At X = -13.8 ; Y = 183.0 and Radius, 147.6
Factor of Safety
1.090 ***
Failure Surface Specified By 11 coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.00 40.77
2 32.68 42.52
3 37.33 44.•3
4 41.93 46.33
.5 46.49 48.38
6 . 51.06 50.54
7 55.47 52.78
8 59.88 55.13
9 64.25 57.57
C:\stedwin\p-686218.OUT Page 3
10 68.56 60.10
11 71.73 62.06
Circle Center At X = -50.8 ; I = 258.3 and Radius, 231.4
Factor of Safety
*** 1.092 •**
Failure Surface Specified By '11 Coordinate Points
Point X-Surf I-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.46 42.82
3 38.17 44.48
4 42.84 46.28
5 47.45 48.22
6 52.00 50.29
7 56.49 52.49
8 60.91 54.82
9 65.27 57.28
10 69.54 59.87
11 72.99 62.10
Circle Center At X = -20.6 ; I = 204.1 and Radius, 170.1
Factor of Safety
*** 1.094 ***
Failure Surface Specified By 11 Coordinate Points
Point X-Surf 1-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.69 41.32
3 38.67 41.83
4 43.57 42.83
5 48.34 44.31
6 52.95 46.26
7 57.34 48.66
8 61.46 51.48
9 65.29 54.69
10 68.79 58.27
11 71.81 62.06
Circle Center At X = 31.0 ; Y = 91.6 and Radius, 50.4
Factor of Safety
*** 1.105 ***
Failure Surface Specified By 11 Coordinate Points
Point X-Surf 1-Surf
No. (ft) (ft)
1 28.69 41.30
2 33.39 43.02
3 38.05 44.83
4 42.67 46.75
5 47.25 48.76
6 51.78 50.88
7 56.26 53.09
8 60.70 55.40
9 65.08 5'7.80
10 69.41 60.30
11 72.35 62.08
Circle Center At X = -48.1 ; I = 259.0 and Radius, 230.8
Factor of Safety
1.107 ***
Failure Surface Specified By 12 Coordinate Points
Point X-Surf 1-Surf
No. (ft) (ft)
1 28.35 41.04
2 33.34 41.29
3 38.30 41.93
4 43.19 42.96
5 .47.99 44.35
6 52.67 46.12
7 57.20 48.24
C:\stedwin\p-686218.olJT Page 4
8 61.55 50.71
9 65.69 53.51
10 69.61 56.61
11 73.28 60.01
12 75.27 62.18
Circle Center At X = 27.6 ; Y = 105.3 and Radius, 64.3
Factor of Safety
**+ 1.114 **
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No (ft) (ft)
1 29.39 41.84
2 34.39 4l74
3 39.37 42.18
4 44.27 43.15
5 49.05 44.64
6 53.63 46.63
7 57.98 49.09
8 62.04 52.01
9 65.7.7 55.35
10 69.11 59.06
11. 71.27 62.04
Circle center At X = 32.8 ; Y 88.4 and Radius, 46.7.
Factor of Safety
*** 1.122 ***
Failure Surface Specified By 11 Coordthate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 28.00 40.77
2 32.59 42.75
3 37.16 44.77
4 41.72 46.84
5. 46.25. 48.95
6 50.76 51.10
7 55.26 . 53.29
8 59.73 55.53
9 64.18 57.80
10 68.61 60.12
11 72.28 62.08
Circle Center At X = -183.0 ; Y = 536.1 and Radius, 538.4
Factor of Safety
*** 1.133 **
Failure Surface Specified By 11 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 30.08 42.37
2 34.82 43.97
3 39.52 45.66
4. 44.19 47.46
5 48.82 49.35
6 53.40 51.34
7 57•95 5343
8 62.44 55.62
9 66.89 57.90
10 71.29 60.28
11 7.4.59 62.15
Circle Center At X = -42.2 ; Y = 265.1 and Radius, 234.2
Factor of Safety
1.149 ***
END OF GSTABL7 OUTPUT
APPENDIX 'D
Grading Guidelines
Grading should be performed to at least the minimum requirements of the local governing agencies,
the California Building Code, 2016, the geotechnical report and the guidelines presented below. All
of the guidelines may not apply to a specific site and additional recommendations may be necessary
during the grading phase.
Site Clearing
Trees, dense vegetation, and other deleterious materials should be removed from the site.
Nonorgathc debris or concrete may be placed in deeper fill areas under direction of the Soils
engineer.
Subdrainage
During grading, the Geologist and Soils Engineer should evaluate the necessity of placing
additional drains.
All subdrainage systems should be observed by the Geologist and Soils Engineer during
construction and prior to covering with compacted fill.
Consideration should be given to having subdrains located by the project surveyors. Outlets
should be located and protected.
Treatment of Existing Ground
All heavy vegetation, rubbish and other deleterious materials should be disposed of off site.
All surficial deposits including alluvium and colluvium should be removed unless otherwise
indicated in the text of this repOrt. Groundwater existing in the alluvial areas may make
excavation difficult. Deeper removals than indicated in the text of the report may be
necessary due to saturation during winter months.
Subsequent to removals, the natural ground should be processed to a• depth of six inches,
moistened to near optimum moisture conditions and compacted to fill standards.
Fill Placement
Most site soil and bedrock may be reused for compacted fill; however, some special
processing or handling may be required (see report). Highly organic or contaminated soil
should not be used for compacted fill.
Material used in the compacting process should be evenly spread, moisture conditioned,
processed, and compacted in thin lifts not to exceed six inches in thickness to obtain a
uniformly dense layer. The fill should be placed and compacted on a horizontal plane, unless
otherwise found acceptable by the Soils Engineer.
If the moisture content or relative density varies from that acceptable to the Soils engineer,
the Contractor should rework the fill until it is in accordance with the following:
Moisture content of the fill should be at or above optimum moisture. Moisture should
be evenly distributed without wet and dry pockets. Pre-watering of cut or removal areas
should be considered in addition to watering during fill placement, particularly in clay
or dry surficial soils.
Each six inch layer should be compacted to at least 90 percent of the maximum density
in compliance with the testing method specified by the controlling governmental agency.
In this case, the testing method is ASTM Test Designation D-1557-91.
Side-hill fills should have a minimum equipment-width key at their toe excavated through
all surficial soil and into competent material (see report) and tilted back into the hill. As the
fill is elevated, it should be benched through surficial deposits and into competent bedrock
or other material deemed suitable by the Soils Engineer.
Rock fragments less than six inches in diameter may be utilized in the fill, provided:
They are not placed in concentrated pockets;
There is a sufficient percentage. of fine-grained material to surround the rocks;
The distribution of the rocks is supervised by the Soils Engineer.
Rocks greater than six inches in diameter should be taken off site, or placed in accordance
with the recommendations of the Soils Engineer in areas designated as suitable for rock
disposal.
In clay soil large chunks or blocks are common; if in excess of six (6) inches minimum
dimension then they are considered as oversized. Sheepsfoot compactors or other suitable
methods should be used to break the up blocks.
The Contractor should be required to obtain a minimum relative compaction of 90 percent
out to the finished slope face of fill slopes. This may be achieved by either overbuilding the
slope and cutting back to the compacted core, or by direct compaction of the slope face with
suitable equipment.
If fill slopes are built "at grade" using direct compaction methods then the slope construction
should be performed so that a constant gradient is maintained throughout construction. Soil
should not be "spilled" over the slope face nor should slopes be "pushed out" to obtain
grades. Compaction equipment should compact each lift along the immediate top of slope.
Slopes should be back rolled approximately every 4 feet vertically as the slope is built.
Density tests should be taken periodically during grading on the flat surface of the fill three
to five feet horizontally from the face of the slope.
In addition, if a method other than over building and cutting back to the compacted core is
to be employed, slope compaction testing during construction should include testing the outer
six inches to three feet in the slope face to determine if the required compaction is being
achieved. Finish grade testing of the slope should be performed after construction is
complete. Each day the Contractor should receive a copy of the Soils Engineer's "Daily Field
Engineering Report' which would indicate the results of field density tests that day.
Fill over cut slopes should be constructed in the following manner:
All surficial soils and weathered rock materials should be removed at the cut-fill
interface.
A. key at least 1 equipment width wide (see report) and tipped at least 1 foot into slope
should be excavated into competent materials and observed by the Soils Engineer or his
representative.
The cut portion of the slope should be constructed prior to fill placement to evaluate if
stabilization is necessary, the contractor should be responsible for any additional
earthwork created by placing fill prior to cut excavation.
Transition lots (cut and fill) and lots above stabilization fills should be cappe4 with a four
foot thick compacted fill blanket (or as indicated in the report).
Cut pads should be observed by the Geologist to evaluate the need for overexcavation and
replacement with fill. This may be necessary to reduce water infiltration into highly
fractured bedrock or other permeable zones, and/or due to differing expansive. potential of
materials beneath a structure. The overexcavation should be at least three feet. Deeper
overexcavation may be recommended in some cases.
Exploratory backhoe or dozer trenches still remaining after site removal should be excavated
and filled with compacted fill if they can be located.
Grading Observation and Testing
Observation of the fill placement should be provided by the Soils Engineer during the
progress of grading.
In general, density tests would be made at intervals not exceeding two feet of fill height or
every 1,000 cubic yards of fill placed. This criteria will vary depending on soil conditions
and the size of the fill. In any event, an adequate number of field density tests should be
made to evaluate if the required compaction and moisture content is generally being
obtained.
Density tests may be made on the surface material to receive fill, as required by the Soils
Engineer.
Cleanouts, processed ground to receive fill, key excavations, subdrains and rock disposal
should be observed by the Soils Engineer prior to placing any fill. It will be the Contractor's
responsibility to notify the Soils Engineer when such areas are ready for observation.
A. Geologist should observe subdrain construction.
A Geologist should observe benching prior to and during placement of fill.
Utility Trench Bacicfihl
Utility trench backfill should be placed to the following standards:
Ninety percent of the laboratory standard if native material is used as backfill.
As an alternative, clean sand may be utilized and flooded into place. No specific relative
compaction would be required; however, observation, probing, and if deemed necessary,
testing may be required.
Exterior trenches, paralleling a footing and extending below a 1:1 plane projected from the
outside bottom edge of the footing, should be compacted to 90 percent of the laboratory
standard. Sand backfill, unless it is similar to the inplace fill, should not be allowed in these
trench-backfill areas.
Density testing along with probing should be accomplished to verify the desired results.