HomeMy WebLinkAbout20210208_Soils Report_12-18-2020131 Calle Iglesia, Suite 200, San Clemente, CA 92672 (949) 369-6141 www.lgcgeotechnical.com
December 18, 2020 Project No. 20210-01
Mr. Sean Norton
1300 Nottingham Road
Newport Beach, CA 92660
Subject: Geotechnical Evaluation, Proposed Residential Redevelopment, 6806 West Oceanfront
Avenue, Newport Beach, California
In accordance with your request, LGC Geotechnical, Inc. has performed a geotechnical evaluation for the
proposed residential redevelopment of 6806 West Oceanfront Avenue in the city of Newport Beach,
California. The purpose of our study was to evaluate the site geotechnical conditions and to provide
appropriate geotechnical recommendations and design parameters for site redevelopment. This report
presents the results of our evaluation and geotechnical analysis and provides a summary of our
conclusions and recommendations relative to the proposed site improvements.
Should you have any questions regarding this report, please do not hesitate to contact our office. We
appreciate this opportunity to be of service.
Respectfully,
LGC Geotechnical, Inc.
Kelby Styler, RCE 87413 Kevin Dyekman, CEG 2595
Project Engineer Project Geologist
KMS/KAD/amm
Distribution: (4) Addressee (3 wet-signed copies and 1 electronic copy)
(1) ATP Builders, Inc. (1 electronic copy)
Attn: Erin Kennedy
LGC
Geatechnical, Inc.
PA2021-024
Project No. 20210‐01 Page i December 18, 2020
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION ...................................................................................................................................... 1
1.1 Scope of Services ......................................................................................................................................... 1
1.2 Site Description and Proposed Construction ................................................................................. 1
1.3 Subsurface Evaluation .............................................................................................................................. 1
1.4 Laboratory Testing .................................................................................................................................... 2
2.0 GEOTECHNICAL CONDITIONS ............................................................................................................ 4
2.1 Regional Geology ......................................................................................................................................... 4
2.2 Groundwater ................................................................................................................................................. 4
2.3 Seismic Design Criteria ............................................................................................................................ 4
2.4 Faulting and Seismic Hazards ............................................................................................................... 6
2.4.1 Liquefaction and Dynamic Settlement ................................................................................. 6
2.4.2 Lateral Spreading ......................................................................................................................... 7
2.4.3 Tsunamis and Seiches ................................................................................................................ 7
3.0 CONCLUSIONS ......................................................................................................................................... 8
4.0 RECOMMENDATIONS ............................................................................................................................ 9
4.1 Site Earthwork ............................................................................................................................................. 9
4.1.1 Site Preparation ......................................................................................................................... 10
4.1.2 Removal Depths and Limits ................................................................................................... 10
4.1.3 Temporary Excavations ......................................................................................................... 10
4.1.3.1 Temporary Shoring .................................................................................................... 11
4.1.4 Removal Bottoms and Subgrade Preparation ................................................................ 12
4.1.5 Material for Fill .......................................................................................................................... 12
4.1.6 Placement and Compaction of Fills .................................................................................... 13
4.1.7 Trench and Retaining Wall Backfill and Compaction .................................................. 14
4.2 Preliminary Foundation Recommendations ................................................................................. 14
4.2.1 Conventional Slab-on-Ground Foundations .................................................................. 14
4.2.2 Slab Underlayment Guidelines ............................................................................................ 15
4.3 Soil Bearing and Lateral Resistance ................................................................................................ 15
4.4 Retaining Walls ......................................................................................................................................... 16
4.5 Control of Surface Water and Drainage Control .......................................................................... 18
4.6 Subsurface Water Infiltration .............................................................................................................. 18
4.7 Soil Corrosivity .......................................................................................................................................... 18
4.8 Utility Lines ................................................................................................................................................ 19
4.9 Nonstructural Concrete Flatwork ...................................................................................................... 19
4.10 Grading and Foundation Plan Review ............................................................................................. 20
4.11 Geotechnical Observation and Testing During Construction ................................................. 20
5.0 LIMITATIONS ......................................................................................................................................... 22
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TABLE OF CONTENTS (Cont’d)
LIST OF TABLES, ILLUSTRATIONS & APPENDICES
Tables
Table 1 – Seismic Design Parameters (Page 5)
Table 2 – Lateral Earth Pressures for Retaining Walls (Page 17)
Table 3 – Nonstructural Concrete Flatwork for Very Low Expansion Potential (Page 20)
Figures
Figure 1 – Site Location Map (Page 3)
Figure 2 – Geotechnical Map (Rear of Text)
Figure 3 – Geologic Cross Sections A-A’ & B-B’ (Rear of Text)
Figure 4 – Retaining Wall Backfill Detail (Rear of Text)
Figure 5 – Temporary Shoring Detail (Rear of Text)
Appendices
Appendix A – References
Appendix B – Boring Log
Appendix C – Laboratory Testing Procedures and Test Results
Appendix D – Liquefaction Analysis
Appendix E – General Earthwork and Grading Specifications
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Project No. 20210‐01 Page 1 December 18, 2020
1.0 INTRODUCTION
LGC Geotechnical has performed a geotechnical evaluation for the proposed redevelopment of the
residential property located at 6806 West Oceanfront Avenue, in Newport Beach, California (Figure 1).
This report summarizes our findings, conclusions, and geotechnical design recommendations relative to
the proposed site redevelopment.
1.1 Scope of Services
The purpose of our study was to provide a preliminary geotechnical evaluation relative to the
proposed residential redevelopment of the site. As part of our scope of work, we have: 1)
reviewed readily available geotechnical background information including in-house regional
geologic maps and published geotechnical literature, and previous geotechnical reports for
nearby projects (Appendix A); 2) performed a limited subsurface geotechnical evaluation of the
site consisting of the excavation of one hollow-stem boring advanced to a depth of
approximately 50 feet, and one hand-augured boring excavated, sampled and logged to a depth
of 10 feet; 3) performed laboratory testing of select soil samples obtained during our
subsurface evaluation; and 4) prepared this preliminary geotechnical evaluation report
presenting our preliminary findings, conclusions and recommendations for the redevelopment
of the site.
1.2 Site Description and Proposed Construction
The site consists of a single lot, residential property situated along West Oceanfront Avenue, in
the City of Newport Beach, California. The site is bordered to the west and east by similar
residential properties, to the north by West Oceanfront Avenue, and to the south by
approximately 500 ft of beach followed by the Pacific Ocean.
Based on our review of the conceptual plans, we understand that the proposed project will
consist of demolishing the existing residence and construction of a new three-story residential
structure. The new residence will utilize a mat slab foundation on-grade.
1.3 Subsurface Evaluation
The subsurface exploration conducted on the property included the excavation, logging, and
sampling of one hand-augered boring (HA-1) to depth of approximately 10 feet and one hollow-
stem boring (HS-1) to a depth of approximately 51 feet. The purpose of the exploratory borings
was to observe the sub-surface soil and groundwater conditions and to collect bulk samples for
laboratory testing. The soil observed was visually classified in the field and samples were
retained for laboratory testing and analysis. The approximate locations of the borings are shown
on Figure 2 – Geotechnical Map. The boring logs are presented in Appendix B.
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1.4 Laboratory Testing
Laboratory testing was performed on representative soil samples obtained from our subsurface
evaluation. Laboratory testing included in-situ moisture and density tests, fines content/sieve
analysis, swell/settlement potential, direct shear, expansion index, laboratory compaction, and
corrosion (sulfate, chloride content, pH, and minimum resistivity).
The following is a summary of the laboratory test results.
Dry density of the samples collected ranged from approximately 93.4 pounds per cubic
foot (pcf) to 103 pcf, with an average of approximately 98.5 pcf. Field moisture contents
ranged from approximately 1.4 percent to 26 percent, with an average of approximately
8.7 percent.
Particle size distribution testing (sieve analysis) and fines content tests (passing #200
sieve) were performed on three samples with results indicating sandy soils with fines
contents ranging from 2 to 4 percent. According to the Unified Soils Classification System
(USCS), the tested samples are classified as “coarse-grained” soil.
One direct shear test was performed, and the plot is provided in Appendix C.
One Expansion Index (EI) test was performed. Results indicate an EI value of 0
corresponding to “Very Low” expansion potential.
One laboratory compaction tests of a near surface samples indicated maximum dry density
of 102.0 pcf with an optimum moisture contents of 8.5 percent.
Corrosion testing of near-surface bulk samples indicated a soluble sulfate content of
approximately 71 parts per million (ppm), a chloride content of approximately 41 ppm, a
pH value of approximately 7.19 and a minimum resistivity value of approximately 11,800
ohm-cm.
Laboratory test results are presented in Appendix C. The in-situ moisture and dry density test
results are presented on the boring logs in Appendix B.
PA2021-024
Subject Site
FIGURE 1
Site Location Map
DATE
ENG. / GEOL.
PROJECT NO.
PROJECT NAME
SCALE
December 2020
KMS/KAD
Not to Scale
6806 W. Oceanfront St
20210-01LGC
Geotechnical, Inc.
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Project No. 20210‐01 Page 4 December 18, 2020
2.0 GEOTECHNICAL CONDITIONS
2.1 Generalized Geologic Conditions
Based on regional geologic mapping (USGS, 2004), the site is primarily underlain by Holocene-
age Eolian (wind-blown) deposits (Map Symbol - Qe). Prior to urbanization, these sediments
were locally and intermittently overlain by a relatively thin mantle of back-bay marsh deposits
(silt and clay). The eolian, marine, and marsh deposits are mostly derived from sediments of
the Santa Ana River drainage system across the Orange County coastal flood plain, and from
near-shore erosion of the local coastal bluffs.
The eolian deposits encountered during our subsurface exploration generally consisted of light-
yellow brown, light brown, gray, and dark gray sands with little to no fines content. Additionally,
the deposits were found to be dry to wet and loose to very dense. Detailed descriptions of the
subsurface soils are presented on the logs presented in Appendix B.
2.2 Groundwater
Based on our review of the Seismic Hazard Zone Report for the 7.5-Minute Anaheim and
Newport Beach Quadrangles, the historic high groundwater level for the site is located at a
depth of approximately 3 feet below the ground surface (CDMG, 2001). In addition,
groundwater was encountered during our recent subsurface exploration at a depth of
approximately 8 feet to 10 feet below the existing ground surface correlating to an approximate
elevation of 5 to 3 feet above mean sea level (msl). Fluctuation in site groundwater should be
anticipated as a result of tidal variations due to the close proximity to the ocean.
2.3 Seismic Design Criteria
The site seismic characteristics were evaluated per the guidelines set forth in Chapter 16,
Section 1613 of the 2019 California Building Code (CBC) and applicable portions of ASCE 7-16
which has been adopted by the CBC. Please note that the following seismic parameters are
only applicable for code‐based acceleration response spectra and are not applicable for
where site‐specific ground motion procedures are required by ASCE 7‐16.
Representative site coordinates of latitude 33.6279 degrees north and longitude -117.9533
degrees west were utilized in our analysis. The maximum considered earthquake (MCE)
spectral response accelerations (SMS and SM1) and adjusted design spectral response
acceleration parameters (SDS and SD1) for Site Class D are provided in Table 1 below. Since site
soils are Site Class D, additional adjustments are required to code acceleration response
spectrums as outlined below and provided in ASCE 7-16. The structural designer should
contact the geotechnical consultant if structural conditions (e.g., number of stories, seismically
isolated structures, etc.) require site-specific ground motions.
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TABLE 1
Seismic Design Parameters
Selected Parameters from 2019 CBC,
Section 1613 ‐ Earthquake Loads
Seismic
Design
Values
Notes/Exceptions
Distance to applicable faults classifies the site as a
“Near-Fault” site. Section 11.4.1 of ASCE 7
Site Class D*⟊ Chapter 20 of ASCE 7
Ss (Risk-Targeted Spectral Acceleration
for Short Periods) 1.393g From SEAOC, 2020
S1 (Risk-Targeted Spectral
Accelerations for 1-Second Periods) 0.499g From SEAOC, 2020
Fa (per Table 1613.2.3(1)) 1.000
For Simplified Design Procedure
of Section 12.14 of ASCE 7, Fa shall be taken as 1.4 (Section
12.14.8.1)
Fv (per Table 1613.2.3(2)) 1.801
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
SMS for Site Class D
[Note: SMS = FaSS] 1.393g -
SM1 for Site Class D
[Note: SM1 = FvS1] 0.899g
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
SDS for Site Class D
[Note: SDS = (2/3)SMS] 0.929g -
SD1 for Site Class D
[Note: SD1 = (2/3)SM1] 0.599g
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
CRS (Mapped Risk Coefficient at 0.2 sec) 0.906 ASCE 7 Chapter 22
CR1 (Mapped Risk Coefficient at 1 sec) 0.918 ASCE 7 Chapter 22
*Since site soils are Site Class D and S1 is greater than or equal to 0.2, the seismic response
coefficient Cs is determined by Eq. 12.8-2 for values of T ≤ 1.5Ts and taken equal to 1.5 times the
value calculated in accordance with either Eq. 12.8-3 for TL ≥ T > Ts, or Eq. 12.8-4 for T > TL.
Refer to ASCE 7-16. ⟊Since the site contains soils that may be susceptible to liquefaction, ASCE 7, which has been
adopted by the CBC, requires that site soils be assigned Site Class “F” and a site-specific
response spectrum be performed. However, in accordance with Section 20.3.1 of ASCE 7, if the
fundamental periods of vibration of the planned structure are equal to or less than 0.5 second, a
site-specific response spectrum is not required and ASCE 7/2019 CBC site class and seismic
parameters may be used in lieu of a site-specific response spectrum. It should be noted that the
seismic parameters provided herein are not applicable for any structure having a fundamental
period of vibration greater than 0.5 second.
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A deaggregation of the PGA based on a 2,475-year average return period (MCE) indicates that
an earthquake magnitude of 6.78 at a distance of approximately 8.49 km from the site would
contribute the most to this ground motion. A deaggregation of the PGA based on a 475-year
average return period (Design Earthquake) indicates that an earthquake magnitude of 6.59 at a
distance of approximately 17.56 km from the site would contribute the most to this ground
motion (USGS, 2008).
Section 1803.5.12 of the 2019 CBC (per Section 11.8.3 of ASCE 7) states that the maximum
considered earthquake geometric mean (MCEG) Peak Ground Acceleration (PGA) should be
used for liquefaction potential. The PGAM for the site is equal to 0.669g (SEAOC, 2020). The
design PGA is equal to 0.446g (2/3 of PGAM).
2.4 Faulting and Seismic Hazards
The site is not located within a State of California Fault Rupture Hazard Zone (CDMG, 2007) and
no active or potentially active faults are known to cross the site. The nearest mapped active or
potentially active fault is an on-shore segment of the Newport-Inglewood fault zone located
approximately 0.5 miles northeast of the subject site. In addition, the presence of a blind thrust
fault (San Joaquin Blind Thrust Fault) has been interpolated from limited data to exist at a
depth of approximately eight miles below the nearby uplifted hills to the south east of the site.
However, a fault trace or fault rupture location of San Joaquin Hills Blind Thrust Fault has not
yet been located.
Based on our review, the potential for surface rupture to impact the site is considered remote.
However, the subject site is located within a seismically active area, as is the majority of Southern
California, and will be subjected to strong ground shaking during the design life of the proposed
improvements. Parameters for seismic design are included in the recommendations section of
this report.
2.4.1 Liquefaction and Dynamic Settlement
Liquefaction is a seismic phenomenon in which loose, saturated, granular soils behave
similar to a fluid when subject to high-intensity ground shaking. Liquefaction occurs
when three general conditions coexist: 1) shallow groundwater; 2) low density non-
cohesive (granular) soils; and 3) high-intensity ground motion. Studies indicate that
saturated, loose, near surface cohesionless soils exhibit the highest liquefaction potential,
while dry, dense, cohesionless soils and cohesive soils exhibit low to negligible
liquefaction potential. In general, cohesive soils are not considered susceptible to
liquefaction, but must be evaluated based on Atterberg Limits (Liquid Limit and Plasticity
Index) and moisture content (Bray & Sancio, 2006). Potential impacts of liquefaction on
level ground include settlement, sand boils, and bearing capacity failures below
structures. Dynamic settlement of dry loose sands can occur as the sand particles tend to
settle and densify as a result of a seismic event.
The site is located within a State of California Seismic Hazard Zone (CDMG, 1998) for
liquefaction potential. Liquefaction potential was evaluated using the procedures outlined
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by Special Publication 117A (NCEER, 1997 & CGS, 2008). Liquefaction analysis was based
on the applicable seismic criteria (e.g., PGAM from 2019 CBC), in-situ groundwater depth
of 10 feet below existing grade, and a design groundwater (high groundwater) depth of 3
feet below grade. Seismically induced settlements for liquefaction were estimated by the
procedure outlined by Tokimatsu and Seed (1987). The liquefaction evaluation was
performed on the SPT data from boring HS-1. These methods are based on a relatively
limited empirical data. Therefore, predictions of seismically induced settlement should be
considered approximate.
The site primarily consists of sandy soils that may be susceptible to liquefaction
depending primarily on its apparent density. Based on our evaluation and analysis, the
majority of the sandy soils underlying the site are not considered susceptible to
liquefaction. However, some isolated sandy layers susceptible to liquefaction and
dynamic settlement are present. Total seismic-induced settlement is estimated to be
approximately 1.5 inches and differential seismic settlement is estimated as one-half of
the total seismic-induced settlement over a horizontal span of 40 feet (¾-inch over 40
horizontal feet). Liquefaction calculations are provided in Appendix D.
2.4.2 Lateral Spreading
Lateral spreading is a type of liquefaction-induced ground failure associated with the
lateral displacement of surficial blocks of sediment resulting from liquefaction in a
subsurface layer. Once liquefaction transforms the subsurface layer into a fluid mass,
gravity plus the earthquake inertial forces may cause the mass to move downslope
towards a free face (such as a river channel or an embankment). Lateral spreading may
cause large horizontal displacements and such movement typically damages pipelines,
utilities, bridges, and structures.
Due to the site being relatively level and the lack of an adjacent free face, the potential for
lateral spreading to impact the site is considered low.
2.4.3 Tsunamis and Seiches
Based on the relatively low elevations of the site with respect to sea level and its overall
proximity to the shoreline, there is a possibility of damage to the site during a large
tsunami event. The site is located within the Tsunami Inundation Area delineated on the
Tsunami Inundation Map for Emergency Planning Newport Beach Quadrangle (2009).
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3.0 CONCLUSIONS
Based on the results of our geotechnical evaluation, it is our opinion that the proposed site
redevelopment is feasible from a geotechnical standpoint, provided the following conclusions and
recommendations are incorporated into the site design, grading, and construction.
The following is a summary of the primary geotechnical factors, which may affect future development of
the site.
The site is primarily underlain by Holocene-age Eolian deposits (Map Symbol - Qe). The eolian
deposits encountered during our subsurface exploration generally consisted of light-yellow brown,
light brown, gray, and dark gray sands with little to no fines content. Additionally, the deposits were
found to be dry to wet and loose to dense.
Groundwater was encountered during subsurface evaluation at a depth of approximately 8 to 10
feet below existing ground surface at the site in borings HA-1 and HS-1, respectively. Additionally,
historic high groundwater is estimated to be at a depth of approximately 3 feet below ground
surface (CDMG, 2001). It should be noted, dewatering may be needed at shallower depths, than
encountered during our investigation, due to tidal variations and the actual depth to groundwater
at the time of construction.
The site is not located within a State of California Fault Rupture Hazard Zone (CDMG, 2007) and no
active or potentially active faults are known to cross the site. Therefore, the potential for surface
rupture to impact the site is considered remote. The subject site will likely experience strong
seismic ground shaking during its design life.
The site is located in a seismic hazard zone for liquefaction potential. Subsurface data indicates that
sandy layers susceptible to liquefaction and liquefaction-induced settlement are present at the site.
Our analysis indicates approximately 1.5 inches of seismically induced settlement may occur at the
site during a significant earthquake. Differential seismic-induced settlement is estimated as one-half
of the total settlement over a horizontal span of 40 feet (¾-inch over 40 horizontal feet).
Due to the proposed redevelopment consisting of a residential structure with relatively light loads, it
is our opinion that the potential impacts of liquefaction can by mitigated by minor remedial grading
and the incorporation of a rigid mat slab foundation. However, as with many residential structures in
Southern California, some risk does remain that the proposed structure could suffer some damage if
liquefaction occurs. Repair and remedial work may be required after a liquefaction event.
Due to the relatively shallow site groundwater, stabilization removal bottoms should be anticipated
by the contractor prior to subsequent fill placement. Recommendations regarding the stabilization of
removal bottoms and subgrade are provided herein.
Localized construction dewatering may be needed during grading, utility construction, or any other
excavation which is deeper than approximately 7 feet from existing grade.
Based on preliminary laboratory results, the site soils are anticipated to have a “Very Low” expansion
potential. This must be confirmed at the completion of earthwork grading.
From a geotechnical point of view, the proposed site grading and construction are not anticipated
to impact adjacent properties and/or improvements, provided the geotechnical recommendations
and parameters provided herein are appropriately incorporated into the design and construction
of the project
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4.0 RECOMMENDATIONS
The following recommendations are to be considered preliminary and should be confirmed upon
completion of grading and earthwork operations. In addition, they should be considered minimal from
a geotechnical viewpoint, as there may be more restrictive requirements from the architect, structural
engineer, building codes, governing agencies, or the owner.
It should be noted that the following geotechnical recommendations are intended to provide sufficient
information to develop the site in general accordance with the 2019 CBC requirements. With regard to
the potential occurrence of potentially catastrophic geotechnical hazards such as fault rupture,
earthquake-induced landslides, liquefaction, etc. the following geotechnical recommendations should
provide adequate protection for the proposed development to the extent required to reduce seismic
risk to an “acceptable level.” The “acceptable level” of risk is defined by the California Code of
Regulations as “that level that provides reasonable protection of the public safety, though it does not
necessarily ensure continued structural integrity and functionality of the project” [Section 3721(a)].
Therefore, repair and remedial work of the proposed improvements may be required after a
significant seismic event. With regards to the potential for less significant geologic hazards to the
proposed development, the recommendations contained herein are intended as a reasonable
protection against the potential damaging effects of geotechnical phenomena such as expansive soils,
fill settlement, groundwater seepage, etc. It should be understood, however, that although our
recommendations are intended to maintain the structural integrity of the proposed development and
structures given the site geotechnical conditions, they cannot preclude the potential for some cosmetic
distress or nuisance issues to develop as a result of the site geotechnical conditions.
The geotechnical recommendations contained herein must be confirmed to be suitable or modified
based on the actual as-graded conditions.
4.1 Site Earthwork
We anticipate that earthwork at the site will consist of the removal of existing improvements
followed by the recommended earthwork removals provided herein, and the construction of the
proposed residential structure.
We recommend that earthwork onsite be performed in accordance with the following
recommendations, future grading plan review report(s), the 2019 CBC/City of Newport Beach
requirements, and the General Earthwork and Grading Specifications for Rough Grading included
in Appendix F. In case of conflict, the following recommendations shall supersede those included
in Appendix F. The following recommendations should be considered preliminary and may be
revised within the future grading plan review report or based on the actual conditions
encountered during site earthwork operations.
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4.1.1 Site Preparation
Prior to grading of areas to receive structural fill, the areas should be cleared of existing
pavement, improvements, surface obstructions, and demolition debris. Vegetation and
debris should be removed and properly disposed of off-site. Holes resulting from the
removal of buried obstructions, which extend below proposed finish grades, should be
replaced with suitable compacted fill material. At the conclusion of the clearing
operations, a representative of LGC Geotechnical should observe and accept the site prior
to further grading.
4.1.2 Removal Depths and Limits
In order to provide a relatively uniform bearing condition for the planned structural
improvements, we recommend that removals extend to a depth of 3 feet below existing
grade or 1-foot below the bottom of the designed foundation, whichever is deeper. Where
practical, the removals should extend laterally approximately 3 feet beyond the edges of
the proposed building improvements.
Within pavement and hardscape areas, removals should extend to a depth of at least 2
feet below the existing grade or 1-foot below planned finish subgrade (i.e., below planned
aggregate base/asphalt concrete), whichever is deeper. In general, the envelope for
removals should extend laterally a minimum distance of 2 feet beyond the edges of the
proposed improvements.
Based on our findings, the recommended removal and recompaction depths may extend
to a depth just above the anticipated groundwater table. Care should be taken in order to
avoid creating an unstable removal bottom during grading. Localized construction
dewatering may be needed during grading, utility construction, or any other excavation
which is deeper than approximately 7 feet from existing grade. However, dewatering may
be needed at shallower depths due to tidal variations and the actual depth to
groundwater at the time of construction. Recommendations for subgrade stabilization are
included in Section 3.1.4.
Local conditions may be encountered during excavation that could require additional
removal and recompaction beyond the above-noted minimum in order to obtain an
acceptable subgrade. The actual depths and lateral extents of grading will be determined
by the geotechnical consultant based on the actual subsurface conditions encountered
during grading. Removal and recompaction areas should be accurately staked in the
field by the Project Surveyor.
4.1.3 Temporary Excavations
Temporary excavations should be performed in accordance with project plans,
specifications, and all Occupational Safety and Health Administration (OSHA)
requirements. Excavations should be laid back or shored in accordance with OSHA
requirements before personnel or equipment are allowed to enter. The site soils are
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anticipated to be OSHA Type “C” soils (refer to the attached boring logs). Soil conditions
should be regularly evaluated during construction to verify conditions are as anticipated.
Sandy soils are present and should be considered susceptible to caving. The contractor
shall be responsible for providing the “competent person” required by OSHA standards to
evaluate soil conditions. Close coordination with the geotechnical consultant should be
maintained to facilitate construction while providing safe excavations. Excavation safety
is the sole responsibility of the contractor.
Vehicular traffic, stockpiles, and equipment storage should be set back from the perimeter
of excavations a minimum distance equivalent to a 1:1 projection from the bottom of the
excavation or 5 feet, whichever is greater. Once an excavation has been initiated, it
should be backfilled as soon as practical. Prolonged exposure of temporary excavations
may result in some localized instability. Excavations should be planned so that they are
not initiated without sufficient time to shore/fill them prior to weekends, holidays, or
forecasted rain.
Groundwater or saturated soils are anticipated to be at a depth of approximately 8 feet
below existing grade and may be locally encountered at shallower depths. It should be
noted that any excavation that extends below a 1:1 (horizontal to vertical) projection of
an existing foundation will remove support from the existing structure. Special
consideration may be necessary when working adjacent to sensitive improvements or at
depths which groundwater is encountered.
Static groundwater was encountered at a depth of approximately 8 feet below the existing
ground surface, however, the contractor should anticipate encountering variable
groundwater elevations during construction due to seasonal and/or tidal fluctuations.
4.1.3.1 Temporary Shoring
If necessary, construction of a pipe and board shoring system along the
pertinent portions of the excavation(s) would help reduce the potential of minor
sand sluffing (See attached Figure 5). Heavy-gauge, 2-inch diameter, metal posts
may be driven into the site soils along the edges of the proposed excavations
where the excavations will be within 3 horizontal feet, or closer, to the site
property lines. The posts should be placed at a maximum spacing of 2 feet on
center, be at least 9 feet long and driven into the site soils so that 6 feet of the
posts will be embedded below the proposed removal bottom of approximately 3
feet below adjacent grade. Trench plates or 1.5-inch-thick plywood sheets may
then be forced behind and against the posts, between the posts and the site
property lines. The trench plates/plywood sheets should extend to the bottom of
the proposed excavation. Any voids behind them should be filled with two-sack,
cement slurry. Observation of installation of the shoring system should be
observed by this firm.
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4.1.4 Removal Bottoms and Subgrade Preparation
In general, removal bottom areas and any areas to receive compacted fill should be
scarified to a minimum depth of 6 inches, brought to a near-optimum moisture condition,
and re-compacted per project recommendations. Scarification is generally not required
when clean sands are present, the removal bottom is near groundwater, or very moist to
wet subgrade conditions prevail, which is anticipated for this site.
Based on the presence of shallow groundwater and the potential to encounter saturated
sandy materials at or near the estimated removal depths, some of the removal bottoms
are anticipated to be wet and unstable. We recommend all wet/unstable removal bottoms
be stabilized by the placement and “working in” of crushed rock or an approved alternate
stabilization method. Based on our experience with similar projects, we anticipate the
thickness of crushed rock (1-inch minus) needed to stabilize the removal bottoms will be
on the order to 12 inches thick. The actual thickness of aggregate required to stabilize the
excavation bottom shall be determined in the field based on the actual conditions and
equipment used. It should be anticipated that the first lift of crushed aggregate will be
worked into the pumping subgrade. Subsequent lifts should be properly compacted and
will help bridge the pumping conditions. The thickness of crushed rock required for
stabilization may be reduced by incorporating biaxial geogrid reinforcement (Tensar
TX140 or acceptable equivalent). Contractor may have to minimize construction traffic on
the removal bottom to reduce disturbance. Soft and yielding subgrade should be
evaluated on a case-by-case basis during earthwork operations. Additional
recommendations regarding removal bottom or subgrade stabilization will be provided
as needed during construction.
Removal bottoms and areas to receive fill should be observed and accepted by the
geotechnical consultant prior to fill placement. Soil subgrade for planned footings and
improvements (e.g., slabs, walls, etc.) should be firm and competent.
4.1.5 Material for Fill
From a geotechnical perspective, the onsite soils are generally considered suitable for use
as general compacted fill, provided they are screened of organic materials, construction
debris and any oversized material (material larger than 8 inches in greatest dimension).
From a geotechnical viewpoint, required import soils for general fill (i.e., non-retaining
wall backfill) should consist of clean, granular soils with a Very Low expansion potential
(expansion index 20 or less based on ASTM D4829). Source samples should be provided
to the geotechnical consultant for laboratory testing a minimum of three working days
prior to any planned importation.
Retaining wall backfill should consist of sandy soils with a maximum of 35 percent fines
(passing the No. 200 sieve) per American Society for Testing and Materials (ASTM) Test
Method D1140 (or ASTM D6913/D422) and a Very Low expansion potential (EI of 20 or
less per ASTM D4829). Soils should also be screened of organic materials, construction
PA2021-024
Project No. 20210‐01 Page 13 December 18, 2020
debris, and any material greater than 3 inches. The site is anticipated to contain soils that
meet this-criteria.
Aggregate base (crushed aggregate base or crushed miscellaneous base) should conform
to the requirements of Section 200-2 of the Standard Specifications for Public Works
Construction (“Greenbook”) for untreated base materials (except processed
miscellaneous base) or Caltrans Class 2 aggregate base.
The placement of demolition materials in compacted fill is acceptable from a geotechnical
viewpoint provided the demolition material is broken up into pieces not larger than
typically used for aggregate base (approximately 1-inch in maximum dimension) and well
blended into fill soils with essentially no resulting voids. Demolition material placed in
fills must be free of construction debris (wood, organics, etc.) and reinforcing steel. If
asphalt concrete fragments will be incorporated into the demolition materials, approval
from an environmental viewpoint may be required.
4.1.6 Placement and Compaction of Fills
In general, material to be placed as fill should be brought to near-optimum moisture
content (generally within optimum to 2 percent above-optimum moisture content) and
compacted to at least 90 percent relative compaction (per ASTM D1557). Sandy fill
material with a very low fines content (12 percent or less passing the No. 200 sieve)
should be compacted to at least 95 percent relative compaction (per ASTM D1557). It is
anticipated that most site soils will have a very low fines content thereby requiring a
minimum of 95 percent relative compaction. Moisture conditioning of site soils will be
required in order to achieve adequate compaction. The optimum lift thickness to produce
a uniformly compacted fill will depend on the type and size of compaction equipment
used. In general, fill should be placed in uniform lifts not exceeding 8 inches in compacted
thickness. Each lift should be thoroughly compacted and accepted prior to subsequent
lifts. Generally, placement and compaction of fill should be performed in accordance with
local grading ordinances and with observation and testing by the geotechnical consultant.
Oversized material as previously defined should be removed from site fills.
During backfill of excavations, the fill should be properly benched into firm and
competent soils of temporary backcut slopes as it is placed in lifts.
Aggregate base material should be compacted to a minimum of 95 percent relative
compaction at or slightly above-optimum moisture content per ASTM D1557. Subgrade
below aggregate base should be compacted as discussed at the beginning of this section.
The moisture condition of site soils is anticipated to be very moist (i.e., significantly above
optimum) near the groundwater table. Drying and/or mixing the very moist soils will be
required prior to reusing the materials in compacted fills. Dry soils are also present that
will require additional moisture in order to achieve the required compaction.
PA2021-024
Project No. 20210‐01 Page 14 December 18, 2020
4.1.7 Trench and Retaining Wall Backfill and Compaction
The onsite soils may generally be suitable as trench backfill, provided the soils are
screened of rocks and other material greater than 6 inches in diameter and organic
matter. If trenches are shallow or the use of conventional equipment may result in
damage to the utilities, sand having a sand equivalent (SE) of 30 or greater (per California
Test Method [CTM] 217) may be used to bed and shade the pipes. Sand backfill within the
pipe bedding zone may be densified by jetting or flooding and then tamping to ensure
adequate compaction. Subsequent trench backfill should be compacted in uniform thin
lifts by mechanical means to at least the recommended minimum relative compaction
(per ASTM D1557).
Retaining wall backfill should consist of sandy soils as outlined in preceding Section 3.1.5.
The limits of select sandy backfill should extend at minimum ½ the height of the retaining
wall or the width of the heel (if applicable), whichever is greater (Figure 4). Retaining
wall backfill soils should be compacted in relatively uniform thin lifts to at least 90
percent relative compaction (per ASTM D1557). Jetting or flooding of retaining wall
backfill materials should not be permitted.
In backfill areas where mechanical compaction of soil backfill is impractical due to space
constraints, typically sand-cement slurry may be substituted for compacted backfill. The
slurry should contain about one sack of cement per cubic yard. When set, such a mix
typically has the consistency of compacted soil. Sand cement slurry placed near the
surface within landscape areas should be evaluated for potential impacts on planned
improvements.
A representative from LGC Geotechnical should observe, probe, and test the backfill to
verify compliance with the project recommendations.
4.2 Preliminary Foundation Recommendations
Provided that the remedial grading recommendations provided herein are implemented, the site
may be considered suitable for the support of the residential structure with the implementation
of a rigid foundation system designed to resist estimated liquefaction-induced settlement. We
understand that a conventionally reinforced mat slab has been proposed for the project.
Seismically-induced settlement due to liquefaction is estimated to be on the order of
approximately 1.5-inches. Differential seismic-induced settlement can be estimated as one-half of
the total seismic-induced settlement over a horizontal span of 40 feet. Preliminary conventional
foundation recommendations are provided in the following sections. Recommended soil bearing
and estimated settlement due to structural loads are provided in Section 3.3.
4.2.1 Conventional Slab‐on‐Ground Foundation Parameters
Conventional foundations may be designed in accordance with Wire Reinforcement
Institute (WRI) procedure for slab-on-ground foundations per Section 1808 of the 2019
PA2021-024
Project No. 20210‐01 Page 15 December 18, 2020
CBC to resist potential settlement. The following provisional soil parameters may be
used:
Effective Plasticity Index: 25
Climatic Rating: Cw = 15
Reinforcement: Per structural designer
Slab Thickness: Per structural designer
Minimum Footing Depth: 12 inches below lowest adjacent grade
Moisture condition subgrade soils to 100% of optimum moisture content to a depth
of 12 inches prior to trenching for footings.
The recommended moisture content should be maintained up to the time of the
concrete placement.
4.2.2 Slab Underlayment Guidelines
Guidelines for slab underlayment have traditionally been included with geotechnical
foundation recommendations for sand layers placed below slabs and above/below vapor
retarders for the purpose of protecting the retarder and to assist in concrete curing. Sand
layer requirements are the purview of the foundation engineer/structural engineer and
should be provided in accordance with ACI Publication 302 “Guide for Concrete Floor
and Slab Construction”. Below we have provided guidelines for informational purposes
only. These recommendations must be confirmed (and/or altered) by the foundation
engineer, based upon the performance expectations of the foundation. Ultimately, the
design of the moisture retarder system and recommendations for concrete placement
and curing are the purview of the foundation engineer, in consideration of the project
requirements provided by the architect and developer.
In general, interior floor slabs with moisture sensitive floor coverings should be
underlain by a 15-mil thick moisture/vapor retarder product (polyolefin or equivalent)
to help reduce the upward migration of moisture from the underlying subgrade soils.
The moisture/vapor retarder product used should meet the performance standards of
an ASTM E 1745 Class A material and be properly installed in accordance with ACI
publication 302. It is the responsibility of the contractor to ensure that the
moisture/vapor retarder systems are properly placed in accordance with the project
plans and specifications, and that the moisture/vapor retarder materials are free of tears
and punctures prior to concrete placement. Additional moisture reduction and/or
prevention measures may be needed, depending on the performance requirements of
future interior floor coverings. The recommendations for a 15-mil thick moisture/vapor
retarder product provided above may be superseded should the foundation designer
decide to implement a foundation waterproofing system or similar moisture barrier
system.
4.3 Soil Bearing and Lateral Resistance
Provided our earthwork recommendations are implemented, an allowable soil bearing pressure
PA2021-024
Project No. 20210‐01 Page 16 December 18, 2020
of 1,200 psf may be used for a mat slab embedded a minimum of 6 inches below lowest adjacent
grade. Areas with higher concentrated loads, requiring a higher bearing pressure, should have
deepened footings. An allowable soil bearing pressure of 1,500 pounds per square foot (psf) may
be used for the design of footings having a minimum width of 12 inches and minimum
embedment of 12 inches below lowest adjacent ground surface. This value may be increased by
300 psf for each additional foot of embedment or 100 psf for each additional foot of foundation
width to a maximum value of 2,500 psf. These allowable bearing pressures are applicable for
level (ground slope equal to or flatter than 5H:1V) conditions only. Bearing values indicated
above are for total dead loads and live loads. The above vertical bearing may be increased by one-
third for short durations of loading which will include the effect of wind or seismic forces.
Allowable bearing capacity was calculated utilizing the commonly accepted Terzaghi –
Meyerhof Equation, strength parameters were derived from a direct shear test on a sample
collected at 5 ft below existing ground surface and incorporating a factor of safety of 3 in the
equation. The allowable bearing capacity for a 12-inch-wide and 12-inch-deep continuous
footing is calculated as over 1,800 pounds psf with an increase of over 500 psf for each
additional foot of embedment and an increase of approximately 200 psf for each additional foot
of width. The recommended 1,500 psf bearing for a 12-inch-wide and 12-inch-deep footing
presented above and the recommended increases in capacity with additional embedment
and/or width is, in our opinion, conservative.
In utilizing the above-mentioned allowable bearing capacity, foundation settlement due to
structural loads is anticipated to be on the order of ½-inch. Differential static settlement may be
taken as half of the total settlement over a horizontal span of 40 feet (i.e., ¼-inch over 40 feet).
The majority of this settlement is anticipated to occur during construction. Seismic-induced
settlement due to site liquefaction potential has been discussed in earlier sections of this report.
Resistance to lateral loads can be provided by friction acting at the base of foundations and by
passive earth pressure. For concrete/soil frictional resistance, an allowable coefficient of
friction of 0.3 may be assumed with dead-load forces. An allowable passive lateral earth
pressure of 250 psf per foot of depth (or pcf) to a maximum of 2,500 psf may be used for the
sides of footings poured against properly compacted fill. The allowable passive pressure may be
increased to 340 pcf to a maximum of 3,400 psf for short duration seismic loading. This passive
pressure is applicable for level (ground slope equal to or flatter than 5H:1V) conditions only.
We recommend that the upper foot of passive resistance be neglected if finished grade will not be
covered with concrete or asphalt. Frictional resistance and passive pressure may be used in
combination without reduction. The provided allowable passive pressures are based on a factor
of safety of 1.5 and 1.1 for static and seismic loading conditions, respectively. While not
anticipated, the structural designer should request from the geotechnical consultant any passive
pressure required for depths greater than 3 feet below existing ground surface due to site
groundwater.
4.4 Retaining Walls
Lateral earth pressures for approved native sandy soils meeting indicated project requirements
are provided below. Lateral earth pressures are provided as equivalent fluid unit weights, in psf
per foot of depth (or pcf). These values do not contain an appreciable factor of safety, so the
PA2021-024
Project No. 20210‐01 Page 17 December 18, 2020
retaining wall designer should apply the applicable factors of safety and/or load factors during
design. A soil unit weight of 120 pcf may be assumed for calculating the actual weight of soil over
the wall footing.
The following lateral pressures are presented on Table 2 for approved select granular soils a
maximum of 35 percent fines (passing the No. 200 sieve per ASTM D1140) and an Expansion
Index of 20 or less per ASTM D4829. The retaining wall designer should clearly indicate on the
retaining wall plans the required sandy soil backfill.
TABLE 2
Lateral Earth Pressures – Approved Select Material
Conditions
Equivalent Fluid Unit Weight
(pcf)
Level Backfill
Approved Soils
Active 40
At-Rest 60
If the wall can yield enough to mobilize the full shear strength of the soil, it can be designed for
“active” pressure. If the wall cannot yield under the applied load, the shear strength of the soil
cannot be mobilized, and the earth pressure will be higher. Such walls should be designed for “at-
rest” conditions. If a structure moves toward the soils, the resulting resistance developed by the
soil is the “passive” resistance. The equivalent fluid pressure values assume free-draining
conditions. If conditions other than those assumed above are anticipated, the equivalent fluid
pressure values should be provided on an individual case basis by the geotechnical engineer.
Retaining wall structures should be provided with appropriate drainage and appropriately
waterproofed. The outlet pipe should be sloped to drain to a suitable outlet. Typical retaining
wall drainage is illustrated in Figure 4.
Surcharge loading effects from adjacent structures should be evaluated by the retaining wall
designer. In general, structural loads within a 1:1 (horizontal to vertical) upward projection from
the bottom of the proposed retaining walls will surcharge the proposed retaining structure. If
applicable, typical vehicle traffic may be estimated as equivalent to 2 feet of compacted fill, a
vertical pressure of 240 psf. The retaining wall designer should contact the geotechnical engineer
for any required geotechnical input in estimating any applicable surcharge loads.
If a retaining wall greater than 6 feet in height is proposed, the retaining wall designer should
contact the geotechnical engineer for specific seismic lateral earth pressure increments based
on the configuration of the planned retaining wall structures.
PA2021-024
Project No. 20210‐01 Page 18 December 18, 2020
Retaining wall footings may be designed for an allowable soil bearing pressure of 1,500 psf
having a minimum depth of 12 inches below lowest adjacent ground surface. Lateral resistance
(friction coefficient and passive resistance) is provided in Section 3.3. Earthwork considerations
(temporary backcuts, backfill, compaction, etc.) for retaining walls are provided in Section 3.1
(Site Earthwork) and the subsequent earthwork related sub-sections.
4.5 Control of Surface Water and Drainage Control
From a geotechnical perspective, we recommend that compacted finished grade soils adjacent
to proposed residences be sloped away from the proposed residence and towards an approved
drainage device or unobstructed swale. Drainage swales, wherever feasible, should not be
constructed within 5 feet of buildings. Where lot and building geometry necessitates that the
side yard drainage swales be routed closer than 5 feet to structural foundations, we
recommend the use of area drains together with drainage swales. Drainage swales used in
conjunction with area drains should be designed by the project civil engineer so that a properly
constructed and maintained system will prevent ponding within 5 feet of the foundation. Code
compliance of grades is not the purview of the geotechnical consultant.
4.6 Subsurface Water Infiltration
Recent regulatory changes have recommended that low flow runoff be infiltrated rather than
discharged via conventional storm drainage systems. In general, the vast majority of geotechnical
distress issues are directly related to improper drainage. In general, distress in the form of
movement of improvements could occur as a result of soil saturation and loss of soil support,
expansion, internal soil erosion, collapse and/or settlement. Infiltrated water may enter
underground utility pipe zones and migrate along the pipe backfill, potentially impacting other
improvements located far away from the point of infiltration. In most areas where geotechnical
distress is observed, a drainage system was properly designed and constructed to collected and
transport water. Often a change occurs after construction, either due to a slight decrease in the
efficiency of the system or inadequate maintenance, causing some ponding of water to occur.
Over time this leads to progressive failure of the system.
Due to the site being located in a liquefaction hazard zone and the presence of shallow
groundwater, we recommend that surface water not be intentionally infiltrated at this site.
4.7 Soil Corrosivity
Although not corrosion engineers (LGC Geotechnical is not a corrosion consultant), several
governing agencies in Southern California require the geotechnical consultant to determine the
corrosion potential of soils to buried concrete and metal facilities. We therefore present the
results of our testing with regard to corrosion for the use of the client and other consultants, as
they determine necessary.
Corrosion testing of selected bulk samples indicate soluble sulfate contents of approximately
71 parts per million (ppm), chloride contents ranging from approximately 41 ppm, pH value of
PA2021-024
Project No. 20210‐01 Page 19 December 18, 2020
approximately 7.19, and minimum resistivity value of 11,800 ohm-cm. Based on Caltrans
Corrosion Guidelines (2018), soils are considered corrosive if the pH is 5.5 or less, or the
chloride concentration is 500 ppm or greater, or the sulfate concentration is 1,500 ppm (0.15
percent) or greater.
Based on our laboratory test results of representative site soil samples, onsite soils have a
designated sulfate exposure class of “S0” per ACI 318-14, Table 19.3.1.1. As a result, per Table
19.3.2.1 the minimum compressive strength of structural concrete shall be 2,500 psi.
Laboratory testing may need to be performed at the completion of grading by the project
corrosion engineer to further evaluate the as-graded soil corrosivity characteristics.
Accordingly, revision of the corrosion potential may be needed, should future test results differ
substantially from the conditions reported herein. The client and/or other members of the
development team should consider this during the design and planning phase of the project
and formulate an appropriate course of action.
4.8 Utility Lines
Due to potential for seismically induced site settlements, the owner may consider using flexible
connections for construction of site utility lines to reduce potential distress during an
earthquake event. Estimated seismic-induced settlement is provided in Section 3.2.
4.9 Nonstructural Concrete Flatwork
Nonstructural concrete flatwork (such as walkways, bicycle trails, patio slabs, etc.) has a
potential for cracking due to changes in soil volume related to soil-moisture fluctuations. To
reduce the potential for excessive cracking and lifting, concrete may be designed in accordance
with the minimum guidelines outlined in Table 3. These guidelines will reduce the potential for
irregular cracking and promote cracking along construction joints but will not eliminate all
cracking or lifting. Thickening the concrete and/or adding additional reinforcement will further
reduce cosmetic distress.
PA2021-024
Project No. 20210‐01 Page 20 December 18, 2020
TABLE 3
Nonstructural Concrete Flatwork for Very Low Expansion Potential
Homeowner
Sidewalks Private Drives Patios/Entryways
Minimum
Thickness (in.) 4 (nominal) 4 (full) 4 (full)
Presoaking
Wet down
prior to
placing
Wet down prior
to placing
Wet down prior to
placing
Reinforcement
No. 3 at 24
inches on
centers
No. 3 at 24
inches on
centers
Thickened
Edge (in.) 8 x 8
Crack Control
Joints
Saw cut or
deep open tool
joint to a
minimum of
1/3 the
concrete
thickness
Saw cut or deep
open tool joint
to a minimum
of 1/3 the
concrete
thickness
Saw cut or deep
open tool joint
to a minimum
of 1/3 the
concrete
thickness
Maximum Joint
Spacing 5 feet
10 feet or
quarter cut
whichever is
closer
6 feet
Aggregate Base
Thickness (in.)
4.10 Grading and Foundation Plan Review
When available, grading and foundation plans should be reviewed by LGC Geotechnical in order
to verify our geotechnical recommendations are implemented. Updated recommendations
and/or additional field work may be necessary.
4.11 Geotechnical Observation and Testing During Construction
The recommendations provided in this report are based on limited subsurface observations and
geotechnical analysis. The interpolated subsurface conditions should be checked in the field
during construction by a representative of LGC Geotechnical. Geotechnical observation and
testing is required per Section 1705 of the 2019 California Building Code (CBC).
Geotechnical observation and/or testing should be performed by LGC Geotechnical at the
following stages:
PA2021-024
Project No. 20210‐01 Page 21 December 18, 2020
During earthwork grading (removal bottoms, fill placement, etc.);
During utility trench backfill and compaction;
After preparation of building pads and other concrete-flatwork subgrades, and prior to
placement of aggregate base or concrete;
Preparation of subgrade and placement of aggregate base;
After building and wall footing excavation and prior to placing concrete and/or
reinforcement; and
When any unusual soil conditions are encountered during any construction operation
subsequent to issuance of this report.
PA2021-024
Project No. 20210‐01 Page 22 December 18, 2020
5.0 LIMITATIONS
Our services were performed using the degree of care and skill ordinarily exercised, under similar
circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No
other warranty, expressed or implied, is made as to the conclusions and professional advice included in
this report.
This report is based on data obtained from limited observations of the site, which have been
extrapolated to characterize the site. While the scope of services performed is considered suitable to
adequately characterize the site geotechnical conditions relative to the proposed development, no
practical evaluation can completely eliminate uncertainty regarding the anticipated geotechnical
conditions in connection with a subject site. Variations may exist and conditions not observed or
described in this report may be encountered during grading and construction.
This report is issued with the understanding that it is the responsibility of the owner, or of his/her
representative, to ensure that the information and recommendations contained herein are brought to
the attention of the other consultants (at a minimum the civil engineer, structural engineer, landscape
architect) and incorporated into their plans. The contractor should properly implement the
recommendations during construction and notify the owner if they consider any of the
recommendations presented herein to be unsafe, or unsuitable.
The findings of this report are valid as of the present date. However, changes in the conditions of a site
can and do occur with the passage of time, whether they be due to natural processes or the works of
man on this or adjacent properties. The findings, conclusions, and recommendations presented in this
report can be relied upon only if LGC Geotechnical has the opportunity to observe the subsurface
conditions during grading and construction of the project, in order to confirm that our preliminary
findings are representative for the site. This report is intended exclusively for use by the client, any use
of or reliance on this report by a third party shall be at such party’s sole risk.
In addition, changes in applicable or appropriate standards may occur, whether they result from
legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated
wholly or partially by changes outside our control. Therefore, this report is subject to review and
modification.
PA2021-024
QeA
A'B'B
Limits of Report
HS-1
T.D. = 51'
HA-1
T.D. = 10'
LEGEND
Quaternary Eolian Deposits, Circled Where Buried
Approximate Location of Hollow Stem Auger Boring by
LGC Geotechnical, With Total Depth in Feet
Approximate Location of Hand Auger Boring by
LGC Geotechnical, With Total Depth in Feet
Geotechnical Cross-Section Alignment
Approximate Limits of This Report
Qe
HS-1
T.D. = 51'
HA-1
T.D. = 10'
B B'
FIGURE 2
Geotechnical Map ENG. / GEOL.
PROJECT NO.
PROJECT NAME
SCALE
DATE
1" = 10'
December 2020
6806 West Oceanfront Avenue
KMS/KAD
20210-01LGC Geotechnical, Inc.
131 Calle Iglesia, Ste. 200
San Clemente, CA 92672
TEL (949) 369-6141 FAX (949) 369-6142
0
L J
1u =10'
great
room
_casual dining
~
·'
-:1 ,;., I .. ' 11,=il' _ = L._j~ I ----=----1 _-----
dining area
~
PA2021-024
B B'Elevation(Feet Above MSL)Horizontal Distance (Feet)
Existing Residential Footprint
Qe
A A'Elevation(Feet Above MSL)Horizontal Distance (Feet)
Qe
Existing Residential Footprint
Proposed Residential Footprint
Approx.
Existing
Profile
T.D.=10ft
HA-1
T.D.=51ft
HS-1
Proposed Residential Footprint
PL PL
PL
Approx.
Existing
Profile
FIGURE 3
Geologic Cross Sections
A-A' & B-B'
ENG. / GEOL.
PROJECT NO.
PROJECT NAME
SCALE
DATE
1" = 10'
December 2020
6806 West Oceanfront Avenue
KMS/KAD
20210-01LGC Geotechnical, Inc.
131 Calle Iglesia, Ste. 200
San Clemente, CA 92672
TEL (949) 369-6141 FAX (949) 369-6142
30 30 30 30
I I
I I
I
I I
I I
20 I I I 20 20 I I 20 I I ' I I
f I I I I ' I I
10 10 10 10
,.. I I -----
0 0 0 0
-10 -10 -10 -10
0 10 20 30 40 0 10 20 30 40 50 60 70 80
SCALE: 1 "=10'
1 o· 0 1 o· 20'
I
I
--LGC 9 Geotechn;cal, Inc.
PA2021-024
EXTENT OF FREE DRAINING SAND BACKFILL, MINIMUM
HEEL WIDTH OR H/2 WHICH EVER IS GREATER
NATIVE BACKFILL COMPACTED
TO MINIMUM 90% RELATIVE
COMPACTION PER ASTM1557-D
12" MINIMUM
18"MAXIMUM
WATER PROOFING PER DESIGN ENGINEER_....,....,..........,....,...~,....,....---,---,.,,,..,.....,.-··....,,.,.._.--~:·.,_·:~··",-·-·'--'.-·--,....-.,.,.· -----~......-t,,"i
SAND BACKFILL :::: <::-.:·;'.).:·/.·i.::_·_,::;\·:,'.\-~:'.·::-_
~~:;;::~;~;~~-~-~Ns-~-~T-~-~~-o-
0
T....,,FF,,,,.:.....,.:..':,:--:,-.,,,:.,....'.::"":I·!:f }:}?\lII'.I{}\:;
3/4 INCH CRUSHED ROCK WRAPPED IN
MIRAFI 140N OR APPROVED EQUIVALENT
4 INCH DIAMETER, SCHEDULE 40 PERFORATED
PVC PIPE TO FLOW TO DRAINAGE DEVICE
PER PROJECT CIVIL ENGINEER
FOOTING/WALL PER DESIGN ENGINEER -----+·-· -~ . . '4 '
,4
. 4. 4 . · .. <14
'1-11-- - -
-1 I ll 11111111111111111 I I I I I ~· 4
''1==111 Ill II A_ ,,,_,,
NOTE:
::c
i-: ::c (!)
iii ::c
...J i
PLACEMENT OF SUBDRAIN
PROJECT NAME
GC FIGURE4 PROJECT NO.
Retaining Wall ENG.IGEOL
Backfill Detail SCALE
DATE
AT BASE OF WALL WILL NOT
PREVENT SATURATION OF SOILS
BELOW AND / OR IN FRONT OF WALL
6806 West Oceanfront Avenue
20210-01
KMSIKAD
Not to Scale
December 2020
PA2021-024
PL
Minimum Embedment 6 Feet BelowProposed Removal BottomApproximately 3 FeetBelow Adjacent Grade MaxHeavy-gauge, 2 Inch Diameter, Metal Post
Spaced Maximum 2 Feet Center to Center
Trench Plates or 1.5-inch-thick Plywood Sheets to be
Forced Between the Metal Post and Site Property Line
Voids Behind Trench Plates/Plywood Sheets
to be Filled with Two-sack Cement Slurry
Existing
Grade
Removal
Bottom
FIGURE 5
Shoring Detail
DATE
ENG. / GEOL.
PROJECT NO.
PROJECT NAME
SCALE
December 2020
KMS/KAD
Not to Scale
6806 West Oceanfront Avenue
20210-01
I
l
Geotechnical, Inc.
PA2021-024
Appendix A
References
PA2021-024
Project No. 20210‐01 A‐1 December 18, 2020
APPENDIX A
References
American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other
Structures, ASCE/SEI 7-16, 2017.
________, 2018, Standard 7-16, Minimum Design Loads for Buildings and Associated Criteria for
Buildings and Other Structures, Supplement 1, effective: December 12, 2018
Bray, J.D., and Sancio, R. B., 2006, Assessment of Liquefaction Susceptibility of Fine-Grained Soils, Journal
of Geotechnical and Geoenvironmental Engineering, ASCE, pp. 1165-1177, dated September
2006.
California Building Standards Commission, 2019, California Building Code, California Code of
Regulations Title 24, Volumes 1 and 2, dated July 2019.
Caltrans, 2018, Corrosion Guidelines, Version 3.0, dated March 2018.
California Department of Conservation, Division of Mines and Geology, 1998, State of California Seismic
Hazard Zones, Newport Beach Quadrangle, Official Map, Released April 15, 1998.
________, 2000, Digital Images of Official Maps of Alquist-Priolo Earthquake Fault Zones of California,
Southern Region, CDMG CD 2000-03.
________, 2001, Seismic Hazard Zone Report for The Anaheim and Newport Beach 7.5-Minute
Quadrangles, Orange County, California.
________, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California, CDMG Special
Publication 117A.
Greenbook Committee of Public Works Standards, 2015, Standard Specifications for Public Works
Construction, “Greenbook”.
NCEER, 1997, “Proceeding of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils”, T.
L. Youd and I. M. Idriss Editors, Technical Report NCEER-97-0022, NCEER, Buffalo, NY.
SCEC, 1999, Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines
for Analyzing and Mitigating Liquefaction in California, dated March 1999.
Structural Engineers Association of California (SEAOC), 2019, OSHPD Seismic Design Maps, Retrieved
December 3, 2019, from: https://seismicmaps.org/
Tokimatsu, K., and Seed, H. B., 1987, “Evaluation of Settlements in Sands Due to Earthquake Shaking”,
Journal of Geotechnical Engineering, ASCE, Vol. 113, No. 8, pp. 861-878.
United States Geological Survey (USGS), 2004, Preliminary Digital Geologic Map of the Santa Ana 30’x
60’ Quadrangle, Southern California, Version 2.0, Open File Report 99-172, Prepared in
PA2021-024
Appendix A (Cont’d)
References
Project No. 20210‐01 A‐2 December 18, 2020
Cooperation with the California Geological Survey; Compiled by D.M. Morton.
, 2008, Unified Hazard Tool, Dynamic: Conterminous U.S. 2008 (v3.3.1), Retrieved November 10,
2020, from: https://earthquake.usgs.gov/hazards/interactive/
Wire Reinforcement Institute, Inc., 1996, Design of Slab-On-Ground Foundations (August 1981),
Update March 1996.
PA2021-024
Appendix B
Boring Log
PA2021-024
THIS SUMMARY APPLIES ONLY AT THE LOCATION
OF THIS BORING AND AT THE TIME OF DRILLING.
SUBSURFACE CONDITIONS MAY DIFFER AT OTHER
LOCATIONS AND MAY CHANGE AT THIS LOCATION
WITH THE PASSAGE OF TIME. THE DATA
PRESENTED IS A SIMPLIFICATION OF THE ACTUAL
CONDITIONS ENCOUNTERED. THE DESCRIPTIONS
PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS
AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS.
CN CONSOLIDATION
CR CORROSION
AL ATTERBERG LIMITS
CO COLLAPSE/SWELL
RV R-VALUE
-#200 % PASSING # 200 SIEVE
DIRECT SHEAR
MAXIMUM DENSITY
SIEVE ANALYSIS
SIEVE AND HYDROMETER
EXPANSION INDEX
TEST TYPES:
DS
MD
SA
S&H
EI
SAMPLE TYPES:
B BULK SAMPLE
R RING SAMPLE (CA Modified Sampler)
G GRAB SAMPLE
SPT STANDARD PENETRATION
TEST SAMPLE
GROUNDWATER TABLE Type of TestDESCRIPTIONUSCS SymbolMoisture (%)Dry Density (pcf)Blow CountSample NumberGraphic LogDepth (ft)Elevation (ft)Hole Diameter:
Hole Location: See Geotechnical Map
Drop:
Type of Rig:
Project Number:
Elevation of Top of Hole:Drive Weight:
Drilling Company:
Project Name:
Date:
Geotechnical Boring Log Borehole HA-1
Logged By ARN
Checked By KAD
Quaternary Eolian Deposits (Qe)
@0' - SAND: light brown to gray, dry
@8" - SAND: light brown, slightly moist
@3' - SAND: light brown, slightly moist, medium to
coarse grained sand, occasionally composed of shells
@4' - very coarse SAND interbeds
@8' - Minor to Moderate Caving
@10' - Continuous caving. End Boring
Total Depth = 10'
Groundwater Encountered at 8' Below Existing Ground Surface
Backfilled with Cuttings on 10/20/2020
Last Edited: 10/15/2019SP
10/20/2020
~13' MSL
3"
Hand Auger
N/A
N/A
LGC Geotechnical
6806 West Ocean Front Ave
20210-01
Page 1 of 1
GB-3
GB-2
GB-1
R-1
R-2
N/A
N/A
CR
SA2.8
1.7
3.5
22.4
26.0
30
25
20
15
10
5
0
10
5
0
-5
-10
-15
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-r-
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-r-
-r-
- -r-
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-r-
-r-
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-r-
-r-
-r-
-r-
- -r-
-r-
-r-
--LGC 19 Geotechnical, Inc. ~
PA2021-024
THIS SUMMARY APPLIES ONLY AT THE LOCATION
OF THIS BORING AND AT THE TIME OF DRILLING.
SUBSURFACE CONDITIONS MAY DIFFER AT OTHER
LOCATIONS AND MAY CHANGE AT THIS LOCATION
WITH THE PASSAGE OF TIME. THE DATA
PRESENTED IS A SIMPLIFICATION OF THE ACTUAL
CONDITIONS ENCOUNTERED. THE DESCRIPTIONS
PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS
AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS.
CN CONSOLIDATION
CR CORROSION
AL ATTERBERG LIMITS
CO COLLAPSE/SWELL
RV R-VALUE
-#200 % PASSING # 200 SIEVE
DIRECT SHEAR
MAXIMUM DENSITY
SIEVE ANALYSIS
SIEVE AND HYDROMETER
EXPANSION INDEX
TEST TYPES:
DS
MD
SA
S&H
EI
SAMPLE TYPES:
B BULK SAMPLE
R RING SAMPLE (CA Modified Sampler)
G GRAB SAMPLE
SPT STANDARD PENETRATION
TEST SAMPLE
GROUNDWATER TABLE
30
25
20
15
10
5
0 Type of TestDESCRIPTIONUSCS SymbolMoisture (%)Dry Density (pcf)Blow CountSample NumberGraphic LogDepth (ft)Elevation (ft)Hole Diameter:
Hole Location: See Geotechnical Map
Drop:
Type of Rig:
Project Number:
Elevation of Top of Hole:Drive Weight:
Drilling Company:
Project Name:
Date:
10
5
0
-5
-10
-15
Geotechnical Boring Log Borehole HS-1
11/20/2020
~13' MSL
8"
GeoProbe Limited Access Rig
30"
140 pounds
2R Drilling
20210-01
Logged By ARN
Checked By KAD
Page 1 of 2
@0' - 4 inches of concrete over native
SPT-1 12
2
SP @2.5' - SAND: light yellow brown, loose; scattered shell
fragments
MD,
EI
R-1 55
8
94.5 2.6 SP @5' - SAND: light yellow brown, medium dense, dry
SPT-2 23
4
SP @7.5' - SAND: light brown, slightly moist; loose; sampler
tip is wet
R-2 25
14
SP @10' - no recovery; medium dense
SPT-3 SW
@15' - drillers began adding bentonite slurry to stabilize
boring
-#200
R-3 50/6"SP @20' - no recovery; very dense
SPT-4 1214
22
SP @25' - SAND: gray, wet, very dense; scattered shell
fragments; coarse-grained sandB-1Last Edited: 12/14/20206806 West Ocean Front Ave
Quaternary Eolian Deposits (Qe)
919
19
@15' - SAND: light brown, wet, very dense;
coarse-grained sand; dense
DS
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PA2021-024
60
TEST TYPES:
DS
MD
SA
S&H
EI
DIRECT SHEAR
MAXIMUM DENSITY
SIEVE ANALYSIS
SIEVE AND HYDROMETER
EXPANSION INDEX
55
50
45
40
35Elevation (ft)Depth (ft)Graphic LogSample NumberBlow CountDry Density (pcf)Moisture (%)USCS SymbolDESCRIPTION Type of TestDate:
Project Name:
Project Number:
Elevation of Top of Hole:
Hole Location: See Geotechnical Map
Drilling Company:
Type of Rig:
Drop:
Drive Weight:
Hole Diameter:
30
CN CONSOLIDATION
CR CORROSION
AL ATTERBERG LIMITS
CO COLLAPSE/SWELL
RV R-VALUE
-#200 % PASSING # 200 SIEVE
THIS SUMMARY APPLIES ONLY AT THE LOCATION
OF THIS BORING AND AT THE TIME OF DRILLING.
SUBSURFACE CONDITIONS MAY DIFFER AT OTHER
LOCATIONS AND MAY CHANGE AT THIS LOCATION
WITH THE PASSAGE OF TIME. THE DATA
PRESENTED IS A SIMPLIFICATION OF THE ACTUAL
CONDITIONS ENCOUNTERED. THE DESCRIPTIONS
PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS
AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS.
SAMPLE TYPES:
B BULK SAMPLE
R RING SAMPLE (CA Modified Sampler)
G GRAB SAMPLE
SPT STANDARD PENETRATION
TEST SAMPLE
GROUNDWATER TABLE
-20
-25
-30
-35
-40
-45
Geotechnical Boring Log Borehole HS-1
11/20/2020
~13' MSL
8"
GeoProbe Limited Access Rig
30"
140 pounds
2R Drilling
20210-01
Logged By ARN
Checked By KAD
Page 2 of 2
SPT-5 5
1133 SP @30' - SAND: gray, wet, very dense
SPT-6 14
15
SP @35' - SAND: dark gray, wet, very dense -#200
SPT-7 17
18
35
SP @40' - SAND: dark gray, wet, very dense
SPT-8 9
40
32
SP @45' - SAND: dark gray, wet, very dense; coarse
grained sand
SPT-9 2850/6"SP @50' - SAND: dark gray, wet, very dense -#200
Total Depth = 51'
Groundwater Encountered at Approximately 10' Below
Existing Ground Surface
Backfilled with Bentonite Grout and Capped with
5-inches of Concrete on 11/20/2020
6806 West Ocean Front Ave
Quaternary Eolian Deposits (Qe)
5
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PA2021-024
Appendix C
Laboratory Testing Procedures and Test Results
PA2021-024
Project No. 20210‐01 C‐1 December, 2020
APPENDIX C
Laboratory Test Results
The laboratory testing program was directed towards providing quantitative data relating to the relevant engineering properties of the soils. Samples considered representative of site conditions were tested in general accordance with American Society for Testing and Materials (ASTM) procedure and/or California Test Methods (CTM), where applicable. The following summary is a brief outline of the test type and a table summarizing the test results. Moisture and Density Determination Tests: Moisture content (ASTM D2216) and dry density determinations (ASTM D2937) were performed on driven samples obtained from the test borings. The results of these tests are presented in the boring logs. Where applicable, only moisture content was determined from SPT or disturbed samples.
Expansion Index: The expansion potential of selected samples was evaluated by the Expansion Index Test, Standard ASTM D4829. Specimens are molded under a given compactive energy to approximately the optimum moisture content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared 1-inch-thick by 4-inch-diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric equilibrium is reached. The results of these tests are presented in the table below.
Sample
Location
Expansion
Index
Expansion
Potential* HS-1 @ 0-5 feet 0 Very Low
* ASTM D4829 Grain Size Distribution/Fines Content: Representative samples were dried, weighed, and soaked in water until individual soil particles were separated (per ASTM D421) and then washed on a No. 200 sieve (ASTM D1140). Where applicable, the portion retained on the No. 200 sieve was dried and then sieved on a U.S. Standard brass sieve set in accordance with ASTM D6913 (sieve) or ASTM D422 (sieve and hydrometer).
Sample Location Description % Passing #
200 Sieve HS-1 @ 15 ft Light Brown Sand 2 HS-1 @ 35 ft Dark Gray Sand 4 HS-1 @ 50 ft Dark Gray Sand 4
PA2021-024
APPENDIX C (Cont’d)
Laboratory Test Results
Project No. 20210‐01 C‐2 December, 2020
Laboratory Compaction: The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM D1557. The results are presented in the table below.
Sample Location Sample Description
Maximum
Dry Density
(pcf)
Optimum
Moisture
Content (%) HS-1 @ 1-6 ft Light Brown Sand 102.0 8.2 Direct Shear: Direct shear tests were performed on selected driven samples, which were soaked for a minimum of 24 hours prior to testing. The samples were tested under various normal loads using a motor-driven, strain-controlled, direct-shear testing apparatus (ASTM D3080). The plots are provided in this Appendix. Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods (CTM 417). The test results are presented in the table below.
Sample Location Sulfate Content
(ppm)
Sulfate Content
( %) HA-1 @ 3 ft 71 < 0.01 Chloride Content: Chloride content was tested per CTM 422. The results are presented below.
Sample Location Chloride Content (ppm) HA-1 @ 3 ft 41 Minimum Resistivity and pH Tests: Minimum resistivity and pH tests were performed in general accordance with CTM 643 and standard geochemical methods. The results are presented in the table below.
Sample Location pH Minimum Resistivity (ohms‐
cm) HA-1 @ 3 ft 7.2 11800
I I
I I I
PA2021-024
Expansion
Index
Expansion
Classification1
HS-1 B-1 1'-6' 7.1 115.2 20.8 0 Very Low
Location Sample
No.Depth (ft)
Molding
Moisture
Content (%)
Initial Dry
Density (pcf)
Final
Moisture
Content (%)
EXPANSION INDEX
(ASTM D 4829)
Project Number:
Date:
6806 W. Oceanfront
20210-01
Dec-20GC
:1 OT, c:hn l, lnc.
PA2021-024
Percent Passing No. 200 Sieve
6806 W. Oceanfront Tested By :CB
20210-01 Date:11/20/2020
Weight Weight % Passing
Boring/Total Retained Passing No. 200 Sieve
Trench Sample Depth Dry Weight No. 200 Sieve No. 200 Sieve (Fines Content)
No.No.(ft)(grams)(grams)(grams)(%)
A B C = A-B D= (C / A) * 100
HS-1 SPT-3 15' 103.9 102.1 1.8 2%
HS-1 SPT-6 35' 103.6 99 4.6 4%
HS-1 SPT-9 50' 103.8 99.5 4.3 4%
Project Name :
Project Number :
LGC Geotechnical, Inc.
PA2021-024
HS-1 HS-1 B-1 1'-6'102.0 8.5
Optimum
Moisture
Content (%)
Maximum
Dry Density
(pcf)
Sample DescriptionLocation:Sample No.:Depth (ft)
LABORATORY COMPACTION
(ASTM D 1557)
Light brown sand
Project Number:
Date:
6806 W. Oceanfront
20210-01
Nov-20
90
95
100
105
110
115
120
0 5 10 15 20 25 30Dry Density (pcf)Moisture Content (%)
Gs=2.65
Gs=2.75
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PA2021-024
Project Name:Oceanfront Tested By:G. Bathala Date:12/01/20
Project No.:20210-01 Checked By:A. Santos Date:12/08/20
Boring No.: Sample Type:Ring
Sample No.:Depth (ft.):5.0
Soil Identification:
2.415 2.415 2.415
1.000 1.000 1.000
159.78 162.72 163.89
44.93 45.69 45.88
Before Shearing
140.93 140.93 140.93
138.87 138.87 138.87
60.78 60.78 60.78
0.2561 0.0000 0.2351
0.2668 -0.0097 0.2485
After Shearing
185.92 184.84 206.38
162.81 161.69 182.76
57.45 55.75 75.84
2.70 2.70 2.70
62.43 62.43 62.43Water Density(pcf):
Specific Gravity (Assumed):
Weight of Container(gm):
Weight of Dry Sample+Cont.(gm):
Weight of Ring(gm):
Weight of Container(gm):
Weight of Dry Sample+Cont.(gm):
Weight of Wet Sample+Cont.(gm):
Weight of Wet Sample+Cont.(gm):
Vertical Rdg.(in): Final
Vertical Rdg.(in): Initial
DIRECT SHEAR TEST
Consolidated Drained - ASTM D 3080
Sample Thickness(in.):
Weight of Sample + ring(gm):
R-1
HS-1
Light yellowish brown poorly-graded sand (SP)
Sample Diameter(in):
DS HS-1, R-1 @ 5
PA2021-024
Normal Stress (kip/ft²)
Peak Shear Stress (kip/ft²)
Shear Stress @ End of Test (ksf)
Deformation Rate (in./min.)
Initial Sample Height (in.)
Diameter (in.)
Initial Moisture Content (%)
Dry Density (pcf)
Saturation (%)
Soil Height Before Shearing (in.)
Final Moisture Content (%)
95.6
1.000
2.415
2.64
Boring No.
Sample No.
Depth (ft)
HS-1
R-1
5
9.2
0.9903
21.9
Soil Identification:2.64
94.8
2.64
93.1
0.629
0.0050
2.000
1.443
1.283
0.0050
0.500
0.409
0.358
0.0050
1.000
2.415
1.000
2.415
1.000
0.732
8.8
0.9893
21.9
OceanfrontDIRECT SHEAR TEST RESULTS
Consolidated Drained - ASTM D 3080
9.3
0.9866
22.1
12-20
Project No.:20210-01
Sample Type:
Ring
Light yellowish brown poorly-
graded sand (SP)
0.00
0.50
1.00
1.50
2.00
0 0.1 0.2 0.3Shear Stress (ksf)Horizontal Deformation (in.)
0.00
0.50
1.00
1.50
2.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00Shear Stress (ksf)Normal Stress (ksf)
DS HS-1, R-1 @ 5
a
L~
~ ~
B
• ■ ...
0 □ b,.
Leighton
PA2021-024
Tested Samples:
HS-1 @ 5ft
34.0 Degrees 31.0 Degrees
0.05 ksf 0.03 ksf
At 0.30" Displacement:Peak:
DIRECT SHEAR PLOT
Project Number:20210-01
Date:Dec-20
6806 West Oceanfront Avenue
0
1
2
3
0123Shear Stress (ksf)Normal Stress (ksf)
Peak At 0.30" Displacement0
C
echnleal1 Inc.
PA2021-024
Project Name:Oceanfront Tested By :O. Figueroa Date:11/03/20
Project No. :20210-01 Checked By:J. Ward Date:11/10/20
Boring No.HA-1
Sample No.R-1
Sample Depth (ft)3.0
161.20
159.10
59.00
2.10
100.60
200A
4
860
7:00/7:45
45
21.0583
21.0566
0.0017
69.95
71
ml of Extract For Titration (B)30
ml of AgNO3 Soln. Used in Titration (C)0.6
PPM of Chloride (C -0.2) * 100 * 30 / B 40
PPM of Chloride, Dry Wt. Basis 41
7.19
21.5
TESTS for SULFATE CONTENT
CHLORIDE CONTENT and pH of SOILS
SULFATE CONTENT, DOT California Test 417, Part II
Soil Identification:
Dry Weight of Soil + Container (g)
Temperature °C
pH Value
pH TEST, DOT California Test 643
Furnace Temperature (°C)
PPM of Sulfate (A) x 41150
Beaker No.
Crucible No.
Wt. of Crucible + Residue (g)
Duration of Combustion (min)
Weight of Container (g)
Time In / Time Out
Weight of Soaked Soil (g)
Wt. of Residue (g) (A)
Light yellowish
brown SP
CHLORIDE CONTENT, DOT California Test 422
Wt. of Crucible (g)
PPM of Sulfate, Dry Weight Basis
Moisture Content (%)
Wet Weight of Soil + Container (g)
Leighton
PA2021-024
Project Name:Tested By :Date:
Project No. :Checked By: J. Ward Date:
Boring No.:Depth (ft.) :
Sample No. :
Soil Identification:*
*California Test 643 requires soil specimens to consist only of portions of samples passing through the No. 8 US Standard Sieve before
resistivity testing. Therefore, this test method may not be representative for coarser materials.
Wt. of Container (g)17.81 18000
2.10
161.20
Moisture Content (%) (MCi)
Wet Wt. of Soil + Cont. (g)Specimen
No.
1
2
Water
Added (ml)
(Wa)
20
Adjusted
Moisture
Content
(MC)Dry Wt. of Soil + Cont. (g)
18000
1.000
Chloride Content
(ohm-cm)
Moisture Content Sulfate Content
5
Min. Resistivity
DOT CA Test 643DOT CA Test 417 Part II DOT CA Test 422
(%)(ppm)(ppm)
DOT CA Test 643
4
30
40 130.0031300033.51
12000
11800 27.4 71 41 7.19 21.5
SOIL RESISTIVITY TEST
DOT CA TEST 643
Temp. (°C)pH
Soil pH
12000
13000
159.10
59.00
MC =(((1+Mci/100)x(Wa/Wt+1))-1)x100
Oceanfront 11/09/20
11/10/20
3.0
20210-01
HA-1
J. Gonzalez
R-1
Container No.
Initial Soil Wt. (g) (Wt)
Box Constant
Light yellowish brown SP
Resistance
Reading
(ohm)
25.66
Soil
Resistivity
(ohm-cm)
11000
12000
13000
14000
15000
16000
17000
18000
19000
15.0 20.0 25.0 30.0 35.0Soil Resistivity (ohm-cm)Moisture Content (%)
Leighton
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PA2021-024
Appendix D
Liquefaction Analysis Report
PA2021-024
Based on Proceeding of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, Technical Report NCEER-97-0022, December 31, 1997and Evaluation of Settlments in Sand due to Earthquake Shaking, Tokimatsu and Seed, 1987Seismic Event Profile Constants Depth to GWT Project Name6806 W. OceanfrontMoment Magnitude6.8Total Unit Weight (lb/ft3)120 During Investigation (ft) 10Project Number20210-01Peak Ground Acceleration 0.67 gUnit Weight of Water (lbs/ft362.4During Design Event (ft) 3BoringHS- 1Determination of Cyclic Resitance RatioThicknessTotal Stress Pore Pressure Effective Sampler SPT Overburden Energy Borehole Rod Length Sampler TypeDepth (ft) Depth (m) SPT Rings (ft) Stress (psf) Pressure (psf) Stress (psf) DiameterNmCNCECBCRCS(N1)60(N1)60csKCRR7.52.50.842.5420 0 420 1.00 4.00 1.70 1.25 1.00 0.75 1.10 7.017.011.000 0.08051.513 2.5720 0 720 0.62 8.06 1.70 1.25 1.00 0.75 1.00 12.8712.871.000 0.1397.52.372.51020 0 1020 1.00 7.00 1.43 1.25 1.00 0.75 1.10 10.3310.331.000 0.112103.019 2.51320 0 1320 0.62 11.78 1.26 1.25 1.00 0.75 1.00 13.8913.891.000 0.150154.638 51920 312 1608 1.00 38.00 1.14 1.25 1.00 0.85 1.10 50.6150.611.000 SPT >30 NF206.150 52520 624 1896 0.62 31.00 1.05 1.25 1.00 0.95 1.00 38.6338.631.000 SPT >30 NF257.636 53120 936 2184 1.00 36.00 0.98 1.25 1.00 0.95 1.10 45.9845.980.988 SPT >30 NF309.144 53720 1248 2472 1.00 44.00 0.92 1.25 1.00 0.95 1.10 52.8252.820.967 SPT >30 NF3510.729 54320 1560 2760 1.00 29.00 0.87 1.25 1.00 1.00 1.10 34.6834.680.947 SPT >30 NF4012.253 54920 1872 3048 1.00 53.00 0.83 1.25 1.00 1.00 1.10 60.3260.320.929 SPT >30 NF4513.772 55520 2184 3336 1.00 72.00 0.79 1.25 1.00 1.00 1.10 78.3278.320.911 SPT >30 NF5015.250 56120 2496 3624 1.00 50.00 0.76 1.25 1.00 1.00 1.10 52.1852.180.895 SPT >30 NFDetermination of Cyclic Stress RatioLiquefaction-Induced Settlement Analysis10 0.67 13.89Total Stress Pore Pressure Effective Depth (ft) Depth (m) SPT Rings Stress (psf) Pressure (psf) Stress (psf)2.5 0.76 4 2.5 300 0 300 0.99615 0.433176 1.285Above GWT2.5#VALUE! 2.55 1.52 13 2.5 600 124.8 475.2 0.99024 0.543692 1.285 0.33 5.02.100.612.8678 5.07.5 2.29 7 2.5 900 280.8 619.2 0.98456 0.622291 1.285 0.23 7.52.600.810.3283 7.510 3.05 19 2.5 1200 436.8 763.2 0.97914 0.669465 1.285 0.29 10.02.000.613.8898 10.015 4.57 38 5 1800 748.8 1051.2 0.96856 0.721194 1.285Corr. SPT>3015.0#VALUE! 15.020 6.10 50 5 2400 1060.8 1339.2 0.9569 0.74571 1.285Corr. SPT>3020.0#VALUE! 20.025 7.62 36 5 3000 1372.8 1627.2 0.94183 0.755082 1.285Corr. SPT>3025.0#VALUE! 25.030 9.14 44 5 3600 1684.8 1915.2 0.92058 0.752469 1.285Corr. SPT>3030.0#VALUE! 30.035 10.67 29 5 4200 1996.8 2203.2 0.89062 0.738289 1.285Corr. SPT>3035.0#VALUE! 35.040 12.19 53 5 4800 2308.8 2491.2 0.85103 0.713049 1.285Corr. SPT>3040.0#VALUE! 40.045 13.72 72 5 5400 2620.8 2779.2 0.80363 0.679 1.285Corr. SPT>3045.0#VALUE! 45.050 15.24 50 5 6000 2932.8 3067.2 0.75271 0.640293 1.285Corr. SPT>3050.0#VALUE! 50.0Total = 1.38FS DepthVol. Strain (%) SP117 Fig7.11Settlement (in.)Blow CountSampling Data During Investigation Sampling Correction FactorsBlow CountSampling Data During Design EventrdCSRThickness(ft)MSF12/17/2020PA2021-024
Appendix E
General Earthwork and Grading Specifications
PA2021-024
General Earthwork and Grading Specifications for Rough Grading
1.0 General
1.1 Intent
These General Earthwork and Grading Specifications are for the grading and earthwork
shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These
Specifications are a part of the recommendations contained in the geotechnical report(s). In
case of conflict, the specific recommendations in the geotechnical report shall supersede these
more general Specifications. Observations of the earthwork by the project Geotechnical
Consultant during the course of grading may result in new or revised recommendations
that could supersede these specifications or the recommendations in the geotechnical report(s).
1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner shall employ a qualified Geotechnical Consultant
of Record (Geotechnical Consultant). The Geotechnical Consultant shall be responsible for
reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary
geotechnical findings, conclusions, and recommendations prior to the commencement of the
grading.
Prior to commencement of grading, the Geotechnical Consultant shall review the "work
plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to
perform the appropriate level of observation, mapping, and compaction testing.
During the grading and earthwork operations, the Geotechnical Consultant shall observe,
map, and document the subsurface exposures to verify the geotechnical design assumptions. If
the observed conditions are found to be significantly different than the interpreted
assumptions during the design phase, the Geotechnical Consultant shall inform the owner,
recommend appropriate changes in design to accommodate the observed conditions, and
notify the review agency where required.
The Geotechnical Consultant shall observe the moisture-conditioning and processing of the
subgrade and fill materials and perform relative compaction testing of fill to confirm that the
attained level of compaction is being accomplished as specified. The Geotechnical Consultant
shall provide the test results to the owner and the Contractor on a routine and frequent basis.
1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable
in earthwork logistics, preparation and processing of ground to receive fill, moisture-
conditioning and processing of fill, and compacting fill. The Contractor shall review and
accept the plans, geotechnical report(s), and these Specifications prior to commencement of
grading. The Contractor shall be solely responsible for performing the grading in accordance
with the project plans and specifications. The Contractor shall prepare and submit to the
owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork
grading, the number of “equipment” of work and the estimated quantities of daily earthwork
General Earthwork and Grading Specifications for Rough Grading Page 1
PA2021-024
contemplated for the site prior to commencement of grading. The Contractor shall inform
the owner and the
Geotechnical Consultant of changes in work schedules and updates to the work plan at least
24 hours in advance of such changes so that appropriate personnel will be available for
observation and testing. The Contractor shall not assume that the Geotechnical Consultant is
aware of all grading operations.
The Contractor shall have the sole responsibility to provide adequate equipment and methods
to accomplish the earthwork in accordance with the applicable grading codes and agency
ordinances, these Specifications, and the recommendations in the approved geotechnical
report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory
conditions, such as unsuitable soil, improper moisture condition, inadequate compaction,
insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less
than required in these specifications, the Geotechnical Consultant shall reject the work and
may recommend to the owner that construction be stopped until the conditions are rectified. It
is the contractor’s sole responsibility to provide proper fill compaction.
2.0 Preparation of Areas to be Filled
2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently
removed and properly disposed of in a method acceptable to the owner, governing agencies,
and the Geotechnical Consultant.
The Geotechnical Consultant shall evaluate the extent of these removals depending on
specific site conditions. Earth fill material shall not contain more than 1 percent of organic
materials (by volume). Nesting of the organic materials shall not be allowed.
If potentially hazardous materials are encountered, the Contractor shall stop work in the
affected area, and a hazardous material specialist shall be informed immediately for proper
evaluation and handling of these materials prior to continuing to work in that area.
As presently defined by the State of California, most refined petroleum products (gasoline,
diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be
hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the
ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall
not be allowed. The contractor is responsible for all hazardous waste relating to his work. The
Geotechnical Consultant does not have expertise in this area. If hazardous waste is a concern,
then the Client should acquire the services of a qualified environmental assessor.
2.2 Processing
Existing ground that has been declared satisfactory for support of fill by the Geotechnical
Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not
satisfactory shall be over-excavated as specified in the following section. Scarification shall
continue until soils are broken down and free of oversize material and the working surface is
reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction.
General Earthwork and Grading Specifications for Rough Grading Page 2
PA2021-024
2.3 Over-excavation
In addition to removals and over-excavations recommended in the approved geotechnical
report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly
fractured or otherwise unsuitable ground shall be over-excavated to competent ground as
evaluated by the Geotechnical Consultant during grading.
2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units),
the ground shall be stepped or benched. Please see the Standard Details for a graphic
illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet
deep, into competent material as evaluated by the Geotechnical Consultant. Other benches
shall be excavated a minimum height of 4 feet into competent material or as otherwise
recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1
shall also be benched or otherwise over-excavated to provide a flat subgrade for the fill.
2.5 Evaluation/Acceptance of Fill Areas
All areas to receive fill, including removal and processed areas, key bottoms, and benches,
shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the
Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written
acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor
shall provide the survey control for determining elevations of processed areas, keys, and
benches.
3.0 Fill Material
3.1 General
Material to be used as fill shall be essentially free of organic matter and other deleterious
substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils
of poor quality, such as those with unacceptable gradation, high expansion potential, or low
strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other
soils to achieve satisfactory fill material.
3.2 Oversize
Oversize material defined as rock, or other irreducible material with a maximum dimension
greater than 8 inches, shall not be buried or placed in fill unless location, materials, and
placement methods are specifically accepted by the Geotechnical Consultant. Placement
operations shall be such that nesting of oversized material does not occur and such that
oversize material is completely surrounded by compacted or densified fill. Oversize material
shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or
underground construction.
General Earthwork and Grading Specifications for Rough Grading Page 3
PA2021-024
3.3 Import
If importing of fill material is required for grading, proposed import material shall meet the
requirements of the geotechnical consultant. The potential import source shall be given to the
Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its
suitability can be determined and appropriate tests performed.
4.0 Fill Placement and Compaction
4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in
near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical
Consultant may accept thicker layers if testing indicates the grading procedures can
adequately compact the thicker layers. Each layer shall be spread evenly and mixed
thoroughly to attain relative uniformity of material and moisture throughout.
4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a
relatively uniform moisture content at or slightly over optimum. Maximum density and
optimum soil moisture content tests shall be performed in accordance with the American
Society of Testing and Materials (ASTM Test Method D1557).
4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be
uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test
Method D1557). Compaction equipment shall be adequately sized and be either specifically
designed for soil compaction or of proven reliability to efficiently achieve the specified level of
compaction with uniformity.
4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction of slopes shall be
accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in
fill elevation, or by other methods producing satisfactory results acceptable to the
Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to
the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D1557.
4.5 Compaction Testing
Field tests for moisture content and relative compaction of the fill soils shall be performed
by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's
discretion based on field conditions encountered. Compaction test locations will not
necessarily be selected on a random basis. Test locations shall be selected to verify
adequacy of compaction levels in areas that are judged to be prone to inadequate compaction
(such as close to slope faces and at the fill/bedrock benches).
General Earthwork and Grading Specifications for Rough Grading Page 4
PA2021-024
4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of
compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken
on slope faces for each 5,000 square feet of slope face and/or each 10 feet of vertical height
of slope. The Contractor shall assure that fill construction is such that the testing schedule
can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow
down the earthwork construction if these minimum standards are not met.
4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation and horizontal
coordinates of each test location. The Contractor shall coordinate with the project surveyor to
assure that sufficient grade stakes are established so that the Geotechnical Consultant can
determine the test locations with sufficient accuracy. At a minimum, two grade stakes within
a horizontal distance of 100 feet and vertically less than
5 feet apart from potential test locations shall be provided.
5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the
grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional
subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions
encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line
and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for
these surveys.
6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical
Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only.
The actual extent of removal shall be determined by the Geotechnical Consultant based on the field
evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut
portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to
placement of materials for construction of the fill portion of the slope, unless otherwise recommended
by the Geotechnical Consultant.
7.0 Trench Backfills
7.1 The Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench
excavations.
7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable
provisions of Standard Specifications of Public Works Construction. Bedding material shall
have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over
General Earthwork and Grading Specifications for Rough Grading Page 5
PA2021-024
General Earthwork and Grading Specifications for Rough Grading Page 6
the top of the conduit and densified by jetting. Backfill shall be placed and densified to a
minimum of 90 percent of maximum from 1 foot above the top of the conduit to the surface.
7.3 The jetting of the bedding around the conduits shall be observed by the Geotechnical
Consultant.
7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one
test should be made for every 300 feet of trench and 2 feet of fill.
7.5 Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications
of Public Works Construction unless the Contractor can demonstrate to the Geotechnical
Consultant that the fill lift can be compacted to the minimum relative compaction by his
alternative equipment and method.
PA2021-024
Fill Slope
,_ fjl..eyr.o" . ·< ··· · .. ·• . .; , ,,:·
--J -.. ~ .. >;;:/0 ;:~~~?E:~r:·>··:·-Competent Material
_ ______.. ' ~ater of 2% Slope or 1 oot Tilt Back
•· _:. ! \ • •• :· ••• ~-~... : ••.
2' Min. j . . . . ... , 15' Min. Key Width
Fill-Over-Cut Slope
Natural
4' Typical
8' Typical
Ground~ o"o.\ .............. '--""""""'""""""'"'""'""'..:........'---'--=-'----t--+-4' Typical
Cut Face. .,, :~r~i~iW(;~~: TIit Bac~;d:::: a~:a~yp;cal
15' Min. Key Width
* Construct Cut Slope First
-Cut-Over-Fill Slope .,,,..,.
Natural Ground~ / ~
Overbuild and Trim Back '\_ ~/ / _,,.. _.......,;;::..._-Cut Face
Proposed Grade /'"""':---:'.'C-:,---..fi~---
1:1 Projection to
Competent Material
.<·
/-;·/'·· / ... <.:: .=--<:·
. ·.,'':_~ ... :\~:·!·'"'.
Competent Material
GC
Geotechnical1 Inc.
% Slope or 1 Foot Tilt Back
15' Min. Key Width Note: Natural Slopes Steeper Than 5:1 (H:V)
Must Be Benched.
KEYING AND BENCHING
-
-
PA2021-024
5' Typical Compacted Fill
if Recommended by Soils Engineer
Proposed Grade I-15' Min.
4" Perf. PVC Back ·.:·t.:;>./*:;;:'.f~~-.;··:: ':· .• .. · :\/;::::
4" Solid PVC O ... -~:'~'~/.'-' '~
al
(30' Max.)
4' Typical
.... , ,~· ··•? ;_· ·~: ... : ': ··:·.!·
Competent Material
\ )-:1 (H:V) Back Cut or as
Designed by Soils Engineer
\
Key Dimensions Per Soils Engineer \ Greater of 2% Slope
?r 1' Tilt Back
Perf. PVC Pipe \
Perforations Down ----------....
12" Min. Overlap,
Secured Every 6 Feet
\
Sched. 40 Solid PVC Outlet Pipe, (Backfilled --+---',.
and Compacted With Native Materials)
Outlets to be Placed Every 100' (Max.) O.C.
'
Geofabric (Mirafi 140N -------~,...___ ____ __
or Approved Equivalent)
GC
Geotechnical1 Inc.
TYPICAL BUTTRESS
DETAIL
PA2021-024
Proposed Grade
5' Typical Compacted Fill
if Recommended by Soils Engineer
f-15' Min.
,):}:t;}/:{~:;._:·:·
~<:~ ... :, ~-
4" Perf. PVC Back '..:\)\\¢, _;_:\ .. •-::-, .. ·· .. · :>.:
4" Solid PVC O , . ~:•~:~:< .-' (30' Max.)
al
_.,: .. -· ;,·~:.•·J,t•: ~ ,.:•;•
Competent Material
\ , 2:1 (H:V) Back Cut or as
\ , Designed by Soils Engineer
l-15• Min. -l \ '
Key Dimensions Per Soils
Engineer {Typically H/2 or 15' Min) ..._____.._ Greater of 2% Slope
\ or 1 foot Tilt Bae
______ ,
Perf. PVC Pipe \
Perforations Down-----------...
\
12" Min. Overlap,
Secured Every 6 Feet ---+-_,
Sched. 40 Solid PVC Outlet Pipe, (Backfilled
and Compacted With Native Materials) ---+--'},.
Outlets to be Placed Every 100' (Max.) O.C.
GC
Geofabric (Mirafi 140N _______ ....,,......__ ____ _
or Approved Equivalent)
TYPICAL STABILIZATION
FILL DETAIL
Geotechnical1 Inc.
PA2021-024
SUBDRAIN OUTLET MARKER -6" & 8" PIPE
PCV SCHEDULE 40
~-----OR80SUBDRAIN --------~
BAGS FILLED WITH DRY CONCRETE
MIX TO BE PLACED FOR SUPPORT
'-----AND WETTED (2 REQUIRED) __ __,
NO. 4 REINFORCED STEEL 11--------BAR 3'-0" LONG (2 REQUIRED) ----u =t~t:
SECTION A-A'
SUBDRAIN OUTLET MARKER -4" PIPE
B
PCV SCHEDULE 40
OR80SUBDRAIN--------~
-----PCV DRAIN GRATE CAP ----
8" X 8" X 16" STANDARD
CONCRETE BLOCK (LOWER CELL
----BACKFILLED WITH EARTH) ---~--u
NO. 4 REINFORCED STEEL 11-----------BAR 3'-0" LONG ------11
SECTION B-B'
LGC SUBDRAIN OUTLET
MARKER DETAIL
Geotechnical1 Inc.
NOTTO SCALE
PA2021-024
Cut Lot
(Exposing Unsuitable Soils at Design Grade)
Remove Unsuitable
Material
1:1 Projection To
Competent Material
·",<:~~:'.:i~:w;~~~:::,:::~;·:;:,;:;:;;:@::1:~~t~ ~:1i;;::@~is:·t;·::N0~::!?:H}:t :;;:;;•,. · 1 ..
1:1 Projection To Competent Material
Competent Material Overexcavate and Recompact
Note 1: Removal Bottom Should be Graded Note 2: Where Design Cut Lots are
With Minimum 2% Fall Towards Street or Excavated Entirely Into Competent
Other Suitable Area (as Determined by Material, Overexcavation May Still be
Soils Engineer) to Avoid Ponding Below Required for Hard-Rock Conditions or for
Building Materials With Variable Expansion
Characteristics.
Cut /Fill Transition Lot
Proposed Grade
-----_,,,,,,,,,.
-1:1 Projection To ----Competent Material -~:!~0~i~i~~~;jr~tr:filf:Illi~i{~'.i}t::·~:;J§{::f t ;:y·;'.~:"::::~~.:::/·• .. ·· 51 ..
::•: -:·· · .. ·· :·-.. . '· ..... -~ co caeot'oC '. ··: .. · ... : ·-·:, l· :.-•• ; ••• e, .:-:. •. . ' and Recompact
;~;;:;1;:li\°rtmC~::~~~:.r,~ . . ~~ro: ~il~r:;~::~~,2'1 (H:~
GC
Geotechnical1 Inc.
*Deeper if Specified by
Soils Engineer
CUT AND TRANSITION
LOT OVEREXCAVATION
DETAIL
PA2021-024
Natural Ground
Proposed Grade ---------------
Notes:
1) Continuous Runs in Excess of 500'
Shall Use 8" Diameter Pipe.
2) Final 20' of Pipe at Outlet Shall be
Solid and Backfilled with Fine-grained
Material.
12" Min. Overlap, _'\ __ _,,
Secured Every 6 Feet '\
611 Collector Pipe
(Sched.40,Perf.PVC)
3/4" - 1
Proposed Outlet Detail
May be Deeper Dependent
upon Site Conditions
6" Perforated PVC Schedule 40
c:::::;!~;;;;;?~~~0~=J~!!!!~~~-,3/4" -1 1/2" Crushed Rock
20' Min. ---i Min.
611 Solid PVC Pipe
Geofabric (Mirafi 140N
or Approved Equivalent)
Remove Unsuitable
Materials
Geofabric (Mirafi 140N
or Approved Equivalent)
GC CANYON SUBDRAINS
Geotechnical1 Inc.
PA2021-024
PLACE CONCRETE 611
BELOW FINISH GRADE
PLACE CONTINUOUS ROW
OF SAND BAGS AROUND MONUMENT
CONCRETE
BACKFILL-
4'
NO CONSTRUCTION EQUIPMENT WITHIN 25 FEET
OF ANY INSTALLED SETTLEMENT MONUMENTS
CREATE PRECISE LOCATION FOR SURVEY
READING (INDENT OR SMOOTHED TOP)
Geotechnical, Inc.
TYPICAL SURFACE SETTLEMENT
MONUMENT
PA2021-024
COEHESIVE BACKFILL
WITH NEWSPAPER
SPACED 6" APART.
18" MIN.
6" MIN.
CONCRE
TOP VIEW
MINIMUM 30" X 30" X 1/4" STEEL PLATE
1----+--c;TANDARD 3/4" PIPE NIPPLE WELDED TO BOTTOM OF
PLATE.
BOTTOM OF rnEANOITT
30" SQUARE, 1/4" THICK STEEL PLATE
WITH 3/8" ANCHORS WELDED TO EACH
CORNER, SET LEVEL IN 6" OF CONCRETE.
21/2' SQUARE PIT, EXCAVATED
ABOUT 2' BELOW LIMIT OF CLEANOUT
TANDARD 3/4" PIPE NIPPLE WELDED TO BOTTOM OF
PLATE, COVER OPENING WITH DUCT TAPE OR EQUIVALENT
BEFORE BURIAL.
1. SURVEY FOR HORIZONTAL AND VERTICAL LOCATION TO NEAREST .01 INCH
PRIOR TO BACKFILL USING KNOW LOCATIONS THAT WILL REMAIN INTACT DURING THE
DURATION OF THE MONITORING PROGRAM. KNOW POINTS EXPLICITELY NOT ALLOWED ARE
THOSE LOCATED ON FILL OR THAT WILL BE DESTROYED DURING GRADING.
2. IN THE EVENT OF DAMAGE TO SETTLEMENT PLATE DURING GRADING,
CONTRACTOR SHALL IMMEDIATELY NOTIFY THE GEOTECHNICAL
ENGINEER AND SHALL BE RESPONSIBLE FOR RESTORING THE
SETTLEMENT PLATES TO WORKING ORDER.
3. DRILL TO RECOVER AND ATTACH RISER PIPE.
GC
Geotechnical1 Inc.
TYPICAL SETTLEMENT
PLATE AND RISER
PA2021-024
Proposed Grade
Deeper in Areas of
Swimming Pools, Etc.
.. :;~: .. ~· .. ·· .. ·:=· . .:::·:-:-:.,._ .. \, ..
,. :~ .. :.•~ ...... '
Slope Face
w,
nd
row Parallel to SI•::::: or Flooded Approv~ i•'.ir-:\ti~il\;,j\((\;:/i:C}: ;i .
-7-G:;;:ra;;;n;;;u;r.la;;;r::-"Dr;;a;+te~r;;;,;;ar-....:..:..---1-~~~
Excavated Trench
or Dozer V-cut
Note: Oversize Rock is Larger
than 811 in Maximum Dimension.
GC
Geotechnical1 Inc.
_':".,
){·-:·:· ....
. ' t '.'.<t:}¾}{iJJS: ' .
Section A-A'
OVERSIZE ROCK
DISPOSAL DETAIL
PA2021-024