HomeMy WebLinkAboutCDP 00-26; PARCEL 20 EAST SIDE OF JEFFERSON ST; PRELIMINARY GEOTECHNICAL EVALUTATION; 2000-04-26l
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PRELIMINARY GEOTECHNICAL EVALUATION
PARCEL 20, EAST SIDE OF JEFFERSON STRJ;:ET .
CARLSBAD, CALIFORNIA.·
. FOR
·.KARNAK ARCHITECTURE/PLANNiNG
2802 STATE STRE;ET; sUire 6-.
CARLSBAD, CAU~ORNIA 92008
W.O. 286~~A-SC . APRIL 26, :2000
RECEIVED
MAR 1·5 2001
ENGINEERING
.DEPARTMENT .
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Geotechnical • Geologic • Environmental
5741 Palmer Way • Carlsbad, California 92008 • (760) 438-3155 • FAX (760) 931-0915
April 26, 2000
w:o. 2864-A-SC
Karnak Architecture/Planning
2802 State Street, Suite C
Carlsbad, California 92008
Attention: Mr. Robert Richardson
Subject: Preliminary Geotechnical Evaluation, Parcel 20, East Side of Jefferson Street,
Carlsbad, California
Dear Sir:
In accordance with your authorization and request, GeoSoils; Inc. (GSI) has performed a
preliminary geotechnical investigation of the subject property. The purpose of the study
was to evaluate the onsite soils and geologic conditions and their effects on: the proposed
site development from a geotechnical viewpoint.
EXECUTIVE SUMMARY
Based on our review of the available data (Appendix A), field exploration, laboratory
testing, and geologic and engineering analysis, the proposed development appears to be
feasible from a geotechnical Viewpoint, provided the recommendations presented in the
text of this report are properly incorporated into the d~sign and construction of the project.
The most significant elements of this study are summarized below:
•
•
Removals of colluvium and the upper 1 to 2 feet of weathered terrace deposits will
be necessary prior to fill placement. Generally, removals are anticipated to be on
the order of 3 to 4 feet across a majority of the site.
Based on our laboratory analysis and experience in the vicinity, soils with a very low
expansion potential exist onsite. Conventional foundations may be utilized for these
soil conditions. At the time of this report, corrosion testing results hac! not been
received. An addendum report presenting those results will be provided when. lab
testing is complete. '
-i-------Subsurface water is not anticipated to affect srte' developme-nf,-prc)\iicJecfinar-----
recommendations contained in this report are incorporated into final.de~ign and
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construction and that prudent surface and subsurface drainage practice$ are
incorporated into the construction plans. Perched groundwater may be
encountered during grading, or may occur after site development. .
• The seismicity acceleration values provided herein should be considered durirlg th'e
design of the proposed development.
• The geotechnical design parameters provided herein should oe considered during
project planning, design and construction by the project structural engineer ahd/or
architects.
The opportunity to be of service is greatly appreciated. If you have any questions
concerning this report or if we may be of further assistance, please do not hesitate to
contact any of the undersigned.
Respectfully submitted,
j DG/JPF/DWS/mo
. ~] Distribution: (4) Addressee
o GeoSoils, Ine.
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TABLE OF CONTENTS
SCOPE OF SERVICES ................................................... 1
SITE DESCRIPTION ...........................................•....... ;. 1
PROPOSED DEVELOPMENT ................................... , .......... 1
FIELD STUDIES ......................................................... 3
REGIONAL GEOLOGY ................................................. , .. 3
EARTH MATERIALS ........................................................ 3
Colluvium (not mapped) ........................•................... 3
Alluvium (May Symbol -Qal) .................................•..•.... 3
Santiago Formation (Map Symbol.-Ts) .. '.' ........................•.... 4
FAULTING AND REGIONAL SEISMICITY ..................................... 4
Faulting ............................................ -....... -....... 4
Seismicity ........................................................ 6
Seismic Shaking Parameters .......................................•. 6
GROUNDWATER .................................. ' .•....... ' ........... ' .. 7
LIQUEFACTION ......................................................... 7
LABORATORY TESTING .................................................. 8
Classification ...................................................... 8
Moisture-Density Relations .......................................... 8
Laboratory Standard ................................. , ..............• 8
Expansion Potential' .... ' ............................................ 8
Shear Testing ................................... , .................. 9
Corrosivity . . . . . . . . . . . . . .............. '.' . . . . . •. '. . . . . . . . . . . . . . . . . . . . 9
DISCUSSION AND CONCLUSIONS ................................. , ....... 9
General ................................................ : ......... 9
Earth Materials ............. , ...............................•... ,.. 10
Expansion Potential ......................................... -. . . . . . 10
Corrosion/Sulfate Testing ........................................... 10
Subsurface and Surface Water ...................................... to
Regional Seismic Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
EARTHWORK CONSTRUCTION RECOMMENDATIONS .. ; .................... 11
General '" ................................................... " . . 11
Site Preparation ~ ........ ~ '_!"_!,, •• _. -'...!._, -'_, ,'--"_-' __ ,-,-,-, __ ,_-,--, __ '.' • '_'.' ~ __ ._ .• __ • _ .... , •. L~_. ~ ._ " L.',' 1.1 ____ . __ _
. -Removals (Unsuitable Surficial Materials) .............................. 11
Fill Placement ........... , .............................. '.' -. . . . . . . . . 12
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Subdrains ....................................... ' ............. ' .... 12
Slope Considerations and Slope Design .............................. 12
Erosion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Remedial Earthwork -Lot Capping and Cut/Fill Transitions ................ 13
General Guidelines ................................. : .......... 13
FOUNDATION RECOMMENDATIONS ...................................... 14
Preliminary Foundation Design ...................................... 14
Bearing Value ................................................ 1'5
Lateral Pressure ....................................... , ' .. , . . . 15
Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5
Very Low to Low Expansion Potential (Expansion Index 0 to 50) ' ... ' ... ·16
Medium Expansion Potential (Expansion Ingex 51 to 90) ............ 16
CORROSION ............................................................ 17
CONVENTIONAL RETAINING WALL RECOMMENDATIONS ...........•........ 17
General ..................... ',' . : ................................ 17
Restrained Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 18
Cantilevered Walls ........................................ '. . . . . . . . 18
Wall Backfill and Drainage ........................................... 1'9
Retaining Wall Footing Transitions ................................... 23
FLATWORK AND ASSOCIATED IMPROVEMENTS ............................ 23
Tile Flooring ...................................................... 24-
Gutters and Downspouts .............................. : ....... ' ..... 24
Exterior Slabs and Walkways ..............................•......... 24
ADDITIONAL RECOMMENDATIONS/DEVELOPMENT CRITERIA ................ 25
Additional Site Improvements ........................................ 25
Landscape Maintenance and Planting ........•.... ~ .......... , ....... 25
Drainage ......................................... ; .............. 26
Footing Trench Excavation ......................................... 26
Trench Backfill ................................................... 27
PLAN REViEW ............................................•............. 27
LIMITATIONS ..................................... , ..................... 28
Meridian Group
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FIGURES:
Figure 1 -Site Location Map ......................................... 2
Figure 2 -Test Pit Location Map ...................................... 4
Figure 3 -California Fault Map ....... ; ................................ 6
Figure 4 -Schematic of Site Wall Drain Option A ........................ 19
Figure 5 -Schematic of Site Wall Drain Option B ........................ 20
Figure 6 -Schematic of Site Wall Drain Option C ........................ 21
ATTACHMENTS:
Appendix A -References ................................... Rear of Text
Appendix B -Test Pit Logs .................................. Rear of Text:
Appendix C -General Earthwork and Grading Guidelines ......... Rear of Text
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PRELIMINARY GEOTECHNICAL EVALUATION
PARCEL 20, EAST SIDE OF JEFFERSON STREET
CARLSBAD, CALIFORNIA
SCOPE OF SERVICES
The scope of our services has included the following:
1. Review of available soils and geologic data for the site area (Appendix A).
2. Geologic site reconnaissance and geologic mapping.
3. Subsurface exploration consisting of six exploratory test pits,using a rubber-tire
backhoe, for geotechnical logging and sampling (AppencHx 8).
4.
5.
6.
Pertinent laboratory testing of representative soil samples collected during our
subsurface exploration program. .
General areal seismicity and liquefaction evaluation.
Appropriate engineering and geologic analysis of data collected and preparation
of this report .
SITE DESCRIPTION
The site consists of a roughly triangular-shaped parcel, located on the east side of
Jefferson Street in the City of Carlsbad, California (see Figure 1). The parcel is bounded
by residential property on the sou~h, Jefferson Street on the west, and Interstate 5 o~ the
, east. .
The site is currently vacant and undeveloped. The site is flat and a cut slope,
approximately 3 to 10 feet high and at a gradient of approximately 11h: 1 (horizontal to
vertical), descends on the west border toward Jefferson Street. The site elevation is
approximately 70 feet above mean sea level.
PROPOSED DEVELOPMENT
It is our understanding that the proposed development would consist of grading to create
a single-family residential pad. It is also our understanding that the building will be a two-
I story structure, utilizing wood-frame or masonry-block construetioA with slab-on-grade
.: floors. Building loads are assumed to be typical for this type of relatively light construction.
_______ .. _. __ §~~?S~~isposal is anticipated to t{~.imqJh~ I11J,micip~1 ~y_s~em. ___ .. .. __ . ____ . ______ _
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Base
Scale
ap: San Luis Rey Quadrangle, California--San Diego Co., 7.5 Minute
1968 (photo revised 1975), by USGS, 1":2000'
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SITE LOCATI'ON MAP
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FIELD STUDIES
Field studies conducted during our evaluation of the property fbr this study consisted of
geologic reconnaissance, geologic mapping, and excavation of six exploratory backhoe
test pits for evaluation of near-surface soil and geologic materials. The test pits wer~
logged by a geologist from our firm, who collected representative samples from the
excavations for appropriate laboratory testing. The logs of the test pits are presented in
Appendix B. Test pit locations are presented on Figure 2.
REGIONAL GEOLOGY
The site is located in Peninsular Ranges geomorphic province of California. The
Peninsular Ranges are characterized by northwest-trending, steep, elongated ranges and
valleys. The Peninsular Ranges extend north to the base ofthe San Gabriel Mountains and
south into Mexico to Baja California. The province is bounded by the east-west trending
Transverse Ranges geomorphic province to the north and northeast, by the Colorado
Desert geomorphic province to the southeast, and by the Continental Borderlands
geomorphic province to the west. ,In the Peninsular Ranges, sedimentary and volcanic
units discontinuously mantle the crystalline bedrock, alluvial deposits have filled in the
lower valley areas, and young marine sediments are currently being deposited/eroded in
the coastal and beach areas.
EARTH MATERIALS
. Earth materials underlying the site consist of colluvium underlain by the Quaternary-age
terrace deposit,S. These earth materials are described, from youngest to oldest:
Colluvium/Topsoil
Colluvium was encountered in our test pits overlying formational materials. This soil
generally consists of brown, silty sand. These materials were· typically dry to damp, loose,
slightly porous with rootlets. The colluvium ranged in thickness from about 1 to. 2 feet
thick, as encountered in our test pits. These soils are considered .unsuitablefor ~upport
of settlement-sensitive structures in their present state.
Terrace Deposits
The site is underlain by the Quaternary-age terrace deposits, underlying the colluvial
materials on the site. These competent native sediments generally consist of orange
brown, silty sand. These sediments were damp to moist and medium dense tb dense.
Generally, the upper 1 to 2 feet of these deposits are weathered.
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TEST PIT LOCAtiON MAP
Figure 2·
W.O. 2864-A-SC. DATE 4/00 SCALE 1~=100'
LEGEND
~ 6 Approximate location of exploratory test pit
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FAULTING AND REGIONAL SEISMICITY
Faulting
The site is situated in an area of active as well as potentially-active faults. OUf review '
indicates that there are no known active faults crossing the site within the areas proposed
for development (Jennings, 1994), and the site is not within an Earthquake Fault Zone
(Hart and Bryant, 1997). '
There are a number of faults in the southern California area that are considered active and
would have an effect on the site in the form of ground shaking, should they be the source
of an earthquake. These include--but are not limited to--the San Andreas fault, the San
Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the
Newport-Inglewood/Rose Canyon fault zone. The location of these and other major faults
relative to the site are indicated on Fi9We 3. The possibility of ground acceleration, or
shaking at the site may be considered as approximately similar to the southern California
region as a whole.
The following table lists the major faults and fault zones in southern California that could
have a significant effect on the site should they experience significant actiVity .
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Coronado Bank-Agua Blanca 21 (34)
Elsinore 24 (38)
La Nacion 26 (41)
Newport-Inglewood-Offshore 7(12)
Rose Canyon 4 (7)
San Diego Trough-Bahia Sol 31 (49) ,
Seismicity
The acceleration-attenuation relations of Joyner and Boore (1982) and Campbell and
Bozorgnia (1994) have been incorporated into EQFAULT (Slake, 1997). For this study,
peak horizontal ground accelerations anticipated at the site were determined based on the
random mean and mean plus 1 sigma attenuation curves developed by Joyner and Boare
(1982) and Campbell and Bozorgnia (1994). These acceleration-attenuatiori,relatibns have
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SAN FRANCISCO
SITE LOCATION (+):
Latitude -33.1721 N
Longitude -117.3488 W
Lot 20, Jefferson Street
CALIFORNIA
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SCALE
(Miles)
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been incorporated in EQFAULT, a computer program by Thomas F. Blake (199.7), which
performs deterministic seismic hazard analyses using up to 150 digitized California faults
as earthquake sources. The program estimates the closest distance between each fault
and a user-specified file. If a fault is found to be within a user-selected radius, the program
estimates peak horizontal ground acceleration that may occur at the site from the upper
bound ("maximum credible") and IImaximum probablell earthquakes on that fault. Site
acceleration as a percentage of the acceleration of gravity (g) is computed by any of the
14 user-selected acceleration-attenuation relations that are contained in EQFAUL T. Bas~d
on the above, peak horizontal ground accelerations from an upper bound event may be
on the order of 0.51 g to 0.76 g, and a maximum probable event may be on the order of
0.36 g to 0.43 g on the Rose Canyon fault zone, located approximately 4.4 miles from the
subject site.
Seismic Shaking Parameters
Based on the site conditions, Chapter 16 of the Uniform Building Code (International
Conference of Building Officials, 1997) and Peterson and others (1996), the following
seismic parameters are provided.
Seismic zone (per Figure 16-2*) 4
Seismic Zone Factor (per Table 16-1*) 0.40
Soil Profile Type (per Table 16-J*) So
Seismic Coefficient Ca (per Table 1B-Q*) 0.44 N;.,
Seismic Coefficient Cv (per Table 1B-R*) 0.B4 Nv
Near Source Factor NA (per Table 16-S*) 1.0
Near Source Factor Nv (per Table 1B-T*) 1..1
Seismic Source Type (per Table 1B-U*) B
Distance to Seismic Source 4.4 mi.(7.1km)
Upper Bound Earthquake MwB.9
I * Figure and table references from Cha~ter 16 of the Uniform Building Cod.e (1997~. I
GROUNDWATER
Groundwater was not encountered during· our investigation. Subsurface water is not
anticipated to adversely affect site development, provided that the recommendations
contained in this report are incorporated into final design and construction. These
observations reflect site conditions at the time of our investigation and do not preclude
future changes in local groundwater conditions from excessive irrigation, precipitation, or
that were not obvious, at the time of our investigation.
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Perched groundwater conditions along fill/bedrock contacts and along zones of
contrasting permeabilities should not be precluded from occurring in the future due to site
irrigation, poor drainage conditions, or damaged utilities. Should perch~d groundwater
conditions develop, this office could assess the affected area(s) and provide the
appropriate recommendations to mitigate the observed groundwater conditions.
LIQUEFACTION
Seisr:nically-induced liquefaction is a phenomenon in which cyclic stresses, produced by
earthquake-induced ground motion, create excess pore pressures in soils. The soils may
thereby acquire a high degree of mobility, and lead to lateral movement, sliding, sand
boils, consolidation and settlement of loose sediments, and other damaging deformations.
This phenomenon occurs only below the water table; but after liquefaction has d~veloped,
it can propagate upward into overlying, non-saturated soil as excess pore W?lter dissipates.
Typically, liquefaction has a relatively low potential at depths greater than 4S feet and is
virtually unknown below a depth of 60 feet.
Liquefaction susceptibility is related to numerous factors and the folloWing conditions
should be present for liquefaction to occur: 1) sediments must be relatively young in age
and not have developed a large amount of cementation: 2) sediments generally consist
of medium to fine grained relatively cohesion less sands; 3) the sediments must have low
relative density; 4) free groundwater must be present in the sediment; and-S) the site must
experience a seismic event of a sufficient duration and magnitude, to induce straining of
soil particles.
" Inasmuch as two to three of these five conditions do not have the potential to affect the site
and the entire site is underlain by dense formational materials, our evaluation 'indicates that
the potential for liquefaction and associated adverse effects within the site is very low, even
with a future rise in groundwater levels, provided our recommendations are implemented.
FIELD TESTING
The field moisture content and dry unit weight were determined in the test pits using
nuclear densometer ASTM test methods 0-2922 and 0-3017. The dry unit weight was
determined in pounds per cubic foot (pef), and the field moisture content was determined
as a percentage of the dry unit weight. The results of these tests are shOWh on the test pit
logs (Appendix 8) .
K"arnak Architecture/Planning
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LABORATORY TESTING
Laboratory tests were performed on representative samples of representative site earth
materials in order to evaluate their physical characteristics. Test procedures used and
results obtained are presented below.
Classification
Soils were classified visually in accordance with ASTM D-2487. The soil classifications are
shown on the test pit logs, Appendix B.
Laboratory Standard
The maximum density and optimum moisture content was determined for the major soil
type encountered in the borings. The laboratory standard used was ASTM D-1557. The
moisture-qensity relationship obtained for this soil is shown on the following table:
TP-2@2-3' Silty SAND, Orange Brown 127.0 10.5
TP-4@ 1-2' Silty SAND, Brown 127.0 10.5
Expansion Potential
ExpanSion index testing was performed on representative samples of the site materials in
general accordance with Standard 18-2 of the Uniform Building Code (UBC). Results are
presented in the following table.
TP-2@ 2-3' Silty SAND, Orange Brown o ,Very ,L.ow
Corrosivity
Laboratory test results for soluble sulfates, pH, and corrosion to metals 'have not been
received as of the date of this report. Testing will be presented as an addendum upon
receipt of the results. Upon completion of grading, additional testing of soils (including,
import materials) should be considered prior to the construct jon of utilities and
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foundations. Based upon the test results, further evaluation by a qualified corrosion
engineer may be considered.
DISCUSSION AND CONCLUSIONS
General
Based on our field exploration, laboratory testing and geotechnical engineering analysis,
it is our opinion that the subject lots appear suitable for the proposed residential
development from a geotechnical engineering and geologic viewpoint, provided that the
recommendations presented in the following sections are incorporated into the design and
construction phases of site development. The primary geotechnical concerns with respect
to the proposed development on the site are:
•
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Depth to competent bearing material.
Expansion and corrosion potential of site soils.
Subsurface and perched water.
Regional seismic activity.
The recommendations presented herein consider these as well as other aspects of the site.
The engineering analyses performed concerning site preparation and the
recommendations presented herein have been completed using the information provided
and obtained during our field work. In the event that any significant changes are made to
proposed' site development, the conclusions and recommendations contained in this
report shall not be considered valid unless the changes are revieWed and the
recommendations of this report verified or modified in writing by this office. Foundation
design parameters are consi'dered preliminary until the foundation design, layout, and
structural loads are provided to this office for review.
Earth Materials
The colluvial materials on the site are generally dry to damp, loose, and porous. They are
not considered suitable for support of settlement-sensitive structures as, well as associated
improvements. Recommendations for the treatment of these materials are presented in
the earthwork section of this report.
Terrace deposits will be encountered during site earthwork. The upper 1 to 2 feet of these
materials are weathered. Recommendations for the-treatment of the upper weathered 1
to 2 feet are presented in the earthwork section of this report.
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Expansion Potential
Our laboratory test results indicate that soils with a very low expansion potential underlie
the site. This should be considered during project design. Foundation design and
construction recommendations are provided herein for both very low expansion potential
classifications.
Corrosion/Sulfate Testing
Typical samples of the site materials were analyzed for corrosion/sulfate potentiat The
testing included determination of pH, soluble sulfates, and saturated resistivity. At the time
of this report the results were not received. An addendum to this report will be issUed
when results are received.
Subsurface and Surface Water
Subsurface and surface water, as discussed previously, are not anticipated to significantly
affect site development, provided that the recommendations contained in this report are
incorporated into final design and construction and that prudent surface and subsurface
drainage practices are incorporated into the construction plans. Perched groundwater
conditions along fill/bedrock contacts and along zones of contrasting permeabilities,
should not be precluded from occurring in the future due to site irrigati'on, poor drainage
conditions, or damaged utilities. Should perched groundwater conditions develop, this
office could assess the affected area(s) and provide the appropriate recommendations to
mitigate the observed groundwater conditions.
The groundwater conditions observed and opinions generated were those at the time of
our investigation. Conditions may change with the introduction of irrigation, rainfall, or
other factors that were not obvious at the time of our investigation.
Regional Seismic Activity
The seismicity acceleration values provided herein should be considered during the design'
of the proposed development.
EARTHWORK CONSTRUCTION, RECOMMENDATIONS
General
All grading should conform to the guidelines presented in Appendix Chapter A33 oUhe
Uniform Building Code (adopted and current edition), the requirements of the City of
Carlsbad, and the Grading Guidelines presented in this report as Appendix C, except
where specifically superseded in the text of this report. Prior to grading, GSl's
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representative should be present at the preconstruction meeting to provide additional
grading guidelines, if needed, and review the earthwork schedule. Earthwork beyond the
limits of the surficial, remedial overexcavations or those indicated on the grading plan
should be reviewed by the geologist and/or geotechnical consultant prior to and following
these additional removals. -
During earthwork construction all site preparation and tMe general grading procedures of
the contractor should be observed and the fill selectively tested by a representative(s) of .
GSI. If unusual or unexpected conditions are exposed in the field Or if modifications are.
proposed to the rough grade or precise grading plan, they should be reviewed by this
office and if warranted, modified and/or additional recommendations will be offered. All
applicable requirements of local and national construction and general industry safety
orders, the Occupational Safety and Health Act, and the Construction Safety Act should
be met. GSI does not consult in the area of safety engineering. Excavations into the
granular material on this site may be unstable.
Site Preparation
Debris, vegetation, and other deleterious material should be r.emoved from the
improvement(s) area prior to the start of construction.
Removals (Unsuitable Surficial Materials) .
Due to the desiccated and relatively loose, porous, and potentially compressible condition
of the colluvial materials on the site, removals should consist of all colluvial materials
(about 1 to 2 feet) and the upper 1 to 2 feet of weathered terrace deposits to competent
materials within areas proposed for settlement-sensitive improvements. Removals should
be completed below a 1: 1 (horizontal to vertical) projection down and away from the
bottom outside edge of any settlement-sensitive improvement or fill area.
Once these materials are removed, the bottom of the excavations should be observea and
approved by a representative of GSI. The bottom areas approved to receive fill should be
scarified in two perpendicular directions -and moisture conditioned (at or above the soils
optimum moisture content) to a depth of 12 inches and compacted to a minimum 90
percent relative compaction. At that time, the removed existing earth materials may be re-
used as fill, provided the materials are moisture conditioned at or above the soils optimum
moisture and compacted in accordance with the recommendations of this report.
Fill Placement
Subsequent to ground preparation, onsite soils may be placed in thin (6±inch) lifts,
cleaned of vegetation and debris, brought to a least optimum . moisture content, and
compacted to achieve a minimum relative compaction of 90 percent.
Karnak Architecture/Planning
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W.o. 2864-A-SC
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If fill materials are imported to the site, the proposed import fill should be submitted to
GSI, so laboratory testing can be performed to verify that the intended import material is
compatible with onsite material. At least three business days of lead time should be
allowed by builders or contractors for proposed import submittals. This lead time will allow .
for particle size analysis, specific gravity, relative compaction, expansion testing, and
blended import/native characteristics as deemed necessary.
Slope Considerations and Slope Design
All slopes should be designed and constructed in accordance with the minimum
requirements of the County of San Diego, the recommendations in AppendixC, and the
following:
1. Fill slopes should be designed and constructed at a 2:1 (horizontal to vertical)
gradient or flatter, and should not exceed 15 feet in height. Fill slopes should be
properly built and compacted to a minimum relative compaction of 90 pen;:ent
throughout, including the slope surfaces. Guidelines for slope construction are
presented in Appendix C.
2. Cut slopes should be designed at gradients of 2:1 , and should not exceed 15 feet
in height. While stabilization of such slopes is not anticipated,. locally adverse
geologic conqitions (Le., daylighted joints/fractures or severely weathered terrace
deposits) may be encountered which may require remedial grading or laying back
of the slope to an angle flatter than the adverse geologic condition.
3. Lo·cal areas of highly to severely weathered terrace deposits may be present.
4.
Should these materials be exposed in cut slopes, the potential for long term
maintenance or possible surficial slope failure exists. Evaluation of cut slopes
during grading woUld be necessary in order to identify any areas of severely
weathered bedrock or non-cohesive sands. Should any of these materials be
exposed during construction, the soils engineer/geologist,: would assess the
magnitude and extent of the materials and their potential affect ,on long-term
maintenance or possible slope failures. Recommendations would then be made
at the time of the field inspection.
Cut slopes should be mapped by the project engineering geologist during grading
to allow amendments to the recommendations should exposed conditions warrant
alternation of the design or stabilization.
Erosion Control
Onsite soils and bedrock materials have a moderate erosion potential. Use of hay bales,
silt fences, and/or sandbags should be considered, as appropriate during construction.
Temporary grades should be constructed to drain at a mini~um of 1 to 2 percent to a
Karnak Architecture/Planning
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or landscaped swales. Evaluation of cuts during grading will be necessary in order to
identify any areas of loose or non-cohesive materials. Should any significant zones be
encountered during earthwork construction, additional remedial grading may be
recommended; however, only the remedial measures discussed herein are anticipated at
this time.
FOUNDATION RECOMMENDATIONS
In the event that the information concerning the proposed development is not correct or
any changes in the design, location, or loading conditions of the proposed structures are
made, the conclusions and recommendations contained in this report are for the subject
parcel only and shall not be considered valid unless the changes are reviewed and
conclusions of this report are modified or approved in writing by this office.
The information and recommendations presented in this section are considered minimums
and are not meant to supersede design(s) by the project structural engineer or-civil
engineer specializing in structural design. Upon request, GSi could provide additional
consultation regarding soil parameters, as related to foundation design. They are
considered preliminary recommendations for proposed construction, in consideration of
,\!~ our field investigation, laboratory testing, and engineering analysis.
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Preliminary Foundation Design
Our review, field work, and laboratory testing indicates that onsite soils have a very low
expansion potential. Final foundation recommendations should be provided at the
conclusion of grading based on laboratory testing of fill materials exposed at finish grade.
Bearing Value
1. The foundation systems should be designed and constructed in accordance with
guidelines presented in the latest edition of the Uniform Building Code.
2. An allowable bearing value of 1500 pounds per square foot may be used-for design
of continuous footings 12 inches wide and 12 inches deep and for design of
isolated pad footings 24 inches square anc;i 24 inches deep founded entirely into
compacted fill or competent bedrock material and connected by grade beam or tie
beam in ate least one direction. This valqe may be increased by 200 pounds per
square foot for each additional 12 inches in depth to a maximum value of 2500
pounds per square foot.. The above values may be increased by one-third When
considering short duration seismic or wind loadS. No increase, in bearing, for
footing width is recommended.
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W.O. 2864~A:"SC
April 26, 2000
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Lateral Pressure
1.
2.
3.
4.
For lateral sliding resistance, a 0.30 coefficient of friction may be utilized fora
concrete to soil contact when multiplied by the dead load.
Passive earth pressure may be computed as an equivalent fluid having q density of
250 pounds per cubic foot with a maximum earth pressure of 2500 pounds per
square foot. .
When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third .
All footings should maintain a minimum 7 -foot horizontal setback from the base of
the footing to any descending slope. This distance is measured from the footing
face at the bearing elevation. Footings should maintain a minimum horizontal
setback of H/3 (H = slope height) from the base of the footing to the descending
slope face and no less than 7 feet nor need be greater than 40 feet. Footings
adjacent to unlined drainage swales should be deepened to a minimum of 6 inches
below the invert of the adjacent unlined swale. Footings for structures adjacent to
retaining walls should be deepened so as to extend below a 1:1 projection from the
heel of the wall. Alternatively, walls may be designed to accommodqte structural
loads from buildings or appurtenances as described in the retaining wall section of
this report.
Construction
.'} l The following foundation construction recommendations are pre.sented as a minimum
criteria from a soils engineering standpoint. The onsite soils expansion potentials are
.-;~ generally in the Very Low to Low (expansion index 0 to 50).
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. Very Low to Low Expansion Potential (Expansion Index 0 to 50)
1.
2.
Exterior and interior footings should be founded at a minimum depth of 12 inches
for one-story floor loads, and 18 inches below the lowest adjacent ground surface
for two-story floor loads. All footings should be reinforced with two No.4 reinfotc:;ing
bars, one placed near the top and one placed near the bott~m of the footing.
Footing widths should be as indicated in the Uniform Building Code (International
Conference of Building Officials, 1997).
A grade beam, reinforced as above, and at least 12 inches wide shOUld be provided
across large (e.g. doorways) entrances. The base of the grade beam snould be at
the same elevation as the bottom of adjoining footings.
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3. Residential concrete slabs, where moisture condensation is undesirable, should be
underlain with a vapor barrier consisting of a minimum of 6 mil polyvinyl .chloride or
equivalent membrane with all laps sealed. This membrane should be covered with
a minimum of 2 inches of sand to aid in uniform curing of the concrete.
4. Residential concrete slabs should be a minimum of 4 inches thick; and should be
reinforced with NO.3 reinforcing bar at 18 inches on center in both directions, or 6x6
-W1.4 x W1.4 welded wire mesh. All slab reinforcement should be swpported to
'ensure placement near the vertical midpoint of the concrete. "Hookingll the wire
mesh is not considered an acceptable method of positioning the reinforcement.
5.
6.
Residential garage slabs should be reinforced as above and poured separately from
the structural footing~ and quartered with expansion joints or saw cuts. A positive
separation from the footings should be maintained with expansion jornt material to
permit relative movement.
Presaturation is not required for these soil conditions. The moisture content bf the
subgrade soJls should be equal to or greater than optimum moisture content in the
slab areas. Prior to placing visqueen or reinforcement, soil moisture content should
be verified by this office within 72 hours of pouring slabs.
CORROSION
At the time of this report the results were not received. An addendum to this report will be
issued when results are received~ Upon completion of grading, testing of soils for corrosion
to concrete and metals (including import ,materials) should be considered 'prior to the,
construction of utilities and foundations. Alternative methods and ,additional 'comments
may be obtained from a qualified corrosion engineer.
CONVENTIONAL RETAINING WALL RECOMMENDATIONS,
General
The equivalent fluid pressure parameters provide for the use of very low expansive select
granular backfill to be utilized behind the proposed walls. The very low expansive granular
backfill should be provided behind the wall at a 1: 1 (h:v) projection from the beel of the
foundation system. Very low expansive fill is Class 3 aggregate baserock or Class 2
permeable rock. Wall backfilling should be performed with relatiVely light eqUipment within
the same 1:1 projection (Le., hand tampers, walk behind tompactors). Highly expans!ve
soils should not be used to backfill any proposed walls. During construction, materials
should not be stockpiled behind nor in front of walls for a distance of 2H where H is the '
height of the wall. '
Foundation systems for any proposed retaining walls should be designed In accordance
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Foundation systems for any proposed retaining walls should be designed in accordance
with the recommendations presented in the Foundation Design $ection of this report.
Building walls, below grade, should be water-proofed or damp-proofed, d$pending on the
degree of moisture protection desired. All walls should be properly designed .in
accordance with the recommendations presented below.
Some movement of the walls constructed should be anticipateq as soil strength
parameters are mobilized. This movement could cause some cracking depending upon
the materials used to construct the wall. To reduce the potential for wall cracking, walls
should be internally grouted and reinforced with steel. To mitigate this effect, the use of
vertical crack control joints and expansion joints, spaced at 20 feet or less along the walls
should be employed. Vertical expansion control joints should be .infilled with a flexible
grout. Wall footings should be keyed or doweled across vertical expansion joints. Walls
should be internally grouted and reinforced with steel.
Restrained Walls
Any retaihing walls that will be restrained prior to placing and compacting backfill material
or that haVe re-entrant or male corners, should be deSigned for an at-rest equivalent fluid
pressures' (EFP) of 65 pcf, plus any applicable surcharge loading. Expansive soils should
not be used as backfill, only granular (very low expansive) backfill shoul~'be used. For
areas of male or re-entrant corners, the restrained wall design should extend a minimum
distance of twice the height of the wall laterally from the corner.
Building walls below grade or greater than 2 feet in height should be water,-proofed or
damp-proofed, depending on the degree of moisture protection desired. The wall shol:Jld
be drained as indicated in the following section. For'structural footing loads within the 1:1
zone of influence behind wall backfill, refer to the following section.
Cantilevered Walls
These recommendations are for cantilevered retaining walls up t6 10 feet high. Active·
earth pressure may be used for retaining wall design, provided the top of the wall is hot
restrained from minor deflections. An empirical equivalent fluid pressure: appro~ch may
be used to compute the horizontal pressure against the wall'. Appropriate fluid unit wei'ghts
are provided for specific slope gradients of the retained material. These do not include
other superimposed loading conditions su~h as traffic, structures, seismic events,
expansive soils, or adverse geologic conditions.
If traffic is within a distance H behind any wall or a 1:1 projection from the ,heel of the wall
foundation a pressure of 100 psf per foot in the upper 5 feet should be used. Structural
loads from adjacent properties and their influence on site walls should be reviewed by the
structural engineer, if within a 1:1 projection behind any site wall. However, for preliminary .
planning purposes, one third of the footing contact pressure should be added to the wall
----~-----..
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in pounds per square foot below the bearing elevation and for a distance of three times the
footing width along the wall alignment. Alternatively, a deepened footing beyond the 1:1
projection (up from the heel) behind the wall may be utilized.
SURFACE SLOPE OF RETAINED EQUIVALENT FLUID WEIGHT'FOR
MATERIAL (horizontal to vertical) NON-EXPANSIVE SOIL*
I Level** I 38 I 2 to 1 55
*To be increased by traffic, structural surcharge and seismic loading as needed.
**Level walls are those where grades behind the wall are level for a distance of 2H.
Wall Backfill and Drainage
All retaining walls should be provided with an adequate backdrain and outlet system
(a minimum two outlets per wall and no greater than 100 feet apart), to prevent' buildup of
hydrostatic pressures and be designed in accordance with minimum standards presented
herein. See site wall drain options (Figure 4, Figure 5, and Figure 6).. Drain pipe should
consist of 4-inch diameter perforated schedule 40 PVC pipe embedded in gravel. Gravel
used in the backdrain. systems should be a minimum of 3 cubic feet per lineal foot of 3fs-
to 1-inch clean crushed rock wrapped in filter fabric (Mirafi 140 or equivalent) and, 12
inches thick behind the wall. Where the void to be fitted is constrained by lot lines br
property boundaries, the use of panel drains (Mirafi 5000 or equivalent) may be considered
with the approval of the project geotechnical. engineer. The surface of the backfill should
be sealed by pavement or the top 18 inches compacted to 90 percent relative compaction
with native soil. Proper surface drainage should also be provided. Weeping of the walls
in lieu of a backdrain is not recommended for wails greater than 2 feet in height. For walls
2 feet or less in height, weepholes should be no greater thaD 6 feet on center in the· bottom
coarse of block and above the landscape zone.
A paved drainage channel (V-ditch or substitute), either' concrete or asph~ltic concrete,
behind the top of the walls with sloping backfill should be considered to reduce the
potential for surface water penetration. For level backfill, the grade should be sloped such
that drainage is toward a suitable outlet at 1 to 2 percent.
Retaining Wall Footing Transitions
Site walls are anticipated to be founded on footings designed in accordance with the
recommendations in this report. Wall footings may transition from formational bedrock to
select fill. If this condition is present the civil designer may specify either:
~--:~~:-:---:--~:---::--------........... -..... ----..--..... ---=-..... -=. =-=--;..;:;;;;.0;0-=---=--;.;..-...... -...... =. =--~-~--:_:.-:'"'--'::::':~ .. :_'":--::=----_.---_. --
Karnak Architecture/Planning W.O. 2864-A-SC
Parcel 20, J~fferson Street April ~6, 2000
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Waterproofing
Manufactured drainage
Geocomposite drain
( Mira drain 5000 or
equivalent )
Note: Filter fabric wraps completely
around perforated pipe and
behind core material, core
material wraps beneath
bottom af pipe.
4" dia. min. perforated ----..
pipe placed with holes 'k---:~&
down and sloped at 1-2%
to suitable outlet
4" min. granular materiaJ
(closs 2 permeable or
')/8-1" clean crushed
rock wrapped in a
filter fabric)
Cap drain (cut off) I18" below soil line
T
~i---Site retaining wall
(structural design
by others)
Pavement section per
GSI recommendations
Parking lot
surface
..
T
Wall footing
. (designed by others)
SC.H EM A TIC· O·~· -SIT-E--WA·ll-D-RAI-N .. ·-----.---------
OPTION· A .V
GeoSoils W.O. 2864-A-SC Figure 4 .
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Waterproofing -----..
. •• • '. ~'.'!,., .... ',
12" thick (min.) drain rock -----I '" . '.": : ' ... .
(class 2 permeable) or ••.•.. :' ~,": II. "1 ,', ':,: other acceptable granular .• ,' '.: (:'~'.?;
material, 1/8-1" clean :. '~""','.' : •• :. '. . ... " ' ... . crushed rock wrapped in •• ' • .; .. ,'!.: •• ~ .. .
a filter fabric (Mirafi 140 . :;.:.'. :':.:: :.:"','
or equivalent) ::. ::::-~ .> ~:~
I. • • , •• I "," .-,.
4" dia. min. perforated
pipe placed with holes
down and sloped at 1-2%
to a suitable outlet
I,', ': .....• ~. -:-.... I
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" • , ..... '... I
" , • , '0 t"
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':_ I. , _ .,
I '0:
I ~ap' drain (cut ,off,)
--L18' below soil I.ine
T
~-Site retaining wall
(structural design
by others)
Pavement section per
GSI recomendations
Parking lot
surface
~ •. v.'b c::::7"~~O 0 • 0 'l? ' O.OAl\O·('IO,(U·~o·O o~~OI\ IO~ T
T 4"Min. . , -' .. ., ~ ~ t ~ ~~ I, , ... ,~II 40 A :
o
• : .....
'~.. , 0 .. 0 1 0 ... 04
, 4" M'I'n ' . 0, I> I 0 4" M' • • o. • ,. o. In. , _" 1>, 0
1,.0' ,'0.0 • I> I o. '. A. 1,.0 1,.0 •• ' . b.. 0 '1
• l 0 ...l 0 0 .. 0 40 • 0 0' A 0 If!. .'
.. 0 .. 04 f o. ..,p •• 0 I 0
4.Q, , .0 4. ~_o."
W'o.ll footing
(designed loy others)
SCHEMATIC OF SITE
OPTION
WALL
B
DRAIN
GeoSoils w,o~ 2864-A-SC Figure 5.
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drain (cut off)
below soil line
If finished surface is within
8" of top of footing wall drains
shall be at 6' intervals along
the length of the wall and
located at the level of the
bottom course of block. The
drains shall be 4" in diameter.
24" thick (min.) drain rock----....
(class 2 permeable) or
other acceptable granular
material, 1/8-1" clean
crushed rock wrapped in
a filter fabric (Mirafi 140
or equivalent)
Waterproofing ----,.
'2
, ._ • a .. 1/; __ ... ':
, " ".".' I • I·~· ~ . e' '1 ~\ " " . ,', '.' .. ". · ~ ~'.~"J ,', ','4.:. · .,' '.: I:,~'.:r:
• I, .,.'.' , " ,e: ~"t.".":'~:
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, t I,' "/"". • I ,f · ~. ~"." " ~, · " ....... '. . :,' ,,', .. , ......
'. '. : I ~ ,t'" I:.I~ •• -',' ,.' •
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-·0 " ~. '. : ..... . .
.... • I I
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-, -. I. , t °0 , ..
\ I • ..
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• ..' f' I '.
0' 0. I • t '0°, '. . ... __ , '10 . ' '. ,-, ~ '. t: ,:'. I:. I
o 'II' a-
I 'I.. • •
• I ~ ... \ 1_
A-"---Site retaining wall
(structural design
by others)
Pavement section per
GSI recomendalions
4" dia. pipe
Parking· lot
surfbce
........
I I ~ I • I 0 -0 • I' 0 .. 0'" , _'. • I , • I ' h. '1 0 • h. b.; •0 I I 4 0 I ~ 0 I 0 ~
I I I (I 0 I . 0 r 1'0 4 4 • p.'
I , . I 0 I ,. ': I r ~ ° I " pI 0 0 ~ 'i o~ , • ~ I ' b. o. I I ,. o. ~ I "I I ,. (10 0' I • 0
, _ p. "I I 0 0.. 'ool ... 1. .. 0"".. 0 , A. II. ° ,.
b. 0 1 ,'0'.0. ~ "'t ..: ... 04 f 0 ~ ...9' • ~ ~. ' b. ~ A· b. ° b. 0 , "" '" ,.0." b. 0 :
I •
\-lull footing (designed by others)
SCHEMATIC OF .SITE WALL DRAIN
OPTION C
GeoSoils w.o. 2864-A-SC Figure 6.
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a) If transitions from rock fill to select fill transect the wall footing alignment at an angle
of less than 45 degrees (plan view), then the designer should perform a minimum
2-foot overexcavation for a distance of two times the height of the wall and increase
overexcavation until such transition is between 45 and 90 degrees to the wall
alignment.
b) Increase of the amount of reinforcing steel and wall detailing (Le., expansion joints
or crack control joints) such that an angular distortion of 1/360 for a distance of 2H
(where H = wall height in feet) on either side of the transition may be
accommodated. Expansion joints should be sealed with a flexible, non-shrink .
grout.
c)
1.
2.
3.
4.
5.
6.
Embed the footings entirely into a homogeneous fill.
FLATWORK AND ASSOCIATED IMPROVEMENTS
Planters and walls should not be tied to building(s).
Driveways, sidewalks, and patios adjacent to the building(s) should be separated
from the building(s) with thick expansion jOint filler material. In addition, all
sidewalks and driveways should be quartered and poured with expansion joints no
farther apart than 8 feet for 4-inch slabs or 10 feet for 5-inch slabs, respectively. To
improve the performance of the driveway and/or sidewalks constructed on the
expansive soils, consideration should be given to pre-saturation of the soils prior to
placement of driveways and sidewalks to 120 percent of optimum moisture.
Consideration should additionally be given for the areas of the driveways and
sidewalks adjacent to planters, lawns, and other landscape areas to have thickened
edges, such that the edge is 4 to 6 inches thick and at least 6 inches below the
adjacent landscaping zone (section).
Overhang structures should be -structurally designed with continuous footings or·
grade beams tied in at least two direction$. Footings that support ov~rhahg
structures should be embedded a minimum of 24 inches from the lowest adjacent
finished subgrade.
Any masonry landscape walls that are to be constructed throughout the property
should be fully grouted and articulated in segments no more than 20 feet long.
Utilities should be enclosed within q closed vault or designed With flexible
connections to accommodate differential settlement and expansive soil conditions.
Finish grade (Precise Grade Plan) on the lot should provide a minimum of 1 to 2
percent fall to the street. It should be kept in mind that drainage reversals could
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occur if relatively flat yard drainage gradients are not maintained due to landscaping
work, modifications to flatwork, or post-sale homeowner modifications.
Tile Flooring
Till? flooring can crack, reflecting cracks in the concrete slab below the tile .. Therefore, the
designer should consider additional steel reinforcem~nt of concrete slabs on-grade where
tile will be placed. The tile installer should consider installation methods-that reduce
possible cr~cking of the tile such as slipsheets. Slipsheets or a vinyl crack isol~tion
membrane (approved by the Tile Council of America/Ceramic Tile Institute) is
recommended between tile and concrete slabs on grade.
Gutters and Downspouts
, Consideration should be given to the installation of gutters and downspouts to collect Joof
water that may otherwise infiltrate the soils adjacent to the structures .. The downspouts
should be drained away from the foundation and collected in drainage swales or other
approved non-erosive drainage systems designed by a Jegist~red civil engineer
(specializing in drainage) to convey water away from the foundation. Gutters and
downspouts are not a geotechnical requirement, however, provided positive drainage is
maintained in accordance with the recommendations of the design civil engineer.
Exterior Slabs and Walkways
Exterior concrete slab on grade construction should be designed and constructed in
accordance with the following criteria:
1. Driveway pavement and all other exterior flatwork should be a minimum 4 inches
thick. A thickened edge should be considered for all flatwork adjacerit to .irrigated
and landscape ,areas.
2.
3.
Slab subgrade should be scarified, moisture conditioned and compacted to a
minimum 90 percent relative compaction. Subgrade should be moisture
conditioned based on the representative expansion potential of the subgrade
exposed (Le. at or above optimum for low expansive and 1-20 perc~nt for medium
to highly expansive). The subgrade moisture content should b~ maintained Until the
slab is poured.
The use of transverse and longitudinal control joints should be considered to help
control slab cracking due to concrete shrinkage or expansion. Two of the best
ways to control this movement is; 1 ) add a sufficient amount of reinforcing steel,
increasing tensile strength of the slab, and/or 2) provide an adequate amount of
control and/or expansion joints to accommodate anticipated concrete shrinkage
and expansion. We would suggest that the maximum control joint spacing foe un-
"-~ ---<---~ ~--. ~-. -~« -. --.~--.< -
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reinforced slabs be placed on i0-foot centers (4 inch slab)" 13-foot centers (5 inch
slab) or the smallest dimension of the slab, whichever is least.
4. No traffic should be allowed upon the newly poured concrete slabs until they have
been properly cured to within 75 percent of design strength.
5. Positive site drainage should be maintained at all times. 'Adjacent .landscaping
should be graded to drain into the street, parking area, or other approved area., All
surface water should be appropriately directed to areas designed for site drainage.
6. Concrete compression strength should be a minimum of 2,500 psi.
ADDITIONAL RECOMMENDATIONS/DEVELOPMENT CRITERIA
Additional Site Improvements
If in the future, any additional improvements are planned for the site, recommendations
concerning the geological or geotechnical aspects of design and construction of said
improvements could be provided upon request this incluaes but not limited to appurtenant
structures.
This office should be notified in advance of any additional fill placement, regrading of the
site; or trench backfilling after rough grading has been completed. This includes any
grading, utility trench, and retaining wall backfills.
,Landscape Maintenance, and Planting
Water has been shown to weaken the inherent strength of soil, and slope stability is
significantly reduced by overly wet conditions. Positive surface drain~ge away from graded
slopes should be maintained and only the amount of irrigation necessarY to su~tain plant
life should be provided for planted slopes. Over-watering should be avoided. Onsite soil
materials should be maintained in a solid to semis'olid state.
Brushed native and graded slopes (constructed within and utilizing onsite materials) would
be potentially erosive. Eroded debris may be minimized and surficial slope stability
enhanced by establishing and maintaining a suitable vegetation cover soon after
construction. Plants selected for landscaping should be light weight, deep 'rooted types
that require little water and are capable of surviving the prevailing climate. Planting of large
trees with potential for extensive root development should not be placed closer than 1 b
feet from the perimeter of the foundation or the anticipated height of the mature tree,
whichever is greater. It order to minimize erosion on the slope ,face, an erosion control
fabric (i.e. jute matting) should be considered.
Karnak Architecture/Planning
, ".Parcel 20, Jefferson Street
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From a geotechnical standpoint, leaching is not recommended for establishing
landscaping. If the surface soils area processed for the purpose of adding amendments
they should be recompacted to 90 percent minimum relative compaction. Moisture
sensors, embedded into fill slopes, should be considered to reduce the potential of
overwatering from automatic landscape watering ·systems. The use of certain fertilizers
may affect the corrosion characteristics of soil. Review of the type and amount
(pounds per acre) of the fertilizers by a corrosion specialist should be considered.
Recommendations for exterior concrete flatwork design and construction can be provided
upon request. If in the future, any additional improvements are planned for the site,
recommendations concernipg the geological or geotechnical aspects of design and
construction of said improvements could be provided upon request. This office should be
notified in advance of any additional fill placement, regrading of the site, or trench
backfilling after rough grading has been completed. This includes any grading, utility
trench, and retaining wall backfills.
Drainage
Positive site drainage should be maintained at all times. Drainage should -not flow
uncontrolled down any descending slope. Water should be directed away from
foundations and not allowed to pond and/or seep into the ground. Pad drainage should
be directed toward the street or. other approved area. Landscaping shOUld be grad~d to
drain into the street, or other approved area. All surface water should be appropriately
directed to areas designed for site drainage.
Roof gutters and down spout.s are recommended to control roof drainage. Down spouts
should outlet a minimum of 5· feet from proposed structures or tightlined into a subsurface
drainage system. We recommend that any proposed open bottom planters adjacent to
proposed structures be eliminated for a minimum distance of 10 feet. As an alternative,
closed bottom type planters could be utilized. An outlet placed in the bottom of the
planter, ·could be installed to direct drainage away from structures or any exterior concrete
flatwork. Drainage behind top of walls should be accomplished along the length ofthe wall
with a paved channel drainage V-ditch or substitute.
Footing Trench Excavation
All footing trench excavations should be observed and approved by a representative of this
office prior to placing reinforcement. Footing trench spoil and any excess soils generated
from utility trench excavations should be compacted to a minimum relative compaction of
90 percent, if not removed from the site.
Karnak Architecture/Planning
Parcel 20, Jefferson Street
File: e:\wp 7\2800\2864a.pge
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Trench Backfill
All excavations should be observed by one of our representatives and conform to OSHA
and local safety codes. Exterior trenches should not be excavated below a 1: 1 projection
from the bottom of any adjacent foundation system. If excavated, these trenches may
undermine support for the foundation system potentially creating adverse conditions.
1. All utility trench backfill in slopes, structural areas and beneath hardscape features
should be brought to near optimum moisture content and then compacted to obtain
a minimum relative compaction of 90 percent of the laboratory standard.
Observations, probing and,.if deemed necessary, testing should be performed by
a representative of this office to verify compactive efforts of the contractor.
2. Soils generated from utility trench excavations should be compacted to a minimum
of 90 percent (ASTM D-1557) if not removed from the site.
3.
4.
5.
Jetting of backfill is not recommended.
The use of pipe jacking to place utilities is not recommended on this site due to the
presence of gravels and cobbles.
Bottoms of utility trenches should be sloped away from struCtures.
PLAN REVIEW
Final site development and foundation plans should be submitted to this office for review
and comment, as the plans become available, for the purpose of minimizin'g any
misunderstandings between the plans and recommendations presented herein. In
addition, foundation excavations and any additional earthwork construction performed on
the site should be observed and tested by this office. If conditions are found to differ
substantially from those stated, appropriate recommendations would be offered at that
time. '
LIMITATIONS
The materials encountered on the project site and utilized in our laboratorY-study are
believed representative of the area; however, soil and bedrock materials vary in character
between excavations and natural outcrops or conditions exposed dUring site grading,
construction, and our post-grading study. Site conditions may vary due-to seasonal
changes or other factors. GSI assumes no responsibility or liability for work, testing; or
recommendations performed or provided by others.
Karnak Architecture/Planning
Parcel 20, Jefferson Street
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Inasmuch as our study is based upon the site materials observed, selective laboratory
testing and engineering analysis, the conclusion and recommendations are professional
opinions. These opinions have been derived in accordance with current standards of
practice, and no warranty is expressed or implied. Standards of practice are subject to
change with time.
During the field exploration phase of our study, odors .or stained or discolored soils were
not observed onsite or in our test pits or test pit spoils. However, these observations were
made during our preliminary geotechnical study and should in no way be used in lieu of
an environmental assessment. If requested, a proposal for a phase I preliminary
environmental assessment could be provided.
Karnak Architecture/Planning
Parcel 20, Jefferson Street
File: e:\wp7\2800\2864a.pge
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W.O. 2864-A-SC
~. April 26, 2000
Page 27
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APPENDIX A
REFERENCES
Blake, Thomas F., 1998, EQFAULT computer program and users manual for the
deterministic prediction of horizontal accelerations from digitized California faults.
Campbell, KW. and Bozorgnia, Y., 1994, Near-Source attenuation of peak horizqntal
acceleration 'from worldwide accelerograms recorded from 1"957 to 1993:
Proceedings, Fifth U.S. National Conference on Earthquake Engineering, vol. III,
Earthquake Engineering Research Institute, pp. 293-292.
Frankel, Arthur D., Perkins, David M., and Mueller, Charles S., 1996, Pre"liminary and
working versions of draft 1997 seismic shaking maps for the United States showing
peak ground acceleration (PGA) and spectral acceleration response at 0.3 and 1.0-
second site periods for the Design Basis Earthquake (1 ° percent chance of
exceedance in 50 years) for the National Earthquake Hazards Reduction Program
(NEHRP): U.S. Geological Survey, Denver, Colorado.
GeoSoils, Inc., Proprietary in-house information
Greensfelder, R. W., 1974, Maximum credible rock acceleration from earthquakes in
California: California Division of Mines and Geology, Map Sheet 23.
Hart, E.W. and Bryant, W. A., 1997, Fault-rupture hazard zones in California: California
Department of Conservation, Division of Mines and Geology, Special Publication 42.
Housner, G. W., 1970, Strong ground motion in earthquake engineering, Robert Wiegel,
ed., Prentice-Hall.
·International Conference of Building Officials, 1997, Uniform building code: Whittier,
California, vol. 1, 2, and 3. .
Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California
Division of Mines and Geology, Map Sheet No.6, scale 1 :750,000.
Joyner, W.B, and Boore, D.M., 1982a, Estimation of response-spectral values?s functions
. of magnitude, distance and·site conditions, in Johnson, J.A., Campbell, KW., and
Blake, eds., T.F., AEG Short Course, Seismic Hazard Analysis, June 18, 1994.
__ , 1982b, Prediction of earthquake response spectra, in Johnson, J.A.. Campbell,
KW., and Blake, eds., T.F., AEG Short Course, Seismic. Hazard Analysis, June 18,
1994.
Krinitzsky, Ellis L., Gould, J.P., and Edinger, P.H., 1993, Fundamentals of earthquake
resistant construction: John H. Wiley & Sons, Inc., 299 p.
GeoSoils, Inc.
. _ ... 1
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Petersen, Mark D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fault parameters
used by the California Division of Mines and Geology to compile the probabilistic
seismic hazard maps of California.
Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported
in Joyner, W.B., and Boore, D.M., 1988, IIMeasurement, charact~rization, and
prediction of strong ground motionll
, in Ea~hquake Engineering and Soil Dynamics
1/, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American
Society of Civil Engineers Geotechnical Special Publication No. 20,. pp. 43-102.
SoWers and Sowers, 1979, Unified soil classification system (After U. S. Waterway~
Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New
York.
Tan, S.S and Kennedy, M.P., 1996, Geologic maps of the Northwestern part of San Diego
County, California, DMG Open-File Report 96-02.
United States Geological Survey, 1968, San Luis Rey quadrangle, Ccllifornia -San Diego
Co., 7.5 minute series (topographic), photo revised 1975.
Weber, Harold F., 1982, Geologic map of the central-north coastal area of San Diego
County, California, showing recent slope failures and pre-development landslides:
United States Geologic Survey, Open-File Report 82-12.
Karnak Architecture/Planning
File:e:\wp7\2800\2864a.pge
GeoSoils, lne.
Appendix A
Page 2
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LOG OF EXPLORATORY TEST PITS
.,)
W.O.2864-A-SC
Karnak/Jefferson Street
April 18, 2000
:'~,TE5T~:' 't:?(~::}f~~\~::~~:., :1i~:~.:WU!j~~:1:~r )}t§iM·~'[~~~t\. ';:ili~~~C~~;;ti:~~;~5;~~~~ ';~~!¥;EIff:}~r ~m~j~itt2~:::;:~f:~;,;;~~f:;" :" :. " , i'~'PIT '~'. "FO'EPTt-t" y, '," ~'~sGR6up>t,,.~,· .. :£~i\1i;[)EPTH;;it~T:' ¢i'MOISTURE~·~'Vffi:"'DRy';~~)11)" :,\:i!>,<!\;!l:ll"<';i' f'r''"';,:" ',:',:: ',,' DESCRIPTION .r~g~'~':~~?!!i1f: jj~~g~!~~~~ljL'r;~[f(:~~~;;~i.~ ~i~~~6r.~i~i~;~.,J,;.. ....
TP-1 0-1 SM Nuke@ V2
1-5 SM Nuke@2
5 SM Nuke@5
4.5 83.8
7.1 118.0
15.2 106.2
COLLUVIUM: SILTY SAND, brown, dry to damp, loose.
TERRACE DEPOSITS: SILTY SAND, orange brown, damp,
dense; fine to medium grained, well sorted, sub-rounded.
SILTY SAND, orange brown, damp to moist, medium dense.
Total Depth = 5'
No groundwater encountered
PLATE B-1
_ .m c:;,<,:: c:::-,; ... ~ t-_~. ---'
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W.O.2864-A-SC I
Karnak/Jefferson Street
April 18, 2000
LOG OF EXPLORATORY TEST PITS
_·'.f ~ ~: .t~ ~'~" ·~~~!'r}.¥.}~i.'~ 'TEST'" 'I' ,"/<)..,"'" :::/ ' ,;!~!L i~it~,I;'~i~l:,\_, .. , _ , "tPIT:~ d" DEPln'or, I ~(r\;'-.......... , :fl"Nd;~ri: ,h~>iii'(ftr;'i;!.'i;: \1J.F'SyMBO'[;1'" ;i~~:,t::::)'~~ ;i:;:i \~~ ;,j,:';~f~~':fi,: " , , ';",::" ;)}l."
TP-2 0-1 SM
1-7 SM
7-8 SP
Tp..:3 0-2 SM
2-7 SM
Nuke@ 1
Bulk @2-3 ..
Nuke@3
, Nuke@5
Nuke@ 1
Nuke@2
, Nuke@4
4.1
11.3
11.8
4.6
11.6
12.5
107.8
110.6
106.0
95.0
114.0
106,0
'!";'.;'" I' :j'~
COLLUVIUM: SILTY SAND, brown, dry to damp, loose;
roots.
TERRACE DEPOSITS: SILTY SAND, orange brown, moist,
medium dense; fine to medium grained, well sorted, sub-
rounded.
SAND, light brown, damp, medium dense; fine to medium
rained, well sorted, sub-angular grains, cohesionless.
Total Depth:::; 81
No groundwater encountered
COLLUVIUM: SILTY SAND, brown, damp, loose; roots and
rootlets, shells.
TERRACE DEPOSITS: SILTY SAND, orange brown, moist,
dense; fine to medium grained, well sorted, SUb-angular
Total Depth = 71
No groundwater encountered
PLATE 8-2
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LOG OF EXPLORATORY TEST PITS
W.O.2864-A-S.C
Karnak/Jefferson Street
April 18, 2000
:: < .'. • • ~:.' .'~, ~. ~ ,';t~~'ys-j}~\) ;~~ :. ~,;;t;' .~!~~ • ~ ~~I/:;./1..":1~~~ ~'~~.:.~~i:n~{' ~ ~.: . ..:": ;--:-'~. '1~\i' I~~~~';:' ,,::~, :,,~~t( ;:;>;~'~{:~;{~':' '!"~.'~ ;'!>\' .~ .: ','.~ ":';R" '3" '. p':, l~: :'''.: ." . " . . , .TEST" ,;;>~~t{;~f:~}W.~?r}b:J~e' .. i~~?f);~zr~}~"£'.~!: f:~~\i!1~~t., :rt~'~SAMP":E~"~; ~ffl~.f:t'):,~t~·}'~~~~~ifUif,~~;·:; !'t~{:xt~'F:IELDB~~{' ,J,:~t .. ~).:.<~:~<[; ~;:"'''''>:i' <; ~t'.t.:: ';', " ... ", . .' '''(H!::,·>t-''.:~t '~~~lci:;; ;/i{·~,,~\·-:-,0""y"""'r;..;.(~,~;~;. 'i$~.", " .... 1'f~~ f~i.\ '; ... ,· .... !,~!:·~)E~.;·(' ... ;.r'~'i .. ~.,,: ... /..;~;;:'i';'" ·"fr·J~l;..!·3'·l·'· .}':.:' ~ "::,' ... : PIT:;:';:' "::': DEPTH,:J, ,r'i':'GROUP"i::':: ':~('yDEPtH:-'~;t '~{,l'MOISTURE~," ',:;-;:'~' DRY,?"':'~ «'~',' :"',' -'-,' ,", " " DESCRIPTION
,::, ~O:~':;: ",:?)~(~:~trl~:\t :L .. ,~X~,,~?t;~:' ,~!~~~J~/~1:~~?!;; ';;~~f1lfJ~);~1~;t:?~t :S~9:~~~ti¥0~: ;~fi~~~/~\;;:f':': '~:< ':: ,: : ~.::,
TP-4 I 0-2 SM Nuke@% 7.1 95.3 COLLUVIUM: SILTY SAND, brown, dry to damp, loose;
Bulk@ 1-2 shells, roots and rootlets.
2-6 SM Nuke@3 11.1 113.7 TERRACE DEPOSITS: SILTY SAND, orange brown, moist,
Nuke@4 11.4 109.4 dense; fine to medium grained, well sorted, sUb-angular.
Total Depth = 61
No groundwater encountered
I Batokfilled 4-:l8-QQ
TP-5 I 0-2 8M Nuke@ 1 6.0 115.1 COLLUVIUM: SILTY SAND, brown, dry to damp, loose;
shells, roots and rootlets.
2-6 I SM Nuke@3 10.9 111.5 I TERRACE DEPOSITS: SILTY SAND, orange brown, moist,
dense; fine to medium grained, well sorted, sub-angular,
dense with depth .
. Iota I, Depth = 61
No groundwater encountered
Backfilled 4-18-_00
",
PLATE B-3
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LOG OF EXPLORATORY TEST PITS
W.O.2864-A-SC
Karnak/Jefferson Street
. April 18; 2000
,' .. ~ , " ~'.! ;I~~' :;~::~'; " •• \ ,t' ~.~ '~;;-; :":~: T3J ,fi:t ... j" .'t~.\ ;~~>;)~.'.'!~.:~:. I.~J:A.~ t7~ ~\ 'J.~ ~ ~':·~i·' . \'':"' .' :{' ;~r ~.", 'tt.~· , '/'¥j( ,:~< r'~ :.,=:':~~;-~'~~~; .. ;:~ :t}<' r, rt :,'.: .. ~.; '1--; ~.' TEST' !", .. ",~'. "". "'."" ,,""', ,,{;.:' '::'iiiSAMPLE,·~jj:: ,:.,,, , •........... /,.f;· 'i·~!FIELD:.,'tI.;t'<: f."",!,''':'':'' '."' ... '
.:' PIT:'~:: :!.~DEPTHi;" :i~\\G;~~'u~:M~: ~~1~DEPTH~f~;'~ :~~M-di~TU~~·~~t ~N~f:bR'rll~\; ~:~~~:~:7";t.;!<"\;,,.~;:~~ ;-~" DESCRIPTION .; ~~:: i~i)~~~1;;:~,~J,;~~~~'; ~~~~~~ '~:~~~~1.t~~~ ;~~~~WI,?~t~;(::.;:~I;,· "..'
TP-6 0-2 SM Nuke@ 1
2-8 SM Nuke@3
8-9 SP
6.8 103.5
13.3 113.4
COLLUVIUM: SILTY SAND, brown, dry to damp, loose;
shells, roots and rootlets, blocky
TERRACE DEPOSITS: SILTY SAND, orange brown, moist,
dense; fine to mediumll'"i:lined, w~!Lsor!ed, sl.lb-angular.
SANDSTONE, light brown, moi~t, dense; cohesionless.
Total Depth = 9'
No groundwater encountered
Backfill~B.::OO
PLATE 8-4
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GENERAL EARTHWORK AND GRADING GUIDELINES
General
These guidelines present general procedures and requirements for earthwork and grading
as shown on the approved grading plans, including preparation of areas to filled,
placement of fill, installation of subdrains and excavations. The recommendations
contained in the. geotechnical report are part of the earthwork and grading guidelines and
would supersede the provisions contained hereafter in the case of conflict. Evaluations
performed by the conSUltant during the course of grading may resiJlt in new
recommendations which could supersede these guidelines or the recommendations
contained in the geotechnical report. .
The contractor is responsible for the satisfactory completion of all earthwork in-accordance
with provisions of the project plans and specifications. The project soil engineer and
engineering geologist (geotechnical consultant) or their representatives shOUld provide
observation and testing services, and geotechnical consultation during the duration of the
project.
. EARTHWORK OBSERVATIONS AND TESTING
Geotechnical Consultant
Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer
and engineering geologist) should be employed for the purpose of observing earthwork
procedures and testing the fills for conformance with the recommendations of the
geotechnical report, the approved grading plans, and applicable grading codes and
ordinances.
The geotechnical consultant should provide testing and observation so that determination·
may be made that the work is being accomplished as specified. It is the responsibility of
the contractor to assist the consultants and keep. them apprised of anticipated work
schedules and changes, so that they may schedule their personnel: accordingly.
All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be
observed and documented by the project engineering geologist and/or soil engineer prior
to placing and fill. It is the contractors·s responsibility to notify the engineering geologist
and soil engineer when such areas are ready for observation ..
Laboratory and Field Tests
Maximum dry density tests to determine the degree of compaction should b~ performed
in accordance with American Standard Testing Materials test method ASTM designation
0-1557-78. Random field compaction tests should be performed in accordance with test
method ASTM designation 0-1556-82, 0-2937 or 0-2922 and 0-3017, at intervals of
approximately 2 feet of fill height or every 100 cubic yards of,·fill placed. These criteria
GeoSoils, Inc. ......... J
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would vary depending on the soil conditions and the size of the project. The location and
frequency of testing would be at the discretion of the geotechnical consultant.
Contractor's Responsibility
All clearing, site preparation, and earthwork performed on the project should be conducted
by the contractor, with observation by geotechnical consultants and staged approval by
the governing agencies, as applicable. It is the contractor's responsibility to prepare the
ground surface to receive the fill, to the satisfaction of the soil engineer, and to place,
spread, moisture condition, mix and compact the fill in accordance with the
recommendations of the soil engineer. The contractor should also remove all major non-
earth material considered unsatisfactory by the soil engineer.
It is the sole responsibility of the contractor to provide adequate equipment and methods
to accomplish the earthwork in accordance with applicable grading guidelines, codes or
agency ordinances, and approved. gr~ding plans. Sufficient watering-apparatus and
compaction equipment should be provided by the contractor with due consideration for
the fill material, rate of placement, and climatic conditions. If, in the, opinion of the
geotechnical consultant, unsatisfactory conditions such as questionable weather,
excessive oversized rock, or deleterious material, insufficient support equipment, etc., are
resulting in a quality of work that is not acceptable, the consultant wm inform the
contractor, and the contractor is expected to rectify the conditions, and if necessary, stop
work until conditions are satisfactory.
During construction, the contractor shall properly grade all surfaces to maintain good
drainage and prevent ponding of water. The contractor shall take remedial measures to
control surface water and to prevent erosion of graded areas until such time as permanent
drainage and erosion control measures have been installed.
SITE PREPARATION
All major vegetation, including brush, trees, thick ,grasses, organic debris, and other
deleterious material should be removed and disposed of off"site. These removals must be
concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials
determined by the soil engineer or engineering geologist as being unsuitable in-place
should be removed prior to fill placement. Depending upon the soil conditions, these
materials may be reused as compacted fills. Any materials incorporated as part of the
compacted fills should be approved by the soil engineer.
Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic
tanks, wells, pipelines, or other structures not located prior to grading are to be removed
or treated in a manner recommended by the soil engineer. Soft, dry, sp.ongy, highly
fractured, or otherwise unsuitable ground extending to such a depth that surface
processing cannot adequately improve the condition should be overexcavated down to,
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firm ground and approved by the soil engineer before compaction and filling operations
continue. Overexcavated and processed soils which have been properly mixed and
moisture conditioned should be re-compacted to the minimum relative compaction as
specified in these guidelines.
Existing ground which is determined to be satisfactory for support of the fills should be
scarified to a minimum depth of 6 inches or as directed by the soil' engineer. After the
scarified ground is brought to optimum moisture content or greater' and mixed, the
materials should be compacted as specified herein. If the scarified zone is grater that 6,
inches in depth, it may be necessary to remove the excess and place the material in lifts
restricted to about 6 inches in compacted thickness.
Existing ground which is not satisfactory to support compacted fill should be
overexcavated as required in the geotechnical report or by the on-site solis engineer
and/or engineering ge,ologist. Scarification, disc harrowing, or other acceptable form of
mixing should continue until the soils are broken down and free oflarge lumps or clods,
until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or
other uneven features which would inhibit compaction as described previously. -
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to,vertical),
the ground should be stepped or benched. The lowest bench, which will act as a key,
should be a minimum of 15 feet wide' and should be at least 2 feet deep into firm material,
and approved by the soil engineer and/or engineering geologist. In fill over 'cut slope
conditions, the recommended minimum width of the lowest bench or key is also 15 feet
with the key founded on firm material, as designated by the Geotechnical Consultant. As
a general rule, unless specifically recommended otherwise by the Soil Engineer, the
minimum width of fill keys should be approximately equal to % the height of the slope.
Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable
material. Benching may be used to remove unsuitable materials, although it is understood
that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered
for unsuitable materials in excess of 4 feet in thickness. '
All areas to receive fill, including processed areas, removal areas, and the toe of fill
benches should be observed and approved by the soil engineerand/br engineering
geologist prior to placement of fill. Fills may then be properly placed and compactec;i until
design grades (elevations) are attained.
COMPACTED FILLS
Any earth materials imported or excavated on the property may be utilized in the fill
'provided that each material has been determined to be suitable by the soil engineer.
These materials should be free of roots, tree branches, other organic matter or other'
deleterious materials. All unsuitable materials should be removed from the, fill as directed
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by the soil engineer. Soils of poor gradation, undesirable expansion potential, or .
substandard strength characteristics may be designated by the consultant as ·l:Jnsuitable
and may require blending with other soils to serve as a satisfactory fill material. '
Fill materials derived from benching operations should be dispersed throughout the fIJI
area and blended with other bedrock derived material. Benching operations should not
result in the benched material being placed only within a single equipment width away
from the fill/bedrock contact.
Oversized materials defined as rock or other irreducible materials with a maximum
dimension greater than 12 inches should not be buried or placed in fills unless the location
of materials and, disposal methods are specifically approved by the soil engineer.
Oversized material should be taken off-site or placed in accordance with recommendations
of the soil engineer in areas designated as suitable for rock disposal. Oversized material
should not be placed within 10 feet vertically of finish grade (elevation) or within 20 feet
horizontally of slope faces.
To facilitate future trenching, rock should not be placed within the range of foundation
excavations, future utilities, or underground construction unless specifically approved by
the soil engineer and/or the developers repre~entative.
If import material is required for grading, representative samples of the materials to be'
utilized as compacted fill'should be analyzed in the laboratory by the soil engineer to
determine its physical properties. If any material other than that previously tested is
encountered during grading, an appropriate analysis of this material should be conducted
by the soil engineer as soon as possible.
Approved fill material should be placed in areas prepared to receive fill in !lear horizontal
layers that when compacted should not exceed 6 inches in thickness. The soil engineer
may approve thick lifts if testing indicates the grading procedures ar~ such that adequate
compaction is being achieved with lifts of greatert,hickness. Each layer should: be spread
evenly and blended to attain uniformity of material andmoistu~e suitable for compaction ..
Fill layers at a moisture content less than optimum should be watered and miXed, and wet
fill layers should be aerated by scarification or should be blended with drier material.
Moisture condition, blending, and mixing of the fill layer should continue until the fill
materials have a uniform moisture content at or above optimum moisture.
After each layer has been evenly spread, moisture conditioned and mixed,it should be
uniformly compacted to a minimum of 90 percent of maximum density as qetetmined by
ASTM test designation, 0-1557-78, or as otherwise recommended by the soil engineer.
Compaction eqUipment should be adequately sized and should be specifically designed
for soil compaction or of proven reliability to efficiently achieve the Specified degre,e of
compaction.
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Where tests indicate that the density of any layer of fill, or portion thereof, is below the
required relative-compaction, or improper moisture is in evidence, the particular layer or
portion shall be re-worked until the required density and/or moisture content has been
attained. No additional fill shall be placed in an area until the last placed lift of fill has been
tested and found to meet the density and moisture requirements, and is approved by the
soil engineer.
compaction of slopes should be accomplished by over-building a minimum -of 3 feet
horizontally, and subsequently trimming back to the design slope configuration. Testing
shall be performed as the fill is elevated to evaluate compaction as the fill core is being
developed. Special efforts may be necessary to attain the specified compaction in the fill
slope zone. Final slope shaping should be performed by trimming and removing loose
materials with appropriate eqUipment. A final determination of fill slope compaction should
be based on observation and/or testing of the finished slope face. Where compacted fill _
slopes are designed steeper than 2: 1 (horizontal to vertical), specific material types, a
higher minimum relative compaction, and special grading procedures, may be
recommended.
If an alternative to over-building and cutting back the compacted fill slopes is selected,
then special effort should be made to achieve the required compaction in the outer 10 feet
of each lift of fill by undertaking the following:
1.
2.
3.
4.
An extra piece of equipment consisting of a heavy short shan ked sheepsfodt should
be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The -
sheepsfoot roller should also be used to roll perpendicular to the slopes, and
extend out over the slope to provide adequate compaction to the face of the slope.
Loose fill should not be spilled out over the face of the slope as each lift is
compacted. Any loose fill spilled over a previously completed slope face should be
trimmed off or be subject to re-rolling.
Field compaction tests will be made in the outer (horizontal) 2 to 8 feet oflhe slope
at appropriate vertical intervals, subsequent t9 compaction operations:
After completion of the slope, the slope face should be shaped wi~h a small tractor
and then re-rolled with a sheepsfoot to achieve compaction to near the slope face.
Subsequent to testing to verify compaction, the slopes should be -grid-rolled to
achieve compaction to the slope face. Final testing should be used to confirm
compaction after grid rolling.
5. Where testing indicates less than adequate compaction, the contractor will be
responsible to rip, water, mix and re-compact the slope material as necessary to
achieve compaction. Additional testing should be performed to verify compaction.
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6. Erosion control and drainage devices should be designed by the project civil
engineer in compliance with ordinances of the controlling governmental agencies,
and/or in accordance with the recommendation of the soil engineer or engineering
geologist.
SUBDRAIN INSTALLATION
Subdrains should be installed in approved ground in accordance with the approximate
alignment and details indicated by the geotechnical conSUltant. Subdrain locations or
materials should not be changed or modified without approval of the geotechnical
consultant. The soil engineer and/or engineering geologist may recommend and direct
changes in subdrain line, grade and drain materic;ll in the field,pending exposed
conditions. The location of constructed subdrains should be recorded by the project civil
engineer.
EXCAVATIONS
Excavations and cut slopes should be examined during grading by the engineering
geologist. If directed by the engineering geologist, further excavations or overexcavatibn
and re-filling of cut areas should be performed and/or remedial grading, of cut slopes
should be performed. When fill over cut slopes are to be graded, unless'otherwise
approved, the cut portion of the slope should be observed by the engineering geologist
prior to placement of materials for construction of the fill portion of the slope.
The engineering geologist should observe all cut slopes and should be notified by the
contractor when cut slopes are started.
If, during the course of grading, unforeseen adverse or potential adverse geologic
conditions are encountered, the engineering geologist and soil engineer shoulej
investigate, evaluate and make recommendations to treat these problems. The need for
cut slope buttressing or stabilizing should be based on in-grading evaluation by the
engineering geologist, whether anticipated or not. , .
Unless otherwise specified in soil and geological reports, no cut stopes should be
excavated higher or steeper than that allowed by' the ordinances af controlling
governmental agencies. Additiona"y, short-term stability of temporary cut slopes is the
contractors responsibility.
Erosion control and drainage devices should be designed by the project civil engineer and
should be constructed in compliance with the ordinances of the controlling goVernmental
agencies, and/or in accordance with the recommendations of the soil engineer or
engineering geologist. '
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COMPLETION
Observation, testing and consultation by the geotechnical consultant should be conducted
during the grading operations in order to state an opinion that all cut and filled areas are
graded in accordance with the approved project specifications.
After completion of grading and after the soil engineer and engineering geologist have
finished their observations of the work, final reports should be submitted subject to review
by the controlling governmental agencies. No further excavation or filling should -be
undertaken without prior notification of the soil engineer and/or engineering geologist.
All finished cut and fill slopes should be protected from eroSion and/or be planted in
accordance with the project specifications and/or as recommended by a landscape
architect. Such protection and/or planning should be undertaken as soon as practical after
completion of grading.
JOB SAFETY
General
At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is
the company's safety considerations for use by all employees on multi-employer
construction sites. On ground personnel are at highest risk of injury and possible fatality
on grading and construction projects. GSI recognizes that construction activities will vary
on each site and that site safety is the prime responsibility of the contractor; however,
everyone must be safety conscious and responsible at all ,times. To achieve our goal of
avoiding accidents, cooperation between the client, the contractor and GSI persorinel must
be maintained.
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of field personnel on grading
and construction projects:
Safety Meetings: GSI field personnel are directed to attend contractors .regularly
scheduled and documented safety meetings.
Safety Vests:
Safety Flags:
Safety vests are provided for and are to be worn by GSI personnel at
all times when they are working in the field.
Two safety flags are provided to GSI field technicians; one is to be
affixed to the vehicle when on site, the other is to be placed atop the
spoil pile on all test pits.
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Flashing Lights: All vehicles stationary in the grading area shall use rotating or-flashing
amber beacon, or strobe lights, on the vehicle during all field testing.
While operating a vehicle in the grading area, the emergency flasher
on the vehicle shall be activated.
In the event that the contractor's representative observes any of our' personnel not
following the above, we request that it be brought to the attention of our office.
Test Pits Location, Orientation and Clearance
The technician is responsible for selecting test pit locations. A primary concern should be
the technicians's safety. Efforts will be made to coordinate locations with the grading
contractors authorized representative, and to select locations folloWing or behind the
established traffic pattern, preferably outside of current traffic. The comractors authorized
representative (dump man, operator, supervisor, grade checker, etc.) should direct
excavation of the pit and safety during the test period. Of paramount concern should be
the soil technicians safety and obtaining enough tests to represent the fill.
Test pits should be excavated so that the spoil pile is placed away form oncoming traffic,
whenever possible. The technician's vehicle is to be placed next to the test pit, opposite
the spoil pile. This necessitates t8e fill be maintained in a dri\teable condition.
Alternatively, the contractor may wish to park a piece of equipment in front of the test
holes, particularly in small fill areas or those "Yith limited access.
A zone of non-encroachment should be established for all test pits. No grading equipment
should enter this zone during the testing procedure. The zone should extend
approximately 50 feet outward from the center of the test pit. This zone is established for
safety and to avoid excessive ground vibration which typically decreased test results.
When t~king slope tests the technician should park the vehicle directly above or below the
test location. If this is not possible, a prominent flag should be placed at the top of the
slope. The contractor's representative should effectively keep all equipment at a safe
operation distance (e.g. 50 feet) away from the slope during this testing .
The technician is directed to withdraw from the active portion of the fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in
a highly visible location, well away from the equipment traffic pattern.
The contractor should inform our personnel of all changes to haul roads, cut and fill areas
or other factors that may affect site access and site safety.
In the event that the technicians safety is jeopardized or compromised as a result of the
contractors failure to comply with any of the above, the technician is required, by company
policy, to immediately withdraw and notify his/her supervisor. The grading contractors
representative will eventually be contacted in an effort to effect a solution. However, in the
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interim, no further testing will be performed until the situation is rectified. Any fill place can
be considered unacceptable and subject to reprocessing, recompaction or removal.
In the event that the soil technician does not comply with the above, or other established
safety guidelines, we request that the contractor brings this to his/her attention and notify
this office. Effective communication and coordination between the contractors
representative and the soils technician is strongly encouraged in order to implement the
above safety plan.
Trench and Vertical Excavation
It is the contractor's responsibility to provide safe access into trenches where compaction
testing is needed.
Our personnel are directed not to enter any excavation or vertical cut which 1) is 5 feet or
deeper unless shored or laid back, 2) displays any evidence of instability, has any loose
rock or other debris which could fall into the trench, or 3) displays any other evidence of
any unsafe conditions regardless of depth.
All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters,
should be shored or laid back.
Trench access should be provided in accordance with CAL-OSHA and/or state and local
standards. Our personnel are directed not to enter any trench by being lowered or "riding
down" on the equipment.
If the contractor fails to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify his/her supervisor.
The contractors representative will eventually be contacted in an effort to effect a solution.
All backfill not tested ,due to safety concerns or other reasons cOUld, be subject to'
reprocessing and/or removal.
If GSI personnel become aware of anyone working beneath an unsafe trench wall or
vertical excavation, we have a legal obligation to put the contractor and owner/developer
on notice to immediately correct the situation. If corrective steps are not taken, GSI then
has an obligation to notify CAL-OSHA and/or the proper authorities.
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, -Appendix C
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FILL OVER . NATURAL DETAIL
SIOEHILL FILL
COMPACTED FilL
MAINTAIN MINIMUM 15' WIDTH
TOE OF SLOPE AS SHOWN ON GRADING PLAN
PROVIDE A 1:1 MINIMUM PROJECTION FROM
DESIGN TOE OF SLOPE TO TOE OF KEY
AS SHOWN ON AS BUILT
NATURAL SLOPE TO
BE RESTORED WITH
~
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4' MINIMUM
BENCH WIDTH MAY VARY
'1 J =:E.MINIM~M
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NOTE: 1, WHERE THE NAtURAL.,SLOPE APPROACHES OR EXCEEDS THE
'MINIMUM KEY WIDTH DESIGN SLOPE RATIO, SPECIAL RECOMMENDATIONS WOULD BE
2'X 3' MINIMUM KEY DEPTH
2' MINIMUM IN BEDROc,:KOR
APPROVED MATERIAL.
PROVIDED BY THE SOILS ENGINEER~
2. THE NEED FOR AND DISPOSITION OF-DRAINS WO~lD BE DETERMINED
BY THE SOILS ENGINEER BASED UPON EXPOSED,CONOITIONS.
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FILL OVE'R CUT DETAIL
CUT/FILL CONTACT MAINTAIN MINIMUM 15' FILL SECTION FROM
1. AS SHOWN ON GRADING PLAN BACKCUT TO FACE OF FINISH SLOPE ------------------2. AS SHOWN ON AS BUILT
H
ORIGINAL TOPOGRAPHY
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//~\ BEDROCK GR APPROVED MATERIAL
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COMPACTED FILL
15' MINIMUM OR H/2
NOTE: THE CUT PORTION OF THE SLOPE SHOULD BE EXCAVATED AND
EVALUATED BY THE SOILS ENGINEER AND/QR ENGINEERING
GEOLOGIST PRIOR TO CONSTRUCTINO THE FILL PORTION.
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STABILIZATION FILL FOR UNSTABLE MATERIAL
EXPOSED IN PORTION OF CUT .SLOPE
N'ATURAL SLOPE
"
REMOVE: UNSTABLE
REMOVE: UNSTABLE MATEijlAL ~
/
."SS ! !~. v ...... u ADE 'I .1.1 ____ , '-« ,,'hi'''Mb' Y!}
UNWEATHERED BEDROCK
OR APPROVED MATERIAL
MATERIAL "iH --COMPACTED STABILIZATION FILL
. ~AWliw7 --7~' MINIMUM TILTED BACK ."...--A1\-,'\ ~\V\JIN~\:I
I" -~ w D IF RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING =37 GEOLOGIST, THE REMAINING CUT PORTION OF THE SLOPE MAY
t"il ".lb .• "'" ';!1_~, REOUIRE REMOVAL AND REPLACEMENT WITH COMPACTED FILL.
NOTE: 1. SUBDRA1NS ARE NOT REOUI,RED UNU::SS SPEGIFIED· BY SD.lLS ENGINEER AND/OR ENGINEERING GEOLOGIST,
2~. ·W· SHAll:. f3E Eo.UlPMENT WIDTH (15') FOR SLOPE HEIGHTS LESS THAN 25 FEET. FOR SLOPES GREATER'
THAN 25 FEET ·W· $HALLBI; DETERMINED BY THE PilOJECT SOILS ENOINEERANO lOR ENGINEERING
GE,OLOG!ST. AT NO TIME SHALL ·W· BE LESS tHAN H/2.
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SKIN FILL OF NATURAL GROUND
ORIGINAL SLOPE
15' MINIMUM TO BE MAINTAINED FROM
PROPOSED FINISH SLOPE FACE TO BACKCUT
~
3' MINIMUM KEY OEPTH
NOTE: 1. THE. NEED ANO DISPOSITION OF DRAINS WILL BE DETERMINED! BY THE SOILS ENGINEER AND/OR
ENGIN'EERING GEOLOGIST BASED ON FIELD CONDITIONS.
2. PAD OVEREXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED TO BE
NECESSARY BY THE SOILS ENGINEER ANDIOR ENGINEERING GEOLOGIST •
... . .. ...
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DAYLIGHT CUT LOT DETAIL
RECONSTRUCT COMPACTED FILL SLOPE AT 2:1 OR FLATTER
(MAY INCREASE OR DECREASE-PAD AREAL
OVEREXCAVATE AND RECOMPACT --"""\
REPLACEMENT FILL
AVOID AND/OR CLEAN UP SPILLAGE OF
MATERIALS ON THE NATURAL SLOPE
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NOTE: 1 •. SUBDRAIN AND KEY WIDTH REQUIREMENTS WILL BE DETERMINED BASED ON EXPOsEQ SUBSURFACE
CONDITIONS AND THICKN~ss OF OVERBURDEN.
2. PAD OVER EXCAVATION AND RECOMPACTIONsHOULD BE PERFORMED IF DETERMINED NECESSARY BY
THE SOILS ENGINEER AND/OR tHE ENGINEERING GEOLOGIST.
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TEST PIT SAFETY DIAGRAM
SIDE VIEW
( NOT TO SCALE )
/00 FEET
t-
tH LL
o _ 50 FEET ·In SO FEET _ ~--------~~~------~~~~~~------~~~~--------~.
I.'
FLA::t. .
SPOIL I I
P1LE
'-. / ~ FLAG
APPROXIMATE CENTER LL
CF TEST PIT ~
{ NOT TO SCALE }