HomeMy WebLinkAboutCT 81-46; Carlsbad Airport Center Unit 3; Soils Report; 1989-08-22-
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ENGlNEEWNG DEPT. llBR,Qy
city Of Carlsbad 2075 Las Palinas Drive
Carlsbad, CA 92009-4859
SUPPLEMENTAL
QEOTECNNICAL INVESTIGATION
CARLSBAD AIRPORT CENTER, UNIT 3
CARLSBAD, CALIFORNIA
a- t34\p
PREPARED FOR
CENTRE DEVEMPMENT
2111 PAMMAR AIRPORT ROAD
CARLSBAD, CALIFORNIA 92009
PREPARED BY
SAN DIEGO GEOTECHNICAL CONSULTANTS, INC.
9240 TRADE PLACE, SUITE 100
SAN DIEGO, CALIFORNIA 92126
AUGUST 22, 1989
JOB NO. 05-4879-015-00-00
LOG NO. 9-1891
SAN DIEGO GEOTECHNICAL CONSULTANTS, INC
SOIL ENGINEERING 8 ENGINEERING GEOLOGY
August 22, 1989 -
Centre Development - 2111 Palomar Airport Road Carlsbad, California 92009
Attention: Mr. Jerry Morrissey
Job No. 05-4879-015-00-00 Log No. 9-1891
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SUBJECT: SUPPLEMENTAL GEOTECHNICAL INVESTIGATION Carlsbad Airport Center, Unit 3 Carlsbad, California
Gentlemen:
As requested, San Diego Geotechnical Consultants has completed a
supplemental geotechnical investigation for the proposed Unit 3 of
the Carlsbad Airport Center in Carlsbad, California. This report
presents the results of our investigation, as well as our
conclusions and recommendations regardingyourproposed development
of this site.
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In general, the development will be feasible from a geotechnical
standpoint. The major geotechnical constraints will be difficult
excavation of volcanic rock in deeper cuts, the generation of
oversize material from ripping or blasting of volcanic rock, the
removal of compressible alluvium and colluvium in canyons, and the
stability of proposed cut slopes.
We sincerely appreciate this opportunity to serve you. If you have
any questions, please call us at your convenience.
Very truly yours,
SAN DIEGO GEOTECHNICAL CONSULTANTS, INC.
ezaz!! Vice President
AFB/cf
A SUSSlDlARY OF THE IRVINE CONSULTING GROUP, INC.
974” TRADE PLACES S”,TE 100. SAN DIEGO. CA 92,2S.,S,9,53S-,102 . FAX: 16191536-I DOS
TABLE OF CONTENTS
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1.0 INTRODUCTION ................... . . . 1 1.1 Authorisation ................ . . . 1 1.2 Scope of Services .............. . . . 1
2.0 PROPOSED DEVELOPMENT ............... . . . 3
3.0 SITE DESCRIPTION ................. . . . 3
4.0 SITE INVESTIGATION ................ . . . 4 4.1 General ................... . . . 4 4.2 Field Exploration .............. . . . 4 4.3 Laboratory Testing Program ......... . . . 5
5.0 GEOTECRNICAL SETTINQ AND SUBSURFACE CONDITIONS . . 5.1 Regional Geology .............. 5.2 Geologic Units ............... 5.2.1 Santiago Peak Volcanics (Map Symbol Jsp) ......... 5.2.2 Santiago Formation (Map Symbol Tsa) 5.2.3 Terrace Deposits (Map Symbol Qln) . 5.2.4 Alluvium (Map Symbol Qal) ..... 5.2.5 Topsoil [not shown on man) 5.2.6 Artificial Fill (Qaf) ... : : : : 5.3 Groundwater ................. 5.4 Geologic Structure .............
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6.0 SEISMICITY .................... 6.1 Earthquake Effects ............. 6.1.1 Surface Fault Rupture ....... 6.1.2 Earthquake Accelerations ..... 6.1.3 Seismically Induced Slope Failures 6.1.4 Seismically Induced Settlement . . 6.1.5 Liquefaction ........... 6.1.6 Lurching and Shallow Ground Rupture 6.1.7 Tsunamis, Seiches, and Reservoir Failures ........
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7.0 GEOTECRNICAL EVALUATION AND RECONNENDATIONS 7.1 General . . . . . . . . . . . . . . . . 7.2 Grading and Earthwork . . . . . . . . . 7.2.1 General . . . . . . . . . . . 7.2.2 Geotechnical Observation . . 7.2.3 Site Preparation . . . . . . 7.2.4 Rippability . . . . . . . . . 7.2.5 Fill Materials . . . . . . . 7.2.6 Fill Compaction . . . . . . . 7.2.7 Shrinkage and Bulking . . . . .
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16 16 17 17 18 18 19 21 23 23 7.2.8 OVereXCaVatiOn of Volcanic Rock . . . . , 23
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TABLE OP CONTENTS (Continued)
7.2.9 Cut-Fill Transitions ...... . . . . 24 7.2.10 Trench and Wall Backfill .... . . . . 24 7.3 Slope Stability .............. . . . . 25 7.3.1 Bedrock and Soil Characteristics . . . . 25 7.3.2 Cut and Fill Slopes ....... . . . . 26 7.3.3 Fill-over-cut Slopes ...... . . . . 28 7.3.4 Construction Slopes ....... . . . . 29 7.3.5 Natural Slopes ......... . . . . 30 7.3.6 Slope Protection and Maintenance . . . . 30 7.4 Settlement Considerations ......... . . . . 31 7.5 Surface and Subgrade Drainage ....... . . . . 32 7.6 Foundation Recommendations ........ . . . . 34 7.7 Reactive Soils .............. . . . . 34 7.8 Pavements ................. . . . . 35 7.9 Review of Grading Plans .......... . . . . 36
8.0 LIMITATIONS OF INVESTIGATION . . . . . . . . . . . . . . 36
ATTACNNENTS
Ficrures
1 Location Map - 2 Seismic Map
APDendices
A B
C D E
Plate
1
References Field Exploration Program Boring Logs, Figures B-2 through B-8 Test Pits, Figures B-9 through B-14 Laboratory Data, Figures C-l through C-6 Quantities of Remedial Earthwork, Figure D-l Standard Guidelines for Grading Projects
Geotechnical Map
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SUPPLEMENTAL GEOTECRNICAL INVRSTIGATION
CARLSBAD AIRPORT CENTRE, URIT 3,
CARLSBAD, CALIFORNIA
1.0 INTRODUCTION
This report presents results of a geotechnical investigation
of a proposed commercial project site in Carlsbad, California.
The purpose of our investigation was to evaluate the surface
and subsurface soils and geologic conditions at the site and,
based on those conditions, to make recommendations regarding
mass grading and other geotechnical aspects of the project.
Because the project will create rough-graded lots that will
be sold and developed separately, individual foundation
investigations should be made for each lot when precise
grading plans, building locations, and loading conditions are
known. Our conclusions and recommendations are based on
analysis of the data from our field exploration and laboratory
tests, and from our experience with similar soils and geologic
conditions in this area.
1.1 Authorisation
This investigation was authorised by Mr. Jerry Morrissey
of Centre Development on June 20, 1989. Our scope of
services for this investigation generally conformed to
that outlined in our Proposal No. SDP9-5278 dated June
20, 1989.
1.2 Scone of Services
The scope of services for this investigation included the
following tasks:
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 2
a. Review of pertinent geotechnical literature, aerial
photographs, and an 80-scale topographic map by
Bodas Engineering, Inc., dated July 8, 1988.
b. Geologic reconnaissance of the site:
C. Subsurface exploration consisting of three 30-inch
diameter bucket auger drill holes and six test pits.
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d. Downhole logging of the drillholes with collection
of bulk, disturbed, and relatively undisturbed
samples for laboratory testing;
e. Logging of test pits by our field geologist to
determine depths of alluvium/colluvium;
f. Laboratory testing of samples obtained during the
field exploration; -
g. Analysis and calculations of field data, which
provides the basis for our estimate of anticipated
removal quantities;
h. Analysis of slope stability and design of cut slope
buttresses:
1. Geologic and engineering analysis of the field and
laboratory data to develop our conclusions and
recommendations: and
j. Preparation of this report with its accompanying
maps, figures, and other information to present our
findings, conclusions, and recommendations. -
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 3
2.0 PROPOSED DEVELOPMENT
The proposed development is divided into about 23 separate
commercial lots. We understand that the site will be rough
graded during the initial phases of mass grading, after which
each lot will be developed separately. Our review of the
grading plans indicate that cut slopes to a maximum height of
approximately 35 feet, and fill slopes to a maximum height of
approximately 75 feet are proposed.
3.0 SITE DESCRIPTION
Unit 3 of the Carlsbad Airport Center will occupy an
undeveloped parcel of irregular shape located in Carlsbad,
California. The site includes about 100 acres of hills and -
associated small drainage basins located northwest of the
existing Carlsbad Airport Centre, Unit 1.
The location and topography are shown on the attached Location
Map (Figure 1). The site is bounded on the north by College
Blvd. on the west by Palomar Airport Road, on the south by
Unit 1 of the Carlsbad Airport Centre and on the east by
McClellan Palomar Airport.
Topographically, the site includes both low- and high-relief
areas. The eastern and central portions are marked with
steeply descending slopes. Natural slopes within the project
are approximately 1.5:1 (horizontal:vertical) or steeper on
the canyon sidewalls in the eastern and central portions of
the site. Maximum relief for the site is about 200 feet, with
elevations ranging from about 130 to 330 feet above mean sea
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 4
level. The site is drained from north to south by two canyons
in the central and eastern portions. No structures or
improvements were noted on the site. Access to the site is
from College Boulevard or Palomar Oaks Way.
4.0 SITE INVESTIGATION
4.1 General
Before starting our field work, we reviewed a previous
geotechnical report by H.V. Lawmaster and Company
(Reference 2). Moore and Tabor's as-graded report for
Unit 1 (Reference 3) was also reviewed. In addition we
reviewed the log of an exploratory boring completed by
us as part of the investigation described in Reference
1.
We also studied aerial photos and topographic maps of the
site to aid in determining the locations of our
subsurface explorations. This information, combinedwith
our field investigations, laboratory test results,
seismicity review, and previous experience in the general
area, forms the basis for the conclusions and
recommendations in this report. The study methods used
conform to generally accepted standards of practice for
geotechnical investigations in southern California.
4.2 Field Exnloration
Field work began on June 22, 1989, and was completed on
June 27, 1989. During this period, 3 borings were
advanced through the surficial deposits and into the
bedrock. Six test pits were also excavated during this -
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 5
period. The approximate locations of the test pits and
boreholes are shown on the Geotechnical Map (Plate 1).
These locations were made in the field by pacing and by
inspection of available maps. Locations should not be
considered more accurate than is implied by the methods
of measurement used.
The boreholes were advanced using a 30-inch bucket auger
drill rig. Samples were obtained using a 2.5-inch
(inside diameter) modified California sampler. The rig's
kelly bar was the drive weight for sampling in the bucket
auger drillholes. For each drive sample, we recorded the
number of blows needed to drive the sampler a measured
number of inches into the soil. The test pits were
excavated by a Kubota KH-170L tracked backhoe. Each
boring or test pit was backfilled upon completion of
logging and sampling by our field geologist. The logs
are attached in Appendix B as Figures B-l to B-15. The
boundaries shown between soil types on the logs were
interpolated between sample locations and are
approximate. Transitions between soil types may actually
be either abrupt or gradual.
4.3 Laboratorv Testina Proaram
Typical samples of the earth materials found during the
field work were taken to our laboratory for testing. The
testingprogramincludedparticle-size, Atterberglimits,
direct shear, maximum density, expansion, and sulfate
content tests. Appendix C contains descriptions of the
test methods and summaries of the results.
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 6
5.0 GEOTBCBNICAL SETTING AND SUBSURFACE CONDITIONS
5.1 Reaional Geoloav
The site is located in the Peninsular Ranges geomorphic
province of California near the western margin of the
Southern California Batholith. Along this margin, the
terrain changes from the typically rugged landforms
developed over granitic rocks to flatter, more subdued
landforms underlain by sedimentary bedrock units of the
coastal plain. Specifically, Jurassic metavolcanics and
Eocene sedimentary rocks lie beneath the site. Alluvial
sediments are present in the canyon bottoms. The
distribution of the geologic units is shown on the
attached Geotechnical Map (Plate 1).
5.2 Geoloaic Units
5.2.1 gPeak
The Jurassic age Santiago Peak Volcanics are
exposed under a small area in the eastern part
of the site. This is a series of mildly
metamorphosed volcanic rocks. Regionally, the
Santiago Peak Volcanics vary in composition
from basalt to rhyolite. On the site, they are
predominantly andesite. The Santiago Peak
Volcanics are moderately to highly jointed.
Joint spacings are variable, and clay filling
in the joints is usually present. The Santiago
Peak Volcanics are weathered to depths varying
from of about two feet on top of peaks to about
12 feet on lower slopes. Excavation in the -
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 7
Santiago PeakVolcanics will be difficult. The
highly weathered rock within about two to
twelve feet of the existing ground surface can
generally be excavated with conventional heavy
earthmoving equipment. Below that depth heavy
ripping or blasting should be expected. Heavy
ripping or blasting will generally produce
oversize materials. The difficulty of handling
and placing these materials will tend to slow
the progress of fill placement and compaction.
5.2.2 Santiaao Formation (MaD Svmbol Tsal
The Eocene-age Santiago Formation underlies
the majority of site. As observed, the unit - is massive to thick-bedded silty to clayey
sandstone with interbedded sandy claystone and
siltstone. Santiago Formation rocks can
generally be excavated by conventional earth
moving eguipment,.and are suitable for use in
fills. The claystones and some siltstones are
moderately to highly expansive.
5.2.3 Terrace DeDOSitS (Man Svmbol Olnl
Pleistocene terrace deposits are present in the
eastern most corner of the site. At this
location the formation consists of iron
stained, reddish brown, interbedded sandstone
and conglomerate. The rock is cemented,
however conventional heavy earthmoving
equipment is typically able to excavate it.
The material generated should be non-expansive
and suitable for use in fills.
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5.2.4 Alluvium IMaD Svmbol Oal)
Alluvium is present in the drainage courses
especially in the north-south valley in the
center of the site. As mapped for this
project, the alluvium also includes adjacent
deposits of colluvium on canyon side slopes.
Most alluvium and colluvium consists of dry to
moist, porous, soft, silty and sandy clay and
clayey sand. Alluvium in the main drainage in
the center of the site was observed to thicken
from zero thickness at the north end to a
maximum depth of about 28 feet at the southern
end of the drainage. As observed, the alluvium
appeared to be deepest near the center of the
drainage courses, with shallower depths
observed along the margins. The colluvium was
observed to a maximum depth of about five feet
and averaged about three feet deep. The
primary concern with regard to alluvium and
colluvium is their potential for settlement in
response to loads imposed on them by fills or
structures. Unacceptable settlement may occur
after construction if they are not removed and
recompacted, especially if these soils become
saturated at a later date. Special
recommendations to deal with alluvium which
cannot be removed due to a high water table are
presented in Section 8.2.3.
A small area of the downstream portion of the
main drainage was mapped as agricultural fill
in our earlier report on this site (Reference
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Centre Development August 22, 1989 Job NO. 05-4879-015-00-00 Log NO. 9-1891 Page 9
1) - Our recent exploratory boring in that area
indicates that the surficial soils are
predominantly alluvium and should be removed
and recompacted along with the alluvium.
5.2.5 TODSOi.1 (not shown on man).
The topsoil seen on the site consisted of
loose, dry, fine-grained silty sand. Fills or
structures should not be founded directly on
natural topsoil due to its limited strength and
potential for settlement and seepage. Topsoil
may be used in compacted fills if vegetation
and organic material is removed. The topsoil
was not mapped and is not shown on Plate 1.
5.2.6 Artificial Fill IOaf)
Two areas of documented compacted fill exist
in the southern portion of the site.
Observation and testing of these fills was
performed by San Diego Geotechnical
Consultants. As part of grading Unit 1, a fill
slope was built which extends into proposed Lot
69 of Unit 3. In 1989, An area of imported
compacted fill was placed in proposed Lots 50,
64, 65, and 66. Procedures for preparing the
surfaces of these fills to receive additional
fill are contained in Appendix D.
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5.3 Groundwater
Groundwater was not observed in any of the borings or
test pits. Groundwater conditions may fluctuate with
seasonal rainfall conditions, and will probably change
in response to development of the site.
5.4 Geoloaic Structure
Most of the dominant structural features in the area are
associated with pre-Tertiary folding along north-south
axes. The post-Cretaceous sequences have been gently
folded and tilted generally to the west. Dips ranging
from 4 to 15 degrees to the southwest were measured on
bedding planes in the Santiago Formation. Discontinuous
northeast-trending faulting is associated with the post-
Cretaceous folding. Faulting has been mapped in adjacent
areas, and one fault trace extends into the project area
(Plate 1). This fault trace is considered inactive,
based on our previous work in the area, available
geotechnical literature, and our evaluation of site
features.
6.0 SEISMICITY
As with all of southern California, this site lies in a
seismically active area. There are, however, no known active
faults either on or adjacent to the site. Figure 2 shows the
known active faults and earthquake epicenters (M > 5.0) in the
region and their relationship to the site. Because the active
faults lie at some distance, the seismic risk at this site is
thought to be only low to moderate in comparison with many
other areas of southern California.
LI*I.“Dt S,“.OL <“.~“,,“~I a 00, L051110*s or I.ICE”‘l”‘ ..~“O.I”1IE~ LOC.,Io*
MAP OF HISTORIC EARTHQUAKE EPICENTERS, MAGNITUDE > 5.0
)B NO.: DATE: FIOURE:
05-4879-015-00-00 AUGUST 1989 2
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Seismic hazards at the site are the result of ground shaking
caused by earthquakes on distant, active faults. The hazard
level is sufficient to place the area in seismic risk zone 3
as defined in the Uniform Building Code. Table 1 lists the
known major active and potentially active faults within a lOO-
kilometer radius and the estimated bedrock accelerations
resulting from the maximum probable earthquakes on those
faults. By definition, the maximum probable earthquake is the
largest event likely to occur in a loo-year interval, but is
in no case smaller than the largest historic earthquake
(Reference 7).
6.1 Earthcuake Effects
6.1.1 Surface Fault Ruuture
Because no active or potentially active faults
are known to cross the site, the probability
of surface fault rupture is very low.
6.1.2 Earthouake Accelerations
In our opinion, based on the information now
available, the most significant event likely
to affect this project will be an earthquake
on the Elsinore Fault. While a maximum
probable event on the Rose Canyon Fault would
generate high accelerations at the site, the
capability of the Rose Canyon Fault to generate
such an earthquake has not been demonstrated.
Recent work on the Rose Canyon fault zone has
shown that strands within the zone are active.
A single trace has been shown to offset topsoil
1 I I I I I I 1 I I t I 1 I I 1 I I I
TABLE 1 S
Maximum Credible Earthcuake' maximum Probable Earthcuake 1
FAULT DISTANCE
Peak Repeatable Peak Repeatable Bedrock HighBedrock Bedrock
ML2 Acceleration3 Acceleration4 ML5 Acceleration3
Rose Canyon6 10 miles SW 7.0 0.37g 0.24g 6.0 0.22g 0.14g Elsinore 25 miles NE 7.5 0.24g 0.24g 7.0 0.18g 0.18g Coronado g anks 40 miles SSW 6.5 0.07g 0.07g 6.0 0.04g 0.04g La Nation 35 miles SE 6.8 0.11g 0.11g 6.0 0.06g 0.06g San Jacinto 48 miles NE 7.5 0.11g 0.11g 7.5 0.11g 0.11g Newport-Inglewood 40 miles NW 7.0 0.1og 0.1og 6.5 0.06g 0.06g San Clemente 57 miles SW 7.5 0.09g 0.09g 7.3 0.09g 0.09g 1
" The maximum credible earthquake is the largest earthquake that appears capable of occurring under the presently known tectonic framework. The maximum probable earthquake is the largest earthquake that is likely to occur during a loo-year interval.
2 Values are local magnitudes, taken from Jennings (1975), and Greensfelder (1974).
3 From attenuation chart in Seed and Idriss (1982).
4 After Ploessel and Slosson (1974).
5 Values are local magnitudes, generally taken from Seismic Safety Study for City of San Diego (1974).
6 The earthquake capability of the Rose Canyon and La Nation Faults has not been established. As of this writing, recently discovered evidence of activity on the Rose Canyon Fault is being evaluated by state and local government agencies. Although they are classed as only potentially active, they are included for information purposes due to their proximity to the site.
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Centre Development August 22, 1989 Job No. 05-4879-015-00-00 Log No. 9-1891 Page 12
in one location and appears to have created
topographic features common in active faulting
(offset drainages, pressure ridges, enclosed
depressions and fault scarps). The age of the
most recent movement, the fault's recurrence
interval (expected period between major
earthquake events), the relationship between
the active trace and other faults within the
fault zone have not yet been established. As
a result, the impact on seismic safety is not
known. The degree of the hazard may not be
determined for years.
It is presently the City of San Diego's opinion
not to make changes to their design
requirements. It should be noted that the
California Division of Mines and Geology (CDMG)
could establish Alquist-Priolo Special Studies
Zones along the fault at any time. Upgrading
the San Diego area from seismic zone 3 to
seismic zone 4 would likely follow designation
of Special Studies Zones by the State of
California.
We have reviewed the existing information
available regarding the fault and conclude that
a magnitude 6.8 earthquake is an appropriate
maximum credible event for a 20 mile rupture
length (offshore La Jolla to Coronado Bridge).
A maximum probable event of magnitude 6.5 is
hypothesized for the same fault.
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As of the date of this report, we are providing
designparameters fortwo earthquake scenarios;
The Rose Canyon Fault and the next nearest
active fault (See Table I). Until additional
data becomes available or there are changes to
local codes, we recommend that the fault be
considered for design purposes.
For Elsinore events, we estimate a peak bedrock
acceleration at the site of about 0.17g for a
maximum probable earthquake of magnitude 7.0.
We do not expect surface accelerations at this
site to differ significantly from the bedrock
accelerations. The repeatable high bedrock
acceleration is used as a design value for -
events occurring within 20 miles of the site.
Beyond 20 miles, the peak acceleration is the
recommended design value (Reference 5).
Because the Elsinore Fault is about 25 miles
from the site, we recommend use of the peak
bedrock acceleration for the structures at this
site.
6.1.3 Seismicallv Induced Slooe Failures
Seismically-induced slope failures are not
likely to occur at this site under the design
earthquake loading, provided that proper
grading and construction practices are used.
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6.1.4 Seismicallv Induced Settlement
The bedrock under this site should not undergo
significant settlement as a result of seismic
shaking. However, uncompacted alluvial
deposits may experience significant settle-
ments. Any measures taken during grading to
mitigate the compressibility of the alluvium
will also decrease the potential for seismi-
cally induced settlement. Recompaction of
those soils should reduce the potential for
seismicallyinducedsettlementtoinsignificant
levels.
6.1.5 Licuefaction
Liquefaction is unlikely at this site due to
the absence of saturation, the fines present
in the soils, and the density of the soil.
6.1.6 Lurchina and Shallow Ground Runture
Shallow ground rupture should not be a hazard,
given the apparent absence of active faults in
the area. Ground cracking also should not be
a major hazard. However, it is possible that
some cracking may occur at any site during a
major earthquake.
6.1.7 Tsunamis, Seiches. and Reservoir Failures
The site is not subject to inundation by
tsunamis or seiches because of its elevation
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above sea level and its distance inland from
a major body of water. No reservoirs exist
that are capable of flooding the property.
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7.0 GEOTECHNICAL EVALUATION AND RECOMNENDATION8
7.1 General
We did not identify any geotechnical conditions during
our investigation that would prevent development of Unit
3 as it is now planned. However, the recommendations in
this report should be followed to minimize delay,
inconvenience, or loss that might arise from the
geotechnical conditions that do exist.
To reduce the potential for excessive settlements, the
existing surficial soil, colluvium, and alluvium should
be removed prior to fill placement. Also, we recommend
that fill depths be made as uniform as practical beneath
the building areas to reduce differential settlement.
Most of the required excavation can be accomplished by
conventional heavy grading equipment; however, blasting
may be necessary in the volcanic rocks. Hard rock
affects grading not only as it is excavated
(rippability), but also when it is reused as fill
(oversized rock disposal or rockfill).
If practical, soils having significant potentials for
expansion should be buried at least five feet beneath
finish grade. The use of expansive soils at shallower
depths will require that specially designed foundations
or special site preparation be used.
Specific foundation recommendations should be made when
details of the buildings to be constructed are known.
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However, shallow footing foundations should be suitable
if (a) all footings in a building will bear entirely on
bedrock or entirely on compacted fill, (b) the pads are
graded so that fills will have relatively uniform
thicknesses under individual buildings, and (c)
compressible soils are removed prior to placing fill.
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Two proposed cut slopes were investigated for potential
buttressing. The results of analysis based on borehole
data indicated that buttresses are not necessary.
Geologic mapping of backcuts may reveal the existence of
weak clay layers or seepage zones requiring further
analysis.
The remainder of this report explains our geotechnical
recommendations in more detail. These recommendations
are based on empirical and analytical methods typical of
the state of practice in Southern California. If these
recommendations appear to not cover any specific feature
of the proposed development, please contact San Diego
Geotechnical Consultants at once for revisions or
additions to our recommendations.
7.2 Gradina and Earthwork
7.2.1 General
The proposed development will use cut and fill
grading to produce building pads, slopes and
street improvements. This grading and
earthwork should be done in accordance with the
"Standard Guidelines for Grading Projects"
attached to this report as Appendix E, and with
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Chapter 70 of the Uniform Building Code. Where
special recommendations in the body of this
report conflict with the guidelines in Appendix
D, the recommendations in the report should
govern,
7.2.2 Geotechnical Observation
San Diego Geotechnical Consultants personnel
should continuously observe the grading and
earthwork operations for this project. Such
observations are essential to identify field
conditions that differ from those predicted by
preliminary investigations, to adjust designs
to actual field conditions, and to determine
that the grading is in general accordance with
the recommendations of this report. Our
personnel should perform sufficient testing of
fill during grading to support the geotechnical
consultant's professional opinion as to
compliance of the fill with compaction
requirements.
7.2.3 Site Prenaration
The ground should be stripped and prepared to
receive fill as recommended in Appendix E,
Section 3. In addition, the existing topsoil,
colluvium, and alluvium should be removed to
the depth at which bedrock is encountered.
In drainageways where groundwater is present,
full removal of alluvium may not be practical.
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Removals is these areas should extend to depths
at which water inflows or the onset of surface
V'pumpingl* make further removals unfeasible.
Such subgrades may require stabilization prior
to placing fill. A heavy geofabric intended
for stabilization use, such as Marifi 500X,
Propex 2002, or Typar 3341, should be installed
on the exposed subgrade. The geofabric should
then be covered with a minimum of 12 inches of
coarse sand, gravel or crushed rock. If
substantial thicknesses of alluvium are left
in place under fills, settlement monuments
should be installed and monitored during fill
placement. Such situations should be evaluated
by our personnel during grading.
7.2.4 RiDDabilitv
The proposed grading of the eastern most
portion of the site may involve cuts of up to
20 feet in Santiago Peak volcanic rock.
Excavability of this rock will probably be a
significant factor in site development.
Seismic refraction data was interpreted to
estimate the rippability of the rock. The
velocity of a compressional wave can be
correlated to rock hardness and used as a
indicator of rock behavior during excavation.
The seismic traverses provide useful data down
to depths of about 20 to 30 feet. The seismic
results contained in Reference 1 were
extrapolated to provide information in Unit 3.
Also, a seismic traverse from a previous study
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by H.V. Lawmaster on Lot 42, Unit 2 was
examined (Reference 2).
From the data available, the uppermost two to
five feet in the Santiago Peak Volcanics
outcrop area appears rippable with relative
ease by a Caterpillar D-9 bulldozer fitted with
a single-shank ripper. Areas of weathered
bedrock, rippable with moderate difficulty,
exist in places to depths of five to 15 feet
below the present ground surface. These
weathered areas are however, discontinuous.
In many areas, the easily-ripped surficial
layer rests directly on less-weathered rock
that is rippable only with much difficulty, if
at all. Hard rock, which lies at depths of
about four to 15 feet below the present
surface, will probably require a combination
of blasting and heavy ripping. Blasting may
also be needed where solid boulders
("floaters*') are found in otherwise rippable
material.
Once excavated, many of the rock fragments may
be too large for use in normal compacted soil
fills without special placement techniques (see
Appendix E, Section 6.3) or placement as
rockfill. The size of rock fragments may be
controlled somewhat by careful design of
blasting patterns.
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7.2.5 Fill Materials
Any soil imported or excavated from cuts may
be reused for compacted fill if, in the opinion
of the geotechnical engineer, it is suitable
for such use. Debris and organic matter should
be removed from the soil before it is placed.
The criteria governing placement of fills
depend on the size of material present. In
general, fills can be divided into *'soilll,
"soil-rock", and tlrockll fills:
a. %oillN fills are fills containing no rocks
or hard lumps larger than 12 inches in
maximum dimension and containing at least
60 percent (by weight) ofmaterialpassing
the 3/4 inch U.S. Standard sieve.
b. "Soil-rockl' fills are fills that contain
no rocks larger than four feet in maximum
dimension and that have a matrix of soil
fill. Rocks larger than 12 inches may be
placed in windrows and by using the other
techniques described in Appendix D. some
boulders too large for windowing will
require special handling during grading.
C. "Rock'N fills are fills containing rock
fragments no larger than 2 feet in maximum
dimension, with no appreciable fine-
grained soil matrix. Rock fills require
special testing to monitor compaction.
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Fill placed within three feet of finish grade
should be select finish-grade soil that
contains no rocks or hard lumps greater than
six inches in maximum dimension. For
landscaping purposes, theuppermost four inches
of fill should contain no rocks or hard lumps
greater than two inches in maximum dimension.
Soils with an expansion index of 21 or higher
should not be used within three feet of finish
grade if practical.
Typical samples of soil to be used for soil
fill should be tested by the geotechnical
engineer to evaluate their maximum density,
optimum moisture content and, where
appropriate, shear strength and expansion
characteristics. During grading operations,
the contractor may encounter soil types other
than those tested for this report. The
geotechnical engineer should be consulted to
evaluate the suitability of these soils for use
as fill and finish-grade soils. Imported soils
should, if practical, be relatively well-
graded, granular, nonexpansivesoilscontaining
small to moderate amounts of silty to clayey
fines. The geotechnical engineer should be
contacted at least two working days before the
first use of an imported soil to assess its
desirability as a fill soil.
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7.2.6 Fill Comnaction
Soil and soil-rock fills should be placed as
described in the standard guidelines of
Appendix D, except where those guidelines are
superseded by recommendations in this report.
The minimum compaction for fills is 90 percent
of modified Proctor maximum dry density (ASTM
D 1557-78). The water content at placement
should be at, or slightly above the optimum
water content.
7.2.7 Shrinkaae and Bulkinq
Removal and recompaction of the surficial soil,
alluvial deposits, and other cut materials will
probably result in shrinkage of about 5 to 10
percent. Bulking-in sedimentary bedrock and
weathered volcanic soil/rock mixtures can be
expected to be about 5 to 10 percent. Blasting
or hard ripping of solid rock will probably
result in bulking of 10 to 20 percent.
7.2.8 Overexcavation of Volcanic Rock
Where hard volcanic rock is exposed at finish
grade, it is recommended that an overexcavation
of at least three feet be made, and that
compacted fill be placed up to finish grade.
This will permit the economical excavation of
utility and foundation trenches, and will
improve the drainage of the lots. If deeper
utility trenches will be cut, the over-
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excavation depth should be increased
accordingly.
7.2.9 Cut-Fill Transitions
Buildings should not be located over cut/fill
transitions because of differential settlement
that may occur between bedrock and compacted
fill. In addition, large changes in fill depth
below structures may cause damaging
differential settlements. The potential for
such conditions should be evaluated during
review of the grading plans. Mitigation of
differential settlements usually involves
overexcavation of the rock to produce near-
uniform fill thicknesses under the pads, with
or without special foundation design.
7.2.10 Trench
Unless we recommend otherwise in specific
cases, backfill in trenches and behind
retaining walls should be compacted to at least
90 percent of modified Proctor maximum density
(ASTM D1557). The backfill should be placed
in uniform lifts of six to eight inches.
Mechanical compactors normally should be used
to achieve the reguireddensity; water-flooding
should not be used. When specified, strict
attention should be given to special require-
ments for bedding or hand compaction around
pipes and conduits.
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7.3 Sloue Stabilitv
7.3.1 Bedrock and Soil Characteristics
Slope stability conditions vary greatly over
the site. Although most of the soil and rock
have moderately high shear strength. weaker
rock is present also. This weaker rock often
includes low-strength clay seams.
Nevertheless, both the natural and man-made
slopes should be stable over the life of the
project if proper care, prudence, and skill are
applied to their construction and maintenance.
The current absence of free groundwater over
most of the site enhances the stability of
slopes. %are should be taken to prevent or
minimizethe development of groundwater seepage
during the post-construction period through
site drainage and avoiding excessive
irrigation.
Soil strength parameters used in analysis were
based on laboratory test results, on data from
other local projects, and on our experience and
judgement. For silty sandstone and similar
weak rocks (mostly Santiago Formation), a
cohesion of 100 psf and an effective friction
angle of 31 degrees was chosen. For clayey
sandstone and claystone, a cohesion of 400 psf
and a friction angle of 26 degrees was used.
Fills built from mixtures of these rocks were
assumed to have a cohesion of 200 psf and a
friction angle of 29 degrees. For pre-sheared
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clay seams in the bedrock, a residual friction
angle of 12 degrees was assumed, with no
cohesion.
Cut slopes in the Santiago Peak Volcanics were
not analysed for stability in the usual way.
The stability of hard rock slopes is controlled
by jointing, the nature of fracture fillings,
and the presence of seepage. Analyses based
on mass strength parameters are usually
misleading because they do not account for the
geometry or mechanisms of rock failure.
Accordingly, the stability of the rock slopes
was judged on the basis of experience and local
practice.
7.3.2 Cut and Fill Slones
The proposed fill and cut slopes will mostly
be built to maximum heights of 60 feet. We
assume that they will be built at slope ratios
of 2.0 (horizontal) to 1.0 (vertical) or
flatter, will have level surfaces behind their
crests, will not be subject to significant
surcharge loads, andwillnotbecome saturated.
Under these assumptions, the slopes may be
built to the following maximum heights:
Slone Tvoe and Material Sloue Heiaht. Feet
Cut: Silty Sandstone (Tsa) 51
Cut: Clayey Rocks (Tsa) 83
Fill; Mixed Soils 72
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These heights are based on Taylor's charts,
with static factors of 1.5. They therefore
should meet local state-of-practice standards
for slope stability.
Slopes not conformingtothe stated assumptions
(i.e., containing pre-sheared clay seams)
should be individually studied prior to
construction. TWO proposed cut slopes
identified as cross sections DD and EE on Plate
1 were analysed using the STABL5 computer
program. The locations of the cross sections
are shown on the accompanying Plate 1. Thirty
inch diameter exploratory borings were drilled
in these slopes and logged downhole by our
geologist. The logs, shown in Figures B- and
B- I indicate that only traces of clay seams
were present. Therefore strength parameters
for intact rock were used in the stability
analysis and factors of safety in excess of 1.5
were obtained for the slopes without
buttresses. During construction, our geologist
should map all back-cuts to determine that the
assumptions used in the analyses are
applicable.
Cut slopes in Santiago Peak Volcanic rocks
should be stable to heights of at least 35 to
40 feet. As discussed above the stability of
these hard rock slopes will depend heavily on
the joint patterns in the rock and structural
factors that must be assessed during grading.
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Despite the overall stability of the slopes,
some erosion, ravelling, or thin surficial
sliding may occur on otherwise stable slopes
if they are not well vegetated or maintained
after construction. Groundwater seepage,
fractures and other unfavorable geologic
structures, or variations in soil and rock
properties may lower the stability of cuts
greatly. Such conditions usually can be
assessed only when soil and rock is exposed
during grading. For this reason, San Diego
Geotechnical Consultants personnel should
observe all slopes during grading to evaluate
the geologic conditions.
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7.3.3 Fill-over-cut Slooes
Where fill-over-cut slopes are proposed, as at
cross section DD, a keyway, at least one
equipment-width wide (about 12 to 15 feet),
should be built at the cut/fill contact. Also,
a subsurface drain should be placed along the
rear of the keyway. The drain may consist of
perforated PVC pipe surrounded by gravel or
crushed rock and wrapped with geofabric. This
drain should lap up onto the rear of the keyway
at least six inches above the cut/fill contact.
Alternative drain designs should be submitted
to San Diego Geotechnical Consultant for review
prior to use.
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7.3.4 Construction Slones
In the absence of surcharge loads, groundwater
seepage, or presheared clay seams, temporary
excavations and slopes may be cut to the slope
ratios and heights listed below:
Sloue Ratio Heiahtof Slone. Feet
(Horiz.:Vert.) Fill Oal Tsa &p
Vertical 4 3 4 4
0.75:1.0 26 7 15 10
1.00:1.0 44 11 26 20
1.25:l.O -- 20 48 --
Slopes higher than those listed above should
be built on the basis of specific recommen-
dations made by the geotechnical engineer.
If surcharge loads (such as equipment, material
stockpiles, or spoil banks) are placed along
the edges of excavations or slopes, the slope
ratios should be flattened from those given
above. For planning purposes, we recommend
flattening when surcharge loads fall within a
zone defined by a 1:l plane rising from the
nearest bottom corner of the excavation or
slope. Contact San Diego Geotechnical
Consultants if such surcharges will exist for
specific recommendations.
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Water should not be allowed to flow freely over
the tops of temporary slopes. Workmen should
be protected from the local revelling and
surficial sliding that may still occur at the
slope ratios listed above. Temporary slopes
and excavations subjected to severe vibratory
loads shouldbe analyzed for dynamic stability.
All temporary excavations should meet at least
the minimum requirements of applicable
occupational safety and health standards. San
Diego Geotechnical Consultants should be
contacted for further recommendations if soil
conditions are found that deviate from those
assumed or if evidence of instability appears
at the site.
7.3.5 Natural Slones
With the existing slope ratios and groundwater
conditions, the natural slopes on and near this
site presently appear stable. If drainage is
provided and the grading recommendations in
this report are observed, development of this
tract or adjoining properties should not cause
these slopes to become unstable. However, we
should review this conclusion when grading
plans are complete and during the grading
operation.
7.3.6 Slone Protection and Maintenance
Although graded slopes on this site should be
grossly stable if built in accordance with the
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recommendations in this report, the soils will
be somewhat erodible. For this reason, the
finished slopes should be planted as soon as
practical after the end of construction. Pre-
ferably, deep-rooted plants adapted to semi-
arid climates should be used. In addition,
runoff water should not be permitted to drain
over the edges of slopes unless the water is
confined to properly designed and constructed
drainage facilities.
7.4 Settlement Considerations
Both the weight of the new fill and the loads imposed by
buildings and structures will produce settlement. Some
degree of settlement will occur in compacted fill and in
the underlying native soil and rock. However,
settlements within rock of the Santiago Formation and the
Santiago Peak Volcanics should be negligible. Native
alluvium, topsoil and colluvium are compressible and
should be removed and replaced as compacted fill.
If groundwater prevents the full removal of alluvium or
other compressible soils from beneath fills, buildings
or other settlement-sensitive structures should not be
built until primary settlement of both the alluvium and
the fill is essentially complete. Settlement monuments
should be installed at the base of fills and surveyed at
intervals during and after fill placement if more than
five feet of alluvium will remain in place. San Diego
Geotechnical Consultants can then review the survey data
to evaluate the progress of settlement. Our experience
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in the area is that settlement is largely complete within
three to four months after completion of the fill.
Compacted fills normally settle under their own weight
by approximately l/4 percent to l/2 percent of their
original height. Although much of this settlement occurs
during the construction period, the structures planned
for this site should be designed to withstand settlements
of this magnitude. If this settlement is not tolerable,
the total amount of settlement affecting structures can
be reduced by delaying construction of buildings until
the settlement is largely complete. This will require
that surface settlement monuments be installed and
monitored. Compaction of the fill at water contents
above optimum should minimize the potential for future
settlements if the fill later becomes saturated.
Estimates of settlement due-to building loads depends on
the design of the building and on the foundation system
selected for use. Reliable estimates therefore cannot
be made until foundation investigations are made for
individual buildings. If designed for appropriate
bearing pressures, shallow foundations should generate
total and differential settlements that fall within
limits generally considered acceptable.
7.5 Surface and Subarade Drainaae
Foundation and slab performance depends greatly on how
well the runoff waters drain from the site. this is true
both during construction and over the entire life of the
structure. The ground surface around structures should
be graded so that water flows rapidly away from the
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structures without ponding. The surface gradient needed
to achieve this depends on landscaping type. Pavements
or lawns within five feet of buildings should slope away
at gradients of at least 2 percent. Densely vegetated
areas should have minimum gradients of 5 percent away
from buildings in the first five feet if it is practical
to do so. Terrace drains should be constructed on fill
slopes at intervals not exceeding 30 to 40 vertical feet.
The benches for terrace drains should be at least six
feet wide. Drainage facilities should be regularly
maintained, cleaned, and repaired so that they will
function properly.
Planters should be built so that water from them will not
seep into the foundation areas or beneath slabs and
pavements. Maintenance personnel should be instructed
to limit irrigation to the minimum actually necessary to
properly sustain the landscaping plants. Should
excessive irrigation, waterline breaks, or unusually high
rainfall occur, saturated zones and "perched" groundwater
may develop in the soils. Consequently, the site should
be graded so that water drains away readily without
saturating foundation or landscaping areas. Potential
water sources, such as water mains, drains, and pools,
should be frequently examined for signs of leakage or
damage. Any such leakage or damage should be repaired
promptly.
Subdrains should be installed at the base of fills placed
in drainageways or over areas of actual or potential
seepage. The general locations of subdrains should be
indicated on the grading plans. Specific locations
should be determined in the field during grading, with
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installations being reviewed by San Diego Geotechnical
Consultants prior to the fill placement. Appendix E
includes typical details of subdrains.
7.6 Foundation Recommendations
Bearing capacities, foundation reinforcement, pressures
on retaining walls, and other foundation recommendations
depend on the specific buildings to be constructed.
Therefore separate foundation investigations should be
made for each lot when it is developed. The foundation
recommendations can then be guided by the specific
requirements of each structure.
In general, the proposed building pads should be suitable
for the support of moderate foundation loads typical of
one- and two-story concrete tilt-up structures. The
allowable bearing pressures for conventional spread
footings and strip footings should be at least 2000
pounds per square foot. Foundation costs can be
minimized if (1) the lots are capped with at least 3 feet
of nonexpansive or low-expansive soil, and (2) buildings
are not located over transitions from bedrock to fill or
over areas where large changes in fill depth occur across
the building footprint.
7.7 Reactive Soils
Based on chemical tests and our experience with similar
soils, either Type I or Type II Portland cement may be
used for concrete in contact with the soil. However, the
absence of water-soluble sulfates in the soil and rock
should be confirmed at the completion of grading.
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7.8 Pavements
R-value tests were not made because the soil types in the
subgrades of streets and parking areas will not be known
until grading is complete. It is conservative to assume,
however, that relatively poor subgrades and thick
pavement sections will be needed. For traffic indices
of 4.5, 7.0, and 8.0 which are typical for the street
areas, the following pavement sections can be used for
planning purposes:
Traffic Index 4.5 7.0 8.0
R-value 10 10 10
Pavement Thickness 3 " 4 " 4"
Aggregate Base 8 " 14.5" 18"
Total Thickness 11" 18.5" 22"
Please not that these pavement sections may not be the
final ones used and that actual sections will vary across
the site. R-value tests .should be performed after
aradina for final desian of oavement sections. The
pavement subgrades should be prepared as recommended in
Section 8.2.3 and compacted to at least 95 percent of the
Modified Proctor maximum dry density (ASTM D 1557-78).
Aggregate base course material should conform to the
CALTRANS Standard Specifications for Class II base, and
should be compacted to a minimum relative compaction of
95 percent.
If rigid pavements are required at loading docks or trash
enclosures, we recommend a full-depth Portland cement
concrete section with a minimum thickness of six inches.
The concrete should be durable and resistant to scaling,
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with a modulus of rupture equal to at least 600 pounds
per square foot. We further recommend that #3 deformed
steel reinforcement bars be placed on 18-inch centers in
both directions for crack control. Steel dowels should
be installed at all cold joints, and contraction joints
should be placed at spacings of 25 feet.
7.9 Review of Gradina Plans
San Diego Geotechnical Consultants should review the
grading plans for the proposed development prior to
construction. This review will allow us to assess the
compatibility of those plans with the recommendations in
this report. If the final plans differ materially from
our present understanding -of the project, further
investigation and analysis or recommendations for design
changes may be necessary.
8.0 LIMITATIONS OF INVESTIGATION
Our investigation was performed using the degree of care and
skill ordinarily exercised, under similar circumstances, by
reputable soils engineers and geologists practicing in this
or similar localities. No other warranty, expressed or
implied, is made as to the conclusions and professional advice
included in this report.
The samples taken and used for testing and the observations
made are believed typical of the entire project. However,
soil and geologic conditions can vary significantly between
drillholes, test pits, or other exploration locations. As in
most projects involving earthwork, the conditions revealed by
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in our preliminary findings. If such changed conditions are
found, they should be evaluated by the project soils engineer
and geologist. It may then be necessary to adjust the project
designs or to recommend alternate designs.
This report is issued with the understanding that the owner,
or his representative, is responsible for bringing the
information and recommendations contained herein to the
attention of the architects and engineers involved in the
project. The owner or his representative is also responsible
for assuring that the information and recommendations are
incorporated into the plans, and that the necessary steps are
taken to see that the contractor and subcontractors carry out
the recommendations in the field.
This firm does not practice or consult in the field of safety
engineering. We do not direct the contractor's operations,
and we cannot be responsible for anyone other than our own
personnel on the jobsite. therefore, the safety of other
persons at the jobsite is the responsibility of the
contractor. The contractor should notify the owner promptly
if he considers any of the recommendations in this letter to
be unsafe.
Our findings in this report are valid as of the date of issue.
However, changes in the condition of a site can occur with the
passage of time, due either to natural processes or the works
of man on this or adjacent properties. In addition, changes
to the applicable or appropriate laws, regulations, and
standards of practice may occur as a result of either new
legislation or the broadening of knowledge. Our findings may
be invalidated wholly or in part by such changes, over which
we have no control. The validity of this report therefore -
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should not be relied upon after a period of three years
without a comprehensive review by San Diego Geotechnical
Consultants.
***
SAN DIEGO GEOTECBNICAL CONSULTANTS, INC.
Victoria Stocker " Radond M. Masson Staff Geologist Project Engineer
Kenneth W. Shaw,.C.h.G. 1251 Registration Expires: 6-30-90 Chief Geologist Registration Expires: 3-31-91 Principal Engineer
VS/RMM/KWS/AFB/cf
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APPENDIX A
References
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References
1. San Diego Geotechnical Consultants, Inc., 1988, Supple- mental Geotechnical Investigation, Carlsbad Airport Center Unit 2, and Offsite Fill Area, Carlsbad,
California, Job No. 05-4879-011-00-00.
2. H. V. Lawmaster 8 Company, Inc., 1980, Preliminary Geotechnical Investigation, Proposed Palomar Business Park, North San Diego County, California: Unpublished report no. 79-9394/654Gto Palomar Business Park, January
15, 1980 (includes grading plan review letters dated June
8, 1982 and September 27, 1982).
3. Moore & Taber, 1987, Report of Geotechnical Services, Carlsbad
Tract No. 81-45, Airport Business Center, Unit No. 1,
City of Carlsbad, California: Unpublished Report to Centre Development Company, February 25, 1987.
4. Bonilla, M. G., 1970, Surface Faulting and Related Effects,
b Wiegel, R. L. (ea.), Earthcuake Enaineerinq:
Englewood Cliffs, New Jersey, Prentice-Hall, p. 47-74.
5. Seed, H. B., and Idriss, I. M., 1982, Ground motions and soil
liquefaction during earthquakes, Earthquake Engineering
Research Institute, Monograph Series.
6. Ploessel, M. R., and Slosson, J. E., 1974, Repeatable high
ground accelerations from earthquakes, California
Geology, September.
7. California Division of Mines and Geology, 1975, Recommended Guidelines for Determining the Maximum Credible and the
Maximum Probable Earthquakes: California Division of Mines and Geology Notes, Number 43.
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- APPENDIX B
Field Exploration
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DEFiNlTlON OF TERMS
MORE THAN
SILTS AND CLAYS LIQUID LIMlT IS
LESS THAN 60%
SILTS AND CLAYS
LlQUlD LIMIT IS
GREATER THAN 60s
ILTS AND CLAYS SAND I GRAVEL
FM! ( MEDIUM ( COARsE COBBLES BOULDERS COARSE 1 FINE (
200 40 10 4 314’ 3’ 12-
US. STANOARO SERIEB SEW CLEAR SQUARE SlEVE OPENINQa
x GROUNDWATER LEVEL AT TIME OF ORILLINQ:
3 QROUNOWATER LEVEL MEASURED LATER IN STANOPIPE.
0
LOCATION OF SAMPLE TAKEN USlNa A STANDARD SPLIT TUBE SAMPLER.
Z-INCH 0.0.. l-S/S-INCH I.D. DRIVEN WITH”A 140.POUNO HAMMER FALLhO
30-tNCHEB.
1
LOCATION OF SAMPLE TAKEN.USlNO A MODIFIEO CALIFORNIA SAMPLER.
J-l/S-INCH 0.0.. WITH 2-$12..(NCH 1.0. LINER AINQS. DRIVEN USlNa THE
WSIOHT OF KELLY BAR (LARQE DIAMETER BORINQS) OR USINQ A 140 POUND
HAMMER FALLINQ 30-INCHES (SMALL DIAMETER EOl?lNa,:
LOCATION OF SAMPLE TAKEN riSlN0 A J-INCH 0.0. THIN-WALLED TUBE SAMPLER
(SHELBY TUBE) HYDRAULICALlY PUSHED.
LOCATION OF SULK SAMPLE TAKEN FROM AUQER CUTTINQS.
KEY TO LOGS - UNIFIED SOIL CLASSlF1CAT1ON SYSTEM <ASTM D-24871
OS NO.: DATE: FIOURE:
05-4879-015-00-00 AUGUST 1989 Be,-.
.-
-.
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-
..-
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.
-
..~
_-
-
-
-.
)ATE OBSERVED: 6-27-89 METHOD OF DRILLING: 30" Bucket Auaer
-
- -
\ = ,
;y ;P i” i
-
- -
- -
- jar -
,EVATIONZN/A LOCATION: See MaD
LOG OF BORING NO. 1
Sheet 1 of 1
DESCRIPTION
ALLUVIUM fOa1): Tan gray sandy silty CLAY, mottled, moist to very moist, medium stiff
.-__--_--_-----__------------ At 15’ change to medium to light brown
silty SAND, very moist to moist,
medium dense
At 22’ change to slightly silty SAND, tan moist to very moist, medium dense
At 26’ to 27’ Rocks, graphic granite, and Poway clastes
I
SANTIAGO FORMATION (Tsak White,
tan slightly silty to clean SAND,
moist, medium dense to dense
IOrange staining limited I
Total Depth 29’
No Water No Caving
No Samples
.~
..,~
-~
.-
-
-
-
-.
,-
-.
-
-
-
..-
)ATE OBSERVED: b-27-89 METHOD OF DRILLING: 30" Bucket Aww
\ =
1
!!I
ii
;a
I@
,
-
-
- Sal -
,EVATION~& LOCATION: See Mar, =
LOG OF BORING NO. 2
Sheet 1 of 2
DEfCRTPTION
TOP SOIL (Oall: Medium brown silty
SAND, dry to damp, loose to dense
SANTIAGO FORMATION (Tsal: Light
grayish white SANDSTONE, damp to moist, dense to medium dense, fine to medium grained, massive
At 13’ Marker bed 6” to 1’ thick, light
pink, slighlty silty SANDSTONE
At 13.5’ Dark gray siltstone nearly
horizontal undulates around hole.
Grayish green, slightly silty SANDSTONE, fine grained, moist, hard.
.-_----_-----------_--------- At 20’ Gray green SILSTONE, moist, hard, orange iron oxidation staining At 22’ Gray CLAYSTONE, 3/4” thick,
continues around hole, horizontal.
At 22.5’ Light gray silty SANDSTONE bed about 4” thick, slightly remolded contact with claystone above.
At 23’ Dark gray CLAYSTONE, moist,
stiff, massive At 28’ SILTSTONE becomes medium
brown in color, massive, hard
At 34’ Gypsum filled fractures and concretions
At 38’ Dark olive gray SILSTONE, moist,
hard, massive, random gypsum
1
1 EXPANSION
SOIL TEsr
‘ARTICLE SIZE
ITTERBERG LIMITS
)IRECT SHEAR
SXPANSION HAXIMUM DENSITY WLFATE
3IRECT SHEAR
C. ImE: B-3
-~
-
-
-
-
.-
-
-
-
-
-
-
-
.-
IATE OBSERVED: 6-27-w METHOD OF DRILLING: 30" Bucket Auger
)GGE :R( -
c EL
't- ii= 22 =z 0 -
-
XJI
I I
I
,
I
ND z no Da ill” kip JL am 23 Ho -
-
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;EVATION:N/A LOCATION: See Mao
LOG OF BORING NO. 2
Sheet 2 of 2
DESCRIPTION
At 50’ Cemented zones, irregular, not continuous, 1’ to 2’ thick
Total Depth 54’ No Water
No Caving
Xego usdechllmLal Consultants,
SOIL TEST
‘ARTICLE SIZE 1lTERBERG LIMITS
-.
_.
-
-
-
.-
-
. .
-.
.-
-.
.~
-
-
)ATE OBSERVED: 6-27-89 METHOD OF DRILLING: 30" Bucket Auner
LOGGEDBY:. v =
u E 5 !m
-
ii
4
)5-4879-015-00-00
-
-
-
ian -
.EVATION:N/A LOCATION: See Mao
LOG OF BORING NO. 3
Sheet 1 of 2
DESCRIPTION
TOP SOIL (Oall: Brown silty clayey SAND, loose, dry to damp
SANTIAGO FORMATION (Tsak Yellow tan silty SAND, damp to moist, medium dense to dense, massive
At 5.5’ More orange in color
At 9’ Bedding dipping 7SW Strike N30W
Nearly vertical fracture, nearly entire hole length, discontuous At 10.5’ Increase in iron oxidation, color bright orange
At 11.5’ Above more SILT more staining
orange red
At 15.5’ color change light tan silty SAND,
fine grained, moist, dense
At 21’ Micaceous zone (muscovite) Discontinuous iron oxide staining along traces of bedding, near horizontal
At 26’ traces of bedding, layers of more micaceous rich SANDSTONE, near horizontal, undulating around hole
At 31’ Gray CLAYSTONE stringer up to
l/4” thick dipping 2-3E, striking N-S
At 31’ to 32’ Red bed about 40 west to near horizontal,
N-S strike
At 36’ Zone green gray sandy SILTSTONE with iron oxide, staining, moist,
hard
At 37.5’ Bedding red oxide zones, bedding .
SOIL TEST
IAXIMIJM DENSITY
lXPANSION SULFATI
)IRECT SHEAR
)IRECT SHEAR
‘ARTICLE SIZE \TTERBERG LIMITS
-.
-
,-
-
-
-
-
-
-
-
.-
.-
-
IATE OBSERVED: 6-27-W METHOD OF DRILLING: 30" Bucket Auger
,OGGE
; kl k i: m:
F 3;
t: d*
i-7 .: .::” ‘. .:. .: .’ .:, - : : :’ 5-: :.:I.: .:.:
: : :’ .;
.:,. :
o-: :,::‘: .’
5-
O-
5-
‘O-
5-
E .EVATION:N/A LOCATION: See Mao
LOG OF BORING NO. 3
Sheet 2 of 2
DESCRIPTION
At 40’ Light tan silty SANDSTONE with stringers of gray micaceous sandstone At 40.5’ to 42.5’ Orange stained vien
dipping 68SE, S45W
At 45’ Chunks of gray green laminated SILTSTONE, moist, hard, not seen during down hole logging
Total Depth 51’
No Water
No Caving Backfilled 6-27-89
SOIL TEST
-
San Diego Geotechnical Consultants, Inc. 17 B-
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-
.-
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_-
.-.
.-
-.
!!!
c !L
it- ;= IW $
0
-
IO.
-
IATE OBSERVED: 6-28-88
-
97.t
-
- -
San Diego Geotechnical Consultants, Inc. I FIGUKE :P
METHOD OF DRILLING: 8" Hollow Stem Aum 140 lb. Hammf
EVATIONAUI LOCATION: See Geotec
LOG OF BORING NO. 4
w: 30” Fall
:a1 MaD
Sheet 1 of 2
DESCRIPTION
m Medium brown SAND, dry to lamp, loose to medium dense, fine grained
ALLUVIUM (Oalk Medium brown
clayey SAND, moist, stiff
.----_-_-_-_--_-_----------- Medium brown clayey SAND, damp, medium dense, fine grained
SOIL TEST
Consolidation, Sieve
knalysis, Atterberg
imits
Sampler bouncing on quartz gravel clast
3S’-38’
SANTIAGO FORMATION (Tsal:
NDSTC-JNE
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-
-
,-
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-
-
..-
DATE OBSERVED: 6-28-88 METHOD OF DRILLING: 8" I+J~~J xem AUK!
15-
50-
55-
60-
55-
‘O-
‘5-
F = I
!U
Ii 1: 19
, 1 -
140 lb. Ha ,EVATION~%!~ LOCATION: See Gem
LOG OF BORING NO. 4
Sheet 2 of 2
DESCRIPTION
damp to moist, very dense, fine grained, micaceous
Total Depth: 42’
No Water
Backfilled 6-28-88
Dieeo Geotechnical Consultants.
SOIL TEST
I I I I 1 I I I I I I I I I / I I
PROJECT NAME: Carlsbad Airport Centre TRENCH NO.: 18 ENQINEERINQ PROPERTIES
,o* NO. 05-4879-015-00-00 DATE: 6-22-89 g F Y
z
%
8;
2 c . . 4
IQWPMENT: Trackhoe 170L 24" bucket 258’ *ai
ELEVATION: 00’ LL& m ii?
ii ‘;
.OQGED By: “’ LOCATION: See Map $5 E: Fi t
3
3 f
z
DESCRIPTION 0 s x
AlluVium (Qal): Tan, silty CLAY and SAND, loose, dry to damp.
Santiago FM (Tsa): Brown CLAYSTONE, mist, dense with lenses of silty and fine
qrained sandy claystone orange and yellow iron oxide staining
along parting planes.
KALE: l”= 10’ horiz & verticalTOPOGRAPHY: TRENCH ORIENTATION: N8’E
IENCH LOO
,ROJE~~ NA~~Carlsbad Airport Centre TRENCH NO.: lg ENQINEERINQ PROPERTIES
,08 NO. 05-4879-015-00-00 DATE: 6-22-89 g F ii
s
2 3 g . .
*ai 2: 0
;Q",PME,,> Trackhoe 170L 24" bucket 256’ Od 2 z: E ” ELEVATION: Ygj
$2
z :
.OQQED BY: “’ See Map gj>’ 5 G LOCATION: < 2 f
z
DESCRIPTION 6 x
Alluvium (Qal): Light tan, clayey silty SAND, dry, loose.
Santiago FM (Tsa): White, light tan clayey SANDSTONE, moist, dense. orange and
red iron oxide staining in lenses.
SCALE: l”=lO* horiz & verticalTOPOQRAPHV: TRENCH ORIENTATION: N14’E
BROJECT NAME: Carlsbad Airport Centre TRENCH NO.: *’ ENSINEERINS PROPERTIES
05-4879-015-00-00 6-22-89 z w IO8 NO.: DATE: F 2 E
z!! z c
l d x
CQ",PMENT: Trackhoe 170L 24" bllrket ELEVATION: 21g’ 3 g -
i$ @I oD* z i 24
-OWED By: “s LOCATION: See Map g=i 5 a Lo
2 DESCRIPTION 0 3 f s
Colluvium (Qal) : Dark gray silty, sandy CLAY, dry, soft to medium stiff rare
polished quartlite pebbles.
Santiago FM (Tsa): Tan and gray silty CLAYSTONE, moist, dense. Orange & red iron
oxide staining and gypsum stringers.
WALE: 1”s 10 1 horix & vertical TOPOGRAPHY: TRENCH ORIENTATION: N60°W
PROJECT NAME: Carlsbad Airport Centre TRENCH NO.: ” ENQINEERINQ PROPERTIES
JO8 NO.: 05-4879-015-00-00 DATE: 6-22-89 f2 “g c
F !i
z
(0: er Y
EQ"IPME,,T: Trackhoe 170L 24" bucket ELEVATION: 239' 26
=oS ii
g5 5
EZ
E -
See Map 3 2 z
LOQQED BY: vs z LOCATION:
2 2 g E DESCRIPTION 0
Alluvium (Qal) : Dark brown silty SAND, dry, loose ocasional pebbles of quartzite.
Santiago FM ITsa): White, light gray silty SAND, fine-grained, dry to moist,
medium dense.
WALE: l”= 1.0’ horiz & verticagOPOQRAPHY: TRENCH ORIENTATION: ~33%
t I I I I I I I I I I 1 t I I I I I I I I 71711-w
I----‘r--- ------ /(
-- Tsa
:ENCH LOG
I I I I I I I I I I I I I / I I I I
SROJECT NAME: rarlsbad Airport Centre TRENCH NO.: 22
,os NO.' 05-4879-015-00-00 DATE: 6-22-89
EQ",,SME,,p Trackhoe 1701. 24" Bucket ELEVATION: 199 '
.OQQED By: V.S. LOCATION: See Map
DESCRIPTION
Alluvium/Topsoil (Qal): Dark brown silty SAND, loose, dry, fine grained.
Santiago FM (Tsa): Weathered, dark brown silty clayey SAND, moist, dense to
very dense, fine grained.
ENOINEERINQ PROPERTIES
(f “fi z c
F *ai 2
Sd !&j ii
er P
zg : ;
2' 5 E* ? t
O@ 00 z
2: 2 f P :
IGALE: 1”~ 1”’ horiz & verti,--1TOPOQRAPliY: ’ TRENCH ORIENTATION: ~235.~
I I I I I I I I I I I I I / I I
DROJECT NAME: Carlsbad Airport Centre TRENCH NO.: 23 ENQINEERINQ PROPERTIES
sos NO. 05-1879-015-00-00 6-22-89 5 Y 2 c . . DATE: F ii
l oi 4 : 2!! Y ”
EOUIPMENT: Trackhoe 1701. 24" Bucket 170’ 0-j (L ELEVATION: Ygj 2 zp
;:
z E
V.S. g5 z LODGED By: LOCATION: See Map 5 E 3 2 I s DESCRIPTION 0
Alluvium (Qal) : Brown silty CLAY, dry medium stiff.
Santiago FM (Tsa): Weathered dark brown silty CLAY, damp to moist, very stiff.
APPENDIX C
Laboratory Testing Program
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Laboratorv Testina Procram
Typical soils samples from the site were tested to determine their engineering properties. The test methods used conform generally
to those of the American Society for Testing and Materials (ASTM)
or those of other recognized standard-setting organizations. The
following section describes the testing program.
Classification
During fieldwork, the soil and rock was classified by the Unified Soil Classification System (visual-manual procedure) of ASTM D2488-
84. These classifications were checked and, if necessary, modified
on the basis of laboratory test results (ASTM D 2487-85). The logs in Appendix B show the classifications.
Particle Size Analvsis
Mechanical analyses of particle-size distribution, as described in
ASTM D 422-63, were made on four selected samples. Figures C-l
through C-4 show the results.
Atterbera Limits
ASTM D 4318-84 was used to determine the liquid limit, plastic
limit, and plasticity index of three selected samples. Figures C-
l to C-4 show the results.
Direct Shear
Consolidated, drained, direct shear tests (ASTM D 3080-72) were made on four relatively undisturbed samples of Santiago Formation rocks from drillholes B-2 and B-3. The test results are plotted
on Figures C-5 and C-6.
Maximum DensitY/Ootimum Moisture Content
The moisture - density relationship for two samples of Santiago
Formation material were determined using ASTM D 1557-78. Table C-
l lists the test results.
Exoansion
The expansion potential of three samples of Santiago Formation rock from drillholes B-2 and B-3, was tested using the UBC 29-9
expansion index method. Table C-2 lists the results.
sulfate Content
Two samples of Santiago Formation rock from drillhole B-3 were
tested for water-soluble sulfate minerals with CALTBABS Method 417
(Part I.) The results are listed in Table C-3. -
I I I I I I ’ I I I I / / I I
SAND QRAVEL COARSE 1 SILT CLAY MEDIUM FINE
SIEVE SIZES-U.S. STANDARD
3/4" 112” 114” 4 10 20 40 100 200 100 100
00 SO
60 SO
70 70
0 m 60 60 2 : it
2 = z 60 60 -( Y
z ;I!
0 iii z 40 40 z Q Q
30 30
20 20
10 10
O- I 10 10.0 1.0 0.1 .Ol .OOl
PARTICLE SIZE-MILLIMETERS
SORINQ NO. DEPTH (FEET) SYMBOL LIOUID LIMIT PLASTICITY INDEX CLASSIFICATION
? 6 0 NP SM-SILTY SANDSTONE
I I I I I t I I I , / I / I I i I
I SAND GRAVEL
I
SILT CLAY COARSE MEDIUM FINE
SIEVE SIZES-U.S. STANDARD
3/4” 112” 114” 4 10 20 40 100 200 100 100
90 90
SO SO
70
= z 40 0
30
20 lllll I I I 20
70
60
I I I
IO IO
0 !lIIll III I 1 Ill I I I II I IIIIII I I I lllll I I I 0
10.0 1.0 0.1 .Ol .OOl
PARTICLE SIZE-MILLIMETERS
BORINQ NO. 1 DEPTH (FEET) I SYMBOL ( LIQUID LIMIT I PLASTICITY INDEX 1 CLASSIFICATION
2 40 1 0 62 I 16 MH-SILTSTONE
I I I I I I I I I I I
SAND QRAVEL SILT CLAY COARSE 1 MEDIUM FINE
SIEVE SIZES-U.S. STANDARD
100
60 III1 I I I II u Illlll I I I I I I I
70
: 60
:
z” •I 60
2
ii
3 40 I I 1
60 : : 2
0
10.0 1.0 0.1
PARTICLE SIZE-MILLIMETERS
BORINQ NO. DEPTH (FEET) SYMBOL LIOUID LIMIT PLASTICITY INDEX CLASSIFICATION
3 38 l NP SM-SILTY SANDSTONE
, I I 1 ! I I I I / / i I / /
1 I
: ,
! I
:
:
! m
i
F
c
F
3 ;
i
; i
SAND QRAVEL COARSE ( MEDIUM I FINE i SILT CLAY
$ 60 0
;
+ 60
2
:
z 40
SIEVE SIZES-U.S. STANDARD
100
60
60 2
:
Y 60 ;
zl a
40 Lj
0
d.1 .dl .OOl
PARTICLE SIZE-MILLIMETERS
BORINQ NO. DEPTH (FEET) SYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION
4 20.0-22.0 0 33.1 13.6 SC-CLAYEY SAND (ALLUVIUM)
_-
-
-.
-
-
-
-
-,.
-
-
q ORINQ DEPTH COHESION. ANOLE OF SAMPLE DESCRIPTIOI NO. (FEET) (PSFI FRICTION?
I I
WHITE FINE TO MEDIUM SAND 2 4000 10 0 36
NORMAL LOAD (PSF)
4000
3000
ii
5
E
:
NORMAL LOAD (PSFI
108 NO.: SHEARING STRENGTH TEST FIGURE:
IS-4879-016-0o-oo C-6
I B”t?P DEPTH CO;p~~\ON. ANQLE 0% SAMPLE DESCRIPTION (FEET) FRICTION. I >..I I -4 BROWN FINE TO MEDIUM SILTY SAND 3 4000. 20 ( 4”” I a1 I
-
3000 - -
c
2
I - L Q
.-
-
NORMAL LOAD (PSF)
BORINQ DEPTH SAMPLE DESCRIPTION 1
4000 4000
3000 3000
2000 2000
1000 1000
0 0
NORMAL LOAD (PSF)
JOB NO.: s-4879-0 15-00-00 SHEARING STRENGTH TEST FIGURE:
- C-Q
-.
-
-.
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-.
TABLE C-l
Maximum Density/Optimum Moisture Relationships
(ASTM D 1557-78)
SAMPLE MAXIMUM OPTIMUM MOISTURE LOCATION DRY DENSITY (PCF) CONTENT (%)
B-2 @ 20' 112.4 15.5
B-3 @ 2' 118.4 11.8
TABLE C-2
Results of Expansion Tests
(UBC Method 29-2)
SAMPLE LOCATION
B-2 @ 20'
B-3 @ 2'
B-2 @ 34'
EXPANSION INDEX
120
28
124
EXPANSION
POTENTIAL
HIGH
LOW
HIGH
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-.
TABLE C-3
Results of Soluble Sulfate Tests
(EPA 300)
SAMPLE SOLUBLE MCATION SULFATE (%)
B-3 @ 20' > 400 < 800
B-3 @ 1' > 400 < 800
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APPENDIX D
Quantities of Remedial Earthwork
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APPENDIX D
QUANTITIES OF REMEDIAL EARTBWORE
Analysis of Field Data and Methods of Calculation
Our estimates of remedial grading quantities in the
proposed fill area for Unit 3 were based on the 80 scale
tentative grading plan prepared by Bodas Engineering,
Inc. Materials requiring remedial removal consist of alluvium in canyon bottoms and colluvium and topsoil on
slopes.
Logs of the test pits are shown in Appendix B as Figures 9 through 15. Remedial removal depths measured in the test pits were recorded and mapped. An average removal
depth of 3 feet was used for topsoil/colluvium areas outside alluvial areas.
The mapped boundary between alluvial removal areas was
arbitrarily defined as the approximate boundary between a slope and a canyon where remedial removal depths reach
approximately 3 feet. This contact was extrapolated from
our field data and is shown on the Geotechnical Map. A
typical cross-section of a canyon illustrating the boundary between an alluvium removal area, and a colluvium and topsoil removal area is shown on Figure D-
1. Typical canyon cleanout areas, and bedrock benching
are also shown on Figure D-l.
Our procedure for developing the remedial quantity figures utilized a digital planimeter to measure mapped
areas, which were multiplied by the appropriate average removal depths. Alluvial depths were extrapolated between test pit data. Average depths were assigned to map areas to calculate cubic yards of removal.
-,
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-~
.-
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v Itemized Tall
The total estimated quantity of remedial earthwork in
Unit 3 is estimated to be 358,000 cubic yards as shown in Table 2.
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Table 2 Removal Quantities for Unit 3
Alluvium (Canyon bottoms) 155,000 cubic yards
Colluvium&Topsoil (Slopes in fill areas) 203,000 cubic yards Total 358,000 cubic yards
The quantities shown include weathered bedrock materials
expected to be removed within the mapped boundaries,
however these quantities do not include benches excavated into bedrock or convenience removals of bedrock to widen
canyon bottoms or haul routes.
Limitations of Investiaation of Remedial Ouantities
Quantities of earth materials were derived as a result
of our field exploration. Assumed depths were extrapolated between test pits and borings, and were
extrapolated up canyon sides to intercept cut/fill
daylights. These quantities are intended to be used for
estimating purposes only.
Final removal depths should be determined in the field during grading by the geotechnical consultant.
Variations in anticipated subsurface conditions as well as methods of field measurements will affect final earthwork quantities.
I I I / ! i I , / I I I I I / I I I
r DAYLIGHT
f- Ocol 6 TOPSOIL
ESTIMATED CENTE CANYON DEPTH
3 FEET
(ARBITRARY) BEDROCK BENCHES
CANYON BENCHES AND
CLEANOUT AREA
TYPICAL CANYON CROSS-SECTION 36 NO.: DATE: FIGURE: - - -_ 1989 D-l
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APPENDIX E
Standard Grading Guidelines
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STANDARD GUIDELINES FOR GRADING PROJECTS
1. GENERAL
1.1
1.2
1.3
1.4
1.5
1.6
Representatives of the Geotechnical Consultant should be present on-site during grading operations in order to make observations and perform tests so that professional opinions can be developed. The opinion will address whether grading has proceeded in accordance with the Geotechnical Consultant's recommendations and applicable project specifications: if the site soil and geologic conditions are as anticipated in the preliminary investigation; and if additional recommendations are warranted by any unexpected site conditions. Services do not include supervision or direction of the actual work of the contractor, his employees or agents.
The guidelines contained herein and the standard details attached hereto represent this firm's standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a portion of the report to which they are appended.
All plates attached hereto shall be considered as part of these guidelines.
The Contractor should not vary from these guidelines without prior recommendation by the Geotechnical Consultant and the approval of the Client or his authorised representative.
These Standard Grading Guidelines and Standard Details may be modified and/or superseded by recommendations contained in the text of the preliminary geotechnical report and/or subsequent reports.
If disputes arise out of the interpretation of these grading guidelines or standard details, the Geotech- nical Consultant should determine the appropriate interpretation.
2. DEFINITIONS OF TERMS
2.1 ALLUVIUM -- Unconsolidated detrital deposits resulting from flow of water. including sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes and estuaries.
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2.2
2.3
2.1,
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
AS-GRADED (AS-BUILT) -- The surface and subsurface conditions at completion of grading.
BACKCUT -- A temporary construction slope at the rear of earth retaining structures such as buttresses, shear keys, stabilization fills or retaining walls.
BACKDRAIN -- Generally a pipe and gravel or similar drainage system placed behind earth retaining structures such buttresses, stabilization fills, and retaining walls.
BEDROCK -- A more or less solid, relatively undis- turbed rock in place either at the surface or beneath superficial deposits of soil.
BENCH -- A relatively level step and near vertical rise excavated into sloping ground on which fill is to be placed.
BORROW (Import) -- Any fill material hauled to the project site from off-site areas.
BUTTRESS FILL -- A fill mass, the configuration of which is designed by engineering calculations to retain slope conditions containing adverse geologic features. A buttress is generally specified by minimum key width and depth and by maximum backcut angle. A buttress normally contains a backdrainage system.
CIVIL ENGINEER -- The Registered Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topographic conditions.
COLLUVIUM -- Generally loose deposits usually found near the base of slopes and brought there chiefly by gravity through slope continuous downhill creep (also see Slope Wash).
COMPACTION -- Is the densification of a fill by mechanical means.
CONTRACTOR -- A person or company under contract or otherwise retained by the Client to perform demolation. grading and other site improvements.
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2.13
2.14
2.15
2.16
2.17
2.18
2.19
2.20
2.21
2.22
2.23
DEBRIS -- All products of clearing, grubbing, demolition, contaminated soil material unsuitable for reuse as compacted fill and/or any other material so designated by the Geotechnical Consultant.
ENGINEERING GEOLOGIST -- A Geologist holding a valid certificate of registration in the specialty of Engineering Geology.
ENGINEERED FILL -- A fill of which the Geotechnical Consultant or his representative, during grading. has made sufficient tests to enable him to conclude that the fill has been placed in substantial compliance with the recommendations of the Geotechnical Consultant and the governing agency requirements.
EROSION -- The wearing away of the ground surface as a result of the movement of wind, water, and/or ice.
EXCAVATION -- The mechanical removal of earth materials.
EXISTING GRADE -- The ground surface configuration prior to grading.
FILL -- Any deposits of soil, rock, soil-rock blends or other similar materials placed by man.
FINISH GRADE -- The ground.surface configuration at which time the surface elevations conform to the approved plan.
GEOFABRIC -- Any engineering textile utilized in geotechnical applications including subgrade stabilization and filtering.
GEOLOGIST -- A representative of the Geotechnical Consultant educated and trained in the field of geology.
GEOTECHNICAL CONSULTANT -- The Geotechnical Engineer- ing and Engineering Geology consulting firm retained to provide technical services for the project. For the purpose of these guidelines, observations by the Geotechnical Consultant include observations by the Geotechnical Engineer, Engineering Geologist and those performed by persons employed by and responsible to the Geotechnical Consultants.
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2.24
2.25
2.26
2.27
2.28
2.29
2.30
2.31
2.32
2.33
2.34
GEOTECHNICAL ENGINEER -- A licensed Civil Engineer who applies scientific methods, engineering principles and professional experience to the acquisition, inter- pretation and use of knowledge of materials of the earth's crust for the evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology, geophysics, hydrology and related sciences.
GRADING -- Any operation consisting of excavation, filling or combinations thereof and associated operations.
LANDSLIDE DEBRIS -- Material, generally porous and of low density, produced from instability of natural of man-made slopes.
MAXIMUM DENSITY -- Standard laboratory test for maximum dry unit weight. Unless otherwise specified, the maximum dry unit weight shall be determined in accordance with ASTM Method of Test D1557.
OPTIMUM MOISTURE -- Test moisture content at the maximum density.
RELATIVE COMPACTION -- The degree of compaction (expressed as a percentage) of dry unit weight of a material as compared to the maximum dry unit weight of the material.
ROUGH GRADE -- The ground surface configuration at which time the surface elevations approximately conform to the approved plan.
SITE -- The particular parcel of land where grading is being performed.
SHEAR KEY -- Similar to buttress, however, it is generally constructed by excavating a slot within a natural slope in order to stabilize the upper portion of the slope without grading encroaching into the lower portion of the slope.
SLOPE -- Is an inclined ground surface the steepnqss of which is generally specified as a ratio of horizontal:vertical (e.g., 2:l).
SLOPE WASH -- Soil and/or rock material that has been transported down a slope by mass wasting assisted by
runoff water not confined by channels (also see Colluvium).
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2.35
2.36
2.37
2.38
2.39
2.40
2.41
2.42
2.43
SOIL -- Naturally occurring deposits of sand, silt, clay, etc., or combinations thereof.
SOIL ENGINEER -- Licensed Civil Engineer experienced in soil mechanics (also see Geotechnical Engineer).
STABILIZATION FILL -- A fill mass, the configuration of which is typically related to slope height and is specified by the standards of practice for enhancing the stability of locally adverse conditions. A stabilization fill is normally specified by minimum key width and depth and by maximum backcut angle. A stabilization fill may or may not have a backdrainage system specified.
SUBDRAIN -- Generally a pipe and gravel or similar drainage system placed beneath a fill in the alignment of canyons or former drainage channels.
SLOUGH -- Loose, noncompacted fill material generated during grading operations.
TAILINGS -- Nonengineered fill which accumulates on or adjacent to equipment haul-roads.
TERRACE -- Relatively level step constructed in the face of graded slope surface for drainage control and maintenance purposes.
TOPSOIL -- The presumably fertile upper zone of soil which is usually darker in color and loose.
WINDROW -- A string of large rock buried within engineered fill in accordance with guidelines set forth by the Geotechnical Consultant.
3. SITE PREPARATION
3.1 Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, roots to trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas.
3.2 Demolition should include removal of buildings, struc- tures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, tunnels, etc.) and other man-made surface and subsurface improvements
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from the areas to be graded. Demolition of utilities should include proper capping and/or re-routing pipe- lines at the project perimeter and cutoff and capping of wells in accordance with the requirements of the governing authorities and the recommendations of the Geotechnical Consultant at the time of demolition.
3.3 Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed off-site. Clearing, grubbing and demolition operations should be performed under the observation of the Geotechnical Consultant.
4. SITE PROTECTION
4.1
4.2
4.3
4.4
4.5
The Contractor should be responsible for the stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary excavations (e.g., backcuts) are made in consideration of stability of the completed project and, therefore, should not be considered to preclude the responsibil- ities of the Contractor. Recommendations by the Geotechnical Consultant should not be considered to preclude more restrictive requirements by the regulating agencies.
Precautions should be taken during the performance of site clearing, excavations and grading to protect the work site from flooding, ponding or inundation by poor or improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site.
During periods of rainfall, the Geotechnical Consultant should be kept informed by the Contractor as to the nature of remedial or preventative work being performed (e.g., pumping:. placement of sandbags or plastic sheeting, other labor, dozing, etc.).
Following periods of rainfall, the Contractor should contact the Geotechnical Consultant and arrange a review of the site in order to visually assess rain related damage. The Geotechnical Consultant may also recommend excavations and testing in order to aid in his assessments.
Rain related damage should be considered to include, but may not be limited to, erosion. silting. saturation, swelling, structural distress and other
adverse conditions identified by the Geotechnical
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Consultant. Soil adversely affected should be classified as Unsuitable Materials and should be subject to overexcavation and replacement with compacted fill or other remedial grading as recommended by the Geotechnical Consultant.
5. EXCAVATIONS
5.1 UNSUITABLE MATERIALS
5.1.1 Materials which are unsuitable should be excavated under observation and recommendations of the Geotechnical Consultant. Unsuitable materials include, but may not be limited to, dry, loose. soft, wet. organic compressible natural soils and fractured, weathered, soft bedrock and nonengineered or otherwise deleterious fill materials.
5.1.2 Material identified by the Geotechnical Consultant as unsatisfactory due to its moisture conditions-should be overexcavated, watered or dried, as needed. and thoroughly blended to a uniform near optimum moisture condition (as per guidelines reference 7.2.1) prior to placement as compacted fill.
5.2 CUT SLOPES
5.2.1 Unless otherwise recommended by the Geotech- nical Consultant and approved by the regulating agencies, permanent cut slopes should not be steeper than 2:l (horizontal:vertical).
5.2.2 If excavations for cut slopes expose loose, cohesionless, significantly fractured or otherwise unsuitable material, overexcavation and replacement of the unsuitable materials with a compacted stabilization fill should be accomplished as recommended by the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant, stabilization fill construction should conform to the requirements of the Standard Details.
5.2.3 The Geotechnical Consultant should review cut slopes during excavation. The Geotechnical Consultant should be notified by the contractor prior to beginning slope excavations.
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5.2.4 If. during the course of grading. adverse or potentially adverse geotechnical conditions are encountered which were not anticipated in the preliminary report, the Geotechnical Consultant should explore. analyze and make recommen- dations to treat these problems.
6. COMPACTED FILL
All fill materials should be compacted to at least 90 percent of maximum density (ASTM D1557) unless otherwise recommended by the Geotechnical Consultant.
6.1 PLACEMENT
6.1.1 Prior to placement of compacted fill. the Contractor should request a review by the Geotechnical Consultant of the exposed ground surface. Unless otherwise recommended, the exposed ground surface should then be scarified (6-inches minimum), watered or dried as needed, thoroughly blended to achieve near optimum moisture conditions. then thoroughly compacted to a minimum of 90 percent of the maximum density.
6.1.2 Compacted fill should be placed in thin horizontal lifts. Each lift should be watered or dried as needed,~blended to achieve near optimum moisture conditions then compacted by mechanical methods to a minimum of 90 percent of laboratory maximum dry density. Each lift should be treated in a like manner until the desired finished grades are achieved.
6.1.3 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1 (horizontal: vertical), horizontal keys and vertical benches should be excavated into the adjacent slope area. Keying and benching should be sufficient to provide at least 6-foot wide benches and a minimum of 4-feet of vertical bench height within the firm natural ground, firm bedrock or engineered compacted fill. No compacted fill should be placed in an area subsequent to keying and benching until the area has been reviewed by the Geotechnical Consultant. Material generated by the benching operation should be moved sufficiently away from the bench area to allow for the recommended review
of the horizontal bench prior to placement
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fill. Typical keying and benching details have been included within the accompanying Standard Details.
6.1.4 Within a single fill area where grading procedures dictate two or more separate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to a false slope, benching should be conducted in the same manner as above described. At least a 3-foot vertical bench should be established within the firm core adjacent approved compacted fill prior to placement of additional fill. Benching should proceed in at least 3-foot vertical increments until the desired finished grades are achieved.
6.1.5 Fill should be tested for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to accepted test methods. Density testing frequency should be adequate for the geotechnical consultant to provide professional opinions regardings-fill compaction and adherence to recommendations. Fill found not to be in conformance with the grading recommendation should be removed or otherwise handled as recommended by the Geotechnical Consultant.
6.1.6 The Contractor shou~ld assist the Geotechnical Consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill.
6.1.7 As recommended by the Geotechnical Consultant, the Contractor may need to remove grading equipment from an area being tested if personnel safety is considered to be a problem.
6.2 MOISTURE
6.2.1 For field testing purposes "near optimum" moisture will vary with material type and other factors including compaction procedure. "Near optimum" may be specifically recommended in Preliminary Investigation Reports and/or may be evaluated during grading.
6.2.2 Prior to placement of additional compacted fill following an overnight or other grading delay, the exposed surface or previously compacted
Standard Guidelines for Grading Projects Page 10
6.2.3
fill should be processed by scarification, watered or dried as needed, thoroughly blended to near-optimum moisture conditions, then recompacted to a minimum of 90 percent of laboratory maximum dry density. Where wet, dry, or other unsuitable materials exist to depths of greater than one foot, the unsuitable materials should be overexcavated.
Following a period of flooding, rainfall or overwatering by other means, no additional fill should be placed until damage assessments have been made and remedial grading performed as described under Section 5.6 herein.
6.3 FILL MATERIAL
6.3.1
6.3.2
6.3.3
6.3.4
Excavated on-site materials which are considered suitable to the Geotechnical Consultant may be utilized as compacted fill, provided trash, vegetation and other deleterious materials are removed prior to placement.
Where import fill materials are required for use on-site, the Geotechnical Consultant should be notified in advance of importing, in order to sample and test materials from proposed borrow sites. No import fill materials should be delivered for use on-site without prior sampling and testing notification by Geotechnical Consultant.
Where oversized rock or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off-site or on-site in areas designated as "nonstructural rock disposal areas". Rock placed in disposal areas should be placed with sufficient fines to fill voids. The rock should be compacted in lifts to an unyielding condition. The disposal area should be covered with at least three feet of compacted fill which is free of oversized material. The upper three feet should be placed in accordance with the guidelines for compacted fill herein.
Rocks 12 inches in maximum dimension and smaller may be utilized within the compacted fill, provided they are placed in such a manner
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that nesting of the rock is avoided. Fill should be placed and thoroughly compacted over and around all rock. The amount of rock should not exceed 40 percent by dry weight passing the 3/4-inch sieve size. The 12-inch and 40 percent recommendations herein may vary as field conditions dictate.
6.3.5 Where rocks or similar irreducible materials of greater than 12 inches but less than four feet of maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the accompanying Standard Details is recommended. Rocks greater than four feet should be broken down or disposed off-site. Rocks up to four feet maximum dimension should be placed below the upper 10 feet of any fill and should not be closer than 20-feet to any slope face. These recommen- dations could vary as locations of improvements dictate. Where practical, oversized material should not be placed below areas where structures or deep utilities are proposed. Oversized material should be placed in windrows on a clean, overexcavated or unyielding compacted fill or firm natural ground surface. Select native or imported granular soil (S.E. 30 or higher) should be placedoughly flooded over and around all windrowed rock, such that voids are filled. Windrows of oversized material should be staggered so that successive strata of oversized material are not in the same vertical plane.
6.3.6 It may be possible to dispose of individual larger rock as field conditions dictate and as recommended by the Geotechnical Consultant at the time of placement.
6.3.7 The construction of a "rock fill" consisting primarily of rock fragments up to two feet in maximum dimension with little soil material may be feasible. Such material is typically generated on sites where extensive blasting is required. Recommendations for construction of rock fills should be provided by the Geotechnical Consultant on a site-specific basis.
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6.3.8 During grading operations, placing and mixing the materials from the cut and/or borrow areas may result in soil mixtures which possess unique physical properties. Testing may be required of samples obtained directly from the fill areas in order to determine conformance with the specifications. Processing of these additional samples may take two or more working days. The Contractor may elect to move the operation to other areas within the project, or may continue placing compacted fill pending laboratory and field test results. Should he elect the second alternative, fill placed is done so at the Contractor's risk.
6.3.9 Any fill placed in areas not previously reviewed and evaluated by the Geotechnical Consultant may require removal and recom- paction. Determination of overexcavations should be made upon review of field conditions by the Geotechnical Consultant.
6.4 FILL SLOPES
6.4.1 Permanent fill slopes should not be constructed steeper than 2:l (horizontal to vertical), unless otherwise recommended by the Geotech- nical Consultant and approved by the regulating agencies.
6.4.2 Fill slopes should be compacted in accordance with these grading guidelines and specific report recommendations. Two methods of slope compaction are typically utilized in mass grading, lateral over-building and cutting back, and mechanical compaction to grade (i.e. sheepsfoot roller backrolling). Constraints such as height of slope, fill soil type, access, property lines, and available equipment will influence the method of slope construction and compaction. The geotechnical consultant should be notified by the contractor what method will be employed prior to slope construction.
Slopes utilizing over-building and cutting back should be constructed utilizing horizontal fill lifts (reference Section 6) with compaction equipment working as close to the edge as prac- tical. The amount of lateral over-building will vary as field conditions dictiate. Compaction testing of slope faces will be required and
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reconstruction of the slope may result if testing does not meet our recommendations.
Mechanical compaction of the slope to grade during construction should utilize two types of compactive effort. First, horizontal fill lifts should be compacted during fill placement. This equipment should provide compactive effort to the outer edge of the fill slope. Sloughing of fill soils should not be permitted to drift down the slope. Secondly, at intervals not exceeding four feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be backrolled with a sheepsfoot-type roller. Moisture conditions of the slope fill soils should be maintained throughout the compaction process. Generally upon slope completion, the entire slope should be compacted utilizing typical methods, (i.e. sheepsfoot rolling, bulldozer tracking, or rolling with rubber-tired heavy equipment). Slope construction grade staking should be removed as soon as possible in the slope compaction process. Final slope compaction should be performed without grade sakes on the slope face.
In order to monitor slope construction procedures, moisture and density tests will be taken at regular intervals. Failure to achieve the desired results will likely result in a recommendation by the Geotechnical Consultant to overexcavate the slope surfaces followed by reconstruction of the slopes utilizing over- filling and cutting back procedures or further compactive effort with the conventional backrolling approach. Other recommendations may also be provided which would be commensurate with field conditions.
6.4.3 Where placement of fill above a natural slope or above a cut slope is proposed, the fill slope configuration as presented in the accompanying Standard Details should be adopted.
6.4.4 For pad areas above fill slopes, positive drainage should be established away from the top-of-slope, as designed by the project civil engineer.
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6.5 OFF-SITE FILL
6.5.1 Off-site fill should be treated in the same manner as recommended in the specifications for site preparation, excavation, drains, compaction, etc.
6.5.2 Off-site canyon fill should be placed in preparation for future additional fill, as shown in the accompanying Standard Details.
6.5.3 Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for future relocation and connection.
6.6 TRENCH BACKFILL
6.6.1 Utility trench backfill should, unless other- wise recommended, be compacted by mechanical means. Unless otherwise recommended! the degree of compaction should be a minimum of 90
percent of maximum density (ASTM D1557).
6.6.2 Backfill of exterior and interior trenches extending below a 1:l projection from the outer edge of foundations should be mechanically compacted to a minimum of 90 percent of the laboratory maximum density.
6.6.3 Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two feet deep may be backfilled with sand (S.E. > 30), and consolidated by jetting, flooding or by mechanical means. If on-site materials are utilized, they should be wheel-rolled, tamped or otherwise compacted to a firm condition. For minor interior trenches, density testing may be deleted or spot testing may be elected if deemed necessary, based on review of backfill operations during construction.
6.6.4 If utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, the Contractor may elect the utilization of light weight mechanical compaction equipment and/or shading of the conduit with clean, granular material, (S.E. > 30) which should be thoroughly moistened in the trench, prior to
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initiating mechanical compaction procedures. Other methods of utility trench compaction may
also be appropriate, upon review of the Geotechnical Consultant at the time of construction.
6.6.5 In cases where clean granular materials are proposed for use in lieu of native materials or where flooding or jetting is proposed, the procedures should be considered subject to review by the Geotechnical Consultant.
6.6.6 Clean granular backfill and/or bedding are not recommended in slope areas unless provisions are made for a drainage system to mitigate the potential build-up of seepage forces and piping.
7. DRAINAGE
7.1
7.2
7.3
7.4
Canyon subdrain systems recommended by the Geotechnical Consultant should be installed in accordance with the Standard Details.
Typical subdrains for compacted fill buttresses, slope stabilizations or sidehill masses, should be installed in accordance with the specifications of the accompanying Standard Details.
Roof, pad and slope drainage should be directed away from slopes and areas of structures to disposal areas via suitable devices designed by the project civil engineer (i.e., gutters, downspouts, concrete swales, area drains, earth swales, etc.).
Drainage patterns established at the time of fine grading should be maintained throughout the life of the project. Property owners should be made aware that altering drainage patterns can be detrimental to slope stability and foundation performance.
a. SLOPE MAINTENANCE
a.1 LANDSCAPE PLANTS
In order to decrease erosion surficial slope stability problems, slope planting should be accomplished at the completion of grading. Slope planting should consist of deep-rooting vegetation requiring little watering. A Landscape Architect would be the test party to consult regarding actual types of plants and planting configuration.
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a.2 IRRIGATION
8.2.1 Slope irrigation should be minimized. If automatic timing devices are utilized on irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall.
8.2.2 Property owners should be made aware that overwatering of slopes is detrimental to slope stability and may contribute to slope seepage, erosion and siltation problems in the subdivision.
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16’ MINIMUM
7
4. DIAMETER PERFORATED
PIPE BACKDRAIN
4’ DIAMETER NON-PERFORATED
PIPE LATERAL DRAIN
SLOPE PER PLAN- \ BENCHIND
“ll.., , 4.
l ------
I/ ///p ///z ig ’ \ F\
L-PROVIDE BACKDRAIN PER BACKDRAIN
DETAIL. AN ADDITIONAL BACKDRAIN
AT MID-SLOPE WILL BE REOUIRED FOR
SLOPE IN EXCESS OF 40 FEET HIGH.
LKEY-DIMENSIONSPER SOILS ENQINEER
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PROVIDE SACKDRAIN PER/
SACKDRAIN DETAIL. AN
ADDITIONAL SACKDRAIN
REQUIRED FOR BACK
SLOPES IN EXCESS OF
40 FEET HIGH. LOCA-
TIONS OF SACKDRAINS
AND OUTLETS PER SOILS
ENGINEER AND/OR EN-
GINEERING GEOLOGIST
DURING GRADING.
L BASE WIDTH ‘W’ DETERMINED
BY SOILS ENGINEER
TYPICAL SHEAR KEY DETAIL I JOB NO.: DATE:
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OVEREXCAVATE
FINAL LIMIT OF DAYLIGHT
EXCAI VA TION L IN E
/
FINISH PAD
I i / OVEREXCAVATE- \ ,
3’ AND REPLACE
WITH COMPACTED
SOUND BEDROCK -
- / %4---\-- \ \
XL, :=I\ - ATYPICAL SENCH~NG
LOVERBURDEN
(CREEP-PRONE) SACKDRAIN PER SACKDRAIN
DETAIL. LOCATION OF BACKDRAIN AND
OUTLETS PER SOILS ENGINEER AND/OR
ENGINEERINQ GEOLOGIST DURING
GRADING
EOUIPMENT WIDTH (MINIMUM 15’)
DAYLIGHT SHEAR KEY DETAIL
30 NO.:
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BENCHING FILL OVER NATURAL
SURFACE OF FIRM
EARTH MATERIAL
FILL SLOPE
A- l
TY;:CAL
k
IO’ MIN. (INCLINED 2% MIN. 1~~0 SLOPE)
BENCHING FILL OVER CUT
FINISH FILL SLOPE
SURFACE OF FIRM EARTH MATERIAL
TYPICAL
16’ MIN. OR STABILITY EQUIVALENT PER SOIL
ENGINEERING (INCLINED 2% MIN. INTO SLOPE)
BENCHING FOR COMPACTED FILL DETAIL
JOB NO.: DATE: FIGURE: _ - -- AUGUST 1989 4’
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FINISH SURFACE SLOPE FINISH SURFACE SLOPE
3 FT3 MINIMUM PER LINEAL FOOT 3 FT3 MINIMUM PER LINEAL FOOT
APPROVED FILTER ROCK* APPROVED FILTER ROCK*
COMPACTED FILL COMPACTED FILL
4’ MINIMUM DIAMETER
SOLID OUTLET PIPE
SPACED PER SOIL
ENGINEER REOUIRE-
MENTS DURING GRADING
4’ MINIMUM APPROVED
PERFORATED PIPE**
(PERFORATIONS DOWN)
MINIMUM 2% GRADIENT
TO OUTLET
BENCH INCLINED TOWARD
DRAIN
TYPICAL BENCHING
DETAIL A-A
TEMPORARY FILL LEVEL
12. MlNlMUM COVER
4
C
I
OMPACTED
k-
4’ MINIMUM DIAMETER
BACKFILL APPROVED SOLID
OUTLET PIPE
12’ MINIMUM-
**APPROVED PIPE TYPE:
SCHEDULE 40 POLYVINYL CHLORIDE
(P.V.C.) OR APPROVED EQUAL.
MINIMUM CRUSH STRENGTH 1000 PSI.
*FILTER ROCK TO MEET FOLLOWING
SPECIFICATIONS OR APPROVED EOUAL
SIEVE PERCENTAGE PASSlN(
1. 100
3/4’ 30-100
318’ 40-100
NO.4 25-40
NO.30 5-15
NO.60 o-7
NO.200 o-3
TYPICAL BACKDRAIN DETAIL
OB NO.: DATE: FIGURE: - - -_ AUC’JST 1989 5~
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FINISH SURFACE SLOPE
MINIMUM 3 FT3 PER LINEAL FOOT MINIMUM 3 FT3 PER LINEAL FOOT
OPEN GRADED AQGREGATE* OPEN GRADED AGGREGATE*
TAPE AND SEAL AT CONTACT TAPE AND SEAL AT CONTACT
COMPACTED FILL COMPACTED FILL
- SUPAC S-P FABRIC OR SUPAC S-P FABRIC OR
APPROVED EQUAL
4’ MINIMUM DIAMETER
SOLID OUTLET PIPE
SPACED PER SOIL
ENQINEER REQUIREMENTS
4” MINIMUM APPROVED
PERFORATED PIPE
(PERFORATIONS DOWN)
MINIMUM 2% GRADIENT
TO OUTLET
SENCU INCLINED
BENCHING TOWARD DRAIN
DETAIL A-A
/-
TEMPORARY FILL LEVEL
I / 1 9
COMPACTED MINIMUM BACKFILL 12” COVER MINIMUM 4” DIAMETER APPROVED
SOLID OUTLET PIPE
*NOTE: AGGREGATE TO MEET FOLLOWINQ
SPECIFICATIONS OR APPROVED EOUAL:
SIEVE SIZE PERCENTAQE PASSING
1 112” 100
I” 5-40
314’ O-17
3/S” o-7
NO. 200 o-3
BACKDRAIN DETAIL (GEOFABRIC)
JOB NO.: DATE: FIGURE:
-
-
.-
_-
-
-
-
_-
-
. .
,-
-
.-
-
CANYON SUBDRAIN DETAILS
SURFACE OF
FIRM EARTH
COMPACTED FILL /
TYPICAL BENCHING REMOVE UNSUITABLE
MATERIAL
INCLINE TOWARD DRAIN
SEE DETAILS BELOW
TRENCH DETAIL
6’ MINIMUM OI --
OPTIONAL V-DITCH DETAIL
SUPAC 8-P FABRIC
OR APPROVED
ILAP -
-MINIMUM 6 FT3 PER LINEAL
FOOT OF APPROVED DRAIN
MATERIAL
ISUPAC S-P FABRIC OR
APPROVED EQUAL
DRAIN MATERIAL SHOULD
CONSIST OF MINUS 1.5’. MINUS I’, OR MINUS .75’
CRUSHEDROCK
MINIMUM 6 FT3 PER LINEAL FOOT
MINIMUM OF APPROVED DRAIN MATERIAL
8O’TO SO’
ADD MINIMUM 4’ DIAMETER
APPROVED PERFORATED
PIPE WHEN LARGE FLOWS
ARE ANTICIPATED
APPROVED PIPE TO BE
SCHEDULE 40 POLY-VINYL-
CHLORIDE (P.V.C.) OR
APPROVED EOUAL. MINIMUM
CRUSH STRENGTH 1000 psi.
GEOFABRIC SUBDRAIN
IOB NO.: DATE: FIQURE: 05-4879-015-00-00 AUGUST 1989 7’
-
-
-
,,-
.-
.-
.-
--
.-
-
.~-
-
-~
/-
FINAL GRADE
/
/ f ~~EG~~Di:p,‘,,“:owN
/
WIDTH VARIES
COMPETENT EARTH
MATERIAL
TYPICAL BENCH
HEIGHT
DOWNSLOPE
KEY DEPTH
/ LIMIT OF KEY
EXCAVATION
PROVIDE SACKDRAIN AS
REQUIRED PER RECOM-
MENDATIONS OF SOILS
ENGINEER DURINQ QRADINQ
WHERE NATURAL SLOPE GRADIENT IS S:l OR LESS.
BENCHING IS NOT NECESSARY. HOWEVER. FILL IS
NOT TO SE PLACED ON COMPRESSIBLE OR UNSUIT-
ABLE MATERIAL.
FILL SLOPE ABOVE NATURAL GROUND DETAIL
08 NO.:
/ I I I I I I I t / ! \ I I / / 1
REMOVE ALL TOPSOIL. COLLUVIUM
AND CREEP MATERIAL FROM
TRANSITION
CUT/FILL CONTACT SHOWN
ON QRAOINQ PLAN
CUT/FILL CONTACT SHOWN
ON l AS-BUILT’
FOUNDATION MATERIAL
*NOTE: CUT SLOPE PORTION SHALL BE MADE
PRIOR TO PLACEMENT OF FILL
OB NO.:
FILL SLOPE ABOVE CUT SLOPE DETAIL
-~ GENERAL GRADING RECOMMENDATIONS
-
CUT LOT
-
-
-- ORIQINAL
QROUND
TOPSOIL. COLLUVIUM AND
WEATHERED BEDROCK,,’
,.
OVEREXCAVATE AND
UNWEATHERED BEDROCK REQRADE
CUT/FILL LOT (TRiNSITION)
- - . ORIGINAL
~~0 GROUND _.HY I
. . ,’
.- .-
-.’
/ //////////A 1
.- COMPACTED FILL
-
OVEREXCAVATE AND
/COLLUVIUM AND ,
WEATHERED I UNWEATHERED BEDROCK
-
-
.-
-
-
-
-
__
-~
-,
-
BUILDING
FINISHED GRADE
6’ OR BELOW DEPTH OF
DEEPEST UTILITY TRENCH
(WHICHEVER GREATER)
TYPICAL WINDROW DETAIL (EDGE VIEW)
L FLOODED
PROFILE VIEW
ROCK DISPOSAL DETAIL
JOG NO.: DATE: FIGURE: - a a-~ AU-9 11~.