HomeMy WebLinkAboutCT 81-10; Carlsbad Research Cntr Phase 2 & 3; Supplemental Preliminary Geotechnical Investigation; 1982-07-26e 2.8s- 37
SAN DIEGO SOILS ENGINEERING, INC.
SOIL ENGINEERING & ENGINEERING GEOLOGY
- July 26, 1982
Carlsbad Research Center
San Diego, California 92111
7330 Engineer Road
Attention: Mr. Michael J. Dunigan
Job No: SD1162-00
Log No: SD2-2475
SUBJECT : SUPPLEMENTAL PRELIMINARY GEOTECHNICAL INVESTIGATION
Carlsbad Research Center, Phases I1 and I11
Carlsbad, California
Gentlemen :
- In accordance with your request, we have performed a Supple-
mental Preliminary Geotechnical Investigation of Carlsbad
Research Center, Phases I1 and 111. Our report, transmitted
- herein, presents our findings, conclusions and recommendations
for the proposed development. Accompanying the report are the various tables, figures and plates which summarize the results
of our investigation and the conclusions and recommendations.
Our preliminary findings have been discussed with a repre-
sentative of your firm, the design civil engineer, Rick
-
- Engineering, and other project.consultants.
c
This opportunity to be of service is sincerely appreciated.
this office.
If you have any questions concerning this report, please contact
Very truly yours,
SAN DIEGO SOILS ENGINEERING, INC.
&L+-* President
GFS : tcm
ENGINEERING DEPT. LIBRARY
2075 Las Palmas Drive Carlsbad CA 92009-4859
City of Carlsbad ~ ~~
6455 NANCY RIDGE DRIVE SUITE 2M) SAN DIEGO, CA 92121 (619) 567-0250
SUBSIDIARY OF IRVINE CONSULTING GROUP, INC.
SUPPLEMENTAL PRELIMINARY
GEOTECHNICAL INVESTIGATION
CARLSBAD RESEARCH CENTER
PHASES I1 AFID 111
PREPARED FOR
CARLSBAD RESEARCH CENTER
* 7330 ENGINEER ROAD
SAN DIEGO, CALIFORNIA 92111
PREPARED BY
SAN DIEGO SOILS ENGINEERING, INC,
4891 MERCURY STREET
SAH DIEGO, CALIFORNIA 92111
JULY 26, 1982
JOB NO: SD1162-00
LOG NG: SD2-2475
.
TABLE OF CONTENTS
__
.
..
.
I .
II .
111 .
I V .
V .
VI .
VI1 .
VI11 .
.
.
.
.
.
1x .
INTROUUCTION ................... 1
SITE UEVELOPMENT ................. 1
SCOPE OF SERVICES ................. 2
SITE DESCRIPTION ................. 3
FIELD INVESTIGATION ................ 5
LABORATORY TESTING ................ 6
GEOLOGY ..................... 7
A . Regional Geology ............... 7
B . Geologic Units ................ 7
1 . Santiago Peak Volcanics (map symbol-Jsp) . 7
2 . Point Loma Formation (map symbol-Kpl) . . 8
3 . Santiago Formation (map symbol-Tsa)
4 . Alluvium (map symbol-Qal) .....
5 . Fill ................
C . Structural Geology ...........
D . Ground Water ..............
SEISMICITY .................
A . Regional Seismicity ..........
B . Earthquake Effects ...........
... 9 ... 9 ... 9 ... 10 ... 10 ... 11 ... 11 ... 11
1 . Earthquake Accelerations ......... 11
2 . Settlement of Soils ........... 12
3 . Liquefaction ............... 12
4 . Lurching and Shallow Ground Rupture ... 12
ENGINEERING CONSIUERATIONS ............ 13
A . General Description of Soils/Bedrock ..... 13
1 . Santiago Peak Volcanics ......... 13
2 . Point Loma Formation ........... 13
3 . Topsoil ................. 14
4 . Alluvium ................. 15
B . Remedial Grading ............... 15
1 . Unsuitable Soils ............. 15
2 . Fill Keys ................ 15
3 . Stabilization Fills ........... 16
4 . Transition Lots ............. 16
.
.
TABLE OF CONTENTS
(continued) .
.
.
.
.
.
.
.
.
.
.
.
.
%
C . Expansive Soils ............... 17
D . Slopes ................... 18
E . Ground Water ................. 18
X . CUNCLUSIONS AND RECOMMENDATIONS .......... 19
A . General ................... 19
B . Grading and Earthwork ............ 19
1 . Clearing and Grubbing .......... 19
2 . .Site Preparation ............. 19
a . Treatment of Surface Soils ..... 19
b . Existing Fill Soils ......... 20
c . Treatment of Alluvium ........ 20
d . Scarification end Processing of
Surface .Soils ........... 20
3 . Bedrock/Soil Characteristics ....... 20
4 . Overexcavation of Transition Lots .... 21
5 . Compaction and Method of Filling ..... 22
6 . Selective Grading ............ 22
7 . Import Fill Material ........... 24
8 . Shrinkage. Bulking and Subsidence
9 . Rippability ...........
10 . Rock Disposal ..........
1 . Fill Slopes ...........
2 . Cut Slopes ............
C . Slopes ...............
a . Santiago Peak Volcanics ...
b . Point Lorna Formation ....
3 . Fill-Over-Cut Slopes .......
.... 24 .... 25 .... 25 .... 26 .... 26 .... 27 .... 27 .... 27 .... 28
4 . Stabilization/Buttress Fills ....... 29
~~ ~
5 . Construction Slopes ........... 29
6 . Natural Slopes .............. 29
D . Restriction on Future Construction ...... 30
E . Surface and Subsurface Drainage ....... 30
X.
TABLE OF CONTENTS
(continued)
F. Foundations and Slabs ............ 31
1. Expansive Soils ............. 31
2. Footing Setbacks. ............ 32
3. Soil Bearing Pressure .......... 32
4. Lateral Load Resistance ......... 33
G. Reta.ining Walls ............... 33
H. Type of Cement for Construction ....... 34
I. Pavements .................. 34
J. Utility Trench Backfill ........... 35
K. Grading Plan Review ............. 35
L. Geotechnical Observation. .......... 36
LIMITATIONS OF INVESTIGATION ............ 37
SUPPLEMENTAL PRELIMINARY GEOTECHNICAL INVESTIGATION
CARLSBAD RESEARCH CENTER, PHASE I1 AND 111
CARLSBAD, CALIFORNIA
I. INTRODUCTION
This report presents the results of our Supplemental Pre-
liminary Geotechnical Investigation of Phases I1 and I11
of Carlsbad Research Center, located in Carlsbad, Calif-
ornia. Our investigation was performed to provide geo-
technical data to aid in overall site planning and develop-
ment.
We were provided with 80 scale and 100 scale Grading Plans
prepared by Rick Engineering Company. The 80 scale grading
plans were utilized as the base map for the attached Geo-
technical Map, Plate No. 1. Our investigation was directed
toward development as shown on the grading plan.
11. SITE DEVELOPMENT
The proposed development consists of commercial, light
industrial and open space areas. Building pads will be
developed by conventional cut and fill grading techniques.
The locations of the proposed lots, streets and open space
areas are shown on the attached Geotechnical Map, Plate
No. 1.
Carlsbad Research Center
July 26, 1982 Job No: SD1162-00 Log NO: SD2-2475
Page Two
Ill. SCOPE OF SERVICES
The scope of services provided during the preparation of
this Supplemental Preliminary Geotechnical Investigation
included:
A.
B.
C.
D.
E.
F.
G.
H.
I.
Review of previous geologic, soils engineering and
seismological reports and maps pertinent to the pro-
ject area (See Appendix A) ;
Analysis of stereographic aerial photographs to eval-
uate the topography and geologic structure of the
area (See Appendix A) ;
Geologic mapping of existing exposures and outcrops;
Subsurface exploration, including six bucket auger
boring$ to a maximum depth of 51 feet and 38 backhoe
test pits excavated to a maximum depth of 14 feet;
Seismic traverses to evaluate rippability conditions;
Logging and sampling of exploratory excavations to
evaluate the geologic structure and to obtain ring
and bulk samples for laboratory testing;
Laboratory testing of samples representative of those
obtained during the field investigation;
Geologic and soils engineering analyses of field and
laboratory data which provide the basis for our con-
clusions and recommendations;
Preparation of this report and accompanying maps,
cross sections and other graphics presenting our
findings, conclusions and recommendations.
Carlsbad Research Center July 26, 1982 Job No: SD1162-00 Log NO: SD2-2475 Page Three
1V. SITE DESCRIPTION
Phases I1 and I11 of Carlsbad Research Center consist of
an irregularly shaped parcel located in Carlsbad, Califor-
nia. The location and topography are shown on the
attached Location Map, Figure 1. The site is bounded on
the east by the recently developed Carlsbad Research Center,
Phase I and on the south by McClellan-Palomar Airport.
Undeveloped areas are present north and west of the site.
Topographically, the site consists of a relatively low
relief area with steeply descending slopes located near
the western and northern boundaries. Natural slopes with-
in the project very from nearly flat to 1.5:l (horizontal
to vertical) or steeper on the canyon sidewalls within
the northern portion of the property. Maximum relief for
the site is about 155 feet with elevations ranging from
approximately 170 to 325 feet above mean sea level.
Drainage on-site is divided by an east-west trending ridge-
line. Drainage south of the ridgeline is to the west along
generally broad drainage courses. North of the ridgeline,
drainage is to the north along steeply descending Letter-
box Canyon and its tributaries.
Access to the site is along unimproved roads from the
existing Carlsbad Research Center Phase I, from El Camino
Real to the north and from Palomar Airport Road to the
southwest.
Portions of the site have been modified by clay mining
operation. Open pit excavations and associated spoil
piles are present on the east-west trending ridgeline.
Carlsbad Research Center
July 26, 1982
Job No: SD1162-00 Log NO: SD2-2475 Page Four
Several concrete truckloading/hopper structures associated
with the mining operation are also present.
Two low height earth embankments are present along the
southern drainage course within the western portion of
the property. Other man-made features on the site consist
of unimproved roads, buried pipelines along existing ease-
ments and minor amount of end-dumped debris and trash.
Minor amounts of fill associated with existing access roads
are located across the site.
At the time of our investigation, a heavy growth of tall
grasses and weeds covered most of the site. Some high
brush was present in the northern drainage courses.
Carlsbad Research Center
July 26, 1982
V. FIELD INVESTlGATIUN
Job No: SD1162-00
Log NO: 5132-2475 Page Five
The field investigation performed during the course of
this investigation consisted of geologic reconnaissance,
mapping and subsurface investigation consisting of six
drilled bucket auger borings, thirty-eight backhoe test
pits and five seismic traverses. The field investigation
was conducted under the direct supervision of our Engineering
Geologist.
A truck-mounted bucket auger drill rig was used to drill
six 24-inch diameter borings to a maximum depth of 51 feet.
The borings were sampled, downhole logged and back-filled,
with samples returned to the laboratory for testing. Logs
of the borings are presented in Appendix B.
A tractor-mounted backhoe was used to excavate thirty-
eight test pits to a maximum depth of 14 feet. The test
pits were logged and backfilled. Logs of the trenches are
presented in Appendix B.
Five seismic traverses were performed utilizing a dual
channel enhancement seismograph. A summary of the infor-
mation obtained is presented in Appendix B.
Carlsbad Research Center July 26, 1982 Job NO: SD1162-00
Log NO: SD2-2475 Page Six
VI. LABORATORY TESTING
Samples representative of the earth materials encountered
during our field investigation were returned to the labor-
atory for testing. The testing program consisted of
moisture-density determinations, direct shear testing of
ring and remolded samples, maximum density-optimum moisture
determinations, Atterberg Limits, particle size analysis,
consolidation tests, expansion tests and sulfate tssts.
.Results and descriptions of the laboratory tests performed
are included in Appendix C.
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00 Log NO: SD2-2475
Page Seven
vr1. GEOLOGY
A. Regional Geology
The subject site is located in the Peninsular Ranges
Geomorphic Province of California near the western
margin of the Southern California Batholith. At the
edge of the batholith, the topography changes from
the typically rugged landforms developed over the
granitic rocks to the flatter, more subdued landforms
underlain by sedimentary bedrock associated with the
coastal plain.
The site is underlain by Jurassic metavolcanics and
Cretaceous and Eocene sedimentary rocks. Alluvial Y
sediments are present in the canyon bottoms.
A brief description of the geologic units observed
within the site follows. The distribution of the
geologic units is shpwn on the attached Geotechnical
Map, Plate 1.
B. Geologic Units
1. Santiago Peak Volcanics (map symbol-Jsp)
The Jurassic Age Santiago Peak Volcanics underlie
the western portion of the site. The Santiago
Peak Volcanics are mildly metamorphosed volcanic,
or metavolcanic rocks. Regionally the Santiago
Peak Volcanics vary from basalt to rhyolite but
on-site they are predominantly andesite.
The Santiago Peak volcanics are moderately to
highly jointed. The joint spacings are variable
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00
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Page Eight
and the joints are generally clay-filled. The
Santiago Peak Volcanics are weathered to con-
siderable depth in Phase I1 and are, apparently,
not as resistant there as in Phase 111.
Excavation in the Santiago Peak Volcanics will be
difficult. The highly weathered material within
about five feet of the existing ground surface
can generally be excavated with conventional heavy
earth-moving equipment. Below that depth heavy
ripping and blasting should be anticipated.
Heavy ripping or even blasting will generally
produce oversize materials which can be considered
additional cost items because of difficulty in
handling.
2. Point Loma Formation (map symbol-Kpl)
The Cretaceous Age Point Loma Formation consists
of a marine interbedded fossiliferous siltstone
and claystone with locally cemented sandstone
lenses. The point Loma Formation observed on-
site is generally flat lying with local dips of
up to five degrees. The unweathered bedrock is
stiff to very stiff, but weathering readily loosens
the material. Point Loma Formation materials
underlie most of the site. In certain areas of
the site,the Point Loma Formation has been altered
by weathering to form an ancient residual surface
called a paleosol. The paleosol is identified on
the map by the symbol Kpl(a). This paleosol was
mined during the early 20th Century to obtain
clay for brick production.
Carlsbad
July 26,
Research Center
1982
Job NO: SD1162-00
Log NO: SD2-2475 Page Nine
Excavation in the Point Loma Formation can be
accomplished with conventional heavy duty earth-
moving equipment. Heavy ripping may be required
in some of the very stiff materials at depth.
The soils produced are reusable as fill material
and are moderately to highly expansive.
3. Santiago Formation (map symbol-Tsa)
The Eocene Age Santiago Formation underlies a
very small portion of the site, near the southwest
property boundary. The Santiago Formation, as
observed, is a massive to thick-bedded silty to
clayey sandstone. Because of its limited areal
extent, the Santiago Formation will not signif-
icantly affect the proposed grading.
4. Alluvium (map symbol-Qal)
Alluvium is present in the west trending drainage
courses and the,north trending tributaries of
Letterbox Canyon to the north. The alluvium con-
sists of dry and porous to soft and moist silty
clay and sandy clay. Alluvium was observed to a
maximum depth of about nine feet and was, on the
average, about five feet deep. As observed, the
alluvium was deepest at the center of the drainage
courses with shallower depths observed along the
margins -
5. Fill ~ -
Fill is present on-site as the result of a prior
mining operation. Tailing mounds from the earlier
open pit clay mining operation are present on the
northern portion of the site. Minor fills related
to dirt roads, retention basins (dams) and random
end-dumping are also present on-site.
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00
Log NO: SD2-2475 Page Ten
C. Structural Geology
The predominant structural features within this portion
of the Peninsular Ranges Geomorphic Province are assoc-
iated with pre-Tertiary folding along north-south axes.
The post-Cretaceous sequences have been folded and
tilted generally to the west.
Discontinuous northeast trending faulting is associated
with the post-Cretaceous folding. Faulting has been
mapped in adjacent and on-site areas. Faulting, as
mapped by others, is indicated on the attached Geo-
technical Map, Plate No. 1.~
It should be noted that the mapped faults are inactive
and pose no significant constraints on the proposed
development. The closest active fault is the Elsinore
Fault located 22 miles to the northeast.
D. Ground Water
Ground water was encountered in alluvial areas near the
alluvium/bedrock contact. This is a locally perched
condition and does not reflect the regional ground water
condition. No standing or flowing surface water was
observed on-site at the time of this investigation.
Ground water conditions will, of course, fluctuate with
seasonal rainfall conditions.
Carlsbad Research Center
July 26, 1982
Job No: SD1162-00
Page Eleven .'
Log NO: SD2-2475
VIII.SEISMZCITY
A. Regional Seismicity
The site can be considered a seismically active area,
as can all of smthern California. There are, however,
no active faults on or adjacent to the site. Seismic
risk is considered low, as compared to other areas of
southern California, due to the distance from active
faults.
Seismic hazards within the site can be attributed
to ground shaking resulting from events on distant
active faults. Listed on Table I are the active
faults which can significantly affect the site.
Figure 2 shows the geographic relationship of the site
to these faults.
€3. Earthquake Effects
1. Earthquake Accelerations
We have analyzed the possible earthquake accel-
erations at the site and, in our opinion, for the
intended use, the most significant event is a
7.0 Magnitude earthquake located on the Elsinore
Fault Zone. The accelerations produced at the
site by such an event would exceed those events
which might occur on other known active faults.
A Magnitude 7.0 earthquake on the Elsinore Fault
Zone could produce a peak ground acceleration of
0.229 at the subject site with the duration of
Carlsbad Research Center July 26, 1982 Job NO: SD1162-00
Log No: SD2-2475
Page Twelve
strong shaking exceeding 30 seconds. Design
of structures should be completed in compliance
with the requirements of the governing juris-
dictions and standard practices of the Structural
Engineers Association of California.
2. Settlement of Soils
The earth materials underlying the site consist
primarily of firm sedimentary and metavolcanic
bedrock which is generally not subject to seis-
mically induced settlement. Topsoil and areas
of uncompacted fill will be compacted during grading.
3. Liquefaction
The bedrock materials underlying the site have a
very low to non-existent potential for lique-
faction.
4. Lurching and Shallow Ground Rupture
Breaking of the ground because of active faulting
is not likely to occur on the site due to the
absence of active faults. Ground cracking due to
shaking from distant events is not considered a
significant hazard, although it is a possibility
at any site.
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Carlsbad Research Center
July 26, 1982
Job No: SD1162-00
Log No: SD2-2475
Page Thirteen
IX. ENGINEERING CONSIUERATIONS
A. General Description of Soils/Bedrock
The Logs of Borings in Appendix B indicates that mate-
.rials at the subject site consist of Santiago Peak
Volcanics and Point Loma Formation bedrock overlain
with clayey topsoil or alluvium. Santiago Formation
sedimentary materials are so limited on-site that they
will have no significant effect on the proposed grading.
Fill derived from the Point Loma Formation bedrock will
be the predominant material encountered during grading.
Brief discussions of the significant engineering char-
acteristics of the various material types are presented
below:
1. Santiago Peak Volcanics
Portions of Santiago Peak Volcanics underlying
the site consist of hard, non-rippable rock.
Excavation and/or blasting of such material may
result in over-size boulders requiring special
removal and burial procedures. As a minor
benefit of rock hardness, however, steeper slopes
may be constructed.
2. Point Loma Formation
The Point Loma Formation bedrock underlying the
site typically consists of siltstone. Typical
grain size curves for the siltstone are presented
in Figures C-1 through C-3, Appendix C and the
results indicate that the siltstone 'is composed
principally of silt (65-75%) with clay particles
TABLE 2
Typical Index and Engineering Properties of Siltstone
Index Properties
1 Natural Total Unit Weight (Pcf) 125 2 5
1 Natural Dry Density (pcf) I 105 2 5
Water Content (%)
Unified Soil Classification
20 2 3
CL
..
Engineering Properties
I Remolded Shear Strength (drained) * I
I I 1 Cohesion (psf) 400
Friction Angle (degrees) 24
I I
Expansion Potential High
L 1
*Applicable to normal stress range (1000-4000 psf).
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00 Log NO: SD2-2475 Page Fourteen
(15-25%). Remolded siltstone typically has a
high expansion potential. Index and engineering
properties of the siltstone are summarized in
Table 2. The engineering characteristics of
this material will result in flatter slopes,
special foundation and slab recommendations and
heavy pavement sections.
It is expected that Point Lorna Formation bedrock
may be excavated utilizing conventional equipment.
The fill material derived from excavation should
be generally blocky requiring considerable effort
to break the material down into a uniform com-
pacted fill. During grading of the first phase
of the Carlsbad Research Center project, a Cat-825
steel-wheel compactor or a DE dozer and 5x5 sheeps-
foot, in combination with rubber tire earth-moving
equipment, worked reasonably well in breaking down
the blocky mate.ria1 and creating a relatively
uniform compacted fill condition.
3. Topsoil
Overlying the bedrock is typically a two to five
foot thick layer of clayey topsoil. The topsoil
is generally loose or soft in the upper two (-1
feet and becomes firmer with depth. Grain size
curves for this soil are presented in Figures C-4
and C-6, Appendix C and the results indicated
that the topsoil is composed principally of clay
(50-60%) and silt '(30-40%). The topsoil is class-
ified as a clay of high plasticity (CH), with
low shear strength and a very high expansion
+
~~ ~
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00
Log No: SD2-2475 Page Fifteen
potential. Topsoil material is considered an
undesirable bearing material due to its
engineering properties. Recommendations for
remedial grading of the topsoil will be provided.
4. Alluvium
At some locations, alluvium overlies the bedrock
materials. The alluvium, which is somewhat
similar to the topsoil, is also considered an
undesirable material requiring remedial grading.
B. Remedial Grading
1. Unsuitable Soils
Due to unfavorable engineering characteristics,
top,soil and alluvium will have overexcavation
recommended, along with selective replacement as
compacted fill. In the drainage areas, alluvium
materials were encountered during our field
exploration and are approximately delineated on
the accompanying plan. The depths of the alluvium
are indicated in the excavation logs. Moist to
saturated conditions were encountered within the
alluvium soils and may be expected during grading.
Moisture conditioning of wet alluvium and/or dry
topsoil may require special equipment and can be
expected to slow production in the early stages of
grading.
2. Fill Keys
Numerous fill slopes are planned in conjunction
with proposed grading. In order to provide support
Carlsbad Research Center July 26, 1982
for succeeding
Job NO: SD1162-00 Log NO: SD2-2475
Page Sixteen
lifts of compacted fill, fill
slopes should be keyed into firm bedrock materials.
Keying consists of overexcavation of surficial
deposits and bedrock materials in order to provide
recommended embedment and key widths.
3. Stablization Fills
Stabilization fills are typically recommended to
enhance the stability of locally adverse geologic
conditions. Stabilization consists of overex-
cavating the slope face and replacement with a
uniform compacted fill. Stabilization recommenda-
tions can be expected for cuts within the Point
Loma Formation.
4. Transition Lots
Inconsideration of anticipated cut/filled grading
techniques, it is possible that future buildings
would stradle cut-fill transitions created as a x
result of grading. Such transitions are con-
sidered generally undesirable because non-
uniform bearing conditions result from different
materials being exposed at grade. To
mitigate the potential adverse affects of cut-fill
transitions, overexcavation of the cut portion
and replacement as compacted fill are generally
recommended. Depth of overexcavation is generally
referenced from the bottom of the proposed found-
ation and is limited laterally to specified dis-
tances outside building lines and/or exterior
foundations. In light of the fact that building
Carlsbad Research Center
July 26, 1982
1 ocatio Ins and fou
Job NO: SD1162-00 Log No: SD2-2475 Page Seventeen
.ndation conditions will not likely
be known prior to grading, it is considered a
reasonable alternative to elect not to proceed
with remedial grading of cut/fill transitions
until such time as individual site development
plans are available. At that time, specific over-
excavation recommendations can be developed. As
an alternative to not overexcavating, however, a
conservative depth of overexcavation could be
assumed and the entire pad overexcavated. For this
option, graded conditions would require review at
such time as individual sites are developed. It
has been our experience for industrial developments,
that this second alternative has not been cost
effective.
C. Expansive Soils
Results of expansion tests suggests that fill derived
from the on-site materials will be highly expansive.
Expansive soils can cause heaving/cracking of concrete
walks, driveways, floor slabs, etc. On some projects,
the potential adverse effects of expansive soils can
be mitigated by selective grading. On this project, due
to the predominance of expansive soils, selective grad-
ing will not be recommended. The potential adverse
effects of the expansive soils on foundations and slabs
can be mitigated by special construction techniques
(e.g. deeper foundations and heavy reinforcement). Using
special construction techniques in pavement areas
(e.g. chemical treatment of subgrade) are not generally
cost effective and therefore, no recommendations for
Carlsbad Research Center July 26, 1982
Job NO: SD1162-00
Log No: SD2-2475
Page Eighteen
special treatment will be provided. Under these
circumstances, potential for heaving cracks developing
will exist. The treatment of heaving cracks is con-
sidered normal maintenance consisting of sealing and
sanding on an as-needed basis.
D. Slopes
Slope stability analyses were performed for the pro-
posed cut and fill slopes. Results of slope stability
analyses (Appendix D) indicate that 2:l (horizontal to
vertical) slopes would posses an acceptable factor of
safety against gross instability. However, 2:l
(horizonta1:vertical) slopes comprised of the predom-
inant on-site materials would not posses an acceptable
factor of safety against surficial instability. Options
to improve the surficial stability include laying the
slope back to a flatter slope ratio (i.e. 2.5:1) or
facing the outer portion of slopes (i.e. 12 feet) with
select materials. The suitability of individual sources
of proposed select material would require evaluation.
Suitable sources are expected to be comprised of pre-
dominantly granular with minor fractions of silt and
clay. Most D.G. and sandstone derived silty and clayey
sands would be appropriate.
E. Ground Water
Locally very moist or wet conditions were encountered
during site exploration as described in the Logs of
Borings. Ground water, whether natural or that which
may develop as a result of grading, drainage patterns
or irrigation, is often considered a major factor in
undermining slopes in addition to being a nuisance
where local seeps occur. To control ground water sub-
drain systems will be recommended.
Carlsbad Research Center
July 26, 1982
X. CONCLUSIONS ANI, RECUMMENOATIONS
Job NO: SD1162-00 Log NO: SD2-2475
Page Nineteen
A. General
Based on the results of our Supplemental Preliminary
Geotechnical Investigation, we conclude that the pro-
posed development of Carlsbad Research Center Phase I1
and I11 is feasible from geotechnical aspects, provided
the following conclusions and recommendations are
incorporated into the project plans, specifications
and construction practice.
B. Grading and Earthwork
1. Clearing and Grubbing
Prior to grading, the site should be cleared of
surface obstructions and stripped of brush and
vegetation. Vegetation from the clearing oper-
ation should be removed from the site. Obstructions
extending below finish grade should be removed
and replaced with compacted fill.
2. Site Preparation
a. Treatment of Surface Soils
Test excavations indicate that three to four
feet of surficial soils are present on-site.
The upper portions of the surface soils are
generally dry and porous. It is recommended
that the upper two feet of surface soils be
overexcavated in areas to receive fill. Actual
depths of removal may vary as recommended by
the Geotechnical Consultant at the tine o€
grading.
Carlsbad Research Center
July 26, 1982
Job No: SD1162-00
Log No: SD2-2475
Page Twenty
b. Existing Fill Soils
It is recommended that all areas of uncon-
trolled fill be overexcavated in areas to
receive fill.
c. Treatment of Alluvium
It is recommended that loose, porous, or
saturated alluvium be removed to firm ground
prior to fill placement. For budgeting
purposes, it should be assumed that all alluvium
will be removed to bedrock. "The antici-
pated areas of alluvial removals are shown
on the attached Figure No. 3.
d. Scarification and Processing of Surface Soils
Following overexcavation of unsuitable mate-
rials, areas to receive fill and/or other
improvements should be scarified to a depth
of 6 to 8 inches, brought to near optimum
moisture conditions and compacted to at least
ninety percent relative compaction.
3. Bedrock/Soil Characteristics
Predominate material types on-site consist of
siltstone and claystones of the Point Loma Formation
as well as topsoil and alluvium derived'f>om the same.
Generally these material types are readily exca-
vated with conventional earth-moving equipment,
becoming firm to hard at depth increasing the
1
Carlsbad Research Center
July 26, 1982 Job NO: SD1162-00 Log NO: SD2-2475 Page Twenty- One
difficulty of excavation as described in Section
B-9, Rippability. Materials derived from the
excavation will consist of silt and clay blends with
considerable amounts of blocky siltstone and clay-
stone fragments which require moderate to consider-
able compaction effort to be broken down into a
uniform compacted-fill soil.
Moisture conditions in the near surface soils
are anticipated to vary from dry to wet. Moisture
conditions vary in the surface soils depending
on the actual location of the materials on-site
and seasonal moisture variations. If the project
is graded in late summer or fall prior to the next
rainy season, we would anticipate topsoil materials
to be relatively dry and alluvial materials to be
moist to very moist. These materials will require
moisture conditioning in conjunction with place-
ment as compacted fill. Bedrock materials at depth, .,'
however, are anticipated to be at or above optimum
moisture condition, requiring only limited moisture. i.
conditioning during placement as compacted fill. x
4. Overexcavation of Transition Lots
Because the subject lots are large industrial and
commercial lots with building locations as yet
undetermined, no overexcavation of transition-
is required. Overexcavation to eliminate the
cut-fill transition may be a future recommendation
when building location and foundation design are
known.
Carlsbad July 26, Research Center 1982 Job No: SD1162-00
Log No: SD2-2475
Page Twenty-Two
5. Compaction and Method of Filling
Fill placed at the site should be compacted to
a minimum relative compaction of 90 percent,
based on ASTM Laboratory Test Designation D 1557-70.
Fill should be compacted by mechanical means in
uniform lifts of 6 to 8 inches in thickness.
Fills constructed on natural slopes steeper than
5:l (horizonta1:vertical) should be keyed and
benched into bedrock or competent natural ground.
Compaction of slopes should be achieved by over-
building the slopes laterally and then cutting back
to the compacted core at design line and grade.
Although overbuilding and cutting back is the
preferred method, fill slopes may be back rolled
at intervals not greater than four feet as the
fill is placed, followed by final compaction of
the entire slopes. Feathering of fill over the
tops of slopes should not be permitted.
Fills should also be placed and all grading per-
formed in accordance with the City of Carlsbad's
Grading Ordinance and the requirements of the
Uniform Building Code.
6. Selective Grading
As an alternative to laying-back slopes to a
ratio of 2.5:1, slope faces may be constructed
with select materials to a ratio of 2:l. Select
materials should consist of generally well-graded
granular materials with minor silt and clay frac-
tions. Select materials should be nonexpansive.
Carlsbad Research Center
July 26, 1982
Job No: SD1162-00
Log No: SD2-2475 Page Twenty-Three
Suitablity of proposed select material sources
should be determined upon evaluation of the
engineering properties of the materials. Though
limited amounts of select materials may be avail-
able in the southern portion of the site, it is
anticipated that the substantial amount of select
material will be imported. A source of suitable
select material has been identified on the pro-
ject to the south. The material consists of a
silty fine sand generated from the sandstone
formation.
In facing slopes with select material, it is
recommended that a width of not less than 10 feet
be maintained. Unless the minimum width is
increased to provide working area for conventional
slope compaction equipment, it is recommended that
the slopes be overfilled and cut-backed to the
compacted inner core. If the source of silty fine
sand materials to the south is utilized for facing
of slopes, overfilling and cutting-back is strongly
recommended.
From discussions with the Project Civil Engineer,
it is our understanding that some slopes will be
laid back to 2.5:l in lieu of utilizing select
material. A few slopes in more favorable material
types in the southern portion of the project are
not anticipated to be affected by the selective
grading recommendations. Also, the selective
grading recommendations should not be considered
applicable to slopes of ten feet in height or less.
tarlsbad Research Center
July 26, 1982
Job NO: SD1162-00
Log NO: SD2-2475
Page Twenty-Four
Slopes presently anticipated to be affected by
the selective grading recommendations have been
indicated on the accompanying Figure 3.
Due to the undesirable engineering properties of
topsoil and alluvial soils, placement on the
interior of fill masses is recommended in lieu
of placement near slope faces.
7. Import Fill Material
Presently it is anticipated that import fill
materials will be required for selective grading
operations. The type of material considered most
desirable for import is a nonexpansive well-
graded granular material with minor silt and clay
fr?ctions. The Geotechnical Consultant should be
contacted for evaluation of individual import
sources well in advance of planned import oper-
ations.
8. Shrinkage, Bulking and Subsidence
Volumetric shrinkage for the topsoil is estimated
to be from 15 to 20 percent. Shrinkage in the
alluvium is estimated to be from 10 to 15 percent.
Bulking in the Point Loma Formation materials is
expected to be from 5 to 10 percent. Bulking in
the Santiage Peak Volcanics is estimated to be
from 15 to 20 percent.
Because alluvium and porous topsoil are being
removed, subsidence due to equipment will be
negligible.
Carlsbad Research Center July 26, 1982
Job NO: SD1162-00 Log No: SD2-2475
Page Twenty- Five
Due to the fact that shrinkage and subsidence can
vary with many factors, it is recommended that the
above values only be used for preliminary planning
purposes. To provide for unforeseen variations
in actual quantities a "balance area" should be
designated by the Project Civil Engineer.
9. Rippability
Field exploration indicates that some proposed cut
areas are underlain, at varying depths, by non-
rippable materials. The anticipated limits of
nonrippable surface are indicated on the attached
Rippability Map, Figure - 3.
. .. ..
"Nonrippable" is used to describe hard rock which
is not economically excavated with conventional
heavy-grading equipment. The rock may actually
be rippable, but at an unacceptable production
rate. Commonly accepted construction procedures
in nonrippable materials include blasting and
exceptionally heavy-duty grading equipinent such
as Catepillar D-10 or FIAT-ALLIS HD31 bulldozers.
Nonrippable material at pad grade and at street
subgrade will pose significant construction diffi-
culty during later foundation and utility excavation.
Consideration should be given to overexcavation in
these areas to facilitate later construction.
10. Rock Disposal
Grading in the nonrippable materials will produce
rock fragments larger than normally allowed as
fill material. Where practical, it is recommended
Carlsbad Research Center July 26, 1982 Job No: SD1162-00 Log NO: SD2-2475
Page Twenty- Six
that a non-structural, rock disposal area be
identified. Possible areas for consideration
include canyon areas currently outside the limits
of planned grading. Larger rocks may also be
incorporated into the lower portions of compacted
fills, provided the placement and compaction are
performed under the observation and testing of
the Geotechnical Consultant. The recommended Rock
Disposal Methods are presented in Appendix E,,
Standard Guidelines for Grading Projects. The
contractor should be aware that incorporating rock
in compacted fill will significantly reduce the
rate of fill placement and may require bringing in
special rock handling equipment.
C. Slopes
1. Fill Slopes
Fill slopes are proposed on-site to a height of on
the order of 100 feet. One hundred-foot fill
slopes at a ratio of 2:l (horizonta1:vertical)
should possess gross stability in excess of the
generally accepted minimum engineering criteria.
Fill slopes in excess of ten feet in height should
be laid-back to a ratio of 2.5:l or flatter or
should be constructed at 2:l and provided with at
least ten feet of select material on the slope
face to enhance surficial stability.
Fill slopes should be constructed in accordance
with the conclusions and recommendations outlined
herein and the guidelines for grading projects
Carlsbad Research Center July 26, 1982
Job No: SD1162-00
Log NO: SD2-2475
Page Twenty-Seven
which accompany this report as Appendix E.
For 2:l fill slopes of ten feet in height or less,
construction should proceed in accordance with the
guidelines for over-filling and cutting back to
the compacted inner core.
2. Cut Slopes
a. Santiago Peak Volcanics
The orientations of proposed cut slopes in
the Santiago Peak Volcanics are generally
favorable with respect to the geologic struc-
ture. Final determination of the need for
slope stabilizations will be made in the field
during grading. Continuous geologic obser-
vation of cuts in progress is essential.
Cut slopes in this material made at slope
ratios of 2:l (horizonta1:vertical) or flatter
are anticipated to be surficially and grossly
stable to the proposed heights.
While cut slopes in the Santiago Peak Vol-
vanics pose no significant geotechnical
constraints, the exposed rock slopes may pose
aesthetic and/or landscaping problems. Con-
sideration should be given to overexcavation
if exposed rock slopes are considered a sign-
ificant problem.
b. Point Loma Formation
The orientations of proposed cut slopes in
the Point Lorna Formation are generally favorable
Carlsbad Research Center
July 26, 1982 Job NO: SD1162;OO Log No: SD2-2475
Page Twenty-Eight
with respect to geologic structure and the
daylighting of bedding planes. Some slopes
may expose locally the very gently undulating
bedding in daylighted fashion. Final deter-
mination of the need for slope stabilization
will be made in the field during grading.
Continuous geologic observation of the cuts
in progress is essential. Cut slopes in
this material made at slope ratios of 2:l
(horizonta1:vertical) or flatter are antic-
ipated to be grossly stable to the proposed
heights.
Weathering characteristics of the Point Loma
Formation materials will necessitate special
treatment to mitigate surficial stability
concerns on cut slopes. The Point Lorna For-
mation materials weather or slake rapidily,
generally loosing integrity when exposed in
excavations. The rapid deterioration of
the cut slope face will necessitate miti-
gation measures identical to those previously
recommended for fill slopes made of Point
Loma Formation materials, e.g., blanket
stabilization fills or reduced slope ratios.
3. Fill-Over-Cut Slopes
Where fill-over-cut slopes are proposed, it is
recommended that the cut portion be completed
prior to fill placement. An equipment width
minimum key should be constructed at the cut/fill
~~
July 26, 1982
Carlsbad Research Center Job No: SD1162-00
Log NO: SD2-2475 Page Twenty-Nine
contact. A typical fill-over-cut detail is pre-
sented in the Standard Guidelines for Grading
Projects which accompany this report as Appendix E.
4. Stabilization/Buttress Fills
Blanket stabilization fills are recommended for
cut and fill slopes over 10 feet in height con-
structed of Point Loma Formation materials, where
laying-back the slopes to 2.5:l is not adopted.
Buttress fills are not anticipated at this time,
however, final determination of the need for
stabilization and buttress fills will be made in
the field during grading.
5. Construction Slopes
Coristruction slopes in the Santiago Peak Volcanics
are recommended at slope ratios of 1.5:l (horizon-
ta1:vertical) to a maximum height of 50 feet.
Above that height, construction slopes should be
cut at 2:l (horizonta1:vertical). Construction
slopes in the Point Loma Formation are recommended
at slope ratios of 1.5:l to heights up to 30 feet.
Above that height, construction slopes are recom-
mended at slope ratios of 2:l (horizonta1:vertical)
These recommended ratios can be steepened if the
possibility of construction sliding is acceptable.
6. Natural Slopes
The proposed grading virtually eliminates natural
slopes in Phase 11. Natural slopes will remain
Carlsbad Research Center July 26, 1982
Job No: SD1162-00
Log No: SD2-2475
Page Thirty
in the southwest corner of Phase 111. These
natural slopes will continue to be subject to
erosion and occasional minor surficial instabil-
ity. The potential for erosion and surficial
instability should not significantly impact the
project nor should the project significantly
impact the potential for such instability.
D. Restriction on Future Construction
No significant geotechnical restrictions, such as
restricted use areas, are anticipated on future con-
struction if grading is performed in accordance with
the recommendations presented herein. These recom-
mendations will not, however, preclude setbacks from
buried utilities, easements, etc.
Site specific geotechnical investigations are recom-
mended prior to construction on the graded pads.
Specific foundation recommendations should be made
based upon evaluation of building types and structural
loading conditions.
E. Surface and Subsurface Drainage
Surface runoff into downslope natural areas and graded
areas should be minimized. Where possible, drainage
should be directed to suitable disposal areas via
non-erodible devices (eg. paved swales and storm
drains).
Subdrains should be placed under all fills placed in
drainage courses and at identified or potential seepage
areas. Their specific locations will be determined in
Carlsbad Research Center July 26, 1982 Job No: SD1162-00
Log NO: SD2-2475
Page Thirty-One
the field during grading. General subdrain locations
will be indicated on the approved grading plan. The
subdrain installation should be reviewed by the
Engineering Geologist prior to fill placement.
Typical subdrain details are presented in Appendix E,
Standard Guidelines for Grading Projects. Subdrain
pipe may be coated metal, P.V.C., or approved equiv-
alent (crush strength of 1000 pounds/foot or greater).
Drainage devices will be recommended behind buttresses
and/or stabilization fills to minimize the build-up
of hydrostatic and/or seepage forces. The details
and recommended locations of these back drains are
presented in Appendix E, Standard Guidelines for
Grading Projects. Depending on slope height, more than
one tier of drains may be required. Drains may also
be recommended at contacts between permeable and non-
permeable formations.
P. Foundations and Slabs
1. Expansive Soils
The on-site soils and materials generated from the
predominate bedrock formation on-site will possess
high expansion potential. Though minor amounts
of more favorable materials exist, it is not con-
sidered practical to selectively grade to mitigate
potential adverse affects of expansive soils. The
existence of expansive soils near grade will dic-
tate special foundation and slab configuration
and reinforcement recommendations.
Carlsbad Research Center July 26, 1982
Job NO: SD1162-00 Log No: SD2-2475
Page Thirty-Two
2. Footing Setbacks
Special footing setbacks are presently not
anticipated to be a factor in the development
of the project. If footings are proposed adjacent
to slope areas, we recommend that the footings be
deep and to provide a minimum horizontal distance
of 10 feet from the outer edge of footings to the
adjacent slope face. Footings planned under the
influence of this recommendation should be provided
specific review by the Geotechnical Consultant
prior to construction.
3. Soil Bearing Pressure
Soil bearing compacity will vary on a lot by lot
basis, in consideration of site geotecnnicai con-
ditions and proposed developments. Foundation
bearing compacity recommendations should be
developed subsequent to site specific geotechnical
evaluations as individual lots are proposed for
development.
In general, bearing capacity is expected to be
moderate to high in bedrock areas. In Cowacted
fill areas consisting of the predominate silty and
clayey materials bearing capacity is expected to
be low to moderate. Where future buildings are
proposed in transition areas, overexcavation of
cut-portions or deepened footings could be recom-
mended to create relatively uniform bearing con-
ditions.
Carlsbad Research Center
July 26, 1982 Job NO: SD1162-00 Log NO: SD2-2475
Page Thirty-Three
4. Lateral Load Resistance
Development of recommendations for lateral load
resistance can be best performed subsequent to
site specific evaluations. These site specific
evaluations can be performed as development plans
for individual sites are made available.
G. Retaining Walls
The development of geotechnical design critera for
retaining walls can be best developed following
review of the proposed wall configurations and review
of the site specific geotechnical conditions. Over
most of the site, however, the following critera
may be utilized for preliminary design purposes.
Where f?ee-standing walls are proposed to retain
granular backfill, equivalent fluid weight for static
active lateral earth loadings of 45, 70 and 90
pounds per cubic foot may be utilized for walls re-
taining level, 2.5:l and 2:l backfill conditions
respectively. Appropriate allowances should be made
for anticipated surcharge conditions, unless walls are
also designed to resist seepage and/or hydrostatic
forces. Walls should be provided with designed drain-
age systems.
It should be noted that. the use of heavy compaction
equipment in close proximity to retaining walls can
result in excess wall movement (strains greater than
those normally associated with the development of
active conditions) and/or soil pressures exceeding
Carlsbad Research Center July 26, 1982
Job No: SD1162-00
Log NO: SD2-2475 Page Thirty-Four
design values. In this regard, care should be taken
during back-filling operations.
H. Type of Cement for Construction
'Evaluation of soluable sulfate content of samples
considered representative of the predominate material
types on site suggest that Type V concrete is not ,
a requirement for use in construction. Type I or I1
cement should be utilized. Cement type recommendations
should be verified following site specific investi-
gations on individual lots.
I. Pavements
Due to generally poor subgrade characteristics of
the predominant soil types, generally heavy pavement
sections can be anticipated. For traffic index
values of 7.0, 8.0 and 8.5 which are expected for the
street areas, the following preliminary pavement
sections can be utilized for planning purposes.
Traffic Index 7.0 8.0 8.5
R-value 7.0 7.0 7.0
Pavement Thickness 4 " 4 " 5 "
Aggregate Base 15" 18" 19"
Total Thickness 19 " 22" 24"
From review of the above sections, it is apparent that
street areas during rough grading should be kept about
two feet low to accomodate the pavement sections.
Pavement recommendations should be reviewed as final
grades are achieved.
Carlsbad Research Center July 26, 1982
Job No: SD1162-00
Log No: SD2-2475
Page Thirty-Five
If practical, selective grading in street areas may be
considered for the purpose of reducing pavement
section requirements. If it is considered practical to
place about one-foot of good granular material in
street subgrade areas, the required aggregate base
material section could be reduced substantially.
J. Utility Trench Backfill
Utility trench backfill should, unless otherwise
recommended, be compacted by meachanical means. Unless
otherwise recommended, the degree of compaction should
be a minimum of 90% of the laboratory maximum density.
As an alternative, granular material (Sand Equivalent
greater than 30) may be thoroughly jetted in-place.
Jetting ,should only be considered to apply to trenches
no greater than two feet in width and four feet in
depth. Following jetting operations, trench backfill
should be thoroughly mechanically compacted and/or
wheel rolled from the surface.
K. Grading Plan Review
When final grading plans for the proposed development
are completed, the plans should be reviewed by the
Geotechnical Consultant to determine compliance with
the recommendations presented herein. Substantial
changes from the present plan may necessitate additional
investigation and analyses.
July 26, 1982
Carlsbad Research Center Job NO: SD1162-00 Log 110: SD2-2475 Page Thirty- Six
L. Geotechnical Observation
Continuous observation by the Geotechnical Consultant
is essential during grading to confirm conditions
anticipated by the preliminary investigation, to adjust
designs to actual field conditions and to determine
that grading proceeds in general accordance with the
recommendations contained herein.
Carlsbad Research Center
July 26, 1982
Job NO: SD1162-00
Log NO: SD2-2475
Page Thirty-Seven
X. LIMITATIONS OF INVESTZGATION
Our investigation was performed using the degree of care
and skill ordinarily exercised, under similar circum-
stances, by reputable Soils Engineers and Geologists
practicing in this or similar localities. No other
warranty, express 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 representative of the entire area. How-
ever, soil and geologic conditions can vary significantly
between borings, test pits and surface outcrops.
As in most major grading projects, conditions revealed
by excavation may be at variance with preliminary findings
If this occurs, the changed conditions must be evaluated
by the Geotechnical Consultant and designs adjusted or
alternate designs recommended.
Very truly yours,
SAN DIEGO- SOILS ENGINEERING, INC.
Chief Engineer
GWA: SWJ : tcm
" + Ste hen W. N*b ensen, C.E.G. 1074 Manager, Geblogic' Services
APPENDIX A
REFERENCES
1. "Eocene and Related Geology of a Portion of the San Luis
Rey and Encinitas Quadrangles, San Diego County," December 1972: University of California, Revierside, Masters
Thesis prepared by K. L. Wilson;
2. Mines and Mineral Resources of San Diego County, 1963:
California Division of Mines and Geology, County Report 3;
3. Crustal Strain and Fault Movement Investigation, January 1964: California Department of Water Resources Bulletin
No. 116-2;
4. "Accelerations in Rocks for Earthauakes in the Western ~~~ ~ United Stages," Bulletin of the Seismological Society Of
America, Vol. 63, No. 2, Schnabel and Seed, April 1973;
5. Fault Hazard Zones in California, Revised January 1977:
California Division of Mines and Geology, Special Publi-
cation 42;
6. "Fault Map of California," 1975: California Division Of Mines and Geology, Geologic Data Map No. 1;
7. California Geology, California Division of Mines and "Repeatable High Ground Accelerations from Earthquakes,"
Geology, Ploessel and Slosson, September 1974;
8. Clay Mineralogy and Slope Stability, Special Report 133,
California Division of Mines and Geology, 1977;
9. Seismicity of the Southern California Region 1932-1972, - 1973: California Institute of Technology, Seismological Laboratory;
10. Research Center, Carlsbad,California" April 1981, Woodward- "Preliminary Soil and Geologic Investigation, Carlsbad
Clyde Consultants;
11. "Additional Studies, Carlsbad Research Center, Carlsbad,
12. "Addendum to Additional Studies, Carlbad Research Center,
California" August 1981, Woodward-Clyde Consultants;
Consultants;
Carlsbad, California" September 1981, Woodward-Clyde
13. "Aerial Photographs," USDA Flight AXN-8M, 1953, Photo
NOS. 71-73, 99-101.
APPENDIX B
SUBSURFACE EXPLORATION
The subsurface exploration consisted of 6 borings to a maximum
depth of 51 feet and 38 test pits excavated to a maximum depth of
14 feet. -The borings were drilled with a truck-mounted bucket
auger drill rig and the pits were excavated with a tractor
mounted backhoe.
The subsurface exploration was conducted under the direction of
the Engineering Geologist. The borings and pits were logged,
sampled and backfilled. Samples of the materials encountered
were returned to the laboratory for testing.
Logs of our borings are presented as Figures B-2 through B-8.
The logs of test pits are presented as Figures B-9 through €3-46.
The locations of the borings and pits included in this appendix
are shown on the attached Geotechnical Map, Plate No. 1.
California Sampler blow counts were obtained by driving a 2.625
inch, inside diameter sampler. with a hammer dropping through a
12 inch free fall. A 1600 pound hammer was used at depths less
than 25 feet and an 800 pound hammer was used at depths greater
than 25 feet. Unless otherwise shown, the blows per foot recorded
on the Boring Logs represent the number of blows used to drive
the sampler 12 inches. Samples shown on the Boring Logs as
"UNDISTURBED SAMPLES" were obtained with the California Sampler.
Seismic Traverses
Seismic traverses were made to determine rock hardness in pro-
posed cut areas. Velocities of shock waves were measured along
these traverses to determine the rippability characteristics of
the bedrock underlying the property. A summary of the seismic
data utilized during evaluation of the site is included as
Table B-1.
A. Equipment
The equipment utilized during the seismic survey phase of
this investigation was a signal enhancement seismograph,
manufactured by Bison Instruments, Inc. The energy source
employed was a sledge hammer, with an impulse spacing of
10 feet. The traverses were each 200 feet long.
B. General Seismic Parameters
In general, seismic velocity is closely related to rock
hardness. Soil and 1oose.surface material generally have
a seismic velocity of about 1000 feet per second. Velocities
of 1000 to 2500 feet per second are characteristic of soft
sediments and easily ripped weathered bedrock. Velocities
of 3000 to 5500 feet per second are typical of firm
materials that require moderate to heavy ripping. Blasting
is commonly required to excavate bedded materials that have
a velocity 6500 feet per second or faster, while massive
volcanic materials with velocities greater than 5500 feet
per second generally require blasting.
Traverse No.
2
3
4
5
TABLE B-1
(Feet) Depth
0-5
5-20
20+
0-7
7-50
0-5
5-30
0-5
5-20
20+
0-5
5+
Velocity (Feet per Second)
1,600
5,800
14,000
1,500
4,000
1,000
2,900
1,000
4,500
10,000
4,000
6,000
MORE THAN HALF
OF COARSE
MORE THAN HALF
FRACTION IS
LIOUID LIMIT IS
LESS THAN 50%
LlOUlD LIMIT IS
DEFINITION OF TERMS
200
U.S. STANDARD SERIES SIEVE
40 10 4 3/48 3" 12n
CLEAR SOUARE SIEVE OPENINGS
SILTS AND CLAYS SAND GRAVEL
FINE I MEDIUM . COARSE I FINE I COafSE COBBLES BOULDERS
GRAIN SIZES
~~ ~~~~~
r
NON-PLASTIC SILTS
SANDS.GRAVELS AM3 BLows/FooTt PLASTIC SILTS
AND BLOWS/FOOT' STRENGTH*
VERY LOOSE 0-2 0 - 1/4 VERY SOFT 0- 4
STIFF
ch-1 FIRM
2-4 1/4 - 1R SOFT
4-8
1-2 8 -16
VERY STIFF 2 -4
HARD
16 -3
OVER 4 UJER 32
LOOSE
sWFOIUM DENSE
4 -10
OJER 50
30 -50 DENSE
10 -30
VERY DENSE
RELATIVE DENSITY CONSISTENCY
Wht SDOCMI CASTM 0-1586). 'Number 01 blows of 140 pound hammer lallong 30 inches to drive a 2 inch 0 D (1-3/8 tnch 1.0)
by the standard penetration lest (ASTM 0-1586). pocket pcnetforneter. torwane, or visual 0bservatt.m
(Lhconlmed COmpleSlivC strength in tons/sa. It as deterrnmed by laboratory terrtrq w mprommated
KEYTOEXPLORATORYBORINGLOGS
Unified Soil Classification System (ASTM D-2487)
OB NO.: SD1162-00 DATE: July, 1982 FIGURE: B-1
SAN DIEGO SOILS ENGINEERING. INC
BORING NO. 1
MSCRIPTION
roPsoIL: Brown CLAY, wet, soft,
iith organics
3EDROCK: POINT LOMA FORMATION; ;reen grey clayey SILTSTONE, noist, stiff to very stiff.
lery fractured and weathered to
5'. Occasionally jointed, orang
staining in joints
!E' massive, very few joints
!13' and 14' minor cemented zone
121' cemented lens, 6" thick,
lorizontal
)ark green grey SILTSTONE, moist
'ery stiff, massive.
."""""""
'otal Depth 30' lo Water
:o Caving
80K TE8T
SIEVE ANALYSIS
IYDROMETER
>ATE OBSERVED. 4 - 9 -8 7 METHOD OF DRILLINQ: 24 BurkPt AugPr
I TOPSOIL: Brown CLAY, wet, soft with organics
BEDROCK: POINT LOMA FORMATION;
light green grey clayey SILTSTO moist, stiff to very stiff, wit orange staining. Weathered and
fractured to 5', jointed below
I @ 6.5' dark brown carbonaceous
bed, 1" thick, horizontal .04 I horizontal
@ 10.5' cemented layer, 3" thic
I @ 15.5' cemented layer, 2" thic,
@ 17-20' vertical joint, iron stained material
02 @ 21' joint NIOOW, 90° I
23' gypsum seam, .5" thick, orizontal
I@ 27-28' minor cemented layers
ayers, massive
OOIL TEOT
ZONSOLIDATION
UXIMUM DENSIT!
DIRECT SHEAR (Remolded)
SIEVE ANALYSIS SYDROMETER
4TTERBERG LIMI': EXPANSION TEST
SULFATE TEST
IIRECT SHEAR
(Ring Samples)
J i LOG OF BORING IFlQURE: B-3
OAN DEQO SOIL8 ENalNEERlNQ IN(
DATE OBSERVED: 4-9-82 METHOD OF DRILLING: 24" Bucket A'qer
ID ELEVATION 315 ' - LOCATION See Map +
*c
OP
Y" v* <k
Lev
dg z:
BORING NO. 2
SOIL TEST
DESCRIPTION
.05 Black-grey clayey SILTSTONE, ZONSOLIDATION
moist, very stiff with hard MAXIMUM DENSITY
layers, massive SIEVE ANALYSIS HYDROMETER
TTERBERG LIMI'I
XPANSION TEST
SULFATE TEST
tal Depth 51'
Water
Caving
SAN DIEGO SOILS ENGINEERING. IN'
"
VATKHI: 386'- t LOCATION See
BORING NO. - 3
DESCRIPTION
TOPSOIL: Red brown CLAY, mois firm
BEDROCK: POINT LOMA FORMATION
Green grey clayey SILTSTONE,
moist, stiff to very stiff, wi. orange staining. Weathered an( fractured to 6'
horizontal @16' cemented layer, 6" thick,
horizontal @18.5' cemented layer, 10" thic
horizontal @22' gypsum seam, .5" thick,
024' cemented layer, 6" thick,
horizontal
@28' cemented layer, 7" thick, LoLi zsnta 1. """"
Black grey clayey SILTSTONE,
moist, very stiff with hard
layers, massive
rota1 Depth 36'
Vo Water
Vo Caving
LOG OF BORING
8OIL TE8T
SIEVE ANALYSIS
1YDROMETER
-
8AN DlEQO SOL8 ENQINEERINQ INC.
LOGGED BY T
11162-0C -
VATION: 256' - -E LOCATION see mP
BORING NO. 4
DESCRIPTION
1LLUVIUM: Light to medium browr
silty CLAY, moist, soft.
3EDROCK: Point Loma Formation;
Jreen-brown clayey SILTSTONE; noist, stiff.
!9%' Cemented lens.
Total Depth 10" No Water No Caving
LOG OF BORING
SOIL TEST
)ATE OBSERVED: -- METHOD OF DRILLING 24" Bnrket Auger
C
,162-0
VATION: 260 ' - LOCATION See MaD t
BORING NO. 5
DESCRIPTION
BEDROCK: Santiago Peak Vol-
colors, white, pink, red and
canics; very weathered, varied
moist, medium dense to dense,
light green, metavolcanics,
texture chalky to hard rock.
LE - - -
" "
" -
L LOG OF BORING LI
SAN DIEGO SOILS ENGINEERING. INC
Total Depth 34'
No Water
NO Caving
SOIL TEST
IFIQURE: R-7
BORING NO. 6
DESCRIPTION
POPSOIL: Light brown silty CLAI
to clayey SILT, moist, firm.
3EDROCK: Point Loma Formation
grey with brown mottling SILT- STONE, moist, very stiff.
4pproximately horizontal lamin-
ations, semi-cemented.
2 7' Predominately grey, some
2 9%' Cemented zones
sand.
Horizontal
? 20' Less cemented, softer.
a 22' Cemented, thin layers,
2 224'Fos.siliferous
Horizontal
3 26$'Grey-brown SANDSTONE.
9 30' Cemented layer, 2" thick,
horizontal joint: N26O E,
66" NW.
Total Depth 34'
No Water
No Caving
LOG OF BORING
SOIL TEST
laximum Density
ieve Analysis
.tterberg Limit
ydrometer
:LEVATION: 256 ' - LOCATION See Map +
>
I 1
" "
!
"
31
-
M
I S
H i A
i
1'
1
I
(
I
I
I
" -
FIGURE B-8
1 SAN DlEGO SOILS ENGINEERING. IN1
TEST PIT NO. 1
DESCRIPTION
ALLUVIUM: Brown silty CLAY, moist to saturated, soft
Seepaqe @ 0-3'
BEDROCK: Point Lorna Formation; Yellow - green grey SILTSTONE
wet, stiff to very stiff
Total Depth 6'
Caving @ 0 '-4' Seepage @ 0'-3'
SOIL TEST
DATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
TOPSOIL: Brown silty CLAY, wet, soft
BEDROCK: Point Loma Formation;
,Green grey SILTSTONE, moist, iff, fractured
Total Depth 5+'
No Water No Caving
SOIL TEST
- LC
F U U la
1 c a U C
.
-a
5
la
15
!O
!5
IO
15
,O. -
01
,ATE OBSERVED " METHOD OF DRILLING 24 Backhoe
SED B'I ,. .~ ID ELEVATION 5 ' - LOCATION See Map +
E: TEST PIT NO.
i: z:
3
w- U> <k
DESCRIPTION
TOPSOIL: Brown silty CLAY,
moist to wet, soft
BEDROCK: Point Lorna Formation;
green grey SILTSTONE, moist
ff, fractured
Total Depth 5'
No Water
No Caving
~ATE OBSERVED: 5 - 3 - 8 2 METHOD OF DRILLING: 24 " Backhoe
+
D ELEVATION: 2 84 ' LOCATION See Map
TEST PIT NO. 4
DESCRIPTION
SOIL TEST
I
TOPSOIL: Orange brown CLAY,
moist, firm
CONSOLIDATION
MAXIMUM DENSIT1 BEDROCK: Point Loma Formation;
SIEVE ANALYSIS STONE, moist, stiff, fractured (Ring sample) Dark orange olive green SILT- DIRECT SHEAR
"
,HYDROMETER
ATTERBERG LIMIT
EXPANSION TEST
SULFATE TEST
Total Depth 6'
No Water
No Caving
LOG OF TEST PIT IFIGURE: B-12
SAN DIEGO SOILS ENGINEERING, IN1
I 2-
TEST PIT NO.2
DESCRIPTION
aLUVIUM: Brown CLAY, wet,
;oft
3EDROCK: Point Loma Formation; lark green grey SILTSTONE, moist \" wet, fractured
SOIL TEST
rota1 Depth 6
lo Water
Io Caving
IATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24 " Backhoe
TEST PIT NO.- 6
DESCRIPTION
FILL: Green grey silty Clay
moist, very loose -
Total Depth 5'
NO Water No Caving
SOIL TEST
:LEVATION: 298 ' - LOCATION: See MaD + -
>
!
I I
" " -
" -
~
LOG OF TEST PIT I FIGURE ~-14
SAN DIEGO SOILS ENGINEERING, INC.
IATE OBSERVED: 5-3-82 METHOD OF DRILLINO: 24" Backhoe
Tc
TEST PIT NO.
DESCRIPTION
SDROCK: POINT LOMA FORMATION;
irk grey green SILTSTONE, moist :iff to very stiff, fractured i
le top 3', jointsd to 8'
1-6' joints: N56 8, 75 #: io>, 900; 0 N-S 30 , NJO W, 8OoE
io W, 80 N; 810 E, 90 ;
NZO'E, 80 w
Ita1 Depth 6'
I Water
) Caving
SOIL TEST
iLEVATION LOCATION See Map
"
n
Nc
Nc
LOG OF TEST PIT I SAN DlEGO SOILS ENGINEERING. INC
IFIGURE: 0-15
0 I
KS
1 No.: SDl162-0
DATE OBSERVED: 5-3-82 METHOD OF DRILLING 24" Backhoe
:VATION: 285" LOCATION: See Mal +
TEST PIT NO. 8
DESCRIPTION
ALLUVIUM: Brick red CLAY, wet, firm
BEDROCK: Santiago Peak Volcanics
Orange stained green "weathered tavolcanics" , moist, very
dense
Total Depth 64'
Near Refusal
No Water
No Caving
SOIL TEST
SIEVE
ANALYSIS
IFIGURE: B-16
)ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
.OGGEl
I-
W
Y
CH
11
WND ELEVATION: LOCATION See Map ' - +
ALLUVIUM: Brown red CLAY,
moist to wet, firm
Brown CLAY, moist, firm, with root holes
""""-
BEDROCK: Santiago Peak Volca-
nics; Orange stained green athered metavolcanics
moist, very dense
Total Depth 11%'
Near Refusal
SOIL TEST
No Water
No Caving
FIGURE B-17
SAN DIEGO SOILS ENGINEERING. INC
DATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
,1162-00 -
IVATION: O4 ' - +
LOCATION See MaF
TEST PIT NO. 10
DESCRIPTION
~ ~~
TOPSOIL: Brown CLAY, moist
to wet, firm
~~ BEDROCK: Point Loma Formation;
Light green grey SILTSTONE,
moist, stiff to very stiff,
\ massive with orange staining,
weathered to 5%'
Total Depth 7'
No Water
No Caving
SOIL TEST
- - - - -
I
!
I
I
" " -
" -
-
-
, - LOG OF TEST PIT
SAN DIEGO SOILS ENGINEERING, INC.
10 I
TEST PIT NO. 11
DESCRIPTION
TOPSOIL: Brown sandy CLAY,
dry to moist, soft
BEDROCK: Santiago Peak Volca-
nics; Very liqht green "eathen "
metavolcanics; moist, medium
with orange and red staining dense to 6', dense 6' to 9 I,
Total Depth 9'
No Water
No Caving
SOIL TEST
.LEVATION 307 ' LOCATION See Map
"
-
e3
-
J LOG OF TEST PIT I SAN DlEQO SOILS ENGINEERING, INC
IFIOURE: 8-19
>ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24 " Backhoe
D1162-0 I
TEST PIT N0.K
DESCRIPTION
IUND ELEVATION: 2 8 6 ' - LOCATION: See Map +
I
I
COPSOIL: Dark brown CLAY,
noist, firm
3EDROCK: Point Loma Formation;
lark green grey clayey SILTSTONE ?oist, stiff, massive, with
>range staining, upper 2' weathe
SOIL TEST
d
'otal Depth 8'
Jo Water
Jo Caving
". ... FIGUREB-~O
SAN DlEGO SOILS ENGINEERING. INC
)ATE OBSERVED 5-3-82 METHOD OF DRILLING: 24" Backhne
L
U U
I-
LI
I I- a U C
0
-
5
IO
5
0
5
0
5
KS
62-oc -
256" f
:VATION LOCATION: See Mal
TEST PIT NO. 13
DESCRIPTION
~
ALLUVIUM: Brown CLAY, moist,
soft to firm
BEDROCK: Point Loma Formation;
Grey green SILTSTONE, moist, stiff, with orange staining \
Total Depth 7'
No Water
No Caving
SOIL TEST
- - -
" "
-
-
-
r
LOG OF TEST PIT I ~
SAN DIEGO SOILS ENGINEERING. IHC
[FIQURE: 8-21
)ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
.OGGED BY
-I ICH
51
TEST PIT NO. 14
DESCRIPTION
ALLUVIUM: Brown CLAY, moist,
firm
BEDROCK: Point Loma Formation:
Green brown SILTSTONE, moist,
vff to very stiff
Total Depth 8'
No Water
No Caving
SOIL TEST
>ATE OBSERVED: 5-3-82 METHOD OF DRILLING 24" Backhoe
0 I
TEST PIT N0.A
DESCRIPTION
ALLUVIUM: Brown Clay/Light
brown SAND, moist to saturated,
soft @ 331l-7' Seepage
BEDROCK: Point Loma Formation; ellow green SILTSTONE, moist,
Total Depth 8'
Water @ 331'- 7'
Minor Caving @ 3%' - 7'
SOIL TEST
IFIGUREB-23
)ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
TOPSOIL: Dark brown CLAY, moist
to wet, firm
~~
BEDROCK: Point Loma Formation; qreen SILTSTONE, moist,
/\iff, fractured
I \
Total Depth 5'
No Water
No Caving
SOIL TEST
)UND ELEVATION: 270" +
LOCATION: See Map
>iz i au on TEST PIT NO. 16 : ' w- o> ! ak ' 2- ; oz ' z: DESCRIPTION
-
-
LOG OF TEST PIT FIGURE B-24
SAN DIEGO SOILS ENQINEERING. INC
..
DATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24 I' Backhoe
LC -
c
W
c W
I&
I c
W
-
n
-0
a
5
10
15
10
!5
IO
IS
IO
0 -
31162-0(
TEST PIT NO. 17
DESCRIPTION
ALLUVIUM: Brown sandy CLAY, moist to saturated, soft to
firm
@4' - 6' Seepage
BEDROCK: Point Loma Formation; Green grey SILTSTONE, moist,
,stiff, fractured
Total Depth 8 '
Seepage @ 4 ' - 6 '
No Caving
SOIL TEST
SIEVE
ANALY S IS
+ ' - LEVATION LOCATION: See Map
" "
-
-
LOG OF TEST PIT ~~
SAN DlEGO SOILS ENGINEERING, INC
)ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24 I' Backhoe
VATION: 268" -+
LOCATION: See Ma
TEST PIT NO. 18
DESCRIPTION
ALLUVIUM: Light brown sandy
CLAY/clayey SAND, wet to satu- rated, soft
e1.5' - 5' Seepage
BEDROCK: Point Loma Formation;
qtiff to very stiff Grey green SILTSTONE, moist,
Total Depth I'
Seepage @ l+' - 5'
SOIL TEST
'E OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
,1162-00 L
~~~~~~
ID ELEVATION 274 ' LOCATION See Map
I TEST PIT N0.C
DESCRIPTION
silty SAND, wet to saturated, loose
@ 1' - 4' Seepaqe
BEDROCK: Point Lorna Formation; - Grey green SILTSTONE, moist to wet, stiff, fractured
Total Depth 6'
Seepage @ 1' - 4'
Minor Caving @ 1' - 4'
LOG OF TEST PIT FIGURE B-27
SAN DlEGO SOILS ENGINEERING, INC
SOIL TEST
>ATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24" Backhoe
ID ELEVATION 276" LOCATION: See Ma +
SOIL TEST
DATE OBSERVED: 5-3-82 METHOD OF DRILLING: 24 " Backhoe
TEST PIT N0.L
DESCRIPTION
TOPSOIL: Brown CLAY, moist,
firm
BEDROCK: Point Loma Formation;
ge stained green SILTSTONE, st, stiff, fractured, with
emented zones
Total Depth 4'
No Water No Caving
SOIL TEST
,LEVATION * ' - +
LOCATION: See Map
" "
" - -
-
, LOG OF TEST PIT
SAN DlEGO SOILS ENGINEERING, IN<
DATE OBSERVED: 6-2-82 METHOD OF DRILLING Backhoe
D1162-0
TEST PIT NO. 22
DESCRIPTION
POPSOIL: Red brown CLAY, dry tc
noist, firm, with organics
3EDROCK: Point Lorna Formation;
>live green grey clayey SILT-
;TONE, moist, stiff, fractured
Total Depth 4.5'
No water
No caving
SOIL TEST
DATE OBSERVED 6-2-82 METHOD OF DRILLINQ Backhoe
0 1 _i No': SD1162-0
1
TEST PIT NO. 23
DESCRIPTION
~
TOPSOIL: Brown CLAY, dry to
moist, firm, with organics
BEDROCK: Point Loma Formation; >live green grey clayey SILT-
STONE, moist, stiff, with orange staining
Total Depth 5.5'
SOIL TEST T!
1: I
"
-
-
J
LOG OF TEST PIT "
SAN DIEGO SOILS ENGINEERING. INC
T!
1: I
"
-
-
J
LOG OF TEST PIT "
SAN DIEGO SOILS ENGINEERING. INC
IFIGURE: B-31
DATE OBSERVED 6-2-82 METHOD OF DRILLING: Backhoe ~ ~~~
VATION: 2 8 6: LOCATION See Map
TEST PIT NO. 24
DESCRIPTION
COPSOIL: Brown CLAY, dry to
noist, firm, with organics and roids
3EDROCK: Point Loma Formation;
)live green grey SILSTONE, moist jtif f
Total Depth 5.5'
No Water
No Caving
SOIL TEST
IFIGURE: B-32
L
FILL: Light to medium brown
SAND, moist, loose. -
I TOPSOIL: Dark brown CLAY, moist
firm, with organics.
BEDROCK: Point Loma Formation;
White-green SILTSTONE, moist, hard-cemented. 8"-10" jointed
Total Depth 7%'
Refusal
No Water
No Caving
SOIL TEST
)ATE OBSERVED 4-29-82 METHOD OF DRILLING 24" Backhoe
TEST PIT NO. 26
DESCRWTION
TOPSOIL: Dark brown CLAY, dry
to moist, firm.
L
BEDROCK: Point Lorna Formation: Dark green-grey SILTSTONE,
moist, stiff, fractured to 3' \@ 4' gemenged layer: 4" Thick
N16 W, 4 W. \ L"" ""
I moist, very stiff. Olive-grey clayey SILTSTONE,
I
Total Depth 6'
No Water
No Caving
SOIL TEST
LOGGED BI
11162-0
VATION LOCATION: See Map
TEST PIT NO. 27
DESCRIPTION
TOPSOIL: Brown CLAY, dry, firm
organics. Upper 2 feet is
natural exposure
PALEOSOL: Blue-green and purplt
stained silty CLAY, dry to
moist, fractured.
BEDROCK: Point Loma Formation;
Olive green-grey SILSTONE,
moist, very stiff, with some
urple staining.
Total Depth 10'
No Water
No Caving
SOIL TEST
. ..
- 0
0 ;D1162-0
iRC - VATION LOCATION:-
TEST PIT NO. 28
DESCRfPTlON
POPSOIL: Red brown silty CLAY,
irv to moist, firm.
?ALEOSOL: Green-purple-red
nottled silty CLAY, moist, very
stiff.
Total depth 9' No Water
No Caving
SOIL TEST
LE - -
" "
( " -
I
I
s
-
LOG OF TEST PIT FIGURE: B-36
SAN DIEGO SOILS ENGINEERING. INC
DATE OBSERVED: 4-29-82 METHOD OF DRILLING 24" Backhoe
:VATION: LOCATION: See Map
TEST PIT NO. 29
DESCRIPTION
TOPSOIL: Brown CLAY, moist,
firm.
BEDROCK: Point Loma Formation;
;reen-grey clayey SILTSTONE,
noist, stiff, fractured, calichc
\in upper 3 feet fractures.
Total Depth 6'
No Water NO Caving
SOIL TEST
ELE . - -
i
I
I 1
" "
" -
I
I
-1 3 -
LOG OF TEST PIT
SAN DlEGO SOILS ENGINEERING, INC
DATE OBSERVED: 4-29-82 METHOD OF DRILLING 24" Backhoe
VATION LOCATION See Map
TEST PIT NO. 30
DESCRIPTION
rOPSOIL: Light brown silty SAND
Iry to moist, loose.
3EDROCK: Santiago Peak Volcanic:
;reen Metavolcanic, weathered,
lard with fractures.
Total Depth 6'
Near Refusal
No Water
No Caving
SOIL TEST
3D1162-0
VATION LOCATION see Map
TEST PIT NO. 31
DESCRIPTION
TOPSOIL: Brown SAND, dry, loose
BEDROCK: Santiago Peak Volcanic
Brown-green Metavolcanic, very
hard, fractured.
Total Depth 3' Refusal
No Water
No Caving
SOIL TEST
- -
! -
-
LOG OF TEST PIT I - "
SAN DIEGO SOILS ENGINEERING. IN(
IFIGURE: R-39
t .OGGED BY:
1.: - 'D1162-0
IATION: 240 ' - LOCATION See Map
TEST PIT NO. 32
t
DESCRIPTION
TOPSOIL: Light brown silty CLA
noist, soft to firm, upper 2' loose with roots.
3EDROCK: Point Loma Formation;
~rey and reddish-brown clayey SILSTONE, moist, firm to stiff,
reathered to 8'. ? 8' Red cobble layer
10' Bedding N 45" E, 20" NW.
Total Depth 13'
No Water
No Caving
SOIL TEST
)ATE OBSERVED 6-24-82 METHOD OF DRILLING: 24" Backhoe
D1162-01
iROUND E LE
TEST PIT N0.A
DESCRIPTION
TOPSOIL: Reddish-brown silty
CLAY, moist, soft to firm.
BEDROCK: Point Loma Formation:
mottled grey reddish light brown
SILTSTONE, stiff to very stiff,
iieathered in upper 4', poorly to gel1 bedded.
@ 6' Bedding: N4" E, 10" W
11' Bedding: N30° E, 7O NW
Total Depth 14'
No Water
No Caving
-
SOIL TEST
"
" -
I
1
1
I
I
" -
I LOG OF TEST PIT FIGURE: B-
SAN DIEGO SOILS ENGINEERING. IN(
DATE OBSERVED " METHOD OF DRILLING 24 " Backhoe
ALLUVIUM/COLLUVIUM: Dark brown
silty CLAY, moist, soft to firm.
BEDROCK: Point Lorna Formation;
mottled red and grey SILTSTONE,
slightly moist, stiff, abundant
caliche.
@ 6' Bedding: N30° W, 15ONE
Total Depth 10'
No Caving
No Water
SOIL TEST
"
"
DATE OBSERVED: 6-24-82 METHOD OF DRILLING 24" Backhoe
;D1162-0
L
Total Depth 4' No Water
No Caving
'EDROCK: Santiago Peak Vol-
,anics; red-brown clayey SILT, ry, stiff to hard, weathered
0 4'.
SOIL TEST
)UND ELEVATION: 238 ' - LOCATION: See Map
2 ' E? TEST PIT NO. 35
E w- ! <e ; ig DESCRIPTION ' zg
+
>c -
">
-
LOG OF TEST PIT
SAN DIEGO SOILS ENGINEERING. INC
- "
IFIGURE: R- a
'ATE OBSERVED: 6-24-82 METHOD OF DRILLING 24" Backhoe
LOGGED E'
21162 - !-I -
TEST PIT NO. 36
DESCRIPTION
~
:EDROCK: Santiago Peak Vol- :anlcs; yellow-brown metavolcan- cs, hard.
Total Depth 3 I
Refusal at 3'
No Caving
No Water
SOIL TEST
FIGURE B-44
SAN DlEGO SOILS ENGINEERING. INC
ATE OBSERVED: 6-24-82 METHOD OF DRILLING: 24" Backhoe
lD1162-0 -
TEST PIT NO. 37
DESCRIPTION
~~ ~
BEDROCK: Santiago Peak Vol-
canics; mottled green, red and brown metavolcanics, moderately
hard, weathered to 8'.
Total Depth 8'
NO Water
NO Caving
SOIL TEST
IFIGURE: B-45
ATE OBSERVED: 6-24-82 METHOD OF DRILLING 24" Backhoe
TOPSOIL: Reddish-brown silty
CLAY, moist, soft. 1
I
BEDROCK: Point Loma Formation;
mottled grey SILTSTONE, stiff,
weathered in upper 5'.
I
'X ND
a
- -
W > J n I C
4
(r:
U
x 5 - h
a 3 - - -
"
Total Depth 10'
NO Water
No Caving
3131162-001 LOG OF TEST PIT FIQURE B-46
SAN DIEQO SOILS ENGINEERING. IN'
SOIL TEST
APPENDIX C
LABORATORY TESTING
A. Index Tests
Moisture content and dry density determinations were made
for most ring samples. Results of moisture-density de-
terminations are shown on the Logs of Borings, included in
Appendix B of this report.
Results of Hydrometer Tests and Sieve Analyses performed in
accordance with ASTM: D 422-72, on portions of representative
samples are presented in Figures C-1 through C-9.
Results of Atterberg Limits, consisting of both liquid
limit and plastic limit analyses are plotted on the Plas-
ticity Chart in Figure C-10. Atterberg Limits were performed
in accordance with ASTM: D 423-72. The test results are
also recorded'on the grain size curves.
B. Consolidation Tests
Consolidation tests were. performed on remolded siltstone
(Figures C-11 and C-12), and topsoil (Figure C-13). Water
was added to the apparatus at the load indicated on the
consolidation curves. The consolidation test results are
presented on Figures C-11 through C-13.
C. Direct Shear Tests
Direct shear strength tests were performed on remolded and
selected ring samples. Test results for remolded silt-
stone, topsoil, intact siltstone, and remolded sandstone
(proposed import source) are presented in Figures C-14, C-15,
C-16 and C-17 respectively. All samples were inundated
and allowed to come to equilibrium prior to shearing with
the exception of the topsoil. For the topsoil, approximate
unconsolidated-undrained (g=O analysis) direct shear tests
were performed.
D. Expansion
Expansion tests were performed on representative samples
of the on-site soils remolded and tested under a surcharge
of 144 pounds per square foot in accordance with the Uni-
form Building Code Standard No. 29-2. The test results
are summarized on Table 1, Figure C-18.
E. Maximum Density/Optimum Moisture Content
The maximum dry density/optimum moisture content rela-
tionship was determined for typical samples of the on-site
soils. The laboratory standard used was ASTM: D 1557-78.
The test results are summarized on Table 2, Figure C-18.
F. Sulfate Tests
Sulfate test results are summarized in Table 3, Figure C-19.
PERCENT PASSING
PERCENT PASSING
OB NO.: SD1162-00 PARTICLE SIZE ANALYSIS FIGURE: c-1
SAN DlEGO SOILS ENGINEERING, IN(
PERCENT PASSINQ
OB NO: SD1162-00 PARTICLE SIZE ANALYSIS FIQURE
SAN DIEQO SOILS ENQINEERINQ. INC.
c-2
PERCENT PASSING
PERCENT PASSING
' No.: ~~1162-001 PARTICLE SIZE ANALYSIS FIGURE c-3
SAN DlEQO SOILS ENGINEERING, IN(
PERCENT PASSINQ
PERCENT PASSING
NO.: SD1162-00 FIGURE: c-4 PARTICLE SIZE ANALYSIS
SAN DIEQO SOILS ENGINEERINQ. INC
PERCENT PASSINQ
OB NO.: SD1162-00 PARTICLE SIZE ANALYSIS FIGURE: c-5
SAN DlEQO SOILS ENGINEERINQ. I,
PERCENT PASSING
PERCENT PASSING
' N0.SD1162-00 PARTICLE SIZE ANALYSIS FIGURE C-6
SAN DIEGO SOILS ENGINEERING. INC.
PERCENT PASSINQ
PERCENT PASSINQ
I NO.: SD1162-00 PARTICLE SIZE ANALYSIS FIQURE: c-7
SAN DIEQO SOILS ENQINEERINQ. IN4
PERCENT PASSING
PERCENT PASSING
38 NO.: SD1162-00 PARTICLE SIZE ANALYSIS FIGURE C- 8
SAN DIEQO SOILS ENGINEERING. INC
PERCENT PASSINQ
PERCENT PASSIN0
101) NO: SD1162-00 PARTICLE SIZE ANALYSIS FIOURE: c-9
SAW DIEQO SOILS ENQINEERINQ. IN(
SYMBOL
0
Q
PLASTICITY CHART
Job NO: SD1162-00 Date: July, 1982 Figure: C-10
SAN DIEGO SOILS ENGINEERING. INC
+
BORINQ NO. EXPLANATION SYMBOL DEPTH (FEET)
2 0 10 FIELD MOISTURE
"" """ SAMPLE SATURATED
REBOUND
NORMAL LOAD (PSR
>B NO.: SD1162-00 LOAD CONSOLIDATION TEST FIQURE: c-11
SAN DlEQO SOILS ENGINEERING. INC
NORMAL LOAD (PSD
IB NO.: SD1162-00 LOAD CONSOLIDATION TEST FIQURE: c-12
SAN DIEQO SOILS ENQINEERINQ. INC
BORING NO. DEPTH (FEET) SYMBOL EXPLANATION
T-4 1 0 FIELD MOISTURE
~ """"" SAMPLE SATURATED
I I REBOUND
!
D D 0 000
D 0 000 0 000
e4 m*u, 2 0 000
NORMAL LOAD (PSF)
le NO.: SD1162-00 LOAD CONSOLIDATION TEST FIGURE C-13
SAN DIEGO SOILS ENGINEERING. IN<
0 0
0
N
0 0
:4 0
C
F
0 0 0 m
0
0 0
N
0 0 0 .#-I
(3sd) ssax~s xeaqs yead
C
0 0 0
..
0
0 0 m
- u
(D a Y
ffl ffl a, & OU OW 0 NFI
&
z 0
0 0 0 4
3
0 0 0 m
0 0 0
0
0 0
C
TABLE 1
RESULTS OF EXPANSION TESTS p
Test Location
Medium 63 B-2 at 40'
Medium - High 83 B-2 at 10'
Potential Expansion Expansion Index
L
T-4 at 1' I 1 I 142 Very High
TABLE 2
MAXIMUM DENSITY/OPTIMUM MOISTURE TESTS (A.S.T.M. Test Procedure D 1557-78)
r 1 I 1
Test Location Maximum Dry Density (pcf) I Content (%) I Optimum Moisture I
I B-2 at 10' 108 I ~~ ~
17
B-2 at 40'
14 117 B-G at 6'
21 102
.
T-4 at 1' 14 109
Job NO: SD1162-00 Date: July, 1982 Figure: C-18
TABLE 3
RESULTS OF SULFATE TESTS
Test Location I % Soluble Sulfate 1
B-2 at 10'
0.0189 B-2 at 40'
0.0160
T-4 at 1' 0.0152
< .
Job NO; SD1162-00 Date: July, 1982 Figure: C-19
APPENDIX D
STABILITY ANALYSIS
Appendix D summarizes results of stability analysis.
Gross stability computations for compacted slopes were performed
using Janbu's stability charts with the shear strength parameters
for remolded siltstone presented in Figure C-13. Gross stability
analysis are presented in Figures D-1 and D-2.
Surficial stability analysis were performed assuming an infinite
slope with seepage parallel to the slope face. To determine the
shear strength for surficial stability analysis, drained Direct
Shear tests were performed on remolded siltstone samples at low
normal loads (75-150 psf) and the samples were permitted to swell
prior to shearing. Shearing of samples provided at a strain rate
of on the order of 0.005 inches per minute. The surficial stability
analysis for three feet of seepage is presented in Figure D-3 and
the factor of safety versus depth of seepage is presented in
Figure D-4.
\I I I I I I I I
L I, 1 I I I 5 10 15 20 25 30 35 LO 15 %OPE 4 IDEGREESI
SLOPE DATA:
Slope Height (HI 50 feet Friction Angle (0) 24 degrees
Slope Ratio (M) 26 degrees Cohesion (C) 400 psf
Unit Weight (8) 120 PC f
FACTOR 'OF SAFETY (F . S . ) :
6.7 N, = 27 from chart
GROSS STABILITY ANALYSIS (JANBU'S CHART)
OB NO.: DATE: SD1162-00 FIQURE: July, 1982 D-1
SAN DIEGO SOILS ENGINEFRING. IN1
SLOPE .( IDEGREESI
SLOPE DATA:
Slope Height (H) 100 feet Friction Angle ($1 24 degrees
Slope Ratio (00 22 degrees Cohesion (C) 400 psf
Unit Weight (X) 120 pcf
?ACTOR 'OF SAFETY (F. S . ) :
Icd = 'dHtan$ = C 13.4 N, = 49 from chart
F.S. - Nc C -m= 1.63
GROSS STABILITY ANALYSIS (JANBU'S CHART)
18 NO.: SD1162-00 DATE: July, 1982 FIQURE:
SAN DIEGO SOILS ENGINEERING. IN<
D- 2
NORMAL, STRESS (i) psf
SURFICAL STABILITY DATA:
Slope Ratio (.O
Total Unit Weight (&)
Bouyant Unit Weight ( b;)
Depth of Seepage Flow (D)
22 degrees
120 PCf
57.6 PCf
3.0 feet
FACTOR OF SAFETY (F. S. ) -
NFXDCCOS 2 d = 149 S= 158 from above chart
F.S. = S rt .D COS sin OC - - 1.27
SURFICAL STABILITY ANALYSIS
18 NO.: DATE:
SD1162-00 July, 1982 FIGURE:
SAN DIEDO SOILS ENGINEERING. D-3 INC.
2.5
h
(0
F * 2.0 -
w E., w F
(0
4
1.5
0
e: 0
V H
h A
1.0
0.5
0 1 2 3 4
DEPTH OF SEEPAGE (feet)
SURFICIAL STABILITY DATA:
Slope Ratio &) 21.8 degrees
Total Unit Weight ( ) 120 PCf
Soil Type REMOLDED SILTSTONE
FACTOR OF SAFETY (F. S . ) :
F.S. = 2.30 (D = 1 foot)
F.S. = 1.60 (D = 2 feet)
F.S. = 1.27 (D = 3 feet)
F.S. = 1.13 (D = 4 feet)
SURFICIAL STABILITY ANALYSIS: SUMNARY
>B NO.: SD1162-00 DATE: July, 1982 FIGURE: D-4
P.U nlE" en,, c C.lnl.*C"...- B.8,-
APPENDIX E
...
...
-
.
.
.
.
.
.
.
.
.
1 .
2 .
3 .
4 .
5 .
6 .
7 .
8 .
9 .
10 .
11 .
12 .
STANDARD GUIDELINES FOR GRADING PROJECTS
TABLE OF CONTENTS
Page __
GENERAL ...................... 1
DEFINITION OF TERMS ................. 1
OBLIGATIONS OF PARTIES ............... 5
SITE PREPARATION .................. 5
SITE PROTECTION .................. 6
EXCAVATIONS .................... 8
6.1 UNSUITABLE MATERIALS ............. 8
6.2 CUT SLOPES .................. 8
6.3 PAD AREAS .................. 9
COMPACTED FILL ................... 9
7.1 PLACEMENT .................. 10
7.2 MOISTURE .................. -11
7.3 FILL MATERIAL ................ 12
7.4 FILL SLOPES .................. 14
7.5 OFF-SITE FILL ................ 16
DRAINAGE ...................... 16
STAKING ...................... 17
SLOPE MAINTENANCE .................. 17
10.1 LANDSCAPE PLANTS ............... 17
10.2 IRRIGATION ................. -17
10.3 MAINTENANCE ................. 18
10.4 REPAIRS ................... 18
TRENCH BACKFILL ................. -19
STATUS OF GRADING ................ -20
.
..
STANDARD GUIDELINES FOR GRADING PROJECTS
1. GENERAL
1.1 The guidelines contained herein and the standard
details attached hereto represent this firm's stan-
dard recommendations for grading and other associated
operations on construction projects. These guide-
lines should be considered a portion of the project
specifications.
1.2 All plates attached hereto shall be considered as
part of these guidelines.
1.3 The Contractor should not vary from these guidelines
without prior recommendation by the Geotechnical Con-
sultant and the approval of the Client or his auth-
orized representative. Recommendation by the Geo-
technical Consultant and/or Client should not be
considered to preclude requirements for approval by
the controlling agency prior to the execution of any
changes.
1.4 These Standard Grading Guidelines and Standard De- tails may be modified and/or superseded by recommen-
dations contained in the text of the preliminary
geotechnical report and/or subsequent reports.
1.5 If disputes arise out of the interpretation of these
grading guidelines or standard details, the Geotech-
nical Consultant shall provide the governing inter-.
pretation.
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.
2.2 AS-GRADED (AS-BUILT) - the surface and subsurface con-
ditions at completion of grading.
2.3 BACKCUT - a temporary c,onstruction slope at the rear
of-earth retaining structures such as buttresses,
shear keys, stabilization fills or retaining walls.
2.4 BACKDRAIN - generally a pipe and gravel or similar
drainage system placed behind earth retaining struc-
tures such as buttresses, stabilization fills and
retaining walls.
Page Two
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
BEDROCK - a more or less solid, relatively undis-
turbed rock in place either at the surface or be-
neath 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
imum key width and depth and by maximum backcut angle.
features. A buttress is generally specified by min-
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.
CLIENT - the Developer or his authorized representa-
shall have the responsibility of reviewing the find-
tive who is chiefly in charge of the project. He
Consultant and shall authorize the Contractor and/or
ings and recommendations made by the Geotechnical
other consultants to perform work and/or provide
services.
COLLUVIUM - generally loose deposits usually found
near the base of slopes and brought there chiefly by
see Slope Wash).
gravity through slow continuous downhill creep (also
COMPACTION - is the densification of a fill by mech- anical means.
CONTRACTOR - a person or company under contract or
otherwise retained by the Client to perform demoli-
tion, grading and other site improvements.
DEBRIS - all products of clearing, grubbing, demoli-
tion, contaminated soil material unsuitable for reuse
as compacted fill and/or any other material so desig-
nated by the Geotechnical Consultant.
ENGINEERING GEOLOGIST - a Geologist holding a valid
Engineering Geology. certificate of registration in the specialty of
Page Three
2.16 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 com-
pliance with the recommendations of the Geotechnical
Consultant and the governing agency requirements.
2.17 EROSION - the wearing away of the ground surface as
a result of the movement of wind, water and/or ice.
2.18 EXCAVATION - the mechanical removal of earth materials.
2.19 ,EXISTING GRADE - the ground surface configuration
prior to grading.
2.20 FILL - any deposits of soil, rock, soil-rock blends
or other similar materials placed by man.
2.21 FINISH GRADE - the ground surface configuration at which time the surface elevations conform to the
approved plan.
2.22 GEOFABRIC - any engineering textile utilized in geo-
tion and filtering.
technical applications including subgrade stabiliza-
2.23 GEOLOGIST - a representative of the Geotechnical Con-
sultant educated and trained in the field of geology.
2.24 GEOTECHNICAL CONSULTANT - the Geotechnical Engineering
and Engineering Geology consulting firm retained to provide technical services for the project. For the
purpose of these specifications, observations by the
Geotechnical Consultant include observations by the
Soil Engineer, Geotechnical Engineer, Engineering
Geologist and those performed by persons employed by
and responsible to the Geotechnical Consultants.
2.25 GEOTECHNICAL ENGINEER - a licensed Civil Engineer who
applies scientific methods, engineering principles and professional experience to the acquisition, interpre- tation and use of knowledge of materials of the earth's
crust for the evaluation of engineering problems. Geo-
technical Engineering encompasses many of the engi-
geology, geophysics, hydrology and related sciences. neering aspects of soil mechanics, rock mechanics,
2.26 GRADING - any operation consisting of excavation,
filling or combinations thereof and associated opera-
tions.
2.27 LANDSLIDE DEBRIS - material, generally porous and of low density, produced from instability of natural or
man-made slopes.
2.28 MAXIMUM DENSITY - standard laboratory test for maximum
dry unit weight. Unless otherwise specified, the maximum dry unit weigh-t shall he determined in accor-
dance with ASTM Method of Test D 1557-78.
Page Four
2.29 OPTIMUM MOISTURE - test moisture content at the
maximum density.
2.30 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.
2.31 ROUGH GRADE - the ground surface configuration at which
time the t;arface elevations approximately conform to
the approved plan.
2.32 .SITE - the particular parcel of land where grading is being performed.
2.33 SHEAR KEY - similar to buttress, however, it is gen- erally constructed by excavating a slot within a
natural slope in order to stabilize the upper por-
tion of the slope without grading encroaching into
the lower portion of the slope.
2.34 SLOPE - is an inclined ground surface the steepness
of which is generally specified as a ratio of hori-
zontal: vertical (e.g., 2: 1).
2.35 SLOPE WASH - soil and/or rock material that has been
runoff water not confined by channels (also see
transported down a slope by mass wasting assisted by
Colluvium).
2.36 SOIL - naturally occurring deposits of sand, silt,
clay, etc. or combinations thereof.
2.37 SOIL ENGINEER - licensed Civil Engineer experienced
in soil mechanics (also see Geotechnical Engineer).
2.'38 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 sta-
bilization 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.
2.39 , SUBDRAIN - generally a pipe and gravel or similar
drainage system placed beneath a fill in the align-
ment of canyons or former drainage channels.
2.40 SLOUGH - loose, noncompacted fill material generated
during grading operations.
2.41 TAILINGS - nonengineered fill which accumulates on
or adjacent to equipment haul-roads.
2.42 TERRACE - relatively level step constructed in the
face of a graded slope surface for drainage control , and maintenance purposes.
Page Five
2.43 TOPSOIL - the presumably fertile upper zone of soil
which is usually darker in color and loose.
2.44 WINDROW - a string of large rock buried within en-
by the Geotechnical Consultant.
gineered fill in accordance with guidelines set forth
3- OBLIGATIONS OF PARTIES
3.1 The Geotechnical Consultant should provide observa-
tion and testing services and should make evalua-
tions in order to advise the Client on geotechnical
matters. The Geotechnical Consultant should report
his findings and recommendations to the Client or
his authorized representative.
3.2 The Client should be chiefly responsible for all
aspects of the project. He or his authorized rep-
resentative has the responsibility of reviewing the
findings and rekommendations of the Geotechnical
authorized the Contractor and/or other consultants Consultant. He shall authorize or cause to have
grading the Client or his authorized representative
to perform work and/or provide services. During
should remain on-site or should remain reasonably
accessible to all concerned parties in order to make
decisions necessary to maintain the flow of the
project.
3.3 The Contractor should be responsible for the safety
of the project and satisfactory completion of all
grading and other associated operations on construc-
tion projects, including, but not limited to, earth
work in accordance with the project plans, specifi-
cations and controlling agency requirements. During
gradine the Contractor or his authorized represen-
tative should remain on-site. Overnight and on days
off, the Contractor should remain accessible.
4. SITE PREPARATION
4.1 The Client, prior to any site preparation or grading,
should arrange and attend a meeting among the Grading
Contractor, the Design Engineer, the Geotechnical Con-
sultant, representatives of the appropriate governing
All parties should be given at least 48 hours notice.
authorities as well as any other concerned parties.
4.2 Clearing and grubbing should consist of the removal of
vec~etation such as brush, grass, woods, stumps, trees,
roots of trees and otherwise deleterious natural mater-
ials from the areas to be graded. Clearing and grub-
bing should extend to the outside of all proposed excavation and fill areas.
Page Six
4.3
4.4
4.5
4~. 6
Demolition should include removal of buildings,
structures, foundations, reservoirs, utilities (in-
cluding underground pipelines, septic tanks, leach
nels, etc.) and other man-made surface and sub-
fields, seepage pits, cisterns, mining shafts, tun-
surface improvements from the areas to be graded.
Demolition of utilities should include proper cap-
ping and/or rerouting pipelines at the project per-
with the requirements of the governing authorities
imeter ana cutoff and capping of wells in accordance
and the recommendations of the Geotechnical Consul-
tant at the time of demolition.
Trees, plants or man-made improvements not planned
to be removed or demolished should be protected by
the Contractor from damage or injury.
demolition operations should be wasted from areas
Debris generated during clearing, grubbing and/or
to be graded and disposed off-site. Clearing, grub-
bing and demolition operations should be performed
under the observation of the Geotechnical Consultant.
The Client or Contractor should obtain the required
approvals from the controlling authorities for the project prior, during and/or after demolition, site
preparation and removals, etc. The appropriate ap-
provals should be obtained prior to proceeding with
grading' operations.
5. SITE PROTECTION
5.1
5.2
Protection of the site during the period of grading
should be the responsibility of the Contractor. Un-
less other provisions are made in writing and agreed
upon among the concerned parties, completion of a
portion of the project should not be considered to
preclude that portion or adjacent areas from the
requirements for site protection until such time as
the entire project is complete as identified by the
Geotechnical Consultant, the Client and the regu-
lating agencies.
The Contractor should be responsible for the stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary exca-
vations (e.g., backcuts) are made in consideration of
stability of the completed project and, therefore,
bilities of the Contractor. Recommendations by the
should not be considered to preclude the responsi-
Geotechnical Consultant should not be considered to
preclude more restrictive requirements by the regu-
lating agencies.
Page Seven
5.3 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 provi-
quately direct surface drainage away from and off the
sions should be made during the rainy season to ade-
work site. Where low areas cannot be avoided, pumps should be &opt on hand to continually remove water
during periods of rainfall.
5.4 During periods of rainfall, plastic sheeting should
.be kept reasonably accessible to prevent unprotected
slopes from becoming saturated. Where necessary dur-
ing periods of rainfall, the contractor should install
checkdams, desilting basins, rip-rap, sand bags or other
devices or methods necessary to control erosion and
provide safe conditions.
5.5 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
ing, other labor, dozing, etc.) . (e.g.,pumping, placement of sandbags or plastic sheet-
5.6 Following periods of rainfall, the Contractor should
contact the Geotechnical Consultant and arrange a walk-
lated damage. The Geotechnical Consultant may a150
over of the site in order to visually assess rain re-
recommend excavations and testing in order to aid in
Consultant, the Contractor shall make excavations in
his assessments. At the request of the Geotechnical
order to evaluate the extent of rain related-damage.
5.7 Rain-related damage should be considered tQ include,
but may not be limited to, erosion, silting, saturation,
swelling, structural distress and other adverse condi-
tions identified by the Geotechnical Consultant. Soil
adversely affected should be classified as Unsuitable
Materials and should be subject to overexcavation and
replacement with compacted fill or other remedial grad-
ing as recommended by the Geotechnical Consultant.
5.8 Relatively level areas, where saturated soils and/or
erosion gullies exist to depths of greater than 1.0
tent material. Where less than 1.0 foot in depth, un- foot, should be overexcavated to unaffected, compe-
suitable materials may be processed in-place to achieve
near-optimum moisture conditions, then thoroughly re-
compacted in accordance with the applicable specifica-
tions. If the desired results are not achieved, the
affected materials should be overexcavated, then re-
placed in accordance with the applicable specifications.
Page Eight
5.9 In slope areas, where saturated soil and/or erosion
gullies exist to depths of greater than 1.0 foot,
fill in accordance with the applicable specifications. they should be overexcavated and replaced as compacted
Where affected materials exist to depths of 1.0 foot
or less below proposed finished grade, remedial grad-
ing by moisture conditioning in-place, followed by
able gradfilg guidelines herein may be attempted. If
thorough recompaction in accordance with the applic-
the desired results are not achieved, all affected
compacted fill in accordance with the slope repair
materials should be overexcavated and replaced as
recommendations herein. As field conditions dictate,
other slope repair procedures may be recommended by
the Geotechnical Consultant.
6. EXCAVATIONS
6.1 UNSUITABLE MATERIALS
6.1.1 Materials which are unsuitable should be exca-
vated under observation and recommendations of
ials include, but may not be limited to, dry,
the Geotechnical Consultant. Unsuitable mater-
loose, soft, wet, organic compressible natural
soils and fractured, weathered, soft bedrock
and nonengineered or otherwise deleterious
fill materials.
6.1.2 Material identified by the Geotechnical Consul-
tant as unsatisfactory due to it’s 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.
6.2 CUT SLOPES
6.2.1 Unless otherwise recommended by the Geotechnical
Consultant and approved by the regulating agen-
cies, permanent cut slopes should not be steeper
than 2:l (horizonta1:vertical).
6.2.2 If excavations for cut clopes expose loose, co- hesionless, significantly fractured or otherwise
ment of the unsuitable materials with a compacted
unsuitable material, overexcavation and replace-
” recommended by the Geotechnical Consultant. stabilization fill should be accomplished as
Unless otherwise specified by the Geotechncial Consultant, stabilization fill construction
should conform to the requirements of the Stan-
dard Details.
Page Nine
7.
6.2.3
6.2.4
6.2.5
The Geotechnical Psnsultant should review cut
Consultant should be notified by the contractor slopes during excavation. The Geotechnical
prior to beginning slope excavations.
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 recommenda-
tions to treat these problems.
When cut slopes are made in the direction of
sion swale (brow ditch) should be provided at
the prevailing drainage, a non-erodible diver-
the top-of -cut.
6.3 PAD AREAS
6.3.1 All lot pad areas, including side yard terraces,
above stabilization fills or buttresses should
be overexcavated to provide for a minimum of
3 feet (refer to Standard Details) of compacted
fill over the entire pad area. Pad areas with
both fill and cut materials exposed and pad
areas containing both very shallow (less than
3 feet) and deeper fill should be overexcavated
to provide for a uniform compacted fill blanket
with a minimum of 3 feet in thickness (refer to
Standard Details). Cut areas exposing signi-
ficantly varying material types should also be
overexcavated to provide for at least a 3-fOOt
thick compacted fill blanket. Geotechnical
excavation. The actual depth should be de- conditions may require greater depth of over-
lineated by the Geotechnical Consultant during
grading.
6.3.2 For pad areas created above cut or natural
slopes, positive drainage should be established
away from the top-of-slope. This may be accom- plished utilizing a berm and/or an appropriate
pad gradient. A gradient in soil areas away
from the top-of-slopes of 2 percent or greater is recommended.
COMPACTED FILL
All fill materials should be compacted as specified below
or by other methods specifically recommended by the Geotech-
nical Consultant. Unless otherwise specified, the minimum
degree of compaction (relative compaction) should be 90
percent of the laboratory maximum density.
Page Ten
7.1 PLACEMENT
7.1.1
7.1.2
7.1.3
7.1.4
Prior to placement of compacted fill, the Con-
nical Consultant of the exposed ground surface.
tractor should request a review by the Geotech-
Unless otherwise recommended, the exposed ground surface should then be scarified (six inches mini-
mum), watered or dried as needed, thoroughly
blenaed to achieve near optimum moisture condi-
of 90 percent of the maximam density. The re-
tions, then thoroughly compacted to a minimum
view by the Geotechnical Consultant should not
be considered to preclude requirement of inspec-
tion and approval by the governing agency.
Compacted fill should be placed in thin hori-
zontal lifts not exceeding eight inches in loose
thickness prior to compaction. Each lift
should be watered or dried as needed, thoroughly
blended to achieve near optimum moisture condi-
tions then thoroughly 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.
The Contractor should have suitable and suffi-
cient mechanical compaction equipment and water-
ing apparatus on the job site to handle the amount of fill being placed in consideration
of moisture retention properties of the mater-
be "shut down" temporarily in order to permit
ials. If necessary, excavation equipment should
proper compaction of fills. Earth moving equip-
ment should'only be considered a supplement and
not substituted for conventional compaction
equipment.
When placing fill in horizontal lifts adjacent
vertical), horizontal keys and vertical benches to areas sloping steeper than 5:l (horizontal:
Keying and benching should be sufficient to pro-
should be excavated into the adjacent slope area
mum of four feet of vertical bench height within
vide at least six-foot wide benches and a mini-
the firm natural ground, firm bedrock or engi-
be placed in an area subsequent to keying and
neered compacted fill. No compacted fill should
benching until the area has been reviewed by
the Geotechnical Consultant. Material generated
by the benching operation should be moved suf-
ficiently away from the bench area to allow for
the recommended review of the horizontal bench
benching details have been included within the prior to placement of fill. Typical keying and
accompanying Standard Details.
Page Eleven
7.1.5 Within a single fill area where grading proce-
dures dictate two or more separate fills, tem-
porary slopes (false slopes) may be created. When placing fill adjacent to a false slope,
benching should be conducted in the same man-
ner as above described. At least a 3-fOOt
vertical bench should be established within
the firm core of adjacent approved compacted
Benching should proceed in at least 3-foot
fCll-prior to placement of additional fill.
vertical increments until the desired finished
grades are achieved.
7.1.6 Fill should be tested for compliance with the
recommended relative compaction an3 moisture
conditions. Field density testing should con- form to ASTM Method of Test D 1556-64, D 2922-78
and/or D 2937-71. Tests should be provided for
yards of fill placed. Actual test interval about every two vertical feet or 1,000 cubic
may vary as field conditions dictate. Fill
found not to be in conformance with the grad-
ing recommendations should be removed or other- wise handled as recommended by the Geotechnical
Consultant.
7.1.7 The Contractor should assist the Geotechnical
Consultant and/or his representative by digging test pits for removal determinations and/or for
testing compacted fill.
7.1.8 As recommended by the Geotechnical Consultant,
the Contractor should "shut down" or remove
grading equipment from an area being tested.
7.1.9 The Geotechnical Consultant should maintain a
plan with estimated locations of field tests.
Unless the client provides for actual surveying
of test locations, the estimated locations by the Geotechnical Consultant should only be con-
sidered rough estimates and should not be uti-
lized for the purpose of preparing cross sec-
tions showing test locations or in any case for
the purpose of after-the-fact evaluating of the
sequence of fill placement.
7.2 MOISTURE
7. 2.1 For field testing purposes, "near optimum" mois-
ture will vary with material type and other factors including compaction procedure. "Near optimum" may be specifically recommended in
be evaluated durino grading.
Preliminary Investigation Reports and/or may
Page Twelve
7.2.2 Prior to placement of additional compacted
fill following an overnight or other qradinq
delay, the exposed surface or previously com-
pacted fill should be processed by scarifica-
blended to near-optimum moisture conditions,
tion, watered or dried as needed, thoroughly
then recompacted to a minimum of 90 percent
ofz>-aboratory maximum dry density. Where wet or other dry or other unsuitable materials exist to depths of greater than one foot, the
unsuitable materials should be overexcavated.
7.2.3 Following a period of flooding, rainfall or
overwatering by other means, no additional
fill should be placed until damage assess-
ments have been made and remedial grading
performed as described under Section 5.6
herein.
7. 3 FILL MATERIAL
7.3.1 Excavated on-site materials which are accept-
able to the Geotechnical Consultant may be
utilized as compacted fill, provided trash,
vegetation and other deleterious materials
are removed prior to placement.
7.3.2 Where import materials are required for use
bn-site, the Geotechnical Consultant should be
notified at least 72 hours in advance of im-
porting, in order to sample and test materials
from proposed borrow sites. Vo import mater-
out prior s.ampling and testing by Geotechnical
ials should be delivered for use on-site with-
Consultant.
7.3.3 Where oversized rock or similar irreducible ma-
terial is generated during grading, it is rec-
ommended, where practical, to waste such mater-
ial off-site or on-site in areas designated as
placed in disposal areas should be placed with "nonstructural rock disposal areas". Rock
sufficient fines to fill voids. The rock should
be compacted in lifts to an unyielding condi-
at least three feet of compacted fill which is
tion. The disposal area should be covered with
free of oversized material. The upper three feet should be placed in accordance with the
guidelines for compacted fill herein.
Page Thirteen
7.3.4 Rocks 12 inches in maximum dimension and smal-
ler may be utilized within the compacted fill,
provided they are placed in such a manner that
nesting of the rock is avoided. Fill should
be placed and thoroughly compacted over an6
arcund 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.
, ."
7.3.5 During the course of grading operations, rocks
or similar irreducible materials greater than
may be generated. These rocks should not be
12 inches maximum dimension (oversized material),
placed within the compacted fill unless placed as recommended by the Geotechnical Consultant.
7.3.6 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 accord-
ance with the accompanying Standard Details is
be broken down or disposed off-site. Rocks recommended. Rocks greater than four feet should
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 recommendations could vary as locations
of improvements dictate. Where practical, over-
sized material should not be placed below areas
where structures or deep utilities are proposed.
Oversized material should be placed in windrows
pacted fill or firm natural ground surface.
on a clean, overexcavated or unyielding com-
Select native or imported granular soil (S.E. 30 or higher) should be placed and thoroughly
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.
7.3.7 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.
7.3.8 Material that is considered unsuitable by the
Geotechnical Consultant should not be utilized
in the compacted fill.
Page Fourteen
7.3.9 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 verify conformance with
the specifications. Processing of these ad-
days. The Contractor may elect to move the
digional samples may take two or more working
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.
7.3.10 Any fill placed in areas not previously re-
viewed and evaluated by the Geotechnical Con-
sultant, and/or in other areas, without prior
notification to the Geotechnical Consultant may
require removal and recompaction at the Con- tractor's expense. Determination of overex-
cavations should be made upon review of field
conditions by the Geotechnical Consultant.
7.4 FILL SLOPES
7.4.1 Unless otherwise recommended by the Geotechnical
Consultant and approved by the regulating agen-
kies, permanent fill slopes should not be
steeper than 2:l (horizonta1:vertical).
7.4.2 Except as specifically recommended otherwise
or as otherwise provided for in these grading
guidelines .(Reference 7.4.3), compacted fill
slopes should be overbuilt and cut back to
grade, exposing the firm, compacted fill inner
vary as field conditions dictate. If the de- core. The actual amount of overbuilding may
sired results are not achieved, the existing
slopes should be overexcavated and reconstructed
under the guidelines of the Geotechnical Consul-
tant. The degree of Overbuilding shall be in-
creased until the desired compacted slope sur-
face condition is achieved. Care should be
mechanical compaction to the outer edge of the
taken by the Contractor to provide thorough
overbuilt slope surface.
7.4-~3 Although no construction procedure produces a
slope free from risk of future movement, over-
filling and cutting back of slope to a compacted inner core is, given no other constraints, the most desirable procedure. Other constraints,
however, must often be considered. These con-
straints may include property line situations,
Page Fifteen
access, the critical nature of the development
and cost. Where such constraints are identi-
fied, slope face compaction may be attempted
by conventional construction procedures includ-
ing backrolling techniques upon specific recom-
mendation by the Geotechnical Consultant.
As.a . .~ second best alternative for slopes of 2:l
(horizonta1:vertical) or flatter, slope con-
Fill placement should proceed in thin lifts, i.e.,
struction may be attempted as outlined herein.
six to eight inch loose thickness). Each lift should be moisture conditioned and thoroughly
compacted. The desired moisture condition
should be maintained and/or re-established,
where necessary, during the period between
successive lifts. Selected lifts should be tested to ascertain that desired compaction is
being achieved. Care should be taken to ex-
tend compactive effort to the outer edge of
the slope. Each lift should extend horizontally
as needed to ultimately establish desired grades.
to the desired finished slope surface or more
Grade during construction should not be allowed
to roll off at the edge of the slope. It may
be helpful to elevate slightly the outer edge
of the slope. Slough resulting from the place-
ment of individual lifts should not be allowed
to drift down over previous lifts. At intervals
not exceeding four feet in vertical slope heiqht
or the capability of available equipment, which-
ever is less, fill slopes should be thoroughly
backrolled utilizing a conventional sheepsfoot-
type roller. Care should be taken to maintain
the desired moisture conditions and/or re-
Upon achieving final grade, the slopes should
establishing same as needed prior to backrolling.
backrolled. The use of a side-boom roller will
again be moisture conditioned and thoroughly
probably be necessary and vibratory methods are
strongly recommended. Without delay, so as to
avoid (if possible) further moisture conditioning,
the slopes should then be grid-rolled to achieve
a relatively smooth surface and uniformly com- pact condition.
dures, moisture and density tests will be taken In order to monitor slope construction proce-
at regular intervals. Failure to achieve the
desired results will likely result in a recom-
mendation by the Geotechnical consultant to
Page Sixteen
overexcavate the slope surfaces followed by reconstruction of the slopes utilizing over- filling and cutting back procedures and/or
further attempt at the conventional back-
rolling approach. Other recommendaitons may also be provided which would be commensurate
with field conditions.
7.4.4 Wh'gfe placement of fill above a natural slope
or above a cut slope is proposed, the fill
slope configuration as presented in the ac-
companying Standard Details should be adopted.
7.4.5 For pad areas above fill slopes, positive drain-
age should be established away from the top-
of-slope. This may be accomplished utilizing
a berm and pad gradients of at least 2 percent
in soil areas.
7.5 OFF-SITE FILL
7.5.1 Off-site fill should be treated in the same
manner as recommended in these specifications
paction, etc. for site preparation, excavation, drains, com-
7.5.2 Off-site canyon fill should be placed in prep- aration for future additional fill, as shown
in the accompanying Standard Details.
7.5.3 Off-site fill subdrains temporarily terminated
(up canyon) should be surveyed for future re-
location and connection.
8. DRAINAGE
8.1 Canyon subdrain systems specified by the Geotechnical Consultant should be installed in accordance with the
Standard Details.
8.2 Typical subdrains for compacted fill buttresses, slope
stabilizations or sidehill masses, should be installed
in accordance with the specifications of the accompany-
ing Standard Details.
8.3 Roof, pad and slope drainage should be directed away
from slopes and areas of structures to suitable dis-
posal areas via non-erodible devices (i-e., gutters,
downspouts, concrete swales).
8.4 For drainage over soil areas immediately away from
gradient should be maintained. Pad drainage of at
structures, (ie.,within four feet) a minimum of 4 percent
least 2 percent should be maintained over soil areas.
Pad drainage may be reduced to at least 1 percent for
Page Seventeen
projects where no slopes exist, either natural or man-
made, of greater than 10 feet in height and where no
slopes are planned, either natural or man-made,
steeper than 2: 1 (horizonta1:vertical slope ratio).
8.5 Drainage patterns established at the time of fine grad-
project. Property owners should be made aware that
ing should be maintained throughout the life of the
altering arainage patterns can be detrimental to slope
stability and foundation performance.
1
9. STAKING
9.1 In all fill areas, the fill should be compacted prior to the placement of the stakes. This particularly is
placed until the slope is thoroughly compacted (back- important on fill slopes. Slope stakes should not be
rolled). If stakes must be placed prior to the com-
pletion of compaction procedures, it must be recognized
that they will be removed and/or demolished at such time as compaction procedures resume.
9.2 In order to allow for remedial grading operations, which could include overexcavations or slope stabili-
For finished slope and stabilization backcut areas, we
zation, appropriate staking offsets should be provided.
recommend at least a 10-foot setback from proposed toes and tops-of-cut.
10. SLOPE MAINTENANCE
10.1 LANDSCAPE PLANTS
planting should be accomplished at the completion of
In order to enhance surficial slope stability, slope
grading. Slope planting should consist of deep-rooting
vegetation requiring little watering. Plants native to
the southern California area and plants relative to
native plants are generally desirable. Plants native to other semi-arid and arid areas may also be appro-
priate. A Landscape Architect would be the best party to consult regarding actual types of plants and plant-
ing configuration.
10.2 IRRIGATION
10.2.1 Irrigation pipes should be anchored to slope
faces, not placed in trenches excavated into
slope faces.
10.2.2 Slope irrigation should be minimized. If auto-
matic timing devices are utilized on irrigation
systems, provisions should be made for inter-
rupting normal irrigation during periods of
rainfall.
Page Eighteen
10.2.3 Though not a requirement, consideration should
be given to the installation of near-surface
moisture monitoring control devices. Such de-
vices can aid in the maintenance of relatively
uniform and reasonably constant moisture
conditions.
10.2.4 Property owners should be made aware that over- C" - watering of slopes is detrimental to slope
stability.
10.3 MAINTENANCE
10.3.1
10. 3.2
10.3.3
10.3.4
10.4 REPAIRS
10.4.1
10.4.2
10.4.3
Periodic inspections of landscaped slope areas
should be planned and appropriate measures
should be taken to control weeds and enhance
growth of the landscape plants. Some areas
may require occasional replanting and/or
reseeding.
Terrace drains and downdrains should be period-
ically inspected and maintained free of debris.
Damage to drainage improvements should be re-
paired immediately.
Property owners should be made aware that bur-
bility. A preventative program should be esta-
rowing animals can be detrimental to slope sta-
blished to control burrowing animals.
As a precautionary measure, plastic sheeting
should be readily available, or kept on hand,
periods of heavy or prolonged rainfall. This
to protect all slope areas from saturation by
measure is strongly recommended, beginning with
the period of time prior to landscape planting.
If slope failures occur, the Geotechnical Con-
sultant should be contacted for a field review
of site conditions and development of recommen- dations for evaluation and repair.
If slope failures occur as a result of exposure
and currently unaffected areas should be covered
to periods of heavy rainfall, the failure area
with plastic sheeting to protect against addi-
tional saturation.
priate repair procedures are illustrated for
In the accompanying Standard Details, appro-
cally within the outer one foot to three feet* superficial slope failures (i.e., occuring typi-
of a slope face) .
Page Nineteen
11. TRENCH BACKFILL
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Utility trench backfill should, unless otherwise
otherwise recommended, the degree of compaction should recommended, be compacted by mechanical means. Unless
be a minimum of 90 percent of the laboratory maximum
density .
As an alternative, granular material (sand equivalent
greater than 30) may be thoroughly jetted in-place.
Jetting should only be considered to apply to trenches
no greater than two feet in width and four feet in depth. Following jetting operations, trench backfill should
be thoroughly mechanically compacted and/or wheel-
rolled from the surface.
Backfill of exterior and interior trenches extending
below a 1:l projection from the outer edge of founda-
tions should be mechanically compacted to a minimum
of 90 percent of the laboratory maximum density.
Within slab areas, but outside the influence of foun-
may be backfilled with sand and consolidated by jet- dations, trenches up to one foot wide and two feet deep
materials are utilized, they should be wheel-rolled,
ting, flooding or by mechanical means. If on-site
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.
If utility contractors indicate that it is undesirable
buried conduit, the Contractor may elect the utiliza-
to use compaction equipment in close pcoximity to a
tion of light weight mechanical compaction equipment
and/or shading of the conduit with clean, granular
material, which should be thoroughly jetted in-place
above the conduit, prior to initiating mechanical com-
paction procedures. Other methods of utility trench
compaction may also be appropriate, upon review by the
Geotechnical Consultant at the time of construction.
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 con-
Consultant.
sidered subject to review by the Geotechnical
Clean granular backfill and/or bedding are not recom-
mended in slope areas unless provisions are made for
a drainage system to mitigate the potential build-up
of seepage forces.
Page Twenty
12. STATUS OF GRADING
Prior to proceeding with any grading operation, the Geotech-
nical Consultant should be notified at least two working days
and testing services. in advance in order to schedule the necessary observation
12.1
12.2
Prior to any-significant expansion or cut back in the
be provided with adequate notice (i.e., two days) in
grading o;eration, the Geotechnical Consultant should
order to make appropriate adjustments in observation and testing services.
Following completion of grading operations and/or be-
tween phases of a grading operation, the Geotechnical
Consultant should be provided with at least two working days notice in advance of commencement of additional grading operations.
"
Backhoe Trench I / .Geofabric Alternative
STANDARD DETAIL NO. 1
FILL OVER NATURAL SLOPE
[“ STABILIZATION - FILL
I BUTTRESS FILL
..
STANDARD DETAIL NO. 3 I . ._
BUTTRESS BACKDRAIN SYSTEM
Geofrabic Alternative
FUTURE CANYON FILL
STANDARD DETAIL NO. 5
TRANSITION LOT OVEREXCAVATION
"i
STANDARD DETAIL NO. 7
STANDARD DETAlt NO. 8
0 2000 4000 - Adapted from U.S.G.S. Quadrangle, 1 Q?5
LOCATION MAP-CARLSBAD RESEARCH CENTER-PHASE II: AND
OB NO.: SDll62-00 DATE JULY 1982 FIGURE 1
SAN DlEGO SOILS ENGINEERING, INC.