HomeMy WebLinkAboutCDP 02-42; DUNN RESIDENCE; GEOTECHNICAL INVESTIGATION; 1989-02-17GEOT.BCHNICAL INVESTIGATION
·PROPOSED LOT SPLIT .
THREE-ACRE SITE
2202 HIGHLAND DRIVE
CARLSBAD, CALIFORNIA
PREPARED FOR:
·Karen M. Blumenshine
2202 Highland ·Drive
Carlsbad, California 92028
PREPARED BY:
Ron Gutier (C.E.G.)
and
~N~lson (P .E ~)
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.Job No. GN-1
Log No. 1
Pebl"Ulll'Yl~
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CiTY OF CARLSBAD •
DEVELOF'. EtOC. SE.RV. DIV>
Ger upp~'fG"O A~P0 tr 711/J-r TfA-f<!'"'J
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2.0
3.0
4.0
5.0
6.0
7.0
8.0
GEO'l'ECBNICAL :INVESTIGATION
PROPOSED LOT SPLIT
'l'HBEE-ACRE SITE
2202 HIGHLAND DRIVE
CARLSBAD, CALIFORNIA
TABLE OF CONTENTS
SCOPE OF SERVICES
FIELD EXPLORATION. . . . . . . . . . . . . . . . .
LABORATORY 'l'ESTIN~ . . . . . . . .
3.1
3.2
3.3
3.4
3.5
3.6
Classification . . . . . . . . . . . . .
Particle Size Analysis. . . ...
Expansion Index . . . . . . . . . . . . . . . , .
Maximum Density/Optimum Moisture Content.
Direct Shear . . . . . . . . . . . . . . . .
Consolidation . . . . ............. .
SITE DESCRIP'l'ION . . . . . . . .
4.1
4.2
4.3
4.4
Geologic ·setting . . . . . . . . . . . . . . . . . . . . . .
Proposed Development. . . . . . . . . . . ...... .
Geology and Soils Engineering .............. .
Seismicity . . . . . . . . . . . . . . . . . . . . .
CONCLUSIONS .. . . . . . . . .
RECOMMENDATIONS
6.l Earthwork . . .
SLOPE STABILITY . .
Existing Slopes
Constructed Slopes . . . . .
Temporary Slopes ...... .
7.1
7.2
7.3
7.4
7.5
7.6
Settlements . . . . . . .
Surface and Subsurface Drainages
Foundations and Slab Recommendations
. . . . . . . .
7.6.l
7.6.2
7.6.3
7.6.4
7.6.5
7.6.6
General . . . . . . . . . . . .
Foundations . . . . .
Slabs On-Grade ..
Retaining Walls ...... .
Reactive Soils . . . . . .
Plan Review
LIMITATIONS ...
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.Figure
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Tables
1
.2
Plates
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APPENDIX A
References
APPENDIX B
Location Map
-GEOTECHNICAL .J:NVESTIGAT:tON
.PROPOSED LOT SPLIT
THBEE-ACRE SITE·
..2202 .m:GELAND DRIVE
CARL.SBAD, CALIFORNJ:A
'l'ABLE OF cc»r.l'J!NTS -Continued
.ATTACHMENTS
·seismicity for ·Major Faults
Equivalent ·Earth Pressures {lb/ft3 )
Geologic Map
Cross Sections
Field Exploration
Figures B-1 through B-4
Figures TPl through TPS
Log of Borings
Logs of Test Pits
APPENDIX C
Laboratory Testing
Table C-1
Tabl.e .. C-2
Table c-3
Table c-4
Table C-5
Particle Size Analysis
Expansion Index
Maximum Density/Optimum Moisture Content
Direct Shear
Consolidation
ii
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February 17, 1989
Dr. Karen Blumenshine
2202 Highland Drive
Carlsbad, California 92008
Attention: Dr. Karen Blumenshine
SUBJECT:
Dr. Blumenshine:
GEOTECBNICAL INVESTIGATION
PROPOSED LOT SPLIT
THBEE-ACRE SITE
2202 HIGHLAND DRIVE
CARLSBAD, CALIFORNIA
11
Job No:-GN-l
Log ·No: l
This report presents· the results of our Preliminary Soils Investigation at the
subject site. OUr investigation was performed from October 1987 through February
1989 and consisted of field expl.oration, laboratory testing, engineering analysis
of the field and laboratory data, and the preparation of.this report.
l.0 SCOPE OF SERVICES
·The scope of services provided during the preparation of this Preliminary Geo-
technical Investig•tion included:
{a) Review of previous geologic, soils engineering, and seismological
reports pertinent to the• project area (See Appendix A) 1
(b) ·Analysis of sterographic aerial photographs to evaluate the topography
and geologic.. structure of the area1 • • •
{ c) Geologic mapping of existing exposures and outcrops1
(d) .subsurface exploration· including 2 bucket auger borings to a maximum
depth of 85 . ..f.e.et"_ and 10 backhoe test pits1
(ia) Logging and sampling of expl.orator.y -excavations to evaluate the geo-
logic structure and to obtain ring and bulk samples for laboratory
testing.;
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l>r. Karen 'Blumenahine
°February 17, 1989
Job Ho: GN•l
Log No: .1
.Page .2
(£) Laboratory testing of samples representative of those encountered
during the field investigation;
(g) Geol.ogic and engineering analysis of field and laboratory data, which
provide the basis ·for our conclusions and rec~endations.
(h) Preparation .. of ·this report and accompanying maps, ·and other graphics
presenting our fin~gs, conclusions and recommendations.
2.0 FIELD EXPLORATION
Subsurface conditions were explored by drilling 2 bucket auger borings to d~pths
of 34 and 85 feet. The approximate l.ocations of the borings are shown on the
Geologic Map, Plate .l. The .borings were drilled with a truck-mounted 30-inch
diameter bucket.auger . .I~ addition, eleven test pits were excavated to a maximum
·depth of 25 feet using a track-mounted backhoe.
Drilling of the test pits and borings was supervised by a registered geologist
who logged the geologic materials and obtained bulk and relatively undisturbed
samples for laboratory testing.·
• • 3.0 LABORATORY TESTING
3.1 Classification
Soils were classified visually according to the Unified Soil Classification
System. Classification was .supplemented by index tests, such as Particle Size
Analysis, Hydraneter ·Tests, and Atterberg Limits. Moisture content and .dry
density determinations were made for representative undisturbed samples.
Results of moisture-density determinations, together· with. classifications, are
shown in Ap_pendix C.
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Dr. Karen Blumenahine
February 17, 1989
3.2 Particle Size Analysis
Job No:
Log No:
Page 3
GN-1
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Particle size analyses were performed on representative samples of the site's
subgrade soils in accordance with ASTM D 422-63. Test results are shown in Table
c-1.
3.3 Expansion Index
Expansion Index 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 Uniform Building Code Standard ·No. 29-2. ~e test results
are summarized in Table c-2.
3.4 Maximum Density/Optimum Moisture Content
The maximum dry density/optimum moisture content relationship was determined for
typical samples of the onsite soils. The laboratory standard used was AS'l'M D
1557-78. The test results are summarized in Table C-3.
3.5 Direct Shear
Direct shear strength tests were performed on representative undisturbed and
remolded (to 90 percent compaction) samples of the on-site soils. To simulate
possible adverse field conditions, the samples were saturated prior to shearing.
'l'he tests results are presented in Table C-4.
3.6 Consolidation
A Consolidation test was performed on a representative remolded sample of the
existing fill soils to help determine compressib1lity characteristics at a 901
relative canpaction. The sample was saturated at the beginning of the test to
simulate possible adverse ..fiel.d -conditions. -The test results are presented .in
Table C-5. ·
~Dr. 'lCaren l3lumenah ;i ne
·-·February 17, 1989 '
-4. 0 SI'l'E DESCRIPTION •
Job No: GN.;l
.Log No: :l
Page 4
The site .·consists of an irregularly-shaped 3-acre parcel of land located at ·the
. // northern terminus of_ ·Highland Drive in Carlsbad, CalifoJ;ilia (see Location Map,
Figure 'l) . • -~A ,wooden frame, -single-family dwelling and garage presently-exist on ,
a ·:rid~e top-in the .eastern rtion of the parc_9:J V~etation consists of scrub
/ brush and cactus ·over.most of the site, although eucalyptus trees are present on
fl' (/r ~ slopes in the northern portion of the property~ Topography over the site varies
from relatively flat in the east, to locally vertical in the canyon which bisects
the parcel .in the north-south direction.
A large culvert "functioning -as a part of the City of Carlsbad storm. drain system
is buried at· the head of the canyon in the center of the site. This cul;vert
empties into the bottam of the canyon, although the pipe appears to have broken
at some time prior ·to ·this investigation, causing considerable subsidence and
erosion of surrounding fill soils.
4.1 Geologic Setting
The site is situated near the western margin of the peninsular ranges batholith.
Topography within the area of the batholith, wh.:l:ch outcrops in the eastern
portion of San Diego ·eounty, is steep and mountainous. Topography within the
western portion of the county, where the site is located, is underlain by marine
-and non-marine sediments of Cenozoic age·, and is more subdued.
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Specifically, :the site ·is underlain by sandstone and conglomerate of ·the .Linda
Vista and Santiago formations. The sandstone is poorly bedded (massive) and well
indurated. An approximately 5-foot thick cobble conglomerate unit locally exists
at the base of the Linda Visa Formation.
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LOCATION MAP
JOB NO.: GN-1 DATE: FEBRUARY 1989
ADAPTED FROM U.8.G.8. 7.5'
SAN LUIS REY CALIFORNIA 187-6
TOPO.GRAPHIC QUADRAN.GLE.
FIGURE: 1
Dr. Karen Blumenahine
February 17, 1989
4. 2 • Proposed Development
Job No:
Log No:
Page 5
GN-1
l
The site is to be developed into three parcels. T4_e existing home and appurte-
nant struc :tocated on what is to b~ the easternmost lot.
additional building sites are to be developed on the two new lots proposed
the central portion of the site.
Proposed grading will include removal of the existing nonengineered fill on the
site and replacement _as properly engineered compacted fill. Some elevation
changes ~ay also occur as a result of this grading. At the time of this report,
final grades .and site topography had not yet been determined.
4.3 Geology and Soils Engineering
Red sandstone and conglomerate of the Quaternary age Linda Vista formation covers
ridgetops throughout the site and surrounding area. White sandstone, cobble and
pebble conglomerates, and minor siltstones of the Santiago formation underlie the
Linda Vista formation and crop out at lower elevations. A distinctive cobble
conglomerate unit marks the base of the Linda Vista formatio~· throughout much of
the region. Numerous surficial slope failures exist on the site__:) In addition,
one relatively large landslide and an area of bedrock downslope creep were
observed to the west of the area of proposed grading ..
Colluvium covers natural slopes to maximum depths of under four feet and is
absent on ~teeper slopes. "The colluvium'consists of silts and sands in a loose
condition.· .In addition, nonengineered fill has been dumped over slopes and into
canyon heads in the south central portion of the site. Thi·s fill consists of
silts and sands. in a loose to moderately dense condition, and contains considera-
ble amounts of a cabie, pipe, and other types of debris in some areas. As much
as 2-feet of settlement has been noted on portions of this fill since its place-
ment. In addition, the fill was not properly benched into bedrock and is not
considered suitable to support foundations in its present condition.
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Dr. Karen Blumenahine
February 17, 1989
4.4 Seismicity
Job No:
Log No:
Page 6
GN-1
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No active or potentially active faults exist on or adjacent to the site. There-
fore, the potential for fault rupture is extremely low. However, as is all of
Southern California, the site is in a seismically active area and will likely
experience varying ·degrees of ground shaking as a result of movement along active
faults in the region~
Based on work by Greensfelder (1974) and others, the most significant active and
potentially active faults in the region are the Whittier-Elsinore, San Jacinto,·
San Andreas, Coronado Banks, and Rose Canyon faults. The greatest impact on the
site would most likely result from movement along the active Whittier-Elsinore
fault or along the potentially active Rose Canyon fault.
For events along the Whittier-Elsinore, Coronado Banks, or Rose Canyon faults, we
estimate .a peak bedrock acceleration at the site of approximately 0.15 g for a
maximum probable event of 7.0m on the active Whittier-Elsinore fault, a 6.5m on
the Coronado Banks .fault, or 6.0m on the potentially active Rose Canyon fault.
We do not expect fill accelerations at this site to differ significantly from
bedrock accelerations.
The repeatable high.bedrock acceleration is about 65 percent of the peak accel-
eration and is used as a design value for events occurring within 20 miles of the
site. Beyond 20 miles, the peak acceleration is the recommended design value
(Ploessel and Slosson, 1974).
Because the Coronado Banks fault is more than 20 miles from the site, we recom-
mend the use of .l5g for a repeatable acceleration on the design of structures at
the site.
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Dr. Karen Blumenahine
February 17,. 19'89
Table 1.
Distance
From Site
Fault (miles)
Whittier-Elsinore 19
San Jacinto 4S
San Andreas 65
San Clemente so
Newport-Inglewood 40
Rose Canyon 8
Coronado Banks 21
Seismicity for Major Faults
Maximum Estimated
Probable l
Earthquake
Peak Bedro~2
Acceleration
7.0 .lSg
7.S .09g
8.0 .09g
7.3 .06g
6.S .04g
6.0 .lSg
6.S .lSg
l . Seismic Safety Study City of San Diego (1974) and Bonnilla (1970)
2 Seed and Indriss (1982)
3 Ploessel and Slosson (1974)
4 Potentially active
Job No: GN-1
Log No: 1 •
Page 7
Repeatable
High Bedrock3 Acceleration
.10g
.09g
.09g
.06g
.04g
.10g
.15g
NOTE: Accelerations are based on anticipated bedrock accelerations and do not take into consideration
topography, loose topsoil and alluvial deposits.
We do not consider proposed constructed slopes to be susceptible to failure under
the design earthquake loading, provided the grading recommendations herein are
incorporated into design. However, some minor sloughing of the existing canyon
walls may occur. 'l'he bedrock under this site does not appear likely to undergo
significant settlement as a result of seismic shaking. However, the loose and
medium dense fill soils are presently considered compressible. Any measures
taken to J!litigate the compressibility of the fill during grading would also
affect the potential for seismically induced s~ttlement. Recompaction during
grading should reduce the potential for seismically induced settlement to accept-
able levels. In the event of a significant seismic event, liquefaction within
fill soils at-this site is not considered -likely due to the high relative densi-ty-
of proposed recompacted fill and the absence of groundwater.
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Dr. Karen Blumenahine·
February 17, 1989
Job No:
Log No:
Page 8
GN-1
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The site is not subject to inundation by tsunamis or seiches because of its
elevation and distance from a major body of water. No reservoirs currently exist
that.are capable of .flooding the property.
5.0 CONCLUSIONS
Based on the results of the soil exploration and testing, it is concluded that
slope and site soil modifications will be necessary for the proposed develop-
ments. Modifications which have been recommended are:
(a) Removing and replacing the existing uncompacted fill soils with uni-
formly compacted structural fill.
(b) Regrooming of the existing slopes to a slope ratio of 2.5:l horizontal
to vertical.
(-c) If regrooming of the slope will not leave adequate building area at the
top of the slope, slopes may be retained with a cribwall, permanent
soldierpile and lagging wall or other applicable retaining walls.
(d) Foundations for proposed structures should bear entirely on bedrock or
fill, or if placed over a cut/fill transition, the cut portion of the
building pad should be excavated to a depth of at least 5 feet below
the bottom of footings and replaced with compacted fill and designed
for a moderate bearing capacity.
6.0 RECOMMENDATIONS
6.1 Earthwork
Earthwork and grading on the
70 ~f the Unified Building Cade
·should be performed in accordance with Chapter
Continuous observation of grading by a quali-
fied geotechnical_engineer __ is essential to confirm the findings of this report
and to confirm that grading is accomplished in accor~ance with the recommenda-
tions of this report and those of local governing·agencies.
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Dr. Karen Blumenahine Job No: GN-1
February 17, 1989 Log No: l
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Gi uncompacted fill soi~d on the site should be completely removed down
to competent bedrock. Any· organics or other deleterious materials encountered
should be removed and disposed of offsite. If structures are to be placed across
the cut/fill transition, the cut portion below the buildingiand for 5 feet beyond
the perimeter should be removed· to a depth of 5 feet below the bottom of the
lowest footing. This excavation should then be brought back to the desired grade
by placing fill in 8-inch thick lifts (loose) and compacting to 901 of maximum
dry density at or near optimum moisture content as calculated by ASTM test method
D-1557. All excavations should be observed by a geotechnical engineer or engi-
neering geologist, prior to placing any fill, reinforcing steel, or concrete.
The intent of this recommendation is to reduce differential settlements to a
minimum. Differential settlements will not be completely eliminated and some
settlements will still occur. Details regarding settlements will be presented
later in this report.
Fill soils may be derived from the onsite soils or bedrock. The existing unconi-
pacted fill may be reused provided all organics, large rock and other deleterious
materials are removed. Sufficient observat?-on and testing should be performed in
1J.\~? order·tli@ an opinion can be formed as to the degree of compaction which has been
achieved.
7.0 SLOPE STABILITY
7.1 Existing Slopes
As previously mentioned, the entire northern side of both lots is bounded by
steep slopes of both uncompacted fill and weakly cemented bedrock. The slope
ratio of these slopes approaches vertical in several areas and is typically
between 2:1 (horizontal to vertical), and 1:1 with total height -of up to 100
feet. These slopes have been created by end dumped fill and erosion. Although
these slopes are currently showing no signs ... of deep-seated instability they are
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Dr. Karen Blumenahine
February 17, 1989
Job No:
Log No:
Page 10
GN-1
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most likely standing at a very. low factor of safety. These slopes should be
considered unstable in this present condition. Excessive rainfall or irrigation
causing saturation of the _soils, significant seismic events or even surcharge
loading, such as that resulting from placing a structure 'at the top of the slope,
could cause failure of the existing slopes. 7)115 ~'T/JJFJ,,{>J'f (.;p5t;Jf) 7}-tA-1
AP ~Jc,71J(L£} ~o;JL,0 BE {5iJtLf ft1/' "fJ.,([;" TO() b'f 7),f~ S £.£J/1€,. ~~ J:''r l}l 1)
7.2 Constructed Slopes l ~ jtJ€ , -~'J)-terJ ?RD)R-> Cfa,-'u"\ ec 5vPfvP..,TE()
If the existing slopes are regroomed to a stable slope ratio, it is recommended
that a maximum slope ratio of 2.5:l (horizontal to verticaj.) be used. Such a
slope may be constructed from the onsite materials provided proper compaction is
achieved. Due to the height of the slopes in question, the above slope ratio
should be used for both cut and fill portions of slopes. Any fill materials
placed on the face and/or the toe of slopes should be properly benched and keyed
into competent bedrock. All benching and keys should he observed by a geotechni-
cal engineer or geologist, prior to fill placement.
Soils on this site are generally susceptible to erosion. It is therefore recom-
mended that slopes be planted as soon as possible after construction. It is
recommended that deep-rooted plants, well adapted to a semi-arid climate, be
used.-Site drainage should be directed away from the top of all slopes.
7.3 Temporary Slopes
Temporary slopes cut into the site materials should be stable for short periods
at a slope ratio of 1:1 for slopes up to 15 feet. Temporary slopes, which exceed
15 feet, should cut at 1.75:1 in order to provide adequate safety for workers and
adjacent property. ~f steeper slope ratios are necessary shoring or bracing may
be needed to provide-a safe and stable working area.
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Dr. Karen Blumenahine
February 17, 1989
Job No: GN-1
Log No: ·l
Page 11
Al though calculations and observations indicate construction slopes should be
stable at these heights and slope ratios, local backcut failures are possible due
to variations.in onsite conditions. No warranties are made as to the stability
of temporary slopes. The contractor should proceed in such a manner as to
provide safe working conditions and to avoid impacting adjacent properties. The
contractor should be respons~le for the stability of all temporary slopes.
Actual backslope ratios are left to the discretion of the contractor, who should
abide by the regulations of the Occupational Safety and Health Administration.
7.4 Settlements
Due to the unacceptably high settlements expected in the existing fill soils, it
has been recommended that these soils be removed and replaced with compacted
fill. It should be noted that this will not completely eliminate settlements,
and that some settlements will still occur. It is recommended that a period of
time of at least 6 months be allowed between placement of the fill and construc-
tion of buildings to allow some settlements to occur without impact on struc-
tures. It is further recommended that this settlement be monitored by survey
monuments placed at the surface of the fill .. The elevation of these monuments
should be checked periodically and plotted on a graph. Once it appears that
settlements have been mostly completed, building construction may begin with
minimal impact due to settlements.
Provided the recommendations contained in this report are completely complied
with, settlements should be less than l inch total and 1/2 inch differential for
structures founded on fi1l soils. If structures are founded entirely on bedrock,
settlements should be negligible. Although settlements are expected to be within
tolerable limits, some minor cracking of slabs and walls should be expected.
These minor cracks can be due to small differential settlements over short dis-
tances and to expansion and temperature stresses.
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Dr. Karen Blumenahine
February 17, 1989
7.5 Surface and SUbsurface Drainages
Job No:
Log No:
Page 12
GN-1
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The performance of foundations is highly dependant on maintaining adequate
surface drainage both during and after construction. The ~round surface around
structures should be graded so that surface water is directed quickly away from
the structure without-ponding.~ It is recommended that a minimum gradient of 2
percent be maintained in paved or lawn areas and a minimum gradient of 5 percent
in heavily landscaped or areas with flow-inhibiting ground cover. Roof drain
runoff should be carried across all backfilled areas and discharged at least 10
feet away from foundations .. Planters should be constructed so that moisture is
not allowed to seep into foundation areas or beneath slabs and pavements.
Poor drainage could result in moisture penetrating into the fill soils and
causing settlements of structures in -excess of those presented in Section 7.4,
Settlements. ~J)
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7.6 Foundation and Slab Recommendations
7.6.1
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General
The recommendations contained in this report considered ·consisten with
standards of practice in the Carlsbad area at the time this report ·was prepared.
Reinforcement recommendations presented are considered the minimum necessary for
the soil conditions encountered in our exploration and are not intended to super-
sede design recommendations made by the Structural Engineer or governing
agencies.
All excavation_s for foundations and overexcavation should be observed by the
soils engineer prio~ to the placement of forms, reinforcement, concrete or
·additional fill. All excavations should be trimmed neat, level and square.
Loose ... or unsuitable materials should be removed prior to the placement of
concrete or fill. Materials from footing excavations _should not be-spread in
slab-on-grade areas unless compacted.
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Dr. Karen Blumenahine
February 17, 1989
7.6.2 Foundations
Job No:. GN-l
Log No: 1
Page 13
It is anticipated that a shallow foundation system will be suitable to support
the proposed structures. Such a foundation system should bear either entirely on
bedrock or on at least 5 feet of compacted fill material.
Footings which bear entirely on bedrock may be designed for a maximum allowable
bearing capacity of 3000 lb/ft2 • Footings which are founded on fill soils should
be designed for a maximum allowable bearing capacity of 2000 lb/ft2 • All foot-
ings should be at least 12 inches wide and founded at least 18 inches below the
lowest adjacent compacted subgrade. All footings should have an equal amount of
reinforcing steel placed at the top of the stemwall and the bottom of the foot-
ing. The minimum amount of steel considered necessary is that resulting from
designing stemwalls as a simply supported beam capable of supporting the applied
loads over a span of 12 feet.
If footings are placed adjacent to slopes it is reccmunended that the foundations
be deepened to provide a minimum horizontal distance from the slope face of at
least 10 feet. If footings are placed which will require the implementation of
this recommendations, foundation plans should be reviewed by the geotechnical
consultant prior to construction.
Lateral loads may be resisted by passive pressure against the vertical faces of
foundations or by friction between. footing bottoms and the underlying soils.
Passive pressures may be assumed as 200 lb/ft2 per foot of depth. A coefficient
of friction of 0 .. 4 may be assumed between concrete and soil. When combining
frictional and passive resistance, the latter should be reduced by one-third.
7.6.3 Slabs On~Grade
on-grade slabs may be used in conjunction with shallow foundation systems. The
design of --these -slabs should be calculated by a structural engineer. This design
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Dr. Karen Blumenahine
February 17, 1989
Job No:
Log No:
Page 14
GN-1
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may be based on a modulus of subgrade reaction of 200 kips per cubic foot. It is
recommended that slabs be un~erlain by at least four inches of crushed rock or
coarse washed sand as a capillary break. If a moisture barrier -is used, it
should be overlain by at least 2' inches of sand to decrease the likelihood of
curing problems. Due to the low expansion potential of the onsite soils, special
slab recommendations regarding expansive soils are not considered necessary.
7.6.4 Retaining Walls
Lateral earth pressures bearing against the back of retaining walls or cribwalls
may be expr~ssed as an equivalent fluid pressure (efp). This efp will vary
depending upon the type of wall constructed and backfill slope ratios. Walls
which are free to rotate at the top, up to 0.1 percent of the wall height should
be designed for the active condition. Walls which will be tied • back or re-
strained at the top should be designed for the at-rest condition. Table 2 •
presents equivalent earth pressures which should be suitable for the onsite
soils. If import soils are used, or soils other than those indicated in this
report are encountered, some adjustments to these earth pressures may be neces-
Si:l,ry.
Table 2. Equivalent Earth Pressures (lb/ft3 )
Hall Condition
Active
(Unrestrained Wall)
At Rest • -·
(Restrained Wall)
Level Backfill
51
75
2.5:1 Sloped Backfill
62
88
The lateral ---earth pressures presented above do not include allowances for addi-
tional--surcharges--at-the -top -of th-e wall or hydrostatic pressures. All backfill
placed behind walls should be completely drained to prevent the buildup of water
behind_the ·wall. Passive pressures used to .resis:t. sl.iding were presented previ-
ously in Section 7.6.2, .Foundations.
' ' ..
Dr. Karen Blumenahine
February 17, 1989
7.6.5 Reactive Soils
Job No:
Log No:
Page lS
GN-1 1·
Although no testing was performed to determine the corrosivity of onsite soils to
concrete, the soils in this area typically contain sulfates in quantities high
enough to be detrimental to Type I cement. For this reason ·the use of .Type II
cement is recommended for all concrete placed in contact with soil or water on
~is site.
7.6.6 Plan Review
It is recommended that all grading plans and foundation plans be reviewed by a
geotechnical engineer prior to implementation. Review of plans may necessitate
additional investigation or a change in recommendations if the _project is signi-
ficantly different from the project currently proposed.
8.0 LIMITATIONS f'J'O
r P~°'O)(O
The findings, recommendation d other information contained in this report are
valid only for the ~osed lot spllt at 2202 ~land Drive, in Carlsbad, Cali-
fornia. This information is not applicable to any other site regardless of
proximity or geographical location to this site. This investigation was per-
formed using the degree of care and skill ordinarily exercised in the Carlsbad
. area at the time ··this report was issued. As with all fields of science, tech-
nological advances are made in the field of engineering ·daily. This report may
not reflect advances made after, or recent to, the date of publication. No
warranty either express or implied is made as to the conclusions and professional
advice included in this· report.
The conclusions and recommendations in this report are based upon geologic and
engineering inferences made from data obtained at selected locations on the site.
Geologic structures or strata may vary between bor~ngs or trenches. Therefore,
some inconsistencies may be encountered during grading .. Should this occur,
additional investigation may be required for the continuance of the project.
i ell I
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at:i
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APPENDIX A
REFERENCES
~. ;
:::::::; ..
· .. :::•
I
I l
REFERENCES
Greensfelder, Roger w., 1974, "Maximum Credible Rock Acceleration from Earthquakes
in California," CDMG Map Sheet 23.
Kennedy, M.P., 1975, Geology of the San Diego Metropolitan Area: California
Division of Mines and Geology Bulletin 200.
Kennedy, M.P., and Welday, E. E., 1980, Character and recency of faulting offshore
metropolitan San Diego, California: California Division of Mines and Geology, Map
Sheet 40, 1:50,000.
f .•.
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' • j·•.··
r··.
1·:· .•:
\·: i:~,'.:·
r
'
APPENDIX B
FIELD EXPLORATION
r i j.·. ;
l.
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f:;~;~~ ,. :,
l-:• •
l L .•
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I I
i I -= i I
LOGS OF BORINGS
t:-:~;;_;..:
I
l • • •
I
!·
I
I i
'
o.(re OBSERVED: l J /7 /87 METHOD OF DRILLING: 30 inch bucket auger
4113 lbs to 25', 2981 lbs to 47', 2168 lbs to 70'
LOGGEO BY: R, G. GROUND ELEVATION: 155± LOCATION: -See Geo technical Map
z -I-0
l:J s w '-2 -:::c: ~ ... Cl> a. Cl) w < Q .J
-o u
-.
-
5-
-.
--
10-
--.
.
15-
.
..... -.
.
20-.
~
.
----
BORING NO. B-1
DESCRIPTION
Fill: Dark brown silty medium SAND,
"-wet, loose contact: erosional,
....,l --
'-...'t,..;h;:;o:;.;r:.:i:::· z:..o:.:n::.t:..a;:;;;l:....---------------1 Bedrock: Linda fista Formation: Red,
brown medium SANDSTONE, slightly moist,
dense, becomes coarse below 5'
contact: horizontal -----------red pebble and cobble CONGLOMERATE,
coarse sand matrix
contact: horizontal, gradational
below 21' becomes white
contact: N75E, 2°E, erosional, undula-
torv
SOIL TEST
undisturbed direct
shear
Ix Santiago Formation:. White/brown silty
25--... 4 ---,i--._ -~e2._ANDSTONE,~ghtly m~. ~e~
.,__ ----I'-.. contact: horizontal
. ..._ grey SILTSTONE, contact: gradational, horizontal
. lwfiiteline SANDSTONE, slight'Iymoist,clense
contact: gradational, horizontal
.
:JS-
.
below 29' becomes silty
@ 31' sharp horizontal erosional contact,
iron staining
contact: gradational, horizontal
below12. ' becomes fine to medium sandstone
contact: horizontal, gradational, undulatory
.... Grey/green ··srLTSTONE, ffight'Iymoist, stiff t _.._ _v 1" thick discontinuous stiff clay seam at upper
contact
contact: horizontal, gradational
.110-11--1--~ ~ ----------------
JOB NO.: GN-1 LOG OF BORING IFIGURE: B-1
DATE OBSERVED: 11/7 /87 METHOD OF DRILLING: 30 inch bucket auger
4113 lbs to 25', 2981 lbs to 47', 2168 lbs to 70'
LOGGED BY: R. G. GROUND ELEVAT10N: 155± LOCATION: See Geo technical Map
-... w w
'--= ...
Q. w Q
~-40
-
---
45-
-
-
-
-
50-
----
55-
-.
--
60-
-
---
65-
.
--
70-
-
-
-0 j:: < 0
i rn
Cl) < ..I CJ
1-C W 0 w -' o mw a.
"-a:-1 :!! .... :::)Q. < en i-::: ci,
:: (I)<
0 00 :5
..I % :::, m ::, m
75-..
-
---_.__ ...
---_i...-,. 1--
80-
JOB NO.: GN-1
BORING NO. B-1
(CONTINUED)
DESCR1PTION
White, fine to medium SANDSTONE,
slightly moist, dense
bedding: horizontal, gradational,
u_?dulatory
1" thick clayey silt seam
bedding: horizontal, erosional,
undulatory
5" thick siltstone bed
contacts: horizontal, gradational.
undulatory
bedding: N55W, 6°E
bedding: horizontal
-~tac~ h~o!!!!l~adational _
/ White fine sandy SILTSTONE, ~lightly
/ moist, stiff
---m=iite ...... flneBANliSTUNF!';slig'fitly moist'-;-
dense
LOG OF BORING
SOIL TEST
sieve, particle
size analysis
l,:IGURE: B-2
l.
1 ·-·.
!
I I I
. . I DATE OBSERVED:
I LOGGED BY: R.G. .,. --,_ Q UJ 0 I-0 w -' w ~ UJ 0 mw Cl.
a:..1 ::::: ... ~ "---.. :::)Q. < = !!: U) t-O: U)
!: 0-,_ Cl) _-c :.:: a. "' 0 0°' -' w < _. z ::,
0 _. = !:) m
._ 80 0
-
-
--
85 , .
-.
-
90-
-
-
-
-
95-.
-.
.
100-
--.
.
105 .
.
--.
110-
.
.
.
115 -
.
.
.
120-
JOB HO.: GN-1
11/7 /87 METHOD OF DRILLING: 30 inch bucket auger
4113 lbs tO 25 It 2981 lbs to 41', 2168 lbs to 70'
GROUND ELEVATION: 155± LOCATION: See Geotechnical MaE
►~ -UJ~ a:o BORING NO. B-1 a:,_ Ca. -::,_ w>-(CONTINUED) ,__ SOIL TEST a,UJ o,_ _,_ <-oz ..10
:so. a.z DESCRIPTION zW Q -0
White fine SANDSTONE, slightly moist,
dense
contacts: horizontal, undulatory, gradational
@ 83 1 clayey siltstone, 7" thick
Total Depth 85'
No water
.
,
LOG OF BORING jFIGURE: B-3
l i. 1· .•
·::t~~
:,~{:\~
i I
OAfE OBSERVED:.
LOGGEO BY: R.G,
z -Q ,-0 ,-0 w L:J ,-0 mw w < ~ 5:! u. a:..1 -... ::> 0.
::i: !:!: (/) t-:: :: ~< ... Cl) a. en 0 QC/) w < ..I z Q -' m :::,
-o 0
---5 ~ 5-
----
10-
--. --
1S-
-.
.
-
20-
-
-
11/7 /87 METHOD OF DRILLING: 30 inch bucket auger
4113 lbs to 25;, 2981 lbs to 47 1 • 2168 lbs to 10'
GROUND ELEVATION: 155± LOCATION: See Geotechnical Map
w ...
-' wa' a. ·a:-:: ::,I-< ,-:: Cl) u,W -1-~ Oz -' ::::o-:::, m c.,
>-G:' a: c.,
Oa.
w;:
c.) ,-<-..I(/) c..z
zW -o
BORING NO. B-2
DESCRIPTION
!!!.!, : Dark brown medium SAND, very
moist, loose
Bedrock: Linda Vista Formation; Red
brown coarse SANDSTONE, slightly
moist, dense, roots in upper 12'
below 15' red and dark brown medium
sandstone
bedding: horizontal
contact: horizontal
Santiago Formation; white.fine SAND-
STONE, slightly moist, dense
SOIL TEST
---------contact: ---rlorizontal-:---i'radationaY-• -
25-
--...... ----------i,. ---
-
30-
.
white .brown pebble Conglomerate,
slightly moist, dense, minor cobbles
contact: NlOW, 4°E, undulatory, sharp
wni te sil t§rlneSAND'S'ffiNE ,"sI'igliITy ---
moist, dense
cross bedding: NSSW, 8°N
contacts: horizontal, gradational
5 Ix undisturbed
1---t-=::....,~~---+--+---+---------------------1--0irect shear----·
35-
JOB NO.; GN-1
Total Depth 34'
No water
LOG OF BORING jFIGURE: B-4
L. : .
LOGS OF TEST PITS
i
f
I· ; .
'
r::~t~
I ·_··
I-· ; .
:-1. I· i
l '
I I
,TE OBSERVED: 10/23/87 METHOO OF ORILLING: Hatachi Trask HQ~
lCiGEO BY: R.G. GROUND ELEV,\TIOH: l.SQ+ LOC,\ T10N: Slile G!i:'2tlilcb:c.i~al ?:ta12
.;:: -►-0 ... 0 w '#-cc 1,1,.
I ... 0 LI.I .., w-0~ TEST PIT NO. 1 I 0 cc w Q. a:.,_ < ::I -: != 1,1,. c:_, =z w .... =>a. < ... w o ► SOIL TEST ~ a, t-:::i: co ~ ... <!:: O') ~ ~< X oz ..la,
O') 0 e Cl) .., 20 a.z DESCRIPTION I < .., :> -LJJ .., m -0 =o (.) ::) CD
Fill: Red brown silty medium SAND, -moist, loose ;
-. ----@ 8' tree limb --~ -
< > -> -5 . > "' t
-~ -------------
"" [> ~ ToEsoil?: Dark brown clayey SAND,
t> moist, loose, slight organic odor,
roots
Total Deoth 25': No water
IGGEC BY: R.G. GROUND ELEVATION: l~Q± LOCATION: ~~~ ~~ot~~bn;Ls;.sl Man
TEST PIT NO. 2
. Fill: Red brown silty medium SAND,
moist, loose -
-contact: N60E. 60N
Bedrock: -Linda Vista Formation; Red
coarse SANDSTONE, slightly moist, -dense :,· -bedding: horizontal -below 6' grades to light brown medium
:=::·:~::
-sandstone
-NOTE: Fill exposed in northern half -of pit to bottom --@ 8-10' pipe, wire and debris in fill
--
;-
Total Depth 16 I
No . water
)8 NO.: C:N-1 I LOG OF TEST PIT I FIGURE: TP-1
'-TE OBSERVED: 10/23/87 METHOD OF DRILLING: Hatachi Track Hoe
)GCiEO BY: E.G. GROUND ELEVATION: lSO+ L0CAT•ON: S~~ ~~Qt~chnt~al MaE
.... -,..~ 2 ... Q II.I ~-ct (J I ... 0 I.IJ .., w-Cc. TEST PIT NO. 3 I 0 mw Q. c:.,_ < ::t -; ~ u. r:::-' :::l:z: ~,.. ... ::> Q. < "'"w SOIL TEST ~ a, ... ::E m ~ ... <!:: 0) :?: ~< :w: oz -'en en 0 Q. z
I < Qo, -' ::EO DESCRIPTION _, ::: ::, -w I -' m ::> m CJ =o 0
Fill: Red brown medium SAND, moist,
"" loose . contact: N60E, 60°N . Bedrock: Linda Vista Formation; Red. . brown coarse SANDSTONE, slightly
-moist, dense
i· .. f ......
j •.
'· bedding: horizontal . below 6' grades to light brown medium -sandstone -
-NOTE: Fill exposed in northern half
-of test pit to bottom
--@ 12' concrete pieces in fill
-
Total Depth 14' -No water .
.
IGGE0 BY: . B.. Q. GROUND ELEVATION: l,20± LOCATION: See Geo technical Ma:e
TEST PIT NO. 4
Fill: Red brown silty medium SAND, . "' slightly moist, loose . Bedrock: Linda Vista Formation; Red . brown coarse SANDSTONE, slightly -moist, dense -. NOTE: _Fill exposed in western portion
. of test pit to bottom
Fill/bedrock
◄ contact: N3SW, 50°W .
-< t> .
< . . t> "': t> ': r> contact: horizontal, undulatorv
-Santiago formation; ·white brown fine to
-medium SANDSTONE. sli~htlv moist. dense
. T~tal Depth 21'
No water
)8 NO.: GN-l I LOG OF TEST PIT jFIGURE: TP-2
,TE OBSERVED:
>GGED BY: s.~. -.
0 ... 0 I.II 0 w .... ... a. < 0 =w :E ~ '-c:_. .... :::> C. < ~ en ID t-:::i: Cl) :t !?< ~ 0, 0 Oen .... < ..., -:::, .... = -() ::) m
.
--------
-. ---. .
GGEC BY: --R. G.
----.
-.
-
.
.
.
---
-
,s NO.: C:N-1 -
10/23/87 METHOD OF DRILLING: H2tacb1 Ir~~k HQ~
GROUND ELEVATION: l 50+ LOCA1'10N: See G!i:cUs;lmis;al tJa.12
,.. t::: -w! a:u TEST PIT NO. 5 Qc. cc: ... -::::,% LU ► SOIL TEST ... w u ... !?t-<-oz -'Cl?
~0 c.z DESCRIPTION -w (.J =o
Fill: Red brown medium SAND, moist;
"" loose
contact: N40W, 75°E
Bedrock: Linda Vista Formation; Red
brown coarse SANDSTONE, slightly
moist, dense
bedding: horizontal
below 7' grades to light brown medium
sandstone
Total Depth 11'
No water .
GROUND ELEVATION: 150± LOCATION: See Geo technical Map
TEST PIT NO. 6
Fill: Red brown medium SAND, moist,
"' loose
contact: E-W, 63°S
Bedrock: Linda Vista Formation; Red
brown medium to coarse SANDSTONE,
slightly moist, dense
Total Depth 10'
No-water .
I LOG OF TEST PIT jFIGURE: TP-3
'. .. ..
1· .• :·
t i
I !· ! .
I
J.TE OBSERVED: 10/23/87 METHOD OF DRILLING: Hatachi Track Hoe
)CiGED BY: B.1 ~ I GROUND ELEVATION: 150+ LOCAi10N: s~~ ~~Qt~chni&;!i!:l Ma12 . z >-~ 0 .... C w -w! Ct<.) I ... 0 w .... Qo.. TEST PIT NO . 7 I < 0 mw Cl,. ex:.,_ :,: -. : u ... c:: .... ::, z UJ ► ... ,:) Cl. < -~ 0, ... w u ... SOIL TEST
'· :t ... ~ CD ~ ... <-0, ~< ~ oz .... C,
0, 0 c.z i < Q Cl) ..I 20 DESCRIPTION ..I -,:) -w I .... m -(,J ::c 0 :, m
Fill: Red brown silty medium SAND, . '
~ slightly moist, dense . contact: N45E, 50°W . Bedrock: Linda Vista Formation; Red . brown coarse SANDSTONE, slightly
-~ moist, dense sieve, particle
. size analysis
NOTE: Fill exposed in west portion of . test pit to bottom -@ 3' wire and debris ---
Total Depth 12' -No water .
--.
GGED BY: R1 G1 GROUND ELEVAT.ION: l,20± LOCATION: See Geotechnical MaE
TEST PIT NO. 8
Fill: Dark brown silty medium SAND, --moist, loose . .
. rx consolidation, re-
-contact: N2,E. 7,W molded direct
. Bedrock: Linda Vista Formation; Red shear expansion,
brown coarse SANDSTONE, slightly moisture density, . moist, dense sieve particle . below 7' grades to light brown medium size analysis . sandstone (fill) -. . .
.
Total Depth 14' -No water .
.
8 NO.: GN-1 I -LOG OF TEST PIT jFIGURE: 1'P-4
ATE OBSERVED: 10/23/87 METHOO OF ORILLINQ~ liatacb:i It:ack Bee
OGGED BY: R.~. GROUND ELEVATION: lSQ+ LOCAT10N: See Gectecb;c:fcal Map
... .::: -►~ -2 ... 0 UJ
w! a:c., 0 LI.I .J TEST PIT NO. 2 ,IJ ... c.. Qc., .,,, < 0 mw ~ a: ... -.a. u II. r::.., :::,z UJ ... ~ ... ::::) a. < ...w (.)► SOIL TEST :i:: Cl') ... :I CD ~ ... <t: -II? ~ ~< ~ oz -ICI') :i. Cl') 0 Qa, .J :EO «:i.z DESCRIPTION ,IJ < .., -::::) -w -(,) :::i .., m ::::) m =0 . u
f
i
! ' -Fill: Dark brown silty medium SAND, --'
moist, loose contact: E-W, 60°S -Bedrock: Santiago Formation; white . brown medium SANDSTONE, slightly . moist,~ dense·
5--. crossbedding: horizontal ---
:,-rx
Total Depth 11' -No water --
5-.
.
OGGEC BY: R.G. GROUND ELEVATION: 150+ LOCATION: See Geotecbnical Map
TEST PIT NO. 10 --Fill: Dark brown silty medium SAND, . --moist, loose contact: N40W. 7'i 0 W
Bedrock: Linda Vista Formation; Red -brown medium to coarse SANDSTONE,
'
I,,,,
-slightly moist, dense
s-.
-.
fracture plane: N35W, 1s0 w -
[)-
!Total Depth 11' -INo water .
-
5---
108 NO.: CN-1 I LOG OF TEST PIT !FIGURE: TP-5
APPENDIX C
LABORATORY TESTING
Table c-1
Results of Particle Size Analyses
Percent Passing (Sieve No.)
Sample Location 4 10 20 40 100
TP7 @ 5'
TP8 @ 5'
Bl@ 60 1
99 98 97 80 40
100 88 60 75 37
100 100 100 99 43
Table c-2
Expansion Index (UBC-29-2)
Sample Location Expansion Index Expansion Potential
TP8@ 5 1 2 Very Low
Table C-3
Maximum Density/Optimum Moisture Contents
Sample Location
TPS@ 5'
Maximum Density
(lb/ft3)
128.4
Optimum Moisture
(%)
8.0
200
32
28
8
Table C-4
Results of Direct Shear Tests
~ Residual
Dry
Remolded/ Densi~y Moisture
Boring Soil Descri~tion Phi Cohesion Phi Cohesion ,. Undisturbed (lb/ft ) (\)
TP8@ 51 Dark Brown Silty Sand 28 250 30 60 Remold 116 10
B-1 @ 10' Red Brown Clayey Sand 35 160 29 140 Undisturbed 108 7
B-2@ 33 1 Yellow Brown Clayey Sand 34 260 35 0 Undisturbed 99 6
Table c-5
Results of Consolidation Tests
Boring Number B-8 at 5 Feet .
Initial Void Ratio= 0.44576
Void Ratio at 0.5 ksf = 0.44200
Void Ratio at 0.5 ksf = 0.44200 (Saturated)
Void Ratio at 1.0 ksf = 0.43983~
Void Ratio at 2.0 ksf = 0.43578
Void Ratio at 4.0 ksf = 0.42971
Void Ratio at 8.0 ksf = 0.42002
Void Ratio at o.s ksf "" 0.42899
Percent Consolidation at 0.5 ksf = 0.260
Percent Consolidation at 0.5 ksf = 0.260
Percent Consolidation at 1.0 ksf = 0.410
Percent Consolidation at 2.0 ksf = 0.690
Percent Consolidation at 4.0 ksf = 1.110
Percent Consolidation at a.a ksf = 1.780
Percent Consolidation at 0.5 ksf = 1.160
Initial Moisture Content"" 9 Percent
Final Moisture Content ""14 Percent
Initial Density ""115 pcf
Final Density ""117 pcf
(Saturated)
I I