349, Construct a guest house, Studies & ReportsBASELINE CONSULTANTS INC.
1 5307 MINNESOTA AVE.
PARAMOUNT, CA. 90723 (213) 633-8152
GEOTECHNICAL ENGINEERING
December 2, 1986
Project No. 1531-036
Mr. and Mrs. Peyton Cramer
No. 11 Georgeff Road
Rolling Hills, California 90274
Project Reference: Soils Investigation
Proposed Retaining Walls and Barn Repair
No. 11 Georgeff Road
Rolling Hills, California
Dear Mr. and Mrs. Cramer:
Submitted herewith is a report of a soils investigation for the
referenced project. This investigation was made for the purpose of
obtaining information on subsurface soils on which to base
recommendations for a suitable foundation design for the proposed
retaining walls and barn repair.
Location of the site, relative to general topography, streets,
and landmarks, is shown on the attached Vicinity Map, Plate 1.
As outlined in the proposal of June 4, 1986 (authorized on
September 22, 1986), our work consisted of; geotechnical observations,
subsurface explorations and sampling, field and laboratory testing,
calculations and analyses, and the preparation of this report.
PROPOSED DEVELOPMENT
It is understood that it is proposed to remove the existing,
distressed retaining walls and replace them with new ones, and to.
underpin the foundation of the barn as part of it's remodeling and
renovation. No detailed plans for the proposed remedial repairs exist at
the time of the writing of this report, as they are pending the findings
of this study.
Project No. 1531-036 -2-
Cramer/Georgeff Road
DESCRIPTION OF SITE
The subject site is a trapazoid-shaped parcel, measuring
approximately 150 feet wide by 315 feet deep, situated on the east side
of Georgeff Road in the City of Rolling Hills. The site occupies the
east flank of a north -south trending ridge near the top of the Palos
Verdes Hills. The subject site consists of a generally level building
pad, situated up to 20 feet below Georgeff Road. The pad is presently
occupied by a custom built, one story residence. From the rear of the
building pad, the site descends in a terraced fashion to the barn, which
is located approximately 25 feet below the residence. From the rear of
the barn, a slope descends at a rate of approximately 22 to 1 (horizontal
to vertical) to the bottom of a stream canyon. From the bottom of the
stream canyon, the property ascends at a rate of approximately 21/2 to 1 to
the back of the property.
Maximum topographic relief is estimated to be 75 feet.
FIELD INVESTIGATION
Six (6) test pits were excavated by means of a backhoe, and
three (3) borings were drilled by means of hand equipment, to depths
ranging from four (4) to eight (8) feet at the locations shown on Plate
2. The approximate locations of borings and test pits were determined by
tape and compass measurement from the existing structures. Approximate
elevations of borings and test pits were determined by interpolation
between contours on a Boundary and Topographic Survey Plan, prepared by
Robert Herkus .and Associates, dated May 23, 1986. The locations and
elevations should be considered accurate only to the degree implied by
the method used.
A continous record of the soils and bedrock encountered during
the excavating was made by our field representative and is presented on
Plates 3 through 7, Summary of Borings and Test Pits.
The lines designating the interface between materials on the
Summary of Borings and Test Pits represent approximate boundaries. The
actual transition between materials was gradual.
Project No. 1531-036 -3-
Cramer/Georgeff Road
Undisturbed and bulk samples were secured at frequent intervals
from the borings and test pits for laboratory testing.
'SUBSURFACE CONDITIONS
In general, those pits excavated below the barn encountered
natural, very stiff, silty CLAY, varying in thickness from one (1) to
five (5) feet, mantling very weathered and fractured basalt(?) bedrock.
The test pits and borings excavated above the barn, within the terraced
yard, encountered fill ranging in depth from one (1) to five (5) feet.
This fill consists of a mottled mixture of the natural clay and very
weathered basalt bedrock. Below this fill in all borings a natural, very
stiff, black clay, ranging in thickness from one (1) to two (2) feet was
encountered, which was mantling very weathered and fractured basalt(?)
bedrock. In Test Pit Nos. 5 and 6, the natural clay was absent, and the
fill directly overlaid the bedrock. The basalt (?) bedrock was
encountered to the bottom of all test pits and borings.
Creep, which is a nearly imperceptible movement of surficial soils
downslope caused by the forces of gravity, was observed on the property.
It is believed this movement occurs in the loose fill and natural clayey
soils, which is affecting the retaining walls.
Groundwater was not encountered and none is anticipated within
depths pertinent to the proposed construction.
' Surface drainage is comprised of sheet flow and concentrated
flow run-off of incidental rainfall derived primarily within the parcel
boundaries.
LABORATORY TESTS
Laboratory testing was programmed following a review of the
field investigation and after considering the 'probable foundation design
to be evaluated. Laboratory testing included; the determination of
density, moisture content and shearing resistance of the materials, as
well as consolidation, compaction, and expansion characteristics.
Project No. 1531-036 -4-
Cramer/Georgeff Road
The results of tests are plotted or tabulated on the Summary of
Test Pits, Plates 3 through 5, Summary of Borings, Plates 6 and 7, Direct
Shear Test Results on Plate 8, and Consolidation Tests on Plate 9.
A compaction test was performed on the fill. The sample was
taken from Test Pit No. 6, at two (2) to three (3) feet. The test,
performed in accordance with ASTM D-1557-70, indicated a maximum dry
density of 108.0 pounds per cubic foot at an optimum moisture content of
19.0 percent.
An expansion test was performed on the natural black, silty
clay. The sample was obtained fran Test Pit No. 2, at a depth of two (2)
to three (3) feet. The purpose of this test was to evaluate the
potential for volume change and pressure increases with changes in
moisture content. The test, performed in accordance with the Uniform
Building Code Standard Test No. 29-2, indicated an Expansion Index of
116. The material would be classified as having a "high" potential for
expansion.
Details of the sampling and test procedures are given in the
Appendix.
DISCUSSION AND GENERAL COMMENTS
Based on the findings summarized in this report, and provided
the recommendations of this report are followed, and the designs,
grading, and construction are properly and adequately executed, it is our
opinion that construction within the building site would not be subject
to hazards from landslides, slippage, or excessive settlement. Further,
it is our opinion that the proposed building and anticipated site grading
would not adversely effect the stability of the site, or adjacent
properties, with the same provisos listed above.
Project No. 1531-036 -5-
Cramer/Georgeff Road
CONCLUSIONS AND RECOMMENDATIONS
Foundations on Bedrock
An allowable bearing value of 4,000 pounds per square foot is
recommended for foundations placed at a depth of at least 18 inches into
the weathered basalt(?) bedrock. A calculation to support this
recommended bearing value is presented on Plate 10. No footing shall be
closer than five (5) feet from the face of any slope.
Settlement of footings up to 5 feet wide continuous is not
expected to excccd 1/2 inch under the recommended fully applied bearing
pressure. Differential settlement between footings is expected to be on
the order of 1/4 inch.
The bearing capacities given are net allowable bearing values
and the weight of the concrete foundations can be ignored. The bearing
value is for dead plus live load and may be increased by one-third for
momentary wind or seismic loads.
The maximum edge pressure of any eccentrically loaded footing
should not exceed the values recommended for either permanent or
momentary loads.
In order to deepen the existing foundations on the downhill side
of the barn, a slot cutting technique of excavation is recommended.
Using this technique, slots, generally ten (10) feet wide, are excavated
beneath the existing footing. The slots are generally 20 feet apart.
After the footings in the slots are constructed, a series of slots are
excavated and the process is repeated. At no time during this process
shall more than 1/3 of the total footing length be left unsupported by
either the existing soil or the new footings.
Lateral Loads
An allowable lateral bearing value against the sides of footings
of 800 pounds per square foot, per foot of depth, to a maximum of 6,000
pounds per square foot may be used, provided there is positive contact
between the vertical bearing surface and the undisturbed, weathered
basalt(?) bedrock.
Project No. 1531-036 -6-
Cramer/Georgeff Road
Friction between the base of the footings, and/or floor slabs, and the
underlying soil may be assumed as 0.4 times the dead load. Friction and
lateral pressure may be combined, provided either value is limited to
two-thirds of the allowable. The above values may be increased by one-
third for short durations of seismic and wind forces.
Creep
Creep was noted on the easterly descending slope between the
pool and barn, which has, in part, caused the distress in the masonry
retaining walls. Removal and replacement of this creep prone material
with properly compacted fill will eliminate the need, to design against
creep forces.
Retaining Walls
The existing, distressed walls can be replaced with either,
conventional, masonry retaining walls, or by a crib retaining wall. A
crib wall consists of interlocking, reinforced concrete "blocks", stacked
in a box arrangement, and filled with soil. A crib wall, along Palos
Verdes Drive East, was recently completed by the following firm:
Retaining Walls Co.
17151 Newhope Street
Suite 202
Fountain Valley 92708
(714)966-1038
Walls retaining drained earth may be designed for the following:
Surfaces Slope of Equivalent
Retained Material fluid Pressure
Horizontal to Vertical Pounds per Cubic Foot
Level 45
5 to 1 48
4to1 53
3 to 1 57
2 to 1 ' 65
Project No. 1531-036 -7
Cramer/Georgeff Road
Backfill should consist of clean sand and gravel. While all
backfills should be compacted to the required degree, extra care should
be taken working close to walls to prevent excesive pressure.
Temporary Excavation Slopes
Temporary excavation slopes in the existing fill, natural clay,
and bedrock may be made vertical for cuts of less than five (5) feet.
For deeper cuts, temporary excavation slopes shall be made no steeper
than 1:1 (horizontal to vertical). In areas where soils with little or
no binder are encountered, shoring or flatter excavation slopes shall be
made.
Your attention is directed to the fact that while caving was not
encountered in the test excavations, it is possible that a trench or
excavation could react in an altogether different manner.
All excavations shall be made in accordance with the regulations
of the State of California, Division of' Industrial Safety. These
recommended temporary excavation slopes do not preclude local raveling
and sloughing.
Drainage
Site drainage should be dispersed by non -erosive devices in
accordance with the grading regulations of controlling agencies to
preclude concentrated run-off and erosion over the site. In no case
shall water be allowed to pond or drain down the slope in a concentrated
and uncontrolled manner. Water shall be conducted to the existing stream
canyon.
Grading
The following general specifications are recommended:
1. Areas to be graded or paved shall be grubbed and striped of all
vegetation, debris, and other deleterious material. All loose, creep
prone soils and existing fill shall be removed.
\1
PropL ND. 1531-036 -8-
Cramer/Georgeff Road
2. All new fill shall be keyed and benched into the firm, weathered
bedrock. The fill shall be brought to near optimum moisture content,
placed in layers not excccding six (6) inches thick, and compacted to
at least 90 percent.
3. All other fills and backfills shall be compacted to at least 90
percent.
4. The compaction characteristics of all fill soils shall be determined
by ASTM D-1556, or by other acceptable ASTM standard methods which
are acceptable to the governing public agency.
5. All new fill shall consist of clean soil, free of vegetation and
other, debris, and shall be placed in layers not exceeding six (6)
inches at near optimum moisture content. No rocks over three (3)
inches in greatest dimension shall be used. No soil shall be
imported to the site without prior approval by the foundation
engineer. The surface soils on the project would be suitable for use
in compacted fills, provided their expansive characteristics are
considered in all designs.
6. In all cases where the ground slope is steeper than 5 (horiontal) to
1 (vertical), the existing ground shall be benched, as the fill
thereon is brought up in layers. That existing ground which slopes
flatter than 5 to 1 may also require benching, if the foundation
engineer considers such to be necessary.
7. No jetting or water tamping of fill soils shall be permitted.
8. Care shall be exercised during rough grading so that areas involved
will drain properly. Water shall be prevented from running over
slopes by temporary berms.
Project No. 1531-036 -9-
Cramer/Georgeff Road
9. At all times, the contractor shall have a responsible field
superintendent on the project, in full charge of the work, with
authority to make decisions. He shall cooperate fully with the
foundation engineer in carrying out the work.
10. No fill shall be placed, spread, or rolled during unfavorable
weather. When the work is interrupted by rain, operations shall
not be resumed until field tests by the foundation engineer indicate
that conditions will permit satisfactory results.
Inspection
As a necessary requisite to the use of this report, the
following shall be observed by the soils engineer:
1. Inspection of all grading operations.
2. Inspection of all backfill wedges, drainage blankets, and
weep holes for retaining walls.
3. Inspection of all foundation excavations for the structure
or retaining walls.
The consultant should be notified at least two days in advance
of the start of construction. A joint meeting betwccn the client,
contractor, and soils consultant is recommended prior to the start of
construction to discuss specific procedures and scheduling.
REMARKS
The conclusions and recommendations contained herein are based
upon the findings and observations made at the six (6) test pit and three
(3) boring locations. While no great variations in soil conditions are
anticipated, if conditions are encountered during construction which
appear to differ from those disclosed by the the test excavations, this
office should be notified so as to consider the need for modifications.
No responsibility for construction compliance with the design
concepts, specifications, or recommendations is assumed unless on -
site construction review is performed during the course of construction
which pertains to the specific recommendations contained herein.
Project No. 1531-036 -10-
Cramer/Georgeff Road
Footings should be located below a line measured at a 45 degree
angle from the bottom of any utility trench, unless reviewed and approved
by the foundation engineer.
This report is subject to review by controlling public agencies
having jurisdiction.
This report has been compiled for the exclusive use of Mr. and
Mrs. Peyton Cramer and their authorized representatives. It shall not be
transferred to, or used by; a third party, to another project, or applied
to any other project on this site, other than as described herein,
without consent and/or thorough review by this facility.
Should the project be delayed beyond the period of two years
after the date of this report, the site and report shall be reviewed
to consider possible changed conditions.
Samples obtained in this investigation will deteriorate with
time and will be unsuitable for further laboratory testing within thrcc
months from the date of this report: Unless otherwise advised, the
samples will be discarded at that time.
This investigation was made in accordance with generally
accepted engineering procedures, and included such field and laboratory
tests considered necessary in the circumstances. In the opinion of the
undersigned, the accompanying report has boon substantiated by
mathematical data in conformity with generally accepted enginccring
principles and presents fairly the information requested. No other
warranty, expressed or implied, is made as to the professional advice
included in this report.
Michael` David"R
MDR/RAM/ac
(5) Addressee
Ae
ader, Staff Engineer Richard A. Martin, RCE
Respectfully submitted, �ES�ir
RO•
BASELINE CONSULTANTS, INC,.zti`? e A • `'
, �Q - . •. � No. 2'�' 2^•
2e0 4/3G09; .1,1
APPENDIX A
EXPLORATION AND TESTING
Field exploration was actompllshed using atruck mounted bucket auger of 16to24 inches in diameter and/or by
using a backhoe with an 18 to 30 inch scoop bucket,unless otherwise noted. The earth materials encountered
were continuously logged by our field representative and visually classified in accordance with the Unified
Soil Classification 'System.
Undisturbed samples of the soil and/or rock were secured at frequent intervals from the excavations by
driving a thin walled, steel, sampling tube into the ground ahead of the drilling with successive drops of the
drilling bar. The drive energy required for twelve inches of penetration is shown on the Summary of Borings.
Samples of earth materials were retained in one inch high, two and one half inch diameter, brass rings. Representative
bulk samples were obtained and placed in water tight, polyethylene bags for transport.
The field classification was reviewed in the laboratory by visual examination and may have been augmented,
by A.S.T.M. classification tests such cs grain size analysis, and Atterberg Limits tests. Unit dry weight and field
moisture content may have been determined for most of the undisturbed samples. Shear tests performed on
selected samples which were vertically loaded then sheared in the Direct Shear Machine at a constant strain rate.
Consolidation tests may have been performed on selected undisturbed samples confined in an apparatus designed to
accomodate a one inch high sample. Loading is appliedto the specimen in several increments over selected time
intervals,and the vertical defcrmation recorded. UrZconfined compression tests are performed on undisturbed samples
having a length at least two and one times the diameter, under constantly increasing vertical loading. All other
laboratory tests are performed in accordance withA.S.T.M. or U.B.C. designated procedures.
SYMBOLS AND ABBREVIATIONS
Some or all of the following symbol and abbreviations
figures of this report:
- Location of boring
-$i- - Location of pit
- Assumed datum point
Mail/ - Strike and dip of bedding
--ice- Approximate strike and dip
M°t - Strike and dip of fracture
- Strike and dip of foliation
--- - Property line
�--� - Geologic contact
- A pproximate geologic contact
F - Fault
Shear zone
have been used within the text, plates, and
U -Undisturbed sample
B - Bulk sample
S -Direct shear test
C - Consolidation test
E -Expansion test
G - Gradation test
A• - Atterberg Limits test
F - Unconfined compression test
T -Mechanical Analyses
Q . - Sand Equivalency test
R - 'R' Value test
M - Maximum density -Optimum moisture test
ONE
STORY POOL.
RESIDENCE
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P 5 \ 60
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H \ \/1 \ \ Z7Z*7
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096� 910
REFERENCE "BOUNDARY AND TOPOGRAPHIC SURVEY"
BY ROBERT HERKUS & ASSOC., DATED 5/23/86
910
0
CRAMER RESIDENCE
# I I GEORGEFF ROAD
ROLLING HILLS, CA
SCALE: I II 4 0 APPROVED BY:
0
DATE: NOV. I986
BASELINE CONSULTANTS
#I531-096
DRAWN BY
REVISED
I DRAWING NUMBER
2
SUMMARY OF TEST PIT N° 1
Elev. 942
u) 4--
d .
Em A ,.... 2 V i
W T oc
CI0 to lL M 0 U
5
_D 85 12.5
68 17.9
Soft_ Dark
Brown
Very
83 25.4 Stiff
77 23.7 Hard Tan
72 30.9 Very
- 13.2 Hard
DESCRIPTION
CLAY - Silty, scattered rock fragments
BEDROCK- BASALT(?), very weathered
weathered
End of Test Pit @ 8 feet
No Water
No Caving
SUMMARY OF TEST PIT N92 Footing
1\ \ \ \ Elev. 943
S�if �rorwn CLAY - silty, scattered rock fragments
Very Tan BEDROCK - BASALT(?)
- 12.1 Hard
5_
Cramer Residence
No. 11 Georgeff Road
Rolling Hills, California
End of Pit @ 4 feet
No Water
No Caving
JOB NQ 1531-096
PLATE— 3
BASELINE CONSULTANTS
SUMMARY OF TEST PIT N° 3
Elev. 945
N 4--
d
x E A -_v F. .N c DESCRIPTION
Q- o �. °' Ir.•o c c
p p M U 0 \ N.
N N. Footing
--1111 ti f gown CLAY -silty, scattered rock fragments
12.3 very
Hard Tan BEDROCK - BASALT(?)
5
- 11.9
79• 31.8
ZJJ 94 25.9
End of Pit @ 5 feet
No Water
No Caving
SUMMARY OF TEST PIT N2 4
\ \ \ Footing
Very Dark
3 if f Browr
5 _ Very
Hard Tan
-$ 84 12.1
Elev. . 947
CLAY - silty, scattered rock fragments,
porous
BEDROCK - BASALT(?)
Cramer Residence
No. 11Georgeff Road
Rolling Hills, California
End of Pit @ 5 feet
No Water
No Caving
JOB N2 15 1-ncti
PLATE— 4
BASELINE CONSULTANTS
SUMMARY OF TEST PIT N° 5
Elev. 953
a)
0 0
N
t73 CD A '3
N DESCRIPTION
coN N O
LL �O O
2 U V Footing
•
Firm Motld FILL: Mottled, silty CLAY and Bedrock
Dark fragments
88 22.0 Brown
and
Tan
82 19.9
5- Hard TAn .BEDROCK - BASALT (?)
very weathered
93 18.7
94 25.2
100 22.8
93 27.2
96 18.0
End of Pit @' 7 feet
No Water.
No Caving
SUMMARY OF TEST PIT N°
Footing
Motld \\ FT'.T, •
Firm Dark
Brown
and
Tan
Hard Tan
Tar
6
Elev. 963
Mottled, silty CLAY and Bedrock
fragments
BEDROCK - BASALT(?)
very weathered
weathered
End of Pit @ 8 feet
No Water
No Caving
Cramer Residence
No. 11 Georgeff Road
Rolling Hills, California
JOB N2 1531-096
PLATE— 5
BASELINE CONSULTANTS
SUMMARY OF BORING NO. 1
'.DATE DRILLED Mo enber ?6. 198ti ELEV. 853
CL W
Er)o i- v) DESCRIPTION
Wv CC W a >Z Cr)a ZZ J
co p 0 W • 0
U E 0 LL M U C.)
Brown/ FILL: SAND - fine to medium, clayey
106 17.7 Compact Tan
Stiff Black witt CLAY - sandy
98 24.3 Very Dk.Brown CLAY - silty
Stiff Tan
with Tan slightly sandy
5--Very Hard Tan BEDROCK - BASALT(?)
End of Boring @ 5 feet
No Water
1 0—
No Caving
15—
SUMMARY OF BORING NO.2
DATE DRILLED Ncnremh.r 26„ 1986
Tan and
"3 94 28.6 Stiff Dark Browr_
Very Dark
-31I 97 15.4 qi-i ff Brown
5 ! _ i q n ua ,-,a Tan
10-
15—
ELEV. 860
FTLL: Mottled, silty, CLAY and SAND
CLAY - silty
BEDROCK - BASALT(?)
End of Boring @ 5 feet
No Water
No Caving
Cramer Residence
No. 11 Georgeff Road
Rolling HIlls, California
JOB '# 1531-096
PLATE 6
BASELINE CONSULTANTS
SUMMARY OF BORING NO. 3
DATE DRILLED November 26, 1986
I1J I
— Fz- -U
>-z J (n zz
=W W O Ow
EL: � O
Stiff
99 25.7 .Very
Stiff
106
5-
10—
I5—
19.2 Hard
DATE DRILLED
10-
15—
CC
J
O
I'an&n,-.,wn FILL:
Dark
ELEV. 953
DESCRIPTION
Mottled SiltY CLAY and SAND
Brown CLAY - silty
Tan/Brown BEDROCK - BASALT(?)
.End of Boring @ 4 feet
No Water
No Caving
SUMMARY OF BORING NO.
Cramer Residence
No. 11 Georgeff Road
Rolling Hills, California
ELEV.
JOB # 1531-096
PLATE 7
f
BASELINE CONSULTANTS
4
r-
0
a)
a.
5
4
03
0. 3
Y
v
0
c0
Z I
cn
0
RESULTS OF DIRECT SHEAR TEST
All samples were soaked for 24 hours prior to
testing to simulate extreme moisture conditions.
2
CONFINING PRESSURE (kips per sq. ft.)
AL - Test Pit 5 @ 7 feet - very weathered bedrock
Cramer Residence
No. 11 Georgeff Road
Rolling Hills, California
5
Proj. N21531-096
Plate 8
BASELINE CONSULTANTS
CONSOLIDATION
1
.I
CONSOLIDATION TESTS
PRESSURE (kips per square foot)
.2 .3 .4 .5 .6 .8 1.0 2
® - Water Added
1 1 1
1 \
1 1 \ i\
i 1 1 1 `1,..,
I. 1 i 1 1
`1 r 1 1 1 1 r
I• '�— 1 1 1 III
1 1 1 1
1
1
1
1
1
1
1
1
1
Cramer Residence
No. 11 Georgeff Road
Rolling Hills, California
3 4 5
I
I
1
1
1
1 1
I
1 I
1 I
I i
I I
I 1
I I
I
1 i
I I
i I
6 7 8
1 I 1
f1 1 1
I I I
1 1 1
1 1 1
1 1 1
I 1 1
Test Pit
.6 @ 6 ft
I 1•
Test Pit -
6@8ft1
i 1 1
I i
I i
I I
1
1
I
I I
I I
1i
I i
Proj. Na 1531-096
Plate 9
BASELINE CONSULTANTS
BEARING VALUE
Reference: "Soil Mechanics in Engineering Practice", Terzaghi and Peck,
1967, pgs. 222 and 223.
Properties:
Wet Density (' ) = 94 pounds per cubic foot
Cohesion (C) = 550 pounds per cubic foot,
Angle of Friction (0) = 24 degrees.
Footing Depth (D) = 12 inches
Continuous Footing Width (B) = 2 feet (assumed)
Factor of Safety (F.S.) = 3.0
Calculations - Ultimate Bearing Capacity
Qu = CNc + YDNq + 0.5 ¥BNY
From figure 33.4 on page 222
Nc = 19.3
Nq
= 9.6
= 6i
Qu = (550) (19.3) + (95 ) ( 1 ) (9.6) + 0.5 (95 ) ( 2 ) (6 2 )
10,615 + 912 + 617.5
= 12,144 psf
Allowable Bearing Capacity
Qall = Qu/F.S.
= 4048 psf
Use 4000 psf
Project No. 1531-096
Plate 10