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SHANNON 6WILSON, INC � ALASKA
- GEOTECHNICAL AND ENVIRONMENTAL CONSULTANTS FLORIDA
MISSOURI
OREGON
WASHINGTON
June 11, 2010 •
The Macerich Company t
IVED
Attn: Ms. Tomomi K. Marzan ll.•
9585 SW Washington Square Road JUN 1 5
�
Portland, OR 97224 2010
CITY OFTIGARD
RE: GEOTECHNICAL CONCLUSIONS AND RECOMMENDATIONg UILDINGDIVISION
H &M WASHINGTON SQUARE MALL IMPROVEMENT
TIGARD, OREGON
Dear: Ms. Marzan:
This letter report presents the results of our geotechnical study for the proposed H &M store
improvement project inside the Washington Square Mall. The proposed improvement is located
at the northwest portion of the mall and consists of some modifications and the addition of a
• second floor to the existing structure. Based on the information provided, we understand that the
( existing load at each column location is about 25 kips and that the new second floor will add
about 55 kips to each column. The purposes of this geotechnical study are to evaluate the •
bearing capacity of the existing piles and, if necessary, to provide recommendations for
additional foundation methods to support the new structural loads.
LITERATURE REVIEW RESULTS
The original geotechnical investigation for the mall development was conducted by Shannon &
Wilson in the early 1970's. Among the many borings performed on the site, Borings B -3 and B-
21 were located near the proposed H &M improvement area. These borings indicate that
subsurface conditions at the site generally consist of a fine - grained clayey silt deposit overlying
highly weathered basaltic bedrock encountered at depths of about 14 feet at B -3 and 18 feet at B-
21. The approximate locations of the pertinent borings are shown in Figure 1 of this report, and
the logs of these borings are included in Appendix A.
Based on the original design drawings and the communications during the mall construction, we
understand that the proposed H &M improvement area of the mall is supported on driven piles.
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
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The Macerich Company SHANNON 6VVILSON. INC.
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 2
The piles are close -ended 10 -inch steel pipe piles with a wall thickness of 0.188 inch, filled with
concrete. We could not find the original pile driving records, and therefore, the individual pile
length and end driving resistance are not available to us to evaluate the bearing capacities of the
piles in the proposed improvement area. However, we did find the pile driving records for the
Meier and Frank (now Macy's) area (located to the north of the improvement area) which
showed very high pile driving resistance at the end indicating very competent pile capacity.
Also, in a letter dated July 26, 1972 (attached as Appendix B) by the original structural engineer,
Johnson & Nielsen Associates, the piles in the H &M improvement area were designed to be
driven to refusal with a maximum capacity of 50 tons.
FIELD EXPLORATIONS
To verify the depths of competent weathered basaltic bedrock, we conducted soil probes near
two existing pile locations. The locations of the soil probes are shown in Figure 1. The soil
probes were drilled with solid stem auger technique with a small portable drilling unit. Due to
the limited power of the machine and drilling technique, the auger experienced refusal once the
weathered basalt was encountered or after a very short penetration into the basalt, typically less
• than 6 inches. In addition to using the auger refusal of the soil probes as a criterion for
determination of the competent weathered basalt depths, Standard Penetration Tests (SPT) were
conducted at the refusal depths of the probes. Table 1 shows the refusal depths and the SPT blow
counts at the ends of probes.
Table 1: Results of the Soil Probes
Probes Depth of Hard Depth of Refusal SPT N- Values
Drilling (ft) (ft) (blows per foot)
P -1 17 17.5 50/4"
P -2 14 14.3 50/2"
As can be seen, very high SPT N- Values are encountered at the refusal depths, which indicate a
very competent soil/rock condition. Therefore, based on the results of our soil probes, we
estimate that the depths of the competent weathered basaltic bedrock are about 17.5 feet at the P-
1 location and 14.3 feet at the P -2 location.
H &M Washington Square Mall lmprovement.doc 24 -1- 03597 -001
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The Macerich Company SHANNON MWILSON, INC.
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 3
In addition to the soil probes, we also conducted non - destructive geophysical tests consisting of
parallel seismic and borehole magnetic methods in an attempt to determine the length of the
piles. To conduct these tests, temporary PVC casings were installed in the probes to house the
instrumentations required for these tests. The parallel seismic technique involved placing a
geophone in the casing adjacent to the pile to record the seismic wave traveling through the pile
and refracting out to the geophone. For the borehole magnetic investigation, a borehole
magnetometer was lowered in the PVC casing to observe the strong magnetic field associated
with the pile tip.
Detailed geophysical testing results are presented in Appendix C of this report. In summary, the
parallel seismic testing did not yield conclusive results for the pile lengths, which in the opinion
of the geophysicist, is due to the shallow refusal depth of the soil probe which does not have
sufficient penetration below the pile tip to allow accurate time measurements of the seismic
waves traveling between the geophone and the pile. For the magnetic tests, the testing results
indicate that the pile at the P -1 location extends to a depth of 16.5 to 17.5 feet which indicates
that the pile tip is bearing on competent soil/rock formation. However, at the P -2 location, the
tip of the pile is interpreted to be at a depth of 11.5 feet which is about 3 feet above the refusal
depth of the probe, indicating that the pile tip most likely did not reach the competent soil/rock
formation.
CONCLUSIONS AND RECOMMENDATIONS
Our literature review and field probing showed that competent weathered basaltic bedrock is
located at relative shallow depth below the existing grade. However, the non - destructive testing
did not yield conclusive results regarding the pile lengths, and these results have an implication
that some of the piles may not be bearing on the competent soil/rock formation. This does not
conform to the literature research results that the piles should have been driven to refusal with a
maximum capacity of 50 tons during installation.
Considering the new design total loads of about 80 kips (25 kips of existing load, and 55 kips for
the new load) and the competence of the weathered basalt as bearing formation, if the pile was
driven to refusal as designed, the existing pile would have sufficient capacity for the new design
total loads. However, due to the uncertainty in the determination of the actual pile lengths, there
H &M Washington Square Mall lmprovement.doc 24- 1- 03597 -001
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The Macerich Company SHANNON SWILSON, INC
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 4
are some risks of using the existing piles to support the new design total loads, and the Owner
should be aware of the uncertainty and risks should this approach be taken.
As a conservative approach, new foundation supports can be added to the existing piles. For this
approach, we recommend the addition of drilled and injection - grouted micro -piles (such as Titan
IBO Hollow Anchor Bars with suitable bits) which can provide sufficient capacity for the new
load. The installation of the Titan micro -piles involves the drilling of a continuously threaded,
hollow steel bar fitted with a suitable, disposable bit into the ground. During drilling, grout is
injected through the bar and bit, acting as a drilling fluid. Pressure then forces the grout back
along the outside of the bar to form a strong grouted pile. The recommendation for this type of
micro -piles considered the suitability of equipment for the limitation of indoor installation,
power unit concerns, as well as the cost effectiveness issue.
The micro -pile should have a minimum diameter of 4 inches with an embedment length of at
least 8 feet into the competent weathered rock for an allowable geotechnical compressive
capacity of 62 kips. The project structural engineer should verify the structural competence of
the piles for the proposed load. Considering the variation in bedrock depth on site, we
recommend an average micro -pile length of 25 feet for the cost - estimating purposes.
The allowable geotechnical compressive capacity has a factor of safety (FS) of 2, and is based on
an assumed ultimate soil to grout bound strength of 50 psi. To verify this bound strength, we
recommend that the first micro -pile should be developed for proof load test loaded in tension to a
maximum load of 167 percent of the design load or yield strength of the bar, whichever is less.
The test will be made by incrementally loading the pile in tension as listed in the schedule
provided in Table 2.
Table 2 — Test Load Schedule
Load Step Load Hold Time
1 — AL 0.05 DL
2 0.25 DL
3 0.50 DL
4 0.75 DL 1 minute
5 1.00 DL
6 1.33 DL
7 1.67 DL
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
The Macerich Company SHANNON 6VVILSON, INC
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 5
Load Step Load Hold Time
8 1.0 DL _ 10 Minute Creep Test
Al = Alignment Load DL = Design Load
Failure is defined as continued pile tip displacement without supporting an increase in applied
load. Permanent displacement may not exceed 0.10 inch in 10 minutes of creep testing. It is
recommended that Shannon & Wilson provide full -time observation during the load test and the
installation of the micro - piles.
In addition to the compressive capacity evaluation of the micro - piles, we also analyzed the
lateral capacities of the recommended micro -piles and existing steel pipe piles (assuming an
average length of 15 feet) using the computer program LPILE. The lateral capacity of a pile
depends on its length, stiffness in the direction of loading, proximity to other piles and degree of
fixity at the head of the piles, as well as the engineering properties in the soil especially within
the upper portion of the pile. For micro - piles, due to the low tensile strength of the grout, a steel
• tube of 4 -inch outside diameter is assumed to be inserted into the grout at the upper 10 feet of the
micro -pile section to increase the pile's structural capacity. The moment inertia of this
composite micro -pile is provided by the project structural engineer as 92.6 in
The analysis results for the micro -pile and existing pipe are presented in Table 3 for free - headed
conditions with 1 -inch pile head deflection.
Table 3: Lateral Load Information (1 -Inch Deflection)
Pile Type and Loading Unfactored Maximum Depth of Depth to
Diameter (inches) Condition Lateral Bending Maximum Points of
Resistance Moment Moment Fixity
(kips) (in -kips) (feet) (feet)
4 -inch Micro -Pile Free Head 5.5 185 4.0 14.5
(w. Titan 30/11 Bar)
Existing 10" steel Free Head 13.0 510 5.5 14.5
pipe pile
The lateral resistance values have a FS of 1.5. The project structural engineer should verify that
the existing pile and micro -pile will have sufficient structural capacity for the lateral loads.
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
The Macerich Company SHANNON 6VVILSON, INC.
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 6
Due to the close vicinity of the micro -piles to the existing piles, we recommend that the micro -
piles be installed perpendicular to the anticipated lateral load direction in order to eliminate the
potential reduction in capacity caused by the pile group effect.
For the lateral load resistance of the elevator and escalator pits, we recommend that the lateral
loads be resisted with passive lateral earth pressures and frictional resistance between the
crushed rock and on the bottom of foundations. In our opinion, an allowable friction factor of
0.45 for mass concrete on the crushed rock backfill can be used. For the passive earth pressure,
we recommend using partial passive lateral earth pressure of 200H at the side, where H is the
embedment depth of the structural. Partial pressure is recommended as an allowable value due
to the relatively large movement or tilt required to mobilize the full passive earth pressure.
LIMITATIONS
The conclusions, and recommendations contained in this report are based upon site conditions as
they presently exist based on our current level of subsurface exploration. Within the limitations
of our scope, schedule, budget, and analyses presented in this report, our geotechnical findings
were prepared in accordance with generally accepted professional geotechnical engineering
principles and practice in this area at the time this report was prepared. We make no warranty,
either express or implied. Our conclusions and recommendations are based on our understanding
of the project as described in this report and the site conditions as interpreted from the
explorations.
If, during final design and construction, subsurface conditions different from those encountered
in the field explorations are observed or appear to be present, we should be advised at once so
that we can review these conditions and reconsider our conclusions and recommendations where
necessary. If there is substantial lapse of time between this report and the start of work at the
site, or if conditions have changed because of modifications to project layout, natural forces or
construction operations at or adjacent to the site, we recommend that this report be reviewed to
determine the applicability of the conclusions and recommendations concerning the changed
conditions or the time lapse.
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
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The Macerich Company SHANNON WILSON, INC
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 7
This report was prepared for the exclusive use of The Macerich Company. The conclusions and
recommendations portion of the report is interpretive information and should not be provided to
prospective Contractors as a basis for bidding. Also, this report is not a warranty of subsurface
conditions, and our findings are the result of explorations at particular locations and at the time
the explorations were performed. Unanticipated soil cqnditions are commonly encountered and
cannot fully be determined by information from the explorations described in this report. Such
unexpected conditions frequently require that additional expenditures be made to attain properly
constructed projects. Therefore, some contingency fund is recommended to accommodate such
potential extra costs.
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The scope of our geotechnical services did not include any environmental assessment nor
evaluation regarding the presence or absence of hazardous or toxic materials in the soil, surface
water, groundwater, or air, on or below the site, or for evaluation of disposal of contaminated
soils or groundwater, should any be encountered, except as noted in this report.
Shannon & Wilson, Inc. has prepared a document, "Important Information About Your
Geotechnical Report", to assist you and others in understanding the use and limitations of this
• document. This document is included in Appendix D.
Sincerely,
SHANNON & WILSON, INC.
ED PRO
c;% ouNE `isy
OREGON /
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Yuxin Lang, PE
Senior Principal Engineer
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H &M Washington Square Mall Itoprovement.doe 24 - 03597 - 001
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The Macerich Company SHANNON WILSON, INC.
Attn: Ms. Tomomi K. Marzan
June 11, 2010
Page 8
Enclosures: Figure 1 Site Plan
Appendix A Previous Boring Information — Logs of Borings B -3 and B-
21 (Conduced by Shannon & Wilson in 1972)
Appendix B Previous Communication Letter Regarding Pile Foundation
Appendix C Geophysical Testing Report
Appendix D Important Information About Your
Geotechnical/Environmental Report
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
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e LEGEND
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P -1 tep Current Soil Probe Designation
B and Appro ximate Location N
Shannon 8 Wilson 1972 H&M Washingon Square Mall Improvement
Investigation Boring Designation Tigard. Oregon
i and Approximate Location
SITE PLAN
0 5 10 Drawing Provided by Macedch,
1 I I dated May 20, 2010 June 2010 24 -1 -03597 -001
Scale In Feet
LL = IIIa!A 119.1.46Wg.soNOUC FIG. 1
. 4 c ._ .
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SHANNON &WILSON. INC.
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APPENDIX A
PREVIOUS BORING INFORMATION
LOGS OF BORINGS B -3 AND B -21
(CONDUCED BY SHANNON & WILSON IN 1972)
.
STANDARD
S W ow t PENETRATION RESISTANCE
SOIL DESCRIPTION H El Cp z (140 lb. weight, 30 ° drop)
` a. < 03 t • Slows per toot
ro Surface Elevat 233 o ca o 0 50 100 •
(clayey) 0
I
Loose to soft brown SILT 1 I[
2 I . S 12
(medium dense)
13.5
Fragmented dense BASALT with soil 3 = 100
inf ill .
18.8 4 = >100
Bottom of Boring
(1- 28 -70)
...
I
. 1
I1
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I
0
LEGEND • % Water content
I 2.0 "O.D.split spoon sample Impervious seal WASHINGTON SQUARE
It 5.0" O.D. thin -wall sample Water level PROGRESS, OREGON
7 * Sample not recovered Plezometer tip
. Atterberg limits' P Sampler pushed '� LOG OF BORING NO. B -3
I --• 1 Liquid limit USC Unified Soli FEBRUARY, 1972 0 -484
qI ; 4— Natural
Plastic Classification SHANNON & WILSON
Ploetlo limit SOIL MECHANIC• a FOUNDATION ENGINSINS
FIG.3.3
[> STANDARD
_ la o a PENETRATION RESISTANCE
SOIL DESCRIPTION `' W z z '= ��
i ii x (140 lb. weight, 30 drop)
• a d i 0 3 l • Stows per foot
3 Surface Elevation: 225 ± 0.5 o fn " 0 0 50 100
Soft brown SILT (Topsoil) . r - 0.8
(Mon 1 �1 1 i brown and 5/18
I I I . &P. . ... .........
.4
•
i Medium der::;e ,�ecoming loose brown 1
SILT with trace of very fi'e 2 II j
sand. 1
I 3I 15
.
17.5
Medium hard gray and rust
I 4 =
brown fractured basalt. >100
27.3 5= >•I00 • Bottom of Boring ...... .. ... . ...
../14/70)
•
.
• I . .........
..... ..
III . .
•
I •
I ........
0 50 100
1 LEGEND • % Water content
I 2.0 "0.D. spilt spoon sample 'Impervious seal WASHINGTON SQUARE
II 3.0" O.D. thin -wall sample Water level PROGRESS, OREGON
* Sample not recovered Plezometer tip
Atterber limits. P Sampler pushed LOG OF BORING NO. B — 2 I
e I • - ..Liquid limit USC unified Soil FEBRUARY, 1972 0 - 4 84
a�-- - Natural water content Claselflcatlon SHANNON & WILSON
Plostlo limit SOIL MECHANIC• • FOUNDATION IINOINCIA•
I FIG. 3.21
• SHANNON WILSON. INC.
APPENDIX B
PREVIOUS COMMUNICATION LETTER REGARDING
PILE FOUNDATION
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
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JOHNSON & NIELSEN ASSOCIATES consulting structural engineers
• J '' 7462 N. FIGUEROA STREET, LOS ANGELES, CALIFORNIA 90041 • 213 • 266.2237 CARL B. JOHNSON. S. E.
2039 UNIVERSITY AVENUE. RIVERSIDE. CALIFORNIA 92507 • 714 •686.8122 SVEND H. NIELSEN. S. E.
GERALD O. LEHMER, S. E.
July 26, 1972
Mr. Richard Brewer
Senior Vice President
Winmar Company, Inc.
1901 Avenue of the Stars
Los Angeles, California 90067
Re: Lipman -Wolfe Department Store
•
Washington Square
Portland, Oregon
Dear Dick:
I would like to confirm the.fact that on July 19, we were instructed
by Mr. Ray Gamble of Burke, Kober, Nicolais $ Archuleta, after
approval of your office, to proceed with the re- design of the pile
foundations.
The information on the piling has been obtained from Mr. Svend
J Sorensen of the office of Richard R. Bradshaw, Inc. at your
request. We are assuming the following design criteria and are
requesting by copy of this letter to Shannon and Wilson that they
review these criteria since their original soil report did not an-
ticipate the use of this type of piling. If any of these criteria
are in conflict with their foundation recommendations, we request
that they contact us immediately.
1) Piles are to be 10" diameter pile sections with a wall
thickness of 0.188" of A36 or equivalent steel.
2) Piles shall be filled with 3000 psi concrete.
3) Piles shall have a 3/4" thick end plate, and if necessary
for driving, a steel H- section tip welded to the end plate
(W8 x 28 min.) will be added.
4) The piles shall be driven into the decomposed or weathered
bed rock to capacities shown on the drawings with a maximum
of 50 tons per pile. The soil report does not specify the
type of pile - driving formula which should be used, and this
information is requested hereby.
R
eco r on c e ARTHUR T SENTANI. S. E. HENRY OJENDYK. C. E.
• /
i
Ir JOHNSON & NIELSEN ASSOCIATES consulting structural engineers
Page -2-
S) Building loads on piles have been increased by 25% to
allow for the down -drag caused by the consolidation of
the natural soils under the weight of the fill, since
the fill will not have been in place long enough to
sufficiently colsolidate the soils prior to driving
piles. Pile lengths will vary from 30 to 45 feet.
6) Since the values given in the foundation report for
passive resistance on pile caps and grade beams are I
excessively low, we are utilizing a reinforced •5 -1"
thick slab on grade to transfer seismic loads from /
shear walls into the ground by friction.
7) Driving piles and filling with concrete shall be under
the continuous inspection of a qualified inspector
approved by the Structural Engineer.
Very truly yours,
JOHNSON $ NIELSEN ASSOCIATES
By
Carl B. Johnson
CBJ /naf
cc: Burke, Kober, Nicolais 4 Archuleta
Attention: Ray Gamble
Shannon and Wilson
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• SHANNON 6WILSON, INC.
APPENDIX C
GEOPHYSICAL TESTING REPORT
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H &M Washington Square Mall lmprovement.doc 24 -1- 03597 -001
Northwest
N G A Geophysical
Associates, Inc.
1600 SW Western Boulevard, Suite 200
PO Box 1063, Corvallis, OR 97339 -1063
Phone: (541) 757 -7231 FAX: (541) 757 -7331 •
www.nga.com
June 7, 2010
NGA Ref: 741
Yuxin (Wolfe) Lang, PE
Senior Principal /Geotechnical Engineer
Shannon & Wilson, Inc.
3990 Collins Way, Suite 100
Lake Oswego, OR 97035
Re: Pile Tip Depth Determination
Washington Square Mall
Tigard, Oregon
Dear Mr. Lang,
Northwest Geophysical Associates, Inc. (NGA) conducted a geophysical investigation to
determine the depth of the pile tip of two piles in the H -8 retail space in the Washington
Square mall, Tigard, Oregon. To facilitate our investigation, Shannon & Wilson drilled
two test borings, B -1 and B -2, adjacent to the two piles. The investigation included
borehole magnetometer profiles and parallel seismic profiles in the two boreholes.
METHODOLOGY
The magnetic technique looks for perturbations in the earth's geomagnetic field which
are associated with the end of the steel pile. Those perturbations are dependent on the
declination and inclination of the earth's field (D =18 °; I =66° in NW Oregon) as well as
the distance and direction of the magnetometer from the pile. At B -1 the borehole was
approximately 2 feet east of the pile whereas at B -2 the borehole was approximately
2 feet south of the pile. The magnetometer sensor used was a Schonstedt GAU -30
borehole fluxgate gradiometer. That sensor measures the difference in the vertical
magnetic field between two sensors 20 inches apart in the probe.
The parallel seismic technique measures the seismic travel time from a seismic impulse
(hammer blow) on the top of the pile cap to the borehole geophone. The geophone is
moved up the borehole to obtain a travel -time versus depth profile. When the geophone
is alongside the pile, the observed seismic velocity should be close to that of the steel
pile, 20,000 ft/sec. When the geophone is below the pile tip the observed velocity should
be that of the soils or rock beneath the pile.
I ,
Northwest Geophysical Associates, Inc. Page 2
June 7, 2010
RESULTS
The results of the magnetic gradiometer investigation are shown in Figure 1. The profile
from boring B -1 shows an anomaly near the surface extending to 4 or 5 feet depth. That
anomaly is interpreted as due to the top of the pile and the bottom of the column resting
on the pile cap. Below that the magnetic signature is relatively flat to the total depth of
the boring, 15.5 feet. Hence, we interpret the pile tip as being a minimum of 1 -2 feet
below that 15.5 foot depth.
The profile from boring B -2 shows anomalies at 4 feet and 11.5 feet depth. Again, the
upper anomaly is interpreted as originating from the top of the pile and the bottom of the
column. The anomaly at 11.5 feet is interpreted as due to the pile tip. The actual depth
of the tip may be ± 1 or 1 feet due to the asymmetrical nature of the expected pile tip
anomaly. Magnetic modeling of the pile may provide a more accurate depth
determination. Another possible interpretation of the anomaly at 11.5 feet is that it is due
to a welded joint in the pile at that depth. The difference in remnant magnetization in
two sections of pipe welded together can cause a similar anomaly.
Note that the anomalies in B -1 and B -2 have differing character because B -1 is to the east
of the pile while B -2 is to the south of the pile.
The parallel seismic data were inconclusive. Seismic waveforms were recorded at
2.5 foot intervals to the total depth of the boring using a 14Hz BHG -3 borehole
geophone, recorded with a Geometrics Geode seismograph sampling at
0.021 milliseconds (ms). The borings were spudded in shallow excavations, 3 -4 feet
deep, which exposed the pile caps and the top of the steel pipe piles.
The short length of the borings allowed only 2 to 4 measurement points adjacent to the
pile. With the expected seismic velocity of 20 feet/millisecond, timing to 0.05 ms or
better is required. The hammer source available for the survey generated signals with a
broad frequency spectrum between 100 Hz and 250 Hz. Hence, the timing of the
waveform arrival did not have sufficient resolution over the short length of the borings to
provide reliable pile tip depth estimates.
CLOSURE
Northwest Geophysical Associates, Inc. has performed this work in a manner consistent
•
with the level of skill ordinarily exercised by members of the profession currently
practicing under similar conditions. No warranty, express or implied, beyond exercise of
reasonable care and professional diligence, is made. This report is intended for use only
in accordance with the purposes of the study described within.
. p '
Northwest Geophysical Associates, Inc. Page 3
June 7, 2010
We appreciate the opportunity to perform this geophysical investigation. Should you
require further information concerning the field investigation, or this report, please
contact us at your convenience.
Sincerely,
Northwest Geophysical Associates, Inc.
An-dcrel
Rowland B. French, Ph.D., R.G.
President
Attachments: Figure 1
File: NGA WaSqr Pile Rpt01.doc
NGA Project: 741
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B1 B2
Magnetic Gradient (arb.units) Magnetic Gradient (arb.units)
-12000 -8000 -4000 0 4000 8000 12000 -12000 -4000 4000 12000
1 1 1 I 1 l 0 i I 1 1 1 ,
,
I
, r .------ --- " -------.--I H ,
o I
u, •
z - . •
7 I
7
i
o '
•
i
N i '
i
h a, I F INTERPRETED
i w DEPTH OF PILE TIP
. ( - - . i °
• J
LL
•
I ,
1 �
,
- — 20 . ... . ... ._ .
DATE LOGGED: 28-MAY -2010
DEPTH REFERENCE: FLOOR LEVEL
LOGGED BY: RBF 1
TOOLS USED: FIGURE 1
I SCHONSTEDT GAU -30 --
BOREHOLE MAGNETIC PROFILES
Northwest
' G A Geophysical Pile Tip Depth Determination
, Associates, Inc. Washington Square Mall
PO Box 1063 Corvallis, Oregon 97339-1063 Tigard, Oregon
p PHONE: (541) 757 -7231 FAX (541) 757 -7331
J >
SHANNON FWILSON. INC.
APPENDIX D
IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL
REPORT
H &M Washington Square Mall Improvement.doc 24 -1- 03597 -001
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- SHANNON & WILSON, INC. Attachment to and part of Report 24-1 -03597 -001
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- Geotechnical and Environmental Consultants
Date: June, 2010
To: Attn: Tomomi Marzan
The Macerich Company
Important Information About Your Geotechnical/Environmental Report
CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC
CLIENTS.
Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer
may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your
consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than
you should apply this report for its intended purpose without first conferring with the consultant. No party should
apply this report for any purpose other than that originally contemplated without first conferring with the consultant.
THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS.
A geotechnical /environmental report is based on a subsurface exploration plan designed to consider a unique set of
project - specific factors. Depending on the project, these may include: the general nature of the structure and
property involved; its size and configuration; its historical use and practice; the location of the structure on the site
and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the
additional risk created by scope -of- service limitations imposed by the client. To help avoid costly problems, ask the
consultant to evaluate how any factors that change subsequent to the date of the report may affect the
recommendations. Unless your consultant indicates otherwise, your report should not be used: (1) when the nature
of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or
if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the
site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or
orientation of the proposed project is modified; (4) when there is a change of ownership; or (5) for application to an
adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after
factors, which were considered in the development of the report, have changed.
SUBSURFACE CONDITIONS CAN CHANGE.
Subsurface conditions may be affected as a result of natural processes or human activity. Because a
geotechnical /environmental report is based on conditions that existed at the time of subsurface exploration,
construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the
consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions
commonly vary seasonally.
Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater
fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a
geotechnical /environmental report. The consultant should be kept apprised of any such events, and should be
consulted to determine if additional tests are necessary.
MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS.
Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples
are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about
overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your
report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While
nothing can be done to prevent such situations, you and your consultant can work together to help reduce their
• impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in
this respect.
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A REPORT'S CONCLUSIONS ARE PRELIMINARY.
The conclusions contained in your consultant's report are preliminary because they must be based on the assumption
that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site.
Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to
observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar
with the background information needed to determine whether or not the report's recommendations based on those
conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant
who developed your report cannot assume responsibility or liability for the adequacy of the report's
recommendations if another party is retained to observe construction.
THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION.
Costly problems can occur when other design professionals develop their plans based on misinterpretation of a
geotechnical /environmental report. To help avoid these problems, the consultant should be retained to work with
other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental
findings, and to review the adequacy of their plans and specifications relative to these issues.
BORING LOGS AND /OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE
REPORT.
Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site
personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring
logs and data are customarily included in geotechnical /environmental reports. These final logs should not, under
any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit
errors or omissions in the transfer process.
To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready
access to the complete geotechnical engineering /environmental report prepared or authorized for their use. If access
is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming
that a contractor was not one of the specific persons for whom the report was prepared, and that developing
construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may
gain important knowledge from a report prepared for another party, the contractor should discuss the report with
your consultant and perform the additional or alternative work believed necessary to obtain the data specifically
appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply
disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability.
Providing the best available information to contractors helps prevent costly construction problems and the
adversarial attitudes that aggravate them to a disproportionate scale.
READ RESPONSIBILITY CLAUSES CLOSELY.
Because geotechnical /environmental engineering is based extensively on judgment and opinion, it is far less exact
than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against
consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts,
reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the
consultant's liabilities to other parties; rather, they are definitive clauses that identify where the consultant's
responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and
take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged j
to read them closely. Your consultant will be pleased to give full and frank answers to your questions.
The preceding paragraphs are based on information provided by the
ASFE /Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland
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