Report B R A U N sM Braun Intertec Corporation
6032 N. Cutter Circle, Ste. 480
I NTE RTEC PO. Box 17126
Portland, Oregon 97217
503- 289 -1778 Fax:289 -1918
_I Engineers and Scientists Serving
the Built and Natural Environments
December 5, 1997 Project No. EAAX- 96 -415A
Report No. 09 -117 -3446
I
Mr. Andrew Ilg
Super One, Inc.
10895 S.W. Fifth
I Beaverton, Oregon 97005
I Dear Mr. Ilg:
Re: Site Specific Seismic Evaluation for the Proposed Super One 74 -Unit Motel, Pacific
I Hwy. 99W and Durham Road, King City, Oregon
At requested, we have completed a site specific seismic evaluation for the referenced project.
I The purpose of our services was to perform a site specific seismic hazard evaluation for the
referenced project. The scope of our seismic evaluation services generally conformed to the
:, requirements of Uniform Building Code (UBC) Of 1996 Section 1804. The results of our
evaluation are described below.
.1 Summary of Conclusions and Recommendations
Based on the results of our investigation, it is our opinion that the site is generally not
I susceptible to site specific seismic hazards such as subsidence, fault rupture, site amplification,
lateral spread, landslide or slope instability. .The site is indicated to be susceptible liquefaction
induced ground settlement due to the 40 feet of loose to very loose silty sand soils and the high
water table (18 feet below existing ground level) as shown by our test boring. Total liquefaction
induced ground settlement is estimated to be on the order of 3 to 6 inches.
The liquefaction induced round settlement would be large area. expected to extend over a lar
e ground p g
J Therefore, although the general area may experience up to 6 inches of settlement during a major
seismic event, we anticipate that differential settlements will be on the order of 2 inches due to
the type of proposed construction and the uniform subsurface soil conditions. By addressing this
1 magnitude of differential settlement in the design, the structural engineer can normally prevent
collapse of the structure during a major seismic event. The owner must accept that a structure
experiencing this magnitude of settlement during a major seismic event will experience extensive
~` damage due to the settlement and ground shaking. However, we anticipate that a structure may
be designed which will sustain this order of differential settlement and associated damage yet
I piovide occupants the opportunity to safely exit the structure. We understand this motel is not
considered a critical structure per the Oregon State Building Code.
1
1 Super One, Inc.
Project No. EAAX- 96 -415A
Report No. 09 -117 -3446
. December 5, 1997
Page 2
I
Subsurface soils at the site would generally exhibit typical type S behavior. As indicated in
Table 16J of the Uniform Building Code (UBC) of 1996, a site coefficient of 2.0 may be used
for the site.
1 General
Please refer to the attached report for a more detailed summary of our analyses and
recommendations. If we can provide additional assistance or observation and testing services
during design and construction, please do not hesitate to contact us at (503) 289 -1778 or
(800) 783 -6985.
Sincerely,
(2147 1 /0:
Travis T. Nguyen, P.E.
Project Engineer \* PROP
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1
Charles R. Lane, P.E. 41 P4 ES R.
Senior Engineer
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Attachment: Site Specific Seismic Evaluation Report
I
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l
Super One, Inc.
Project No. EAAX- 96 -415A
Report No. 09- 117 -3446
-"' . . December 5, 1997
Page 12
•
11 7.0 Conclusions
11 Based on our study, we made the following conclusions:
• Based on the results of our investigation, it is our opinion that the site is generally not
susceptible to site specific seismic hazards such as subsidence, fault rupture, site
amplification, lateral spread, landslide or slope stability. The site is generally susceptible
to liquefaction- induced ground settlement. Total liquefaction induced ground settlement is
estimated on the order of 3 to 6 inches. Differential settlements are anticipated to be
minimal because of the type of proposed construction. At your request, we can provide
specific foundation recommendations to mitigate potential liquefaction hazards.
• . The soil profile at the site can be considered as Type S with an "S" site factor of 2.0 for
1 the proposed short-story structure.
• For any new construction at the site, UBC static design based on S, site coefficient would
' adequately represent UBC recurrence interval earthquake conditions.
1 8.0 Use of Report
This report is for the exclusive use of the addressee and their representative to use to design the
proposed structure described herein and prepare construction documents. The data, analyses and •
recommendations may not be appropriate for other structures or purposes. We recommend that
parties contemplating other structures or purposes contact us. In the absence of our written
' approval, we make no representation and assume no responsibility to other parties regarding this
report.
1
9.0 Level of Care
' Services erformed by the geotechnical engineers for this project have been conducted with that -
P Y g g P J
level of care and skill ordinarily exercised by members of the profession currently practicing in
1 this area under similar budget and time restraints. No warranty, expressed or implied, is made.
1
1
Super One, Inc.
Project No. EAAX- 96 -415A
I Report No. 09- 117 -3446
December 5, 1997
Page 11
_
The site is enerall flat and _is located at least 4 000 feet from the Tualatin River face).
(free face
g Y ( )
Therefore, it is our opinion, the potential for seismic landsliding or slope instability is minimal.
I
6.4 Liquefaction
' Liquefaction occurs when a saturated deposit of loose, fine grained soils (generally sands and
sand -silt mixtures) is subjected to strong earthquake shaking. Such loose saturated soil deposit
' will have a tendency to compact and thus decrease in volume. If this deposit is saturated and,
thus, cannot drain rapidly, there will be an increase in the pore water pressure. With increasing
oscillation, the pore water pressure can increase to the value of the overburden pressure. The
• shear strength of a cohesionless soil is directly proportional to the effective stress which is equal
to the difference between the overburden pressure and the pore water pressure. Therefore,
when the pore water pressure increases to the value of overburden pressure, the shear strength
' of the soil reduces to zero and the soil deposit turns into a liquefied state.
' As indicated earlier in Section 4.0 of this report the site underlain by 40 feet of very loose to
loose silty sand. Groundwater was encountered at a depth of 18 feet during our explorations.
Thus, the site is underlain by saturated or waterbearing soils which are subject to additional
consolidation. These soils are generally known to be susceptible to liquefaction.
We used Seed, et al (Reference 12) procedures and Stark, et al (Reference 13) procedures to
' evaluate liquefaction susceptibility of on -site soils. We also evaluated the site using Youd, et al
(Reference 14) procedures for liquefaction- induced ground surface disruption. Based on our
analyses, we believe there is a potential for liquefaction at depths ranging from 15 to 40 feet.
The effects of liquefaction include ground settlement and lateral ground displacement. We
estimated ground settlement due to Piquefaction using Tokimatsu and Seed, 1987 procedures
(Reference 15). Based on our evaluation, we estimate total ground settlement of up to 6 inches
due to liquefaction at the site.
' We evaluated lateral ground displacement due to liquefaction at the site using Barlett and Youd
(Reference 16) procedures. Based on our evaluation, we believe the lateral ground displacement
due to liquefaction will be minimal because the site is relatively and is located at least 4,000
' feet from the banks of the Tualatin River (free face). In addition, several existing structures in
the site vicinity are anticipated to minimize lateral spread at the site during liquefaction.
Therefore, in our opinion, lateral ground displacement hazard does not pose a concern for the
proposed construction.
•