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'RIVER TERRACE EAST"'
LOT 176
HUB AND TACK CERTIFICATION
NE & SE1/4SEC. 6, T25, R1W, W.M.
CITY OF TIGARD, WASHINGTON COUNTY, OREGON
SURVEYED FEBRUARY 6, 2018
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PREPARED FOR:
POLYGON NORTHWEST COMPANY
703 BROADWAY ST., SUITE 510
VANCOUVER, WA. 98660
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I, TRAVIS C. JANSEN, A REGISTERED PROFESSIONAL LAND SCALE
SURVEYOR IN THE STATE OF OREGON, HEREBY CERTIFY THAT 20 0 10 20
I HAVE ACCURATELY SURVEYED AND STAKED THE OFFSETS
9 TO THE FOUNDATION ENVELOPE FOR LOT 176 OF THE PLAT 1 INCH =20 FEET
I OF "RIVER TERRACE EAST".
ter- DRAWN BY: 12 DATE: 2/28/18PACIFIC COMMUNITY [ SIGN
REVIEWED BY: TCJ DATE:, 2/28/18
395-041
PLANNING - ENGINEERING SURVEYING
PROJECT NO.: (503)941-9484
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LT -Pt )77
DESIGN FIELD REPORT
Page 1 of 2
GDI Project: Polygon-129-03 Prepared By: Shawn Dimke, P.E., G.E.
Project Name: River Terrace East Date: 3/1/18
Location: SW Scholls Ferry&Roy Rogers,Bvrtn. Report#: i 209
Arrival: 8:15 am Departure: ( 8:55 am
Weather: Light rain, 40s Permit#: TBD
Site Visit Requested By: Tom (Polygon) Met With (on site): Ken (Polygon)
Purpose: Observe Lots 176-179 subgrade
Outstanding Issues: Proof roll road and curb base rock and repair as needed before paving
FR-58 (12/06) Decommission temporary storm and sewer lines through Tract E
FR-177 soft fill from slope cut in lots 153, 154 and 155
FR-208 (2/28) Lots 177-179 soft footing subgrade
Lots 177-179
Upon arrival, I observed Lots 177 to 179 had been excavated to planned subgrade elevation, a thin section of
crushed rock had been placed and concrete forms had been erected.The subgrade under the thin section of
crushed rock consisted of silt with trace to minor clay and variable fractions of gravel. Resistance to penetration
(1/2"diameter steel foundation probe) indicates subgrade conditions vary from soft to stiff. Subgrades were
generally soft to medium stiff in areas nearest the edge of the slope and in areas which required little cut from
existing grades. Based on our observations the shallow fill and fill near the edge of the slope at the site is
presumably not compacted as well as the deeper fill. We observed some of the continuous foundations did not have
the recommended minimum 5-foot horizontal offset from the free face of the slope.
In our opinion the footings can be poured over the current subgrade conditions provided greater settlements of up
to 2-inches total with differential of up to 1-inch over a distance of approximately 25 feet (rather than the typical
estimated maximum of 1-inch total and 0.5-inch differential)are acceptable. For this approach granular fill should
also be placed and compacted (and benched into the existing slope)where necessary to provide the recommended
minimum 5-foot horizontal offset between the edge of the footings and the free face of the slope.
Another approach would be to remove the footing forms in order to cut down all the footing subgrades and backfill
with minimum 12-inch thick granular pads. The footings near the slope could also be lowered to provide the
minimum 5-foot horizontal offset from the free face of the slope.
Another option is to use air knife excavation methods to remove the soft fill from below the footing forms and
increase the amount of concrete placed when the footings are poured. The depth of the concrete for the footings
could also be lowered via this method to provide 5-feet of horizontal offset between the edge of the footing and free
face of the slope.
Lot 176
While on-site I also observed Lot 176 had been cut to subgrade elevation (no crushed rock had been placed yet to
protect the subgrade from disturbance). Resistance to penetration (1/2"diameter steel foundation probe) indicates
subgrade was generally medium stiff to stiff for Lot 176 except for an area nearest the edge of the slope which was
soft to approximately 6-inches. Footings had not been laid out yet but if soft soil is in footing area we recommend
over-excavation and backfill with compacted crushed rock. Footings near the slope should also be embedded as
9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 1503.968.8787 I www.geodesigninc.com
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G EODESIGNZ FIELD REPORT
Page 2 of 2
required for minimum 5-foot horizontal offset from the free face of the slope. Based on our observations, provided
the soft area is removed and backfilled if it is in a footing zone and the footings are embedded for the minimum
required offset from the slope, the footing subgrade observed today for Lot 176 is being prepared in general
accordance with out geotechnical recommendations.
During a follow up conversation with Tom Dicianno we understand the grades and layout of the foundations for lots 176 through 179
may change and if they do the forms will be removed and footings will be re-excavated.
Distribution:
Attachments: Site Plan (1)
Reviewed by: SMD
This report presents opinions formed as a result of our observation of activities relating to geotechnical engineering or environmental services.We rely on the contractor to comply with the plans and
specifications throughout the duration of the project irrespective of the presence of our representative. Our work does not include supervision or direction of the contractor,the contractor's employees
or agents. Our firm is not responsible for site safety.This field report is a DRAFT representation of our field observations,testing,and preliminary recommendations.The report can only be
considered final upon review of the GeoDesign project manager,as indicated by initials in the"Reviewed By'section.
Signature: Shawn Dimke
9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 1503.968.8787 I www.geodesigninc.com