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GEO`DES IGN= FIEL REPORT
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GDI Project: Polygon-129-03 Prepared By: Jonathan Tree
Project Name: River Terrace East Date: 3/20/18
Location: SW Scholls Ferry&Roy Rogers, Bvrtn. Report#: 214
Arrival. 0945 Departure: 1230
Weather: Sunny, 45 degrees Permit#: TBD
Site Visit Requested By: Ken (Polygon) Met With (on site): Eduardo
(Mainstream Landscaping)
Purpose: Observe lot 92 subgrade, observe backfill along walls north of lots and DT of lot 200
wall backfill
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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-214 (03/20/18) Low density backfill for lot 200
Lot 92- Subgrade
I observed crews had excavated to various planned subgrade elevations and placed approx. 2"of%"-0 crushed rock
compacted with a small walk behind vibratory smooth plate. Using a%i " diameter steel foundation probe, I assessed
the relative consistency of the brown SILT with sand subgrade. Based on 12-inch to 18-inch penetration under full
body weight,the subgrade consistency was medium stiff to stiff. One area approximately 4 feet in width was soft to
medium stiff and pumped under foot pressure. The excavators on site removed the soft material and replaced it
with on-site gravel.The gravel was compacted using a small walk behind vibratory smooth plate. After probing the
repaired area, the subgrade was medium stiff to stiff based on penetration of the%z" steel foundation probe.
Based on probing of the subgrade at lot 92, the lot subgrade has been prepared in general accordance with our
geotechnical recommendations. `,-.
L4 ,
Wall backfill on northern side of lots?Ono 206
While on-site, I spoke with Eduardo with Mainstream Landscaping.The crew with Mainstream Landscaping are
constructing the stone brick retaining walls that were observed today. I observed the backfill CR sourced from Baker
(Farmington)%"-0 that had been placed in approx. 4" lifts aid compacted with a TORO FP3000 walk behind gas
vibratory smooth plate compactor according to Eduardo from Mainstream. Eduardo also informed me that the
STRATA SG350 Geotextile Fabric(six feet wide)were rolled perpendicular to the axis of the wall at 16-inches of
crushed rock(CR) increments (see attached photo of exposed geotextile fabric for example).The manufacturer of
the geotextile fabric instructed Eduardo from Mainstream Landscaping to not overlap the fabrics along the edges of
two sheets (see attached photo).
The top soil that covered the backfill had been pot holed to a depth of approx. one to two feet bgs for observation
of the CR backfill (see photo attached). Total CR backfill depths measure approximately four to five feet. Based on
the construction information provided by Mainstream Landscaping (compaction methods drainage, and grid
placement)and the observed crushed rock backfill material the retaining walls for toitilehave been
constructed in general accordance with our geotechnical recommendations.
9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 1503.968.8787 I www.geodesigninc.com
GEODESIGNY. FIELD REPORT
Page 2 of 6
I used a Troxler 3430 nuclear density gauge to evaluate compaction of the top lift of CR wall backfill on the northern
end of lot 200 (see attached photo).The measured maximum density of two tests measured 87.5%pcf at 7.1 %
moisture and 83.1%pcf at 6.5%moisture (see attached NDDS). I recommended that Mainstream wet the CR and
recompact and that the current level of compaction as measured does not meet our geotechnical recommendations.
Before leaving the site, I spoke with Eduardo to inform him that the project manager(Shawn Dimke; Geodesign Inc.)
would like to density test the bottom two to three feet base of CR backfill and the final top two to three feet of every
wall constructed in the future to ensure that the crushed rock backfill behind walls is in general accordance with our
geotechnical recommendations.This was also communicated to Tom from Polygon Homes via phone call after
leaving the site.
Distribution:
Attachments:Site Plan (1); Photos (3); NDDS(1)
Reviewed by.
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 indude supervision or direction of the contractor,the contractor's employees
of our field observations,testing,and preliminary r,;connncndat, :u I Inc report can only be
or agents. Our firm is not rrs;x,ns,bk for site satc•;y 'h,z field report is a DRAFT representation
considered tidal upon revie.,r th.•GeoDesign pr•,3.tt rnat,.,ger,as indicated by initials in the'Reviewed if section --
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Signature:
9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 1503.968.8787 i www.geodesigninc.com