Report RECEIVED
DEC 13 2017
11 Decembei 2 JY , 11(5 R")
Craig Schuck,VP BUILDING DIVISIM
Niki Munson
Riverside Homes LLC
17933 NW Evergreen Parkway,#370
Portland,OR 97006
Re: Geotechnical Construction Observation summary report for Progress Landing,
12 lots in Tigard Oregon
Dear Mr. Schuck and Ms.Munson,
Rapid Soil Solutions (RSS) is pleased to submit this geotechnical construction observations
summary report for Progress Landing Subdivision project located in Tigard, Oregon. The
purpose of this report is to summarize RSS's on-call geotechnical observation and testing
services for infrastructure, roadway, and residential lot construction between the dates of
September 2017 to November 2017.
The subject property is located off of SW 135th Avenue just south of the intersection of SW
Morning Hill Drive. The jurisdictional regulatory agency for the subject site is Washington
County,Oregon.
Construction Observation Methods and Techniques
RSS and ACS Testing performed geotechnical testing services for the site improvements
construction phase of the project as requested on an on-call basis. This summary report is based
upon construction monitoring, QA/QC oversight of fill placement activities, and analytical
laboratory, nuclear gauge density.
Nuclear gauge density testing was performed during construction in accordance with ASTM
D6938 to document placement of structural lot fill, utility trench backfill, road fill, and asphalt
concrete. Nuclear gauge testing consists of measuring the density and moisture content of in-
place construction materials compared to the theoretical maximum density determined by the
Proctor moisture-density test or Rice density test. Project construction specifications, as
indicated on the approved civil plans, require achieving at least 95 percent relative compaction
for soil and aggregate and 91 percent relative compaction for asphalt concrete.
General Information and structural fill placement
As indicated on the grading plans produced by NW Engineers the Subdivision is a single-family
residential project consisting of 12 building lots, asphalt-paved roadways, underground utility
infrastructure, and storm water management facilities. The only lots of have fill placed upon
them were 5-9 and 10,12 where ACS Testing. Those test results have been sent before and
results were achieved e ed with proof rolls and compaction tests. Topsoil
was observed to have been
placed on lots following site improvements construction. The front portion of lots at the site may
contain soft soil resulting from excavation and backfill of power and communication utility
trenches. Bearing capacity of the lots are 1,500 psf.
Rapid
Soil SO Lw ti Ofl S LLC 503-816-3689 mia@rapidsoilsolutions.com
w
Remaining Lots
RSS did not observe or test structural fill placed on remaining lots located within the
limits of subdivision. These lots were either cut below original grade or exist in their
approximate preconstruction state. These lots may be covered with a layer of organic
topsoil spread after construction. If evidence of undocumented fill or previously disturbed
soil is discovered during future foundation excavation, sub-grade assessment should be
conducted by a licensed geotechnical engineer or designated representative prior to footing
construction.
Utilities and Roads
RSS tested trench backfill for storm, water, and sanitary sewer utility infrastructure in
accordance with project plans and specifications. RSS also tested structural fill, crushed
aggregate base, and asphaltic concrete placed in proposed roadway alignments. Test
results generally met project specifications at locations and dates tested.
Recommendations
RSS's construction monitoring indicates future individual home construction is
compatible with tested soil conditions, provided the recommendations outlined below are
followed:
• Residential footings for all lots should extend through the topsoil/strippings layer or
soft surface soils and bear upon firm native soil or engineered structural fill. The estimated
bearing capacity for footings founded on soils as described above is 1,500 psf. Footings
should be embedded at least 18 inches below lowest adjacent exterior grade to increase
overburden resistance and reduce potential frost heave. Wet-weather foundation
construction will likely require sub-grade over-excavation and backfill with compacted
crushed aggregate.
• If fill placement is proposed or necessary to raise foundation subgrade elevations to
desired finished grades, RSS should provide verification of adequate subgrade support
conditions before fill placement, and conduct testing of structural lot backfill prior to
residential construction.
• Competent bearing surface and foundation support is recommended beneath
structural appurtenances (i.e.,driveways, patios, slabs, sidewalks, deck posts,etc.)to limit
potential cracking or damage.
• Residential structures should be provided with adequate foundation and crawl space
drainage. Failure to provide adequate drainage may result in unanticipated foundation
settlement, soil sloughing, or erosion. Drainage implementations may require future
monitoring and periodic modification to maintain functionality and efficiency.
• Finished grade for all lots should provide positive drainage away from structures.
Depressions or areas with potential to retain ponding surface water should be avoided.
• Some total and differential settlement of finished residential structures may be
expected. Most settlement is likely to occur during or soon after construction, but some
Rapid
SoitSol n 1.LC 503-816-3689 mia@rapidsoilsolutions.com
r r
long-term settlement is possible.
Conclusions and Limitations
Based on our observations and density testing of earthwork construction, it is our opinion that
earthwork grading was performed in general accordance of the approved engineering plans. It
should be noted that we were present only on a part time basis during construction operations, but
observed and tested periodically in accordance with Washington County Standards.
If you have any questions concerning our geotechnical services or materials testing, please contact
the undersigned at 503-816-3689.
Thank you,
19244PE Ai
OREGON
44 4.
EXPIRES: 1.,;)1`" �'C I
Mia Mahedy-Sexton,PE GE
Rapid
Soi t w it0 ac 503-816-3689 mia@rapidsoilsolutions.com
srrrncr DATE: Sep 13,2017 ACS Testing,Inc
4111=1NCREfr: 7409 SW Tech Center Dr,Suite 145
PAGE 1 OF: 1 Tigard,OR 97223
oas Phone:503-443-3799 Fax:503-620-2748
503.443.3799 DAILY ASPHALT COMPACTION / IN PLACE SOIL DENSITY
(NUCLEAR METHOD)Asphalt ASTM D2950/Soil Density ASTM D6938 AASHTO T310
RAPID SOIL SOLUTIONS PROGRESS LANDING
3915 5W PLUM STREET 12050 SW 135TH AVE
PORTLAND,OR 97219-6018 TIGARD,OR 97223
Jurisdiction TIGARD
Permit#: N/A
INSPECTOR/CERT Cameron Ingersoll ODOT#49382 ACS Job# 17-6962-24
WEATHER r OVERCAST 17 SUNNY r RAIN SOIL TEST METHOD:O T99 0D698 ❑T180 ❑D1557
AGG: r 3/4"-r 1-1/2"- OTHER: CPN r 8510 r 8036 r 8022 r 8021
NATIVE TYPE: Light Brown Silt r 8037 r 8658 r 8237 r 8511 r 7781
SUPPLIER: Existing TROXLER r 20646 17 38579 r 38580 r 30560
CONTRACTOR LCD ALL GAUGES CALIBRATED BY ODOT
r C MIX r B MIX r LEVEL II r LEVEL III
STANDARD COUNT:
TEST MODE: ❑BACKSCA ITER D DIRECT 8" DEPTH 1) 642 2) 2250
OPT.MOISTURE: 18.9
RICE OR PROCTOR 10212 MAX.DRY DENSITY: 103.6 % OF DENSITY REQ. 95
TEST NO. LOCATION %MOIST. LIFT OR ELEV. DEPTH DENSITY.LBS %MAX DENSITY
1 Lot 4 13.6 El:240.3 8" 103.3 100
2 Lot 3 12.8 El:240.3 8" 103.7 100
3 Lot 10 15.4 El:229.15 8" 102.2 99
4 Street A 15.0 Subgrade 8" 101.0 97
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6
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9
10
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RESULTS GIVEN TO: Robert Hem with LCD
COMMENTS:
Tests taken on existing native for roadway and lot fill.Proof roll performed using a fully loaded water truck.No deflection or yielding
observed.
Reviewed by: Date:Sep 14,2017 0C Mia Mahedy-Sexton
DOUG ;+•1111.J L/VP Operations
NIEttir
ACCREDITED DE/KB