Report NORTHWEST wsT2020 -00231
13737 PA-1,ohittuu
ENGINEERING GROUP RECEIVED
JUL 3 0 2020
Ms. Carley Davis CITY OF TIGARD July 24, 2020
Ram Jack West BUILDING DIVISION
862 Bethel Drive
Eugene, OR 97402
Re: Mr. Steve Everton
Site Inspection
13737 SW Benchview Terrace
Tigard, OR
Dear Ms. Davis,
Per your request, a site inspection and soil borings were performed at the above referenced site
on July 21, 2020. The purpose of the site inspection was to provide consultation regarding the
soil parameters for the proposed deep foundation system. The soil investigation is relatively
conservative and is based on limited surface and subsurface soil observations at the site.
Documents detailing the construction of the residence were not available for review. The
residence is estimated to be approximately twenty-four(24)years old and for orientation purposes
is assumed to face south.
GEOLOGICAL SETTING AND SOILS
The geologic setting in this area is comprised of deposits micaceous sandy sit and clayey silt
defined as Upland silt deposits of the upper Pleistocene (USGS National Geologic Map
Database). It is our opinion that the settlement is a result of improper foundation drainage and/or
undersized foundations. We believe that a suitable support can be achieved by installing helical
piles and helical tiebacks.
Preliminary soil data was obtained from the Web Soil Survey from Natural Resources
Conservation Service produced by the United States Department of Agriculture. This soils survey
indicates that the primary soil at the residence is classified as Cornelius and Kinton silt loam. This
soil has a slow infiltration rate and a slow rate of water transmission. Cornelius and Kinton silt
loam has a low shrink-swell potential with Plasticity Index ranging from 5-15.
SOIL OBSERVATIONS
Surface observations are as follows:
• Vegetation around the residence consists primarily of exposed soils with some small to
medium shrubs.
• Grade has downward slope from the south side to the to the north side of the site. The
slope increases towards the north side of the residence. The south side of the site is
relatively negatively sloped back towards the residence.
• The surface of the soil near the residence was covered with decorative mulch, artificial
turf, and walkway gravel.
Box 10393/Eugene,OR 97440/541.393.7363/WWW.NWENGGROUP.COM
Mr. Steve Everton July 24, 2020
• Foundation Inspection Page 12
13737 SW Benchview Terrace
Tigard, OR
• No roots from bushes or trees are present near the surface.
Two Dynamic Cone Penetrometer (DCP) test was performed on July 21, 2020. DCP tests are
used to measure the strength of the in-situ soil and the thickness of the soil layers. DCP is a hand-
held device which consists of two 5/8" dia. shafts coupled near midpoint. The lead shaft contains
an anvil and a pointed tip which is driven into the soil by dropping a sliding 35-lb hammer
contained on the upper shaft onto the anvil. The underlying soil strength is determined by
measuring the penetration of the lower shaft into the soil after each hammer drop. The number of
drops required for a penetration of 4" is then recorded and converted to an equivalent SPT N-
values which is reported on the attached boring logs (DC-1 and DC-2).
The first DCP boring extended to a depth of ten feet(10'-0") below grade. The upper two feet(2'-
0") of soil consists of stiff to very stiff material. Between two feet (2'-0") and seven feet (7'-0"), a
soft to medium stiff layer of material was found. Between seven feet (7'-0") and ten feet (10'-0"),
a stiff to very stiff layer of material was found. Refusal occurred at ten (10'-0") and the boring was
terminated. The DCP boring log (DC-1) is attached to this report.
The second DCP boring extended to a depth of ten feet and six inches (10'-6") below grade. The
upper two feet and six inches (2'-6") of soil consists of stiff to very stiff material. Between two feet
and six inches (2'-6") and seven feet and six inches (7'-6"), a soft to medium stiff layer of material
was found. Between seven feet and six inches (7'-6") and ten feet and six inches (10'-6"), a stiff
to very stiff layer of material was found. Refusal occurred at ten feet and six inches (10'-6") and
the boring was terminated. The DCP boring log (DC-2) is attached to this report.
RECOMMENDATIONS
It is our opinion that the settlement is the result of improper foundation drainage and/or undersized
foundations. We understand that helical piles are proposed to underpin portions of the north and
west sides of the residence.
A hydraulic torque driver head is used to install the helical pile. Advancement of the pile will
continue until the minimum installation torque is achieved as specified by the torque correlation
method to support the allowable design loads of the structure using a torque factor.
We recommend that the proposed piles achieve a minimum embedment depth of seven (7) feet.
However, it is anticipated the actual pile embedment depth may be greater. The repair work will
not interfere with the existing lateral support conditions. Therefore, there are no lateral design
concerns.
Maintaining uniform moisture around the foundation is very important. The landscape grades
around the residence should be maintained to slope away from the residence where required.
The landscape grades should slope away from the foundation at a minimum of/2" per foot for six
(6'-0)feet. The top soil should extend a minimum of one (1'-0)foot above the bottom of the footing
and should not extend above four(4") inches below the bottom of the siding.All new fill soil should
be clayey sand with a minimum Plasticity Index (PI) of twenty-five (25). Watering the soil around
the foundation is also important during dry periods to help maintain uniform moisture in the soil.
F�h'"`FyT�$'YmM�rI*.,,?. ,.%W.. » , ry v, `.E•W i+N riYCYTA'YXT'n..+.i- wf
P.O. Box 10393/Eugene,OR 97440/541.393.7363/WWW.NWENGGROUP.COM
Mr. Steve Everton July 24, 2020
• Foundation Inspection Page 13
13737 SW Benchview Terrace
Tigard, OR
This report is for the sole use of Ram Jack West and their design consultants for the foundation
repair at the referenced site. Northwest Engineering Group assumes no responsibility or liability
for any engineering judgement, inspection or testing performed by others outside the scope of
this report. Our services do not include any survey or assessment of contamination or potential
contamination of the soil or ground water by hazardous or toxic substances. No warranty is
expressed or implied by this report.
This concludes this report. If I can be of further assistance or should you have any questions
about this report, please do not hesitate to contact me. /60
g�too PRoS�s
Sincerely, ``�` 4 GINEF, %
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SIRES: li,/ /22
Sean Morrison E.I.T. Charles Steffensmeier P.E.
Engineering Technician Civil Engineer
Attachment: Site Plan (SK-0)
Dynamic Cone Penetrometer Test (DC-1)
Dynamic Cone Penetrometer Test(DC-2)
•
P.O. Box 10393/ Eugene,OR 97440/541.393.7363/WWW.NWENGGROUP.COM
- SW BENCHVIEW TERRACE
94' +/-
ENTRY +
1
_Z �' N 10.8' +/-
I
—13737 SW BENCHVIEW TERRACE
DC-1 DC 2 SPECIAL INSPECTIONS:
N
AREA OF
F SPECIAL INSPECTIONS OF PILE
WORK INSTALLATIONS SHALL BE
cv PERFORMED ACCORDING TO ESR
i 1854, SECTION 4.3,PARAGRAPH 2.
INSPECTION SCHEDULE SHALL BE
CONSISTENT OF VERIFYING AND
PROPERTY DOCUMENTING PILE AND BRACKET
tee!--LINE I NUMBERS ON SITE, FOLLOWED BY
OBSERVATION OF THE FIRST
INSTALLATION'S LOCATION,
EMBEDMENT DEPTH, AND FINAL
INSTALLATION TORQUE VALUE,
I CORRELATED TO THE REQUIRED
DESIGN LOAD. ONSITE LOG BOOK
FOR REMAINING INSTALLATIONS
WILL BE VERIFIED.A FINAL
INSPECTION OF THE INSTALLED
I REMAINING PILES AND LOG BOOK
DATA WILL BE DOCUMENTED IN A
BRIEF LETTER SUBMITTED TO THE
„_._ BUILDING AUTHORITY.
SPECIAL INSPECTION OF ALL PILES
96 +, SHALL BE PERFORMED BY
SITE PLAN NORTHWEST ENGINEERING GROUP.
0TREE PRESERVATION NOTES:
1.ALL HOLES ARE EXCAVATED NEXT TO THE
0 STRUCTURE FOUNDATION
NORTH 2. THE TOTAL AREA OF EXCAVATED HOLES<25 SQFT
NORTHWEST STEVE EVERTON SHEET:
13737 SW BENCHVIEW TERR. 5 K-0
ENGINEERING GROUP TIGARD, OR
P.O. BOX 10393 SCALE: DATE:
EUGENE, OR 97440 (5411393-7363 1/30"= 1'-0 07/24/2020
• WILDCAT DYNAMIC CONE LOG Page 1 of 1
• NW Engiineering Group
P.O.Box 10393 PROJECT NUMBER:
Eugene,OR,97440 DATE STARTED: 07-21-2020
DATE COMPLETED: 07-21-2020
HOLE#: DC-1
CREW: Sean Morrison SURFACE ELEVATION:
PROJECT: Steve Everton WATER ON COMPLETION:
ADDRESS: 13737 SW Benchview Terrace HAMMER WEIGHT: 35 lbs.
LOCATION: Tigard,OR CONE AREA: 10 sq.cm
131 OWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm' 0 50 100 150 N' NON-COHESIVE COHESIVE -
- 12 53.3 15 MEDIUM DENSE STIFF
- 16 71.0 20 MEDIUM DENSE VERY STIFF
- 1 ft 12 53.3 15 MEDIUM DENSE STIFF
- 14 62.2 17 MEDIUM DENSE VERY STIFF
- 8 35.5 10 LOOSE STIFF
- 2 ft 8 35.5 10 LOOSE STIFF
- 7 31.1 8 LOOSE MEDIUM STIFF
- 5 22.2 6 LOOSE MEDIUM STIFF
- 3 ft 4 17.8 5 LOOSE MEDIUM STIFF
- 1 m 3 13.3 ••• 3 VERY LOOSE SOFT
- 3 11.6 ••• 3 VERY LOOSE SOFT
- 4 ft 3 11.6 ••• 3 VERY LOOSE SOFT
- 5 19.3 5 LOOSE MEDIUM STIFF
- 5 19.3 5 LOOSE MEDIUM STIFF
- 5 ft 6 23.2 6 LOOSE MEDIUM STIFF
- 7 27.0 7 LOOSE MEDIUM STIFF
- 7 27.0 7 LOOSE MEDIUM STIFF
- 6 ft 7 27.0 7 LOOSE MEDIUM STIFF
- 8 30.9 8 LOOSE MEDIUM STIFF
- 2 m 7 27.0 7 LOOSE MEDIUM STIFF
- 7 ft 10 34.2 ••••..... 9 LOOSE STIFF
- 11 37.6 10 LOOSE STIFF
- 9 30.8 8 LOOSE MEDIUM STIFF
- 8 ft 8 27.4 7 LOOSE MEDIUM STIFF
- 12 41.0 11 MEDIUM DENSE STIFF
- 12 41.0 11 MEDIUM DENSE STIFF
- 9 ft 15 51.3 14 MEDIUM DENSE STIFF
- 14 47.9 13 MEDIUM DENSE STIFF
-
20 68.4 19 MEDIUM DENSE VERY STIFF
- 3 m 10 ft 25 85.5 24 MEDIUM DENSE VERY STIFF
11ft
12ft
- 4m 13ft
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- WILDCAT DYNAMIC CONE LOG Page l of 1
NW Engiineering Group
P.O.Box 10393 PROJECT NUMBER:
Eugene,OR,97440 DATE STARTED: 07-21-2020
DATE COMPLETED: 07-21-2020
HOLE#: DC-2
CREW: Sean Morrison SURFACE ELEVATION:
PROJECT: Steve Everton WATER ON COMPLETION:
ADDRESS: 13737 SW Benchview Terrace HAMMER WEIGHT: 35 lbs.
LOCATION: Tigard,OR CONE AREA: 10 sq.cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg'cm2 0 50 100 150 N' NON-COHESIVE COHESIVE
- 11 48.8 13 MEDIUM DENSE STIFF
14 62.2 17 MEDIUM DENSE VERY STIFF
- 1 ft 13 57.7 16 MEDIUM DENSE VERY STIFF
- 10 44.4 12 MEDIUM DENSE STIFF
- 9 40.0 11 MEDIUM DENSE STIFF
- 2 ft 12 53.3 15 MEDIUM DENSE STIFF
- 5 22.2 6 LOOSE MEDIUM STIFF
- 4 17.8 5 LOOSE MEDIUM STIFF
- 3 ft 5 22.2 •••••• 6 LOOSE MEDIUM STIFF
- 1 m 3 13.3 ••• 3 VERY LOOSE SOFT
- 4 15.4 •••• 4 VERY LOOSE SOFT
- 4 ft 3 11.6 ••• 3 VERY LOOSE SOFT
- 3 11.6 ••• 3 VERY LOOSE SOFT
- 5 19.3 5 LOOSE MEDIUM STIFF
5 ft 8 30.9 8 LOOSE MEDIUM STIFF
- 9 34.7 9 LOOSE STIFF
- 10 38.6 11 MEDIUM DENSE STIFF
- 6 ft 8 30.9 8 LOOSE MEDIUM STIFF
- 7 27.0 7 LOOSE MEDIUM STIFF
- 2 m 10 38.6 11 MEDIUM DENSE STIFF
- 7 ft 14 47.9 13 MEDIUM DENSE STIFF
- 12 41.0 11 MEDIUM DENSE STIFF
- 10 34.2 9 LOOSE STIFF
- 8 ft 10 34.2 9 LOOSE STIFF
- 14 47.9 13 MEDIUM DENSE STIFF
- 18 61.6 17 MEDIUM DENSE VERY STIFF
- 9 ft 15 51.3 14 MEDIUM DENSE STIFF
- 17 58.1 16 MEDIUM DENSE VERY STIFF
- 23 78.7 22 MEDIUM DENSE VERY STIFF
- 3 m 10 ft 20 68.4 19 MEDIUM DENSE VERY STIFF
- 25 76.5 21 MEDIUM DENSE VERY STIFF
- 11 ft
12ft
- 4m 13ft
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