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Carlson Geotechnical
Bend Office (541)330-9155
Eugene Office (541)345-0289 No -sr
A division of Carlson Testing,Inc. Salem Office (503)589-1252 GEOTECHNIGAL
Phone;(503)601-8250 'Tigard Office (503)684-3460
Fax:(503)601-8254
June 4, 2018
Terra Firma Foundation Systems, Inc.
Attn: Ms. Emily Singleton
7910 SW Hunziker Street OFFICIF• COPY
- RECEIVED
Tigard, Oregon 97223
JUN 1 it ?O18
Report of
Geotechnical Engineering Services CITY OF TIGARD
Collins Residence
3IJIWING DIVISION
13739 SW Lauren Lane
Tigard,Oregon
CGT Project Number G1804855
1.0 INTRODUCTION
Carlson Geotechnical (COT), a division of Carlson Testing, Inc. (CTI), is pleased to submit this report
summarizing our geotechnical engineering services for the proposed foundation improvements at the Collins
Residence. The project site is located at 13739 SW Lauren Lane in Tigard, Oregon. We performed our work
in general accordance with CGT Authorization to Proceed and Work Order GP8039, dated May 10, 2018.
Written authorization for our services was provided on May 14, 2018.
2.0 PROJECT UNDERSTANDING
2.1 Proposed Improvements
COT developed an understanding of the proposed project based on our correspondence and review of the
proposed foundation improvements plan sheet. Current plans for the project include installation of a total of
thirty-nine push piers to underpin the west, north, and east perimeter walls, as well as three interior footing
walls, of the existing three-story, residential structure (circa 1997) to help alleviate structural distress. In
addition, a total of five helical anchors will be installed along the west and north perimeter walls of the
structure as part of foundation retrofitting plans. Design of the foundation retrofitting elements will rest with
others. Geotechnical recommendations for use in design and construction of the foundation retrofitting
elements was requested by Terra Firma Foundation Systems(Terra Firma).
2.2 Previous Geotechnical Studies
Geotechnics LLC (Geotechnics) provided geotechnical evaluations of the project site for the current property
owner (Eric and Stasha Collins) between 2013 and 2017, the results of which were presented in three
reports as follows:
• "Geotechnical Recommendations, Retaining Wall, 13739 SW Lauren Lane, Tigard, Oregon, Project No.
13-001-1", dated March 19, 2013. This report is hereafter referred to as"Geotechnics.Report 1".
e "Supplemental Geotechnical Recommendations, Retaining Wall — Results of Slope Monitoring, 13739
SW Lauren Lane, Tigard, Oregon, Project No, 13-001-2", dated August 2, 2013. This report is hereafter
referred to as"Geotechnics Report 2".
• "Inclinometer Monitoring, 13739 SW Lauren Lane, Tigard, Oregon, Project No. 13-001-2", dated March
19, 2013. This report is hereafter referred to as "Geotechnics Report 3",
Carlson Geotechnical Page 1 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
Copies of the above referenced reports were provided to CGT by Terra Firma. The geotechnical studies
performed by Geotechnics included review of a previous geotechnical report' for the site, advancement of
two drilled borings at the site, and inclinometer readings. The field data presented in the referenced
Geotechnics reports was used for informational purposes during preparation of this report for the proposed
improvements of the residential structure foundations.
3.0 SCOPE OF WORK
The purpose of our work was to provide geotechnical recommendations for the proposed, voluntary
underpinning project in a written, stamped report. Geotechnical recommendations were developed based on
review of subsurface data presented in the referenced Geotechnics geotechnical reports referenced above
and the current foundation underpinning plans. This geotechnical report includes the following:
• Review of client-provided documents and site geotechnical reports.
• Review of publically available topographic and hazard mapping for the local area.
• Results of our reconnaissance of the existing residential structure and surrounding ground conditions.
• Geotechnical recommendations for use in design and installation of deep foundation elements.
This current assignment was limited in terms of scope and did not include an evaluation of seismic/geologic
hazards at the site, or recommendations for seismic design criteria. In addition, this assignment did not
include geotechnical evaluation, or development of geotechnical recommendations for mitigation, of the site
(modular concrete block) retaining walls and the west site slope (covered in plastic at the time of this report).
Accordingly, this evaluation is considered "limited". If these items are required, we would be pleased to
provide them for an additional fee.
4.0 DOCUMENT REVIEW
The following documents were provided to us for review as part of this assignment:
• "Geotechnics Report 1". This report included Geotechnics' geotechnical review of a previous
geotechnical report' and publically available geologic and hazard mapping, a site reconnaissance, and
conclusions and recommendations for the site. Of note for the currently planned project (Section 2.1 of
this report), Geotechnics concluded the "...two existing modular block retaining walls should be replaced"
and presented geotechnical engineering recommendations for use in design and layout of a new, soldier
pile retaining wall along the west and northwest portions of the site. In addition, Geotechnics indicated
"Unlike GeoDesign, we did note some distress to the home and foundation as noted above. However,
we do agree that the majority of the floor level elevation difference is probably related to the original
home construction. The magnitude of elevation difference, if reflecting soil movement, would product
much more dramatic and obvious distress such as racked windows and doors, garage slab cracks,
significant wall cracks and numerous foundation cracks. While some minor movement may be occurring,
we agree that underpinning of the home is not necessary. The foundation cracking observed under the
garage may be related to the retaining wall movement but this will be addressed by replacing the exterior
retaining walls, as recommended herein."
• "Geotechnics Report 2". This report included Geotechnics' additional research, including review of a
geotechnical report2 for a neighboring lot, the results of supplemental geotechnical investigation (two
drilled borings), the results of inclinometer readings performed between late May 2013 and late July
"Report of Geotechnical Engineering Services, Collins Residence, 13739 SW Lauren Lane, Tigard, Oregon, GeoDesign Project:
Collins ES-1-01",dated May 18,2012. A copy of this GeoDesign report was not available to CGT during this assignment.
2 "Geotechnical Engineering Report, Fern Street Residence, 13784 SW Fern Street, Tigard, Oregon", prepared by GeoPacific
Engineering, Inc.(GeoPacific)and dated 2007. A copy of this GeoPacific report was not available to CGT during this assignment.
Carlson Geotechnical Page 2 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
2013, the results of surface measurements, the results of a qualitative slope stability evaluation, and
geotechnical conclusions and recommendations for the site. Of note for the currently planned project
(Section 2.1 of this report), Geotechnics concluded "Based on the soil conditions, slope conditions, and
our evaluation, we believe the slope bordering the north side of your home is relatively stable. If any
instability exists, it would be in the shallow surficial soils above the neighbor's driveway, more of an
erosion issue and far from your property." In addition, Geotechnics indicated "Basically, there is no
discernable movement in either of the inclinometers. Some very minor movement might be occurring in
the upper 4 feet of both inclinometers, but the magnitude is so small (less than 0.05') and within the
accuracy of the instrument. Deep-seated movement or landsliding of any kind is not indicated by these
early results. We recommend future monitoring of the inclinometers to confirm the interpreted patterns of
movement. However, design of repairs can proceed based on the preliminary interpretation above."
Later in the report, Geotechnics indicated "Our recommendations have not changed significantly. The
very evident distress to your existing modular-block retaining walls is due primarily to under-design. The
size of the blocks and the lack of geogrid reinforcement are nowhere near adequate for the steep-slope
environment. Because any retaining wall on a steep slope requires deep embedment, pile walls are
more appropriate than modular block/MSE walls. After further evaluations, our recommendation is still
a steel pile and lagging wall with tiebacks, with a few minor revisions from our previous
recommendations." Later in the report, Geotechnics included revised recommendations for use in
design and construction of the recommended retaining wall, as well as a proposed "two-tier wall" for the
northwest corner of the property. Excerpts from this Geotechnics report, including the site plan and logs
of the two geotechnical borings advanced at the site, have been reproduced and attached to this report
as Appendix A.
• "Geotechnics Report 3". This report included the results of Geotechnics' additional monitoring of the
two inclinometers that had been installed at the site in 2013. Of note for the currently planned project
(Section 2.1 of this report), Geotechnics reported a note presented in a 2014 email `B6 has moved about
one-tenth of an inch and 85 has moved about half that amount. The movement for 86 is in the upper 6
feet and for 85 in the upper 3 feet. Although the movement is small, it is towards the slope and over
many years can add up. Also, sometimes movement can occur in small bursts, so future winters might
show more movement. The results do not suggest any change in our design approach.". Geotechnics
also indicated "As shown on the plots, this shallow movement has continued. The direction of movement
in both inclinometers is between the A-positive and 8-negative axes, or roughly in the downslope
direction (perpendicular to slope contour lines shown on Figure 1). Inclinometer 86 has now moved 0.44
inch and 85 has moved 0.14-inch total. The overall rate of movement is similar to previously, although a
minor increase in rate for 86. Movement is now evident on the B-axis of 85 where it wasn't detectable in
prior monitoring. As with our prior opinion, we believe that this shallow movement is not indicative of
deep-seated landsliding. Rather, the movement suggests continued movement of a shallow fill wedge in
the downslope direction. The fill wedge is held in place by a retaining wall. Both the modular block wall
west of B-6 and the smaller landscape walls are exhibiting increased distress and tilting (based on quick
comparison of photographs). The walls are under-designed and failing. The walls should be replaced
before complete failure occurs." Later in the report, Geotechnics included plots showing cumulative
movement indicated by their most current(March 3, 2017) inclinometer readings.
5.0 MAPPING & IMAGERY REVIEW
Review of the Statewide Landslide Information Database for Oregon (SLIDO)3, available at the DOGAMI
website, shows no historic or prehistoric landslides mapped at the site. Hazard mapping4 indicates a non-
3 Oregon Department of Geology and Mineral Industries, 2018. Statewide Landslide Information Database for Oregon (SLIDO),
accessed May 2018,from DOGAMI web site:http://www.oregongeoloqv.orq/sub/slido/index.htm.
Carlson Geotechnical Page 3 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
existent liquefaction hazard and a strong level of expected ground shaking. Local topography was obtained
from using Metro's Regional Land Information System (RLIS) data available from MetroMap websites.
Elevation contours identified from the referenced utility were compared and appeared consistent with our site
observations, and are depicted on the attached Site Plan, Figure 1.
In addition to reviewing mapping, we reviewed historical aerial imagery of the site using on-line medias dating
back to 2000. Other than minor landscaping changes (e.g. removal of concrete steps at northeast portion of
site, alterations in vegetation in front yard area), no significant changes in site conditions were detected
based on review of aerial imagery. Heavy tree cover was present within the west and northwest margins of
the property within each image reviewed and precluded viewing of changes to surface conditions (if any
occurred) in those areas within the indicated time period.
6.0 SITE RECONNAISSANCE
The site is bordered by established residential properties to the north and east, SW Lauren Lane to the
south, and an undeveloped (forested) residential lot to the west. CGT visited the site on May 10, 2018, and
met with the homeowner, Mr. and Mrs. Collins. Aerial imagery (2013) and topography of the site (by others)
are shown on the attached Site Plan, Figure 1. Photographs taken during our reconnaissance of the
property are shown on the attached Site Photographs, Figure 2. Weather conditions during our
reconnaissance were mild with light showers. During the meeting, a CGT Senior Geotechnical Engineer:
1. Discussed site conditions and project objectives with Mr. Collins. Mr. Collins indicated no structural
modifications to the existing residential structure or site retaining walls (referenced above) had occurred
at the site. Mr. Collins indicated his preference to address the distress observed in the residential
structure (e.g. underpin foundation walls and columns), deck structure, and concrete hardscaping (patio
and walkway) along the west side of the structure. Mr. Collins indicated that remediation of the site
retaining walls (discussed above)was not part of the currently planned project.
2. Observed site conditions along the south (front) side of the residential structure. The area immediately
south of the residential structure was relatively level to very gently descending to the west and included a
concrete-paved driveway, concrete walkway, and landscaped features in the yard area (barkdust,
scattered boulders, and scattered shrubs and small trees). A brick-facade retaining wall separated the
driveway and neighboring yard to the east. During our traverse of this area, we did not see any signs of
recent or active indicators of slope instability(such as erosion, arcuate-shaped slopes, leaning or"pistol-
butted"tree trunks, etc.).
3. Observed site conditions along the east side of the residential structure. This area was relatively narrow,
gently descended to the north, and was surfaced with barkdust. During our traverse of this area, we did
not see any signs of recent or active indicators of slope instability (such as erosion, arcuate-shaped
slopes).
4. Observed site conditions along the north (rear yard area) side of the residential structure. This area
included a wood-framed deck, concrete patio, and landscaping features (barkdust, scattered trees, and
shrubs). The area immediately north of the structure gently descended to the northwest. As one
progresses north (away from) the structure, the site included three concrete modular block retaining
walls. The locations and orientations of the retaining walls, as well as overall site surface conditions,
were consistent with those described in Geotechnics Report 1.
' Oregon Department of Geology and Mineral Industries,2017. Oregon Statewide Geohazards Viewer, accessed December 2017,
from DOGAMI web site:http://www.oregongeolouv.orq/sub/hazvu/index.htm.
5 Metro Regional Government,2017. MetroMap Regional Land Information System(RLIS)data,accessed December 2017,from
Metro website: htto://gis.oregonmetro.gov/metromap/.
6 Historical imagery resources included GoogleEarth Pro and the module on Portlandmaps.com:
(https://www.portlandmaps.com/advanced/)
Carlson Geotechnical Page 4 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
5. Observed site conditions along the west side of the residential structure. The area immediately west of
the residential structure included an elevated wood-framed deck (providing access into nearby garage)
and a concrete walkway. Along the west side of the walkway, the site was draped with black plastic
sheeting (with sandbags and strings in place holding the sheeting in place), and descended abruptly to
the west. It was evident the abrupt elevation change indicated the presence of continuation of the same
concrete modular block retaining wall (discussed in Geotechnics Report 1). Beyond (west of) the plastic
sheeting, the site descended in a relatively planar manner to the west/northwest and was forested with
moderate- to large-sized coniferous and deciduous trees. The location and orientation of the retaining
wall, as well as overall site surface conditions, were consistent with those described in Geotechnics
Report 1.
7.0 SITE SUBSURFACE CONDITIONS
As indicated above, this assignment did not include advancement of subsurface explorations at the site.
The geotechnical recommendations presented later in this report were based on the subsurface information,
and data presented by Geotechnics in their 2013 and 2017 reports. Those reports were provided to us
(through the owner)from Terra Firma Foundation Systems. For convenience, CGT has reproduced excerpts
of the referenced Geotechnics Report 2, including a site plan showing the locations of the subsurface
explorations and logs of the explorations, and presented that information in Appendix A, which is attached to
the this report. The following table provides a brief description of subsurface conditions encountered at the
site (by others):
Table 1 Subsurface Explorations & Findings
Geotechnical Firm Subsurface Exploration Undocumented Fill Depth(Type)l Native Soill
GeoDesign B-1 (2012)2 Not Available3 Not Available3
GeoDesign B-2(2012)2 6'/2 feet(not available3) Fine-Grained Colluvium(ML)
GeoDesign B-3(2012)2 9 feet(not available3) Fine-Grained Colluvium(ML)
GeoDesign B-4(2012)2 Not Available3 Not Available3
Geotechnics B-5(2013) 4 feet(ML FILL) Residual Soil(ML)
Geotechnics B-6(2013) 4 feet(ML FILL) Residual Soil(ML)
1 Based on information presented in Geotechnics Report 2
2 Logs of these explorations were not included in Geotechnics Report 2. These records should be sought,if available.
3 Descriptions of subsurface conditions(or fill type)not included in Geotechnics Report 2. These records should be sought,if available.
8.0 CONCLUSIONS
Based on our site reconnaissance, review of publically available mapping, review of the provided site
geotechnical reports, and our analyses, it is our opinion that the voluntary foundation retrofitting and
improvements, as described in Section 2.1 of this report, may proceed as currently proposed. Site
subsurface conditions are conducive for installation of push piers, helical anchors, and helical piles (if
considered). Geotechnical recommendations for push piers and helical piles/anchors are presented later in
this report.
CGT is in agreement with the findings and conclusions presented by Geotechnics in their Report 2 and
Report 3 with regard to the concrete modular block retaining walls that exist within the west and north
portions of the property. Removal and replacement of those retaining walls with engineered retaining wall(s)
Carlson Geotechnical Page 5 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
is recommended. We are also in agreement with Geotechnics within regard to the shallow ground
movements observed at the site and indicated by their inclinometer readings between 2013 and 2017.
Based on review of the data, we agree those movements are not indicative of deep-seated slope instability,
rather due to inadequate design and resultant less than favorable performance (i.e. tilting, leaning) of the
modular block retaining walls. In the event replacement of the subject retaining walls is not performed
concurrently with the residential structure underpinning, we recommend the following:
• A pre- and post-construction survey of the subject retaining walls and nearby ground conditions should
be performed. We recommend a licensed surveyor be retained to conduct this survey.
• Disturbance to the temporary protection measures (e.g. plastic sheeting) in place along the west side of
the property should be avoided to the extent possible. If this cannot be avoided, we recommend the
foundation repair contractor develop a plan to re-establish those measures following underpinning
activities, and a stormwater management plan to identify measures to protect the walls and associated
backfills from stormwater runoff. Those plans should be followed during and following foundation
retrofitting activities.
• Surcharging of the subject retaining walls should be avoided during all phases of foundation retrofitting to
the extent possible. This includes, but is not limited to, stockpiling of materials and equipment within
close vicinity of the retaining walls. As a general guideline, activities related to foundation retrofitting
should, preferably, be conducted at least"H"feet away from the subject retaining walls, where H is equal
to the height of the wall immediately adjacent to the work area.
• Additional monitoring of the subject retaining walls should be conducted by a geotechnical engineer until
replacement plans are prepared.
9.0 GEOTECHNICAL RECOMMENDATIONS
The recommendations presented in this report are based on the information provided to us, results of our
field investigation and analyses, laboratory data, and professional judgment. CGT has observed only a small
portion of the pertinent subsurface conditions. The recommendations are based on the assumptions that the
subsurface conditions do not deviate appreciably from those found during the field investigation. CGT should
be consulted for further recommendations if the design of the proposed foundation improvements changes
and/or variations of geotechnical conditions are encountered during site development.
9.1 Foundation Underpinning—Vertical Support
9.1.1 Option 1 - Push Piers
Push piers consist of steel tube sections hydraulically pushed into the ,ground surface until achieving the
specified design installation pressure. Push piers are proprietary foundation systems. The specialty pile
contractor, in coordination with the project structural engineer, typically develops design plans for push pier
supported foundations and establish driving (hydraulic push) termination criteria. For this site, we
recommend push piers be installed to penetrate the existing fill materials and into the underlying native,
medium stiff to better, residual soils. For this site, we recommend push piers be installed to a minimum
installation depth of 10 feet relative to the current grade adjacent to the continuous wall footing to be
underpinned.
9.1.2 Option 2 - Helical Piles
Overview: Helical piles consist of round or square, steel shafts equipped with welded helical plate(s) and are
advanced into the subsurface using a hydraulic torque motor. The specialty pile contractor, in coordination
with the project structural engineer, typically develops design plans for pile supported foundations.
Geotechnical recommendations for use in the design and construction of helical piles to provide capacity as
part of foundation retrofitting are presented in this section.
Carlson Geotechnical Page 6 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
Soil Strength Parameters: We have provided recommended values for soil parameters for use in helical pile
design in the following table. The parameters provided below were based on the results of the 2009 drilled
borings and our experience with similar soils in the local vicinity. Once plans have been developed showing
pile locations, the geotechnical engineer should be consulted to review the plans.
Table 1 Recommended Soil Strength Parameters for Use in Helical Pile Design
Depths Soil Shear Strength Parameter2
Layer (feet) Description Soil Type 0' c' y' Su
(degrees) (psf) (pcf) (psf)
1 0 to 10 Undocumented Fill(ML FILL) Cohesionless Neglect contribution
2 10 to 28 Stiff, Fine-Grained Colluvium/Residual Soil(ML) Cohesionless 32 0 115 0
3 28+ Very stiff/dense,Decomposed Basalt(ML-GM) Cohesionless 36 0 130 0
1 Relative to existing grades along the portion of the residential structure to be underpinned.
2 If additional soil parameters are required to facilitate design,the geotechnical engineer should be consulted.
Installation Depth Consideration: Generally speaking, the helical piles should be installed to penetrate
existing fill materials and to a sufficient depth to achieve the required torque specified by the designer. For
this site, we recommend helical piles be installed a minimum of 10 feet below the current grade adjacent to
the continuous wall footing to be underpinned.
Load Testing: The load test program, including actual number of load tests, load increments used during
testing, and duration, should be defined by the pile designer. The geotechnical engineer or his representative
should witness the installation of test and production piles, and all phases of load testing (if selected) performed
at the site.
9.2 Foundation Tieback(s)— Helical Anchors
Geotechnical recommendations for use in the design and construction of helical anchors to provide lateral
capacity as part of foundation retrofitting, if required, are presented below.
Soil Strength Parameters: The soil strength parameters presented in Table 1 above are appropriate for use
in helical anchor design.
Installation Depth Consideration: Helical anchors should be installed to a sufficient depth to achieve the
required torque specified by the designer. The required installation depth may vary in the field, depending on
subsurface conditions at individual helical anchor locations. The geotechnical engineer or his representative
should be contacted to observe helical anchor installation.
Load Testing: The load test program, including actual number of load tests, load increments used during
testing, and duration, should be defined by the anchor designer. The geotechnical engineer or his
representative should witness the installation of test and production anchors, and all phases of load testing (if
selected)performed at the site.
10.0 LIMITATIONS &CLOSURE
At our client's request, the scope of our evaluation was limited to the scope of services described in this
report. Other geotechnical considerations described in the 2014 Oregon Residential Specialty Code (ORSC)
have not been addressed. Accordingly, this evaluation must be considered "limited". A more comprehensive
evaluation may be completed if requested by our client, for an additional fee. Such evaluation would include,
Carlson Geotechnical Page 7 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
but not be limited to: assessment of seismic/geologic hazards at the site, recommendations for seismic
design criteria, and other geotechnical considerations. The responsibility for determining the sufficiency of
our evaluation to meet the project needs rests solely with the owner and not with CGT. Please contact us if
additional evaluation is desired.
The observations of existing conditions at the time of our site visit were based solely on visual methods. Our
report pertains to the locations observed at the time of our visits only. Accordingly, the limitations of this
limited geotechnical investigation must be recognized. An investigation using power boring equipment to
explore subsurface conditions at greater depth could be conducted if it is desired to further define the risk of
unforeseen geotechnical issues or seismic hazards at this site.
This report has been prepared for use by the owner/developer and other members of the design and
construction team for the proposed development. The opinions and recommendations contained within this
report are not intended to be, nor should they be construed as, a warranty of subsurface conditions, but are
forwarded to assist in the planning and design process.
Within the limitations of scope, schedule, and budget, our services have been executed in accordance with
the generally accepted practices in this area at the time this report was prepared. No warranty or other
conditions, expressed or implied, should be understood. Information contained herein is not to be
reproduced,except in full,without prior authorization from this office.
V
Should you have any questions regarding the information presented in this report, please contact us at(503)
601-8250.
Sincerely,
CARLSON GEOTECHNICAL
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Note: The observations of existing conditions at the time of our site visit were based solely on visual
methods. Our reports pertain to the locations observed at the time of our visit only. Information contained
herein is not to be reproduced, except in full, without prior authorization from this office, The information
,contained in this report is provided subject to all terms and conditions of CGT's General Conditions in effect
Carlson Geotechnical Page 8 of 9
Collins Residence
Tigard, Oregon
CGT Project No. G1804855
June 4, 2018
at the time this report is prepared. No party other than those to whom CGT has distributed this report shall
be entitled to use or rely upon the information contained in this document.
ATTACHMENTS: Site Plan, Figure 1
Site Photographs, Figure 2
Excerpts from Geotechnics' 2013 Geotechnical Report, Appendix A
G:\GEOTECH\PROJECTS\2018 Projects\G1804855-Collins Residence\G1804855-GEO\008-Deliverables\Reports\Final
Report\Report G1804855-FINAL.docx
Carlson Geotechnical Page 9 of 9
Carlson Geotechnical
l3end Office (541)330-9155 elle. 410,4,
Eugerse Office (541)345-0289 %1
A division of Carlson Testing, Inc. Salem Office (503)589-1252 mum=
Phone:(503)601-8250 Tigard Office (503)684-3460
Fax:(503)601-8254
Appendix A: Excerpts from 2013 Geotechnics LLC
Geotechnical Report
(provided to CGT by client)
Collins Residence
13739 SW Lauren Street
Tigard, Oregon
CGT Project Number G1804855
June 4, 2018
Prepared For:
Terra Firma Foundation Systems, Inc.
Attn: Ms. Emily Singleton
7910 SW Hunziker Street
Tigard, Oregon 97223
Prepared by
Carlson Geotechnical
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— 5— 41
I i! i
(RESIDUAL SOIL)
S-2 SPT 29.8 2-5-6
—6—
i @ 7.5', becomes olive brown, no mottling.
— 7—
id
S-3 SPT 3-3-5 —8_ i
—9—
i
—10—
i
—11— %
—12—
11--12—
—13--
S-4
13—S-4 SPT 27.6 2-S-5
—14—
;
N —15—
3 � ,
c
—16 € Reddish brown mottled black and gray,SILT
w, f with Gravel (ML),very stiff,very moist. Relict
,
—17— i basalt structure.
i
(DECOMPOSED BASALT)
3 —18-- f
5-5 SPT u 38.5 4-6-11 1
o —19—
a
a`
NOTES: Page 1
U
BORING B-5
GE0'rEcHNIcs13739 SW Lauren Ln
LC C Tigard,Oregon
Project Number 13-001-2 Figure 2
DRILLING COMPANY: PLi Systems Inc. SURFACE ELEVATION: 442.5 Feet
DRILLING METHOD: 4"Solid Stem Auger,140#Hammer DATE STARTED: 5-30-13
DRILLING EQUIPMENT: Beretta track rig DATE COMPLETED: 5-30-13
BORING LOCATION: See Figure 1 LOGGED BY: ADM
J
8
00
a 3 ' }
O ~ ce F io L v,
LU LU LU M Z
CL g —^ z a Q MATERIAL DESCRIPTION OTHER TESTS&NOTES
O
vai vai vai 2 OU m C U
(({9
)j
{
—21
Becomes stiff,wet.
—22—
@ 22.5', becomes orange and brown mottled
—21 with black,tan, and green. Relict structure.
S-6 SPT 54.5 5-7-6
—24—
—25—
—26— I
—27--
11
Becomes very stiff.
S-7 SPT 49.9 10-12-8
—28_
2 1 € v
—29— "s
1
i
i
—30— l
;�
(`
—31— i
—32—
i
3 �0', Dark brown mottled tan,yellow, green, and
I= • red,Silty Gravel with Sand(GM),very dense,
____34_Z,: moist.
• ,• (WEATHERED BASALT)
4
N —3�+ •
• + 4
= • • •
S-8 SPT 21-27-36
+
C.1
-36—'� •.1
' .••
PS -31 Total Depth = 36.5 feet.
Inclinometer installed to 35.0'.
A-axis at N27W.
3
—38-
1
—39—
9
Q
> NOTES: Page 2
U
BORING B-5
GE0'rEdHNIcscc c 13739 SW Lauren Ln
Tigard,Oregon
Project Number 13-001-2 Figure 2
DRILLING COMPANY: PLi Systems Inc. SURFACE ELEVATION: 434.0 Feet
DRILLING METHOD: 4"Solid Stem Auger,140#Hammer DATE STARTED: 5-30-13
DRILLING EQUIPMENT: Beretta track rig DATE COMPLETED: 5-30-13
BORING LOCATION: See Figure 1 LOGGED BY: ADM
J
O
00
a T }
ce ~ ici U U
Ln
W UJ W M w N
g g g —^ z a Q MATERIAL DESCRIPTION OTHER TESTS&NOTES
O
VI VI vai f 0 m 0 V
J Brown SILT(ML), soft, moist.
I
— 1— , (FILL)
— 2—
_ 3_-- 3—
—4 € Brown SILT(ML), soft, moist. Low plasticity to
non-plastic.
11
— S (RESIDUAL SOIL)
S-1 SPT 23.4 1-1-2
—6—
becomes stiff
—8—
1
i
_9_
11 —10—
—11— @ 10', becomes olive with occasional black
5-2 SPT 27.6 2-4-6 speckles, low to moderate plasticity.
—12-
-13-
-14—
N —15— ' @15', becomes brown, moderate plasticity.
3 #
5-3 SPT 24.0 2-4-7
u- 16—
7:
li
—17—
3
—1F— s
a
9 —19— '`
a
4 NOTES: Page 1
BORING B-6
jEOTECHNICS 13739 SW Lauren Ln
W Tigard,Oregon
Project Number 13-001-2 Figure 3
DRILLING COMPANY: PLi Systems Inc. SURFACE ELEVATION: 434.0 Feet
DRILLING METHOD: 4"Solid Stem Auger,140#Hammer DATE STARTED: 5-30-13
DRILLING EQUIPMENT: Beretta track rig DATE COMPLETED: 5-30-13
BORING LOCATION: See Figure 1 LOGGED BY: ADM
J
0
00
Lu 2
1 }
DF lceF z to U u
g z
g g ci 30 a Q MATERIAL DESCRIPTION OTHER TESTS&NOTES
vai vai ', 2 LU co ow U
%�) Reddish brown mottled gray, orange, and black
/j/, Fat CLAY(CH), stiff to very stiff, moist. Some
S-4 SPT 15.5 4-6-9 relict structure and occasional small gravel.
_21_,/�/
///
//
—22—v,/,
/j/
—23— '7;
,//
—24—/7i%
//7/
—25--//x,
S-5 SPT11
29.3 3-5-6 —2�j/ Atterberg: LL= 52; PL= 23
/
/�/
—27—(::-.,X,
—28 //;
Dark brown mottled black and orange,Gravelly
SILT(ML),very stiff,very moist. Relict basalt
—29— structure.
11
5 6 SPT 51.9 9-13-13 (DECOMPOSED BASALT)
—30—
—31— Total Depth = 30.5 feet.
Inclinometer installed to 29.0'.
A-axis at N31W.
—32-
-33-
-34—
,
-32-
-33--
-34---
-35—
C
S- —36—
i
0 -37—
3 —38—
g
—39—
2 1
a
I
NOTES: Page 2
ui
BORING B-6
GE0TECHNIcs 13739 SW Lauren Ln
LLCTigard,Oregon
Project Number 13-001-2 Figure 3