HomeMy WebLinkAboutStudies Applicant 4/2/2024 (2)Foundation Engineering, Inc.
Professional Geotechnical Services Memorandum
820 NW Cornell Avenue • Corvallis, Oregon 97330 • 541-757-7645
7857 SW Cirrus Drive, Bldg 24 • Beaverton, Oregon 97008 • 503-643-1541
Date: February 9, 2024
To: Dean Locke, Direction of Projects
Rosboro
From: Mel McCracken, P.E., G.E.
Erin Gillaspie, P.E.
Subject: Geotechnical Investigation
Project: Rosboro Project
Project No.: 2231110
We have completed the geotechnical investigation for the above-referenced project.
Our findings and recommendations are summarized below.
There are numerous values in geotechnical investigations that are approximate
including calculated parameters, measured lengths, soil layer depths and elevations,
and strength measurements. For brevity, the symbol “±” is used throughout this
report to represent the words approximate or approximately when discussing these
values.
BACKGROUND
Rosboro is planning to construct improvements at their existing facility at
2509 Main Street in Springfield, Oregon. The site location is shown in Figure 1A
(Appendix A). The improvements will include replacement of an existing structure
and expanding operations onto an adjacent parcel at the southwest portion of the
facility. The improvements to the southwest will include a new glulam manufacturing
building that will be ±220x660 feet in plan. In addition, an existing former plywood
plant at the south end of the site will be demolished to accommodate a new planar
building with expected dimensions of ±210x340 feet. Both facilities are expected
to consist of pre-engineered metal buildings (PEMB) supported by isolated spread
footings and include a slab-on-grade floor with a thickened edge. The proposed
buildings are expected to include foundation loads of 20 to 200 kips. Both structures
will also include either thickened slab segments or isolated mat foundations to
support equipment.
The site is relatively flat, and the required site grading is expected to be minor.
Grading for the glulam building will require cuts of ±4 feet on the east side of the
structure to provide a level building pad. Limited areas of new pavements are
expected around the new building footprint to connect the new improvements to the
existing pavement. The new pavements are expected to support heavy truck traffic
and heavy forklift traffic moving material throughout the site.
Rosboro Project February 9, 2024
Geotechnical Investigation 2. Project No.: 2231110
Springfield, Oregon Rosboro
We have assumed the building occupancies will not exceed 250 persons and the
buildings will not be considered “Special Occupancy Structures” per
Section 1803.3.2 of the 2022 Oregon Structural Specialty Code (OSSC). Therefore,
a site-specific seismic hazard investigation was not included in our scope of work.
Rosboro is the project owner and kpff is the civil and structural designer. Wilson
Architecture (Wilson) is the project architect. Rosboro retained Foundation
Engineering as the geotechnical consultant. Our scope of work was outlined in a
proposal dated October 24, 2023, and authorized by a signed Professional Services
Agreement dated November 7, 2023.
FIELD EXPLORATION
We drilled eight exploratory borings (BH-1 through BH-8) at the site to provide
subsurface information for designing the building foundations. The borings were
drilled at the approximate locations shown on Figure 2A.
Borings BH-1 through BH-5 were drilled in the vicinity of the planned glulam building
on November 20, 2023. Boring BH-6 was attempted north of the planned planar
building. However, that boring encountered a buried fire suppression line ±2.5 feet
below the ground surface and was abandoned. Therefore, no boring log was
generated for BH-6. However, the boring location is shown in Figure 2A. We returned
to the site on December 4, 2023, and drilled two additional borings (BH-7 and BH-8)
east of the planned planar building.
The drilling was completed using a Canterra CT150, truck-mounted drill rig with
hollow stem augers. Soil samples were obtained at 2.5-foot intervals to ±10 feet,
and at 5-foot intervals thereafter. Disturbed samples were obtained with a split-spoon
sampler. The Standard Penetration Test (SPT), which is run when the split-spoon is
driven, provides an indication of the relative stiffness or density of the foundation
soils. Relatively undisturbed Shelbey tube samples of the fine-grained soil were also
obtained at selected locations and depths.
The borings were continuously logged during drilling. The final logs (Appendix B)
were prepared based on a review of the field logs, the laboratory test results, and an
examination of the soil samples in our office. The sampling depths and SPT data for
each boring are summarized on the appended logs.
The boring locations were not surveyed. Therefore, ground surface elevations shown
on the boring logs are based on topographic plans provided by Rosboro and are
approximate. Upon completion of drilling, the boreholes were backfilled with
bentonite in accordance with Oregon Water Resources Department guidelines.
Outside of active work areas, the backfill was capped with crushed rock. In active
work areas, the backfill was capped with asphaltic concrete (AC) cold patch.
Rosboro Project February 9, 2024
Geotechnical Investigation 3. Project No.: 2231110
Springfield, Oregon Rosboro
LABORATORY TESTING
The laboratory testing included moisture content determinations (ASTM D2216),
expansion index (ASTM D4829), and Atterberg limits (ASTM D4318) tests to help
classify the soils and estimate their overall engineering properties. The results of
these tests are summarized in Tables 1C and 2C (Appendix C). The moisture
contents are also included on the appended logs. We classified untested soil in the
field according to ASTM D2488-09A (Standard Test Method for Description and
Identification of Soils (Visual-Manual Procedure)).
Atterberg limits testing on the fine-grained alluvium indicates a Liquid Limit (LL)
ranging from 77 to 86 and a plasticity index (PI) value ranging from 46 to 54. These
values correspond to a Unified Soil Classification System (USCS) classification of
CH.
An expansion index test was completed on a sample of the high plasticity clay sample
(SS-1-1) to evaluate the swell potential of the medium to high plasticity soils
encountered at shallow depths across the site. The test consists of recording the
swell potential of a remolded soil sample prepared at ±50% saturation. The amount
of swell is expressed in terms of the expansive index (EI). An EI of 49 was recorded
for sample SS-1-1, which empirically corresponds to a low potential for expansion.
The low expansive potential assessment of the surficial fine-grained alluvium is
consistent with our visual observation of the soil characteristics. In the field this
material was typically described as low to medium plasticity clayey silt (ML). We
attribute the higher LL and PI values and corresponding USCS classification of CH to
the moisture-sensitive nature of the fine-grained alluvium.
Field vane measurements were also made on Shelby tube samples of the fine-grained
soils from the borings. The test results, summarized in Table 3C, indicate undrained
shear strengths ranging from ±0.30 to 0.84 tons/ft2 (tsf). This corresponds to a
medium stiff to stiff consistency.
DISCUSSION OF SITE CONDITIONS
Site Topography and Surface Conditions
Most of the new planar building footprint is currently occupied by an existing building
that will be demolished. The ground surface surrounding and inside the existing
building is relatively flat and typically covered with AC pavement.
The planned glulam manufacturing building footprint is currently a storage yard that
includes AC or gravel surfacing with some areas of grass. The eastern portion of the
planned glulam building footprint is elevated ±2 to 3 feet above the western portion.
Rosboro Project February 9, 2024
Geotechnical Investigation 4. Project No.: 2231110
Springfield, Oregon Rosboro
Subsurface Conditions
A general discussion of subsurface conditions is provided in this section. A detailed
description of conditions encountered in each boring (except BH-6 which
encountered a shallow water line) is provided in the boring logs (Appendix B).
Pavements. The borings drilled through existing pavement near the planned glulam
building (i.e., BH-1 and BH-3) encountered a pavement section consisting of ±2 to
4 inches of AC followed by dense crushed gravel or crushed rock (base rock) to a
depth of ±18 to 24 inches. BH-7 and BH-8, advanced through pavement on the east
side of the planar building, encountered ±5 to 8 inches of AC over base aggregate
extending to a depth of ±24 inches. At BH-6 on the north side of the planar building,
the existing AC appeared to be ±3 to 4 inches thick. Base Aggregate (presumably
associated with water line trench backfill) extended to ±2.5 feet.
Site Fill. Several of the borings (BH-2, BH-4 and BH-5) were drilled in gravel surfaced
areas. Our exploration in these areas typically encountered ±2 feet of crushed rock.
However, BH-2 encountered granular fill, which appears to be associated with a
nearby utility line. The fill at this location consisted of dense crushed gravel extending
±7 feet below the current grade.
BH-4 was advanced through an existing granular pad near the northeastern portion
of the glulam building. We originally attempted to drill ±25 feet north of BH-4 (as
shown on Figure 2A). However, at that location the boring encountered practical
drilling refusal and what appeared to be a concrete slab at a depth of ±2.5 feet.
Based on observation of return cuttings and the action of the rig, the fill encountered
at that location above the presumed slab consisted of predominantly crushed rock to
±2 feet, followed by predominantly fine-grained soil from ±2 to 2.5 feet (the depth
of the slab). The crushed rock encountered at BH-4 is underlain by additional site fill
consisting of silt with debris consisting of brick and concrete fragments extending to
a depth of ±3.5 feet. The granular fill encountered below ±2 feet at BH-5 includes
some organics extending to ±4 feet.
Predominantly fine-grained fill was encountered beneath the pavement section in
BH-7 and BH-8 extending to depths of ±3 to 4 feet. The fill is soft to medium stiff
and contains organics at some locations.
Silty Clay (alluvium – Willamette Silt). Brown to dark brown, medium to high plasticity
silty clay was typically encountered beneath the pavement section or any site fill in
all borings. The silty clay extends to the underlying sandy gravel at depths ranging
from ±8.5 to 14.5 feet (±El. 460.5 to 464). The silty clay stratum extends across
the Willamette Valley. The material is typically referred to as Willamette Silt, although
the primary constituent is clay in some geographic areas. At some boring locations,
we noted fine sand near the contact with the underlying sandy gravel.
Rosboro Project February 9, 2024
Geotechnical Investigation 5. Project No.: 2231110
Springfield, Oregon Rosboro
SPT N-values recorded in the Willamette Silt were typically in the range of 5 to 20,
suggesting a medium stiff to very stiff consistency. Field vane shear tests completed
on relatively undisturbed Shelby tube samples indicate the soil has an undrained shear
strength ranging from 0.4 tons/ft2 (tsf) to 0.8 tsf, suggesting a medium stiff to stiff
consistency. The results of the vane shear tests were used to describe soil
consistency on the log and were also used to develop the recommended bearing
resistance for spread footing design.
Sandy Gravel (alluvium). Grey, wet, sandy gravel extends below the Willamette Silt.
SPT N-values ranging from 33 to practical refusal (i.e., greater than 50 blows for a
6-inch increment of drive) were recorded in the gravel, suggesting the coarse-grained
alluvium is dense to very dense.
Groundwater
We observed groundwater infiltration during drilling at depths ranging from ±8.5 to
13.5 feet. Local well logs available from the Oregon Water Resources Department
(OWRD) website suggest the static groundwater level in the project vicinity lies ±6
to 10 feet below the ground surface. Therefore, we anticipate the depth of the
groundwater will fluctuate seasonally between this range of depths. Iron-staining of
the near-surface soils suggest water may also perch at shallower depths during
periods of extended rainfall.
DISCUSSION OF GEOTECHNICAL ISSUES
A general discussion of geotechnical issues is provided in this section. Specific
construction recommendations for these items are provided in the recommendations
section.
Construction Timing
Our field exploration and results of the laboratory moisture content tests indicate the
soils beneath the pavement are wet of their optimum moisture content for
compaction. In our experience, soils beneath pavements often stay wet and are
softer near the contact with the base rock, even during summer. Therefore,
contractors should anticipate moist subgrade conditions into summer months. These
soils may be more sensitive to disturbance and pumping under construction traffic.
Subgrade soils that are too wet for compaction should be overexcavated and
replaced with compacted Base Aggregate, as defined in the recommendations
section.
The construction schedule indicates the bulk of the earthwork will occur in
August, 2024. Subgrade compaction will only be feasible during dry weather
(typically mid-June to mid-October). During wet weather, thickened building pad and
base rock sections are required to help protect the subgrade from construction traffic
and activities.
Rosboro Project February 9, 2024
Geotechnical Investigation 6. Project No.: 2231110
Springfield, Oregon Rosboro
Demolition and Building Pad Construction
The existing building and surrounding pavements at the planar building will be
demolished to accommodate the new structure. We recommend removing all existing
concrete footings and construction debris from the building footprints. Demolition of
existing structure and pavements is expected to result in disturbance to the upper
portion of the existing soil profile.
The building pad footprint should be excavated as required to remove debris. It may
be practical to limit the excavation to the upper granular fill in portions of the building
pad excavation. We recommend the planar building pad be excavated to
accommodate 8 inches of Base Aggregate in areas of stable existing granular fill.
Areas of fine-grained soil or yielding granular soils are expected to require excavation
extending ±2.5 feet below bottom of slab level to bypass the upper fill and provide
an adequate granular pad. Final excavation to fine-grained subgrade should be
completed using an excavator equipped with a smooth-edged bucket to minimize
subgrade disturbance. The compaction and stability of existing granular fill will
require field confirmation at the time of construction. Likewise, the suitability of
fine-grained subgrade soils should be confirmed during excavation. The actual
excavation depth should be evaluated and confirmed by a Foundation Engineering
representative during construction.
Limited portions of the planar building are expected to include recompaction of
suitable, existing granular fill. We do not believe that it will be practical to reuse any
of the on-site granular materials during final grading or backfilling. Therefore, we
anticipate that all excavated materials will be hauled from the site. The improvements
are expected to require imported Base Aggregate to support foundations, building
pads and pavements.
The glulam building pad excavation is expected to extend through the upper fill over
most of the footprint to expose stiff Willamette Silt at the subgrade level. Therefore,
we have assumed the subgrade would consist of compacted fill or stiff silt. We
anticipate a minimum of 12 inches of Base Aggregate would be required to support
the glulam building pad during dry weather conditions. We recommend the thickness
of Base Aggregate be increased to 24 inches if the building will need to accommodate
construction or heavy construction traffic during wet weather months.
Anticipated Foundation Conditions
We understand the finish floor elevations for the new planar building will lie near
existing grades and the glulam building will require cuts into the east portion of the
site to accommodate the proposed finished floor elevation. The borings encountered
a general subsurface profile that includes pavement/fill underlain by fine-grained
alluvium followed by relatively dense coarse-grained alluvium. Based on the
conditions encountered in the borings, we anticipate the glulam building pad will be
underlain by native, stiff Willamette Silt.
Rosboro Project February 9, 2024
Geotechnical Investigation 7. Project No.: 2231110
Springfield, Oregon Rosboro
However, the planar building includes fill extending ±3 to 4 feet below existing
grades. Therefore, we recommend that all foundation excavations plan to extend at
least 4 feet below finished grades. We have concluded conventional spread and
continuous footings will be suitable to support the new structures with the following
site preparation.
Atterberg limits testing suggest the native, fine-grained soils are moisture sensitive
and likely to vary in sensitivity across the building areas. Therefore, care will be
required during subgrade preparation. We anticipate mitigation of any subgrade soils
with moderate to high expansive potential, if encountered at the time of construction,
will consist of overexcavation and replacement with additional Base Aggregate.
SEISMIC DESIGN
Seismic Response Spectrum
A site response spectrum was developed for the parcel in accordance with the
Oregon Structural Specialty Code (OSSC, 2022), which is based on Section 1613 of
the International Building Code (IBC, 2021). The design maximum considered
earthquake ground motion maps in the IBC (2021) are based on modified
USGS (2014) maps with a 2% probability of exceedance in 50 years
(i.e., a ±2,475-year return period). The modifications include factors to adjust the
spectral accelerations to account for directivity and risk.
Based on a review of well logs available from the Oregon Water Resources
Department (OWRS) website, our previous work in the area, and conditions
encountered in the borings, we have concluded a Site Class C (very dense soil and
soft rock) is appropriate for the site. The seismic design parameters and OSSC
response spectrum are shown on Figure 3A.
Liquefaction
Liquefiable soils typically consist of loose sands and non-plastic to low plasticity silt
(i.e., silts with a Plasticity Index (PI) less than 8) that are below the water table.
The site is expected to include a relatively shallow groundwater level throughout the
year. The soils encountered in the borings consist of predominantly stiff, medium to
high plasticity silty clay and dense to very dense sandy gravel. The fine-grained soil
is not expected to liquefy under earthquake loading based on the stiffness and
plasticity of the soil. The gravels are also not considered susceptible to liquefaction
due to their density. Therefore, we believe that the liquefaction risk is very low.
Rosboro Project February 9, 2024
Geotechnical Investigation 8. Project No.: 2231110
Springfield, Oregon Rosboro
ENGINEERING ANALYSIS
Bearing Capacity
We anticipate new footings will bear on compacted Base Aggregate overlying stiff,
undisturbed subgrade consisting of fine-grained alluvium. For the bearing capacity
analysis, we used a presumptive undrained shear strength value of 800 lb/ft2 (psf)
based on vane shear test results and observation of the consistency of soil samples.
We also assumed dimensions of up to 6x6 feet for spread footings and widths of
2 to 3 feet for continuous wall footings.
Our analysis indicates an allowable bearing pressure of 2,000 psf would be
appropriate for footing design, using a factor of safety of 3. This value assumes the
footings will be underlain by at least 12 inches of Base Aggregate extending at least
12 inches beyond the footing edge. The allowable bearing pressures may be
increased by one-third for transient (seismic and wind) loads.
Settlement
No formal settlement analysis was completed based on the relatively light foundation
loads of the new structures. Based on the stiffness of the foundation soils and the
recommended bearing pressure, we anticipate the total and differential movements
will be less than ±1 inch and ±¾ inch, respectively, if foundation preparation is
completed as recommended herein.
Sliding Coefficient and Passive Resistance for Footings
A coefficient of friction of 0.5 between the base of the footing and the Base
Aggregate may be used for sliding analysis. An equivalent fluid density of
±145 lb/ft3 (pcf) may be used to represent the potential passive resistance against
the vertical face of the thickened edge footing. The passive resistance assumes
limited horizontal movement (i.e., less than ±1 inch) for service-level design. This
allowable value assumes all footings will be backfilled with compacted Base
Aggregate.
Slab-on-Grade
Reinforced concrete slab-on-grade floors are planned for the new buildings. The slabs
will support heavy concentrated wheel loads as well as some equipment foundations.
We recommend the glulam floor slabs be supported on a minimum of 12 inches of
compacted Base Aggregate underlain by compacted subgrade soil. Therefore, a
modulus of subgrade reaction (ks) of 250 lb/in3 (pci) is appropriate for design of slabs
for the glulam building.
If suitable existing granular fill is encountered at the planar building, we recommend
compacting the subgrade and supporting the floor slabs on a minimum of 8 inches
of compacted Base Aggregate. Therefore, a reduced modulus of subgrade reaction
(ks) of 200 pci is appropriate for design of planar building slabs.
Rosboro Project February 9, 2024
Geotechnical Investigation 9. Project No.: 2231110
Springfield, Oregon Rosboro
Retaining Wall Design and Construction
The planned improvements are expected to include retaining walls up to ±5 feet
high east of the glulam building. The walls will include relatively level backfill at the
base and may include slightly sloping terrain at the top of the wall. We assumed a
maximum slope of 14 degrees for our analysis.
To determine lateral earth pressures from backfilling, we assumed that the backfill
will consist of Base Aggregate with an in-place unit weight of 125 pcf and a minimum
internal friction angle of 34 degrees. Drained conditions were also assumed. We
estimated the lateral earth pressure against the retaining wall using a Rankine active
earth pressure coefficient (ka) of 0.33. Therefore, we recommend using an equivalent
fluid density of 41 lb/ft3 (pcf) when estimating the static lateral earth pressure on the
walls.
The walls should also be designed to account for a surcharge from traffic operating
behind the walls. AASHTO recommends designing walls for a traffic surcharge
pressure of at least 250 psf if traffic will be maintained at least 1 foot from the wall.
Therefore, using the active earth pressure coefficient (ka) of 0.33, a lateral earth
pressure of 83 psf should be considered for surcharge. If the traffic surcharge
(e.g., wheel loads or outriggers) may extend within 1 foot of the wall, the design
should include a minimum surcharge pressure of 625 psf, corresponding to a lateral
earth pressure of 206 psf.
The walls should be backfilled with granular soil and a foundation drain should be
provided to limit the development of hydrostatic pressures behind the walls.
Equipment used to compact the backfill should be limited to small, walk-behind
equipment adjacent to the wall to prevent overstressing.
Drainage
The static groundwater table is expected to be below the current limits of grading
and excavations. However, water may perch on the near-surface soils during periods
of extended rainfall and elevated groundwater conditions may occur during the wet,
winter months. Based on the anticipated site grading plan, the soil conditions
encountered in the borings, and the expected drainage characteristic of the soil, we
recommend providing perimeter drainage around the new buildings. The ground
surface around the buildings should also be graded to promote runoff away from new
foundations. Foundation drainage may be omitted if the new buildings are surrounded
by hardscape surfaces that abut the buildings. Foundation drains should be provided
for all retaining walls.
Rosboro Project February 9, 2024
Geotechnical Investigation 10. Project No.: 2231110
Springfield, Oregon Rosboro
PAVEMENT SECTIONS (RIGID AND FLEXIBLE PAVEMENTS)
The predominantly fine-grained subgrade will be moisture-sensitive and susceptible
to softening, pumping, and rutting under construction traffic when wet. Wet weather
construction will likely require providing a thickened base rock section or granular
subbase to reduce the risk of pumping. We should be contacted to provide wet
weather construction recommendations if the earthwork and roadway construction is
delayed into the winter months. Dry weather pavement construction is recommended
to the extent practical.
We anticipate that pavement areas may be prepared one of two following ways,
based on the subgrade conditions exposed:
1) If suitable granular fill is exposed at the subgrade level, compact the surface and
cover with compacted Base Aggregate.
2) If stiff fine-grained soil is exposed at the subgrade level, place and compact a
gravel subbase over the relatively undisturbed subgrade and cover with compacted
Base Aggregate.
If unsuitable soil is exposed at the planned subgrade elevation, overexcavation and
replacement with additional imported granular fill will be required, similar to Option 2.
Estimated Traffic
Rosboro indicated the primary traffic will consist of Hyster 210 forklifts weighing
30 kips (unloaded). It is anticipated that the forklifts will operate up to 16 hours per
day and may make a pass every 2.5 minutes. The carrying capacity of the forklifts
is 20 kips, which is consistent with the reported weight of the anticipated loads.
Based on the assumed traffic for the facility, we estimated an Average Daily Traffic
(ADT) that includes a forklift distribution consisting of 60% unloaded, 25% partially
loaded (44 kips) and 15% fully loaded. We also considered additional conventional
truck traffic.
Using the assumed traffic and Equivalent Single-Axle Loading (ESAL) conversion
factors based on AASHTO design standards, we calculated ±31,000,000 ESALs for
a 20-year pavement design life.
Subgrade and Base Rock Design Parameters
The bulk of the new pavement areas are expected to be constructed over firm,
compacted subgrade. Subgrade conditions are expected to vary with location and
may include stiff, native Willamette Silt or granular fill. For pavement design, we
assumed a resilient modulus (MR) of 6,000 lb/in2 (psi), based on our experience with
stiff clay subgrade. We assumed a MR of 20,000 psi for new Base Aggregate, based
on ODOT recommendations.
Rosboro Project February 9, 2024
Geotechnical Investigation 11. Project No.: 2231110
Springfield, Oregon Rosboro
Rigid Pavement Design
Portland Cement Concrete (PCC) pavements are expected at aprons and other high
traffic areas at the facility. Rigid pavement design was completed based on AASHTO
design methods (AASHTO, 1993). We assumed Jointed Plain Concrete Pavement
(JPCP) would be used. Our calculations assumed typical design parameters for plain
concrete pavements in the area and the subgrade conditions observed. Based on the
estimated forklift and truck volume and distribution, we recommend a minimum
12-inch PCC thickness. The new PCC should be underlain by at least 12 inches of
Base Aggregate where the pavements are underlain by fine-grained subgrade.
Flexible Pavement Design
We completed flexible pavement design generally using the ODOT design method
with the assumed traffic and Mr values discussed above. Our analysis indicates a
minimum flexible pavement section consisting of 9 inches of asphaltic concrete (AC)
over 19 inches of Base Aggregate for a 20-year design life.
RECOMMENDATIONS
Based on the anticipated construction schedule, the bulk of the earthwork is
expected to occur during dry weather months. However, some portions of the work
may extend into wet conditions. Therefore, the recommendations provided below
include contingencies for both dry and wet weather construction techniques.
Material Specifications and Compaction Requirements
1. Base Aggregate should consist of 1”-0 or ¾”-0 crushed aggregate that is
durable, well-graded, and relatively clean (i.e., with less than 5% passing
the No. 200 sieve). We should be provided a gradation sheet for the Base
Aggregate for approval prior to delivery to the site.
2. Stabilization Rock should consist of clean, angular, 3” open-graded rock.
The Stabilization Rock should include less than 10% (by weight) passing
the ¼” sieve and less than 2% passing the No. 200 sieve.
3. Drain Rock should consist of 2-inch diameter, clean (less than 2% passing
the #200 sieve), open-graded, crushed gravel or rock. The actual
gradation and maximum aggregate size will depend on the availability from
local suppliers. We should be provided a gradation curve of the intended
fill for approval, prior to delivery to the site.
4. The subgrade should consist of predominantly low to medium plasticity
fine-grained soil that does not contain abundant organics, debris, or high
plastic clay. Existing granular fill will require review and approval at the
time of construction. The subgrade is moisture sensitive and will require
careful treatment throughout demotion, excavation, and building pad
preparation.
Rosboro Project February 9, 2024
Geotechnical Investigation 12. Project No.: 2231110
Springfield, Oregon Rosboro
5. Site stripping should remove the upper pavements and surface soil that
contains the bulk of the demolition debris, organics, and softened soil.
Deeper excavation may be required in some areas (e.g., to remove
abandoned utilities or footings).
6. The Separation Geotextile should meet the minimum requirements of an
AASHTO M 288-17 geotextile for separation and have Mean Average Roll
Value (MARV) strength properties meeting the requirements of an
AASHTO M 288-17 Class 2, woven geotextile. We should be provided a
specification sheet on the selected geotextile for approval prior to delivery
to the site.
7. Drainage Geotextile should consist of a non-woven geotextile with a grab
tensile strength greater than 200 lb., an apparent opening size (AOS) of
between #70 and 100 (US Sieve), and a permittivity greater than
0.1 sec-1.
8. Subgrade compaction is expected to require a large pad foot or kneading
roller to compact the fine-grained soil. Compaction should be completed
using multiple passes of the roller over the moisture-conditioned subgrade.
Final subgrade preparation may require trimming the surface or
compacting the subgrade using a smooth drum roller to provide a firm,
uniform surface. Granular fill subgrade is expected to compact more
efficiently using a vibratory, smooth drum roller. All compacted subgrades
should be compacted to at least 95% relative compaction according to
ASTM D698. Documentation of the subgrade compaction is expected to
include variable materials and should include observation by the engineer
and proof rolling of the compacted surface using a 10-yd3 dump truck, or
other suitable sized piece of construction equipment. Areas of pumping
or deflection observed beneath the truck wheels may be reworked, or
overexcavated and replaced with compacted Base Aggregate and
proof-rolled again. Do not attempt to compact the subgrade during wet
weather.
9. Moisture-condition and compact the Base Aggregate in loose lifts not
exceeding 12 inches. Thinner lifts may be required if light or
hand-operated equipment is used. Compact the Base Aggregate to a
minimum of 95% relative compaction. The maximum dry density of
ASTM D698 should be used as the standard for estimating relative
compaction.
Field density tests should be completed on the compacted Base Aggregate
to confirm adequate compaction. The completed building pad should also
be proof-rolled using a loaded, 10-yd3 dump truck or another approved
vehicle.
Rosboro Project February 9, 2024
Geotechnical Investigation 13. Project No.: 2231110
Springfield, Oregon Rosboro
10. Inform contractors that water infiltration may occur in utility excavations
deeper than ±7 feet. Assume water will be encountered at shallower
depths during the winter months. Trenches should be pumped dry prior
to placing backfill. Trench backfill that extends beneath the new building
should consist of Base Aggregate placed and compacted as specified in
Item 9.
11. Provide contractors with a copy of this memorandum to review
recommendations for site preparation and foundation construction, and
the soil conditions encountered in the borings. We should be provided an
opportunity to meet with the contractor prior to construction to discuss
the site conditions, construction schedule and the contractor’s approach
to site preparation.
Building Pad Preparation and Foundation Construction
Site preparation and foundation construction for the buildings should be completed
as follows:
12. Remove all existing concrete, pavements, and landscaping from the
building areas. Haul all debris from the site.
13. Excavate during dry weather to the required grade to provide a minimum
12-inch thick building pad for the glulam building and a minimum 8-inch
thick building pad for the planar building. Moisture-condition and compact
the subgrade as recommended in Item 8. Areas of the planar building that
cannot be stabilized are expected to require an additional 2 feet of
excavation and replacement with Base Aggregate. Therefore, we
recommend a unit cost will be included in the bid documents for additional
excavation and rock placement. During wet weather, excavate as
necessary to provide a minimum of 24 inches of Base Aggregate over
stiff, uncompacted subgrade. Soft subgrade exposed during wet weather
should be mitigated by overexcavating to firm soil or using Stabilization
Rock in the lower 12 inches of the 24-inch thick building pad.
14. Use Base Aggregate to backfill all plumbing and utility trenches within the
building pad. Compact the trench backfill in lifts as recommended.
Complete final grading and surface compaction of the slab area after all
trenching and footing excavation are complete.
15. Excavate for footings using an excavator equipped with a smooth-edged
bucket to minimize subgrade disturbance. The excavation depth should
accommodate 18 inches of compacted Base Aggregate beneath the
footings at the glulam building. Deeper excavation depths are anticipated
at the planar building to bypass the fill. Therefore, a nominal 24 inches of
Base Aggregate should be anticipated.
Rosboro Project February 9, 2024
Geotechnical Investigation 14. Project No.: 2231110
Springfield, Oregon Rosboro
The fill under the foundations should extend a minimum of 12 inches
beyond the edge of the footing. The excavation distance should be
increased to 18 inches at the planar building where deeper Aggregate Base
is required. The fill should extend the full width of the footing excavation
if thickened edge foundations are used.
16. Place and compact in lifts the required thickness of Base Aggregate to
construct the building pads. The initial lift of Base Aggregate during wet
weather may be increased to 18 inches to help protect the subgrade. The
subgrade soils are moisture sensitive and should be protected from
construction traffic throughout placement and building pad preparation
work.
Foundation Design
17. Design the perimeter strip footings and isolated column footings using an
allowable bearing pressure of 2,000 psf. Provide a minimum footing width
of 18 inches for the perimeter footings and 24 inches for isolated column
footings.
18. Assume the new buildings could experience total and differential
movements (i.e., settlement, heave, or a combination thereof) of 1 inch
and ¾ inch, respectively, if foundation preparation is completed as
recommended herein.
19. Use a coefficient of friction of 0.5 for new footings bearing on Base
Aggregate for sliding analysis. A passive resistance against the vertical
face of the footing of 145 pcf (equivalent fluid density) may be assumed
in combination with the base friction.
20. Design new structures using the response spectrum, Site Class, and
seismic parameters summarized in Figure 3A.
21. Use a modulus of subgrade reaction, ks, of 250 pci, for the glulam building
floor slab design. This value assumes the slabs will be underlain by at
least 12 inches of compacted Base Aggregate placed over compacted
subgrade. Use a modulus of subgrade reaction, ks, of 200 pci, for the
planar building floor slab design. This value assumes the slabs will be
underlain by at least 8 inches of compacted Base Aggregate placed over
compacted granular fill subgrade.
22. Design retaining walls using an equivalent fluid density of 41 pcf to model
lateral earth pressures on the walls, which are expected to be flexible
(active earth pressures). The walls should also be designed for a surcharge
pressure of at least 250 psf. Using the active earth pressure coefficient
(ka) of 0.33, a uniform, lateral earth pressure of 83 psf should be
considered for surcharge. The lateral earth pressure should be increased
to 206 psf if traffic extends within 12 inches of the wall face.
Rosboro Project February 9, 2024
Geotechnical Investigation 15. Project No.: 2231110
Springfield, Oregon Rosboro
23. Provide a suitable vapor barrier under the slabs that is compatible with
the proposed floor covering and the method of slab curing. The type and
placement of the vapor barrier depends on the method of slab. Therefore,
this item should be reviewed by the flooring manufacturer, contractor,
and project engineer and/or architect.
Foundation Drainage
24. Install foundation drains along the perimeter of the new buildings and
behind new retaining walls. The drains should consist of 3 or 4-inch
diameter, perforated or slotted, PVC pipe wrapped in Drainage Geotextile.
The pipe should be set at the base of the perimeter footing or wall
foundation. The pipe should be bedded in at least 4 inches of Drain Rock
and backfilled full depth with Drain Rock. The entire mass of Drain Rock
should be wrapped in a Drainage Geotextile that laps at least 12 inches
at the top.
25. Provide clean-outs at appropriate locations for future maintenance of the
drainage system.
26. Discharge the water from the drain system into the nearest catch basin,
manhole, or storm drain.
Pavement Design and Construction
New parking and access pavements will be constructed for the new buildings.
Pavement preparation and construction should be completed as follows:
27. Demolish and remove existing structures and pavements in the areas of
planned new pavements as required. Excavate existing materials to the
design subgrade level.
28. During dry weather, moisture-condition and compact the subgrade as
recommended in Item 8. Proof-roll the compacted subgrade using a loaded
10-yd3 dump truck to identify any soft or pumping areas. Soft or pumping
subgrade identified during the proof-roll may be moisture-conditioned and
recompacted or overexcavated and replaced with Base Aggregate.
29. Do not attempt to compact the subgrade during wet weather. During wet
weather, excavate as required to provide a minimum of 24 inches of base
rock consisting of Base Aggregate over stiff, undisturbed subgrade. The
final excavation should be completed using an excavator equipped with a
smooth bucket operating from outside of the excavation to minimize
subgrade disturbance. Do not proof-roll the subgrade during wet weather.
Rosboro Project February 9, 2024
Geotechnical Investigation 16. Project No.: 2231110
Springfield, Oregon Rosboro
30. Place a Separation Geotextile over the approved subgrade. The geotextile
should be laid smooth, without wrinkles or folds. Overlap adjacent rolls a
minimum of 2 feet. Pin fabric overlaps or place the building pad fill in a
manner that will not separate the overlap during construction. Seams that
have separated will require removal of the building pad fill to establish the
required overlap.
31. Place Base Aggregate over the Separation Geotextile to construct the
base rock section. The fill should be end-dumped outside the pavement
area and pushed over the Separation Geotextile using a dozer. Compact
the Base Aggregate as recommended in Item 9.
32. Provide a minimum flexible pavement section consisting of 9 inches of AC
over 19 inches of Base Aggregate. The Base Aggregate section is
intended to support limited construction traffic required for paving. We
have assumed that the bulk of the construction traffic would use the
existing pavement.
33. Provide a PCC thickness of 12 inches at locations subject to heavy forklift
traffic. The PCC should be built over at least 12 inches of Base Aggregate
and a Separation Geotextile over compacted subgrade.
34. Gravel surfaced areas that will support occasional heavy traffic should
consist of a minimum of 24 inches of Base Aggregate over a Separation
Geotextile and compacted subgrade.
35. Provide a minimum of 12 inches of compacted Base Aggregate under all
isolated concrete slabs, or other hardscapes. Increase the minimum Base
Aggregate thickness to 24 inches during wet weather, or for any areas
that will be traversed by construction traffic.
DESIGN REVIEW/CONSTRUCTION OBSERVATION/TESTING
We should be provided the opportunity to review all drawings and specifications that
pertain to site preparation and foundation construction. Site preparation will require
field confirmation of subgrade conditions under the foundations, building pads and
new pavements. Mitigation of any subgrade pumping will also require engineering
review and judgment. That judgment should be provided by one of our
representatives. Frequent field density tests should be run on all building pad fill. We
recommend that we be retained to provide the necessary construction observation.
Rosboro Project February 9, 2024
Geotechnical Investigation 17. Project No.: 2231110
Springfield, Oregon Rosboro
VARIATION OF SUBSURFACE CONDITIONS, USE OF THIS REPORT AND WARRANTY
The analysis, conclusions, and recommendations contained herein are based on the
assumption that the soil profiles and the groundwater conditions observed during our
field exploration are representative of the overall site conditions. The above
recommendations assume that we will have the opportunity to review final drawings
and be present during construction to confirm assumed foundation conditions. No
changes to the enclosed recommendations should be made without our approval. We
will assume no responsibility or liability for any engineering judgment, inspection or
testing performed by others.
This report was prepared for the exclusive use of Rosboro and their design
consultants for the Rosboro Project in Springfield, Oregon. Information contained
herein should not be used for other sites or for unanticipated construction without
our written consent. This report is intended for planning and design purposes.
Contractors using this information to estimate construction quantities or costs do so
at their own risk.
Climate conditions in western Oregon typically consist of wet weather for almost
half of the year (typically between mid-October and late May). The recommendations
for site preparation are not intended to represent any warranty (expressed or implied)
against the growth of mold, mildew or other organisms that grow in a humid or moist
environment.
Our services do not include any survey or assessment of potential surface
contamination or contamination of the soil or ground water by hazardous or toxic
materials. We assume that those services, if needed, have been completed by others.
Our work was done in accordance with generally accepted soil and foundation
engineering practices. No other warranty, expressed or implied, is made.
It has been a pleasure assisting you with this phase of your project. Please do not
hesitate to contact us if you have any questions or need further information.
Attachments
Rosboro Project February 9, 2024
Geotechnical Investigation 18. Project No.: 2231110
Springfield, Oregon Rosboro
REFERENCES
ASCE, 2016, ASCE 7-16, Minimum Design Loads and Associated Criteria for
Buildings and Other Structures, American Society of Civil Engineers (ASCE).
AASHTO, 1993, AASHTO Guide for Design of Pavement Structures: American
Association of State Highway and Transportation Officials (AASHTO).
IBC, 2021, International Building Code (IBC): International Code Council, Inc.,
Sections 1613 and 1803.
OSSC, 2022, Oregon Structural Specialty Code (OSSC): Based on the International
Code Council, Inc., 2021 International Building Code (IBC), Section 1613 and
1803.
USGS, 2014, Earthquake Hazards Program, Interactive Deaggregations, Dynamic
Conterminous U.S. 2014 (v.4.2.0): U.S. Geological Survey (USGS), 2% in 50
years return period (2,475 years) PGA spectral acceleration, latitude/longitude
search, reference material has no specific release date, accessed May 2022,
website: https://earthquake.usgs.gov/hazards/interactive/index.php.
Appendix A
Figures
Foundation Engineering, Inc.
Professional Geotechnical Services
DRAFT
DRAFT
BH-1BH-7BH-8BH-6BH-4BH-5BH-2BH-3200100SCALE IN FEET050BH-1BORING NUMBER AND LOCATIONLEGENDFoundation Engineering, Inc.Professional Geotechnical ServicesPROJECT NO.FIGURE NO.DRAWN BY:DATE:BORING LOCATIONSROSBORO PROJECTSPRINGFIELD, OREGONERIN22311102ADEC 2023DRAFT
Foundation Engineering, Inc.
Professional Geotechnical Services
Dec. 5, 2023
PROJECT NO.
FIGURE NO.
DRAWN BY:DATE:
OSSC 2022 SITE RESPONSE SPECTRUM
ROSBORO PROJECT
SPRINGFIELD, OREGONEJG2231110
3A
DRAFT
Appendix B
Boring Logs
Foundation Engineering, Inc.
Professional Geotechnical Services
DRAFT
Foundation Engineering, Inc.Professional Geotechnical Services EXPLORATION LOGS
SYMBOL KEY
DISTINCTION BETWEEN FIELD LOGS AND FINAL LOGS
A field log is prepared for each boring or test pit by our field representative. The log contains information concerning sampling depths
and the presence of various materials such as gravel, cobbles, and fill, and observations of ground water. It also contains our
interpretation of the soil conditions between samples. The final logs presented in this report represent our interpretation of the
contents of the field logs and the results of the sample examinations and laboratory test results. Our recommendations are based on
the contents of the final logs and the information contained therein and not on the field logs.
VARIATION IN SOILS BETWEEN TEST PITS AND BORINGS
The final log and related information depict subsurface conditions only at the specific location and on the date indicated. Those using
the information contained herein should be aware that soil conditions at other locations or on other dates may differ. Actual
foundation or subgrade conditions should be confirmed by us during construction.
TRANSITION BETWEEN SOIL OR ROCK TYPES
The lines designating the interface between soil, fill or rock on the final logs and on subsurface profiles presented in the report are
determined by interpolation and are therefore approximate. The transition between the materials may be abrupt or gradual. Only at
boring or test pit locations should profiles be considered as reasonably accurate and then only to the degree implied by the notes
thereon.
SH - 3 - 4
Bottom of Sample Attempt
Unrecovered Portion
Boring or Test Pit Number
Recovered Portion
Top of Sample Attempt
Sample Type
Sample Number
SAMPLE OR TEST SYMBOLS
C - Pavement Core Sample
CS - Rock Core Sample
OS - Oversize Sample (3-inch O.D. split-spoon)
S - Grab Sample
SH - Thin-walled Shelby Tube Sample
SS - Standard Penetration Test Sample (2-inch O.D. split-spoon)
Standard Penetration Test Resistance equals the number of blows
a 140 lb. weight falling 30 in. is required to drive a standard
split-spoon sampler 1 ft. Practical refusal is equal to 50 or more
blows per 6 in. of sampler penetration.
Water Content (%)
UNIFIED SOIL CLASSIFICATION SYMBOLS
G - Gravel
S - Sand
M - Silt
C - Clay
Pt - Peat
W - Well Graded
P - Poorly Graded
L - Low Plasticity
H - High Plasticity
O - Organic
FIELD SHEAR STRENGTH TEST
Shear strength measurements on test pit side walls, blocks
of soil or Shelby tube samples are typically made with
Torvane or Field Vane shear devices
TYPICAL SOIL/ROCK SYMBOLS WATER TABLE
Water Table Location
Date of Measurement(1/31/16)
Concrete
Organics
Clay
Gravel
Silt
Sand
Sandstone
Basalt
Siltstone
DRAFT
Foundation Engineering, Inc.Professional Geotechnical Services COMMON TERMS
SOIL DESCRIPTIONS
Explanation of Common Terms Used in Soil Descriptions
Field Identification Choesive Soils Granular Soils
SPT*Su** (tsf)Term SPT* Term
Easily penetrated several inches by fist.0 - 2 < 0.125 Very Soft 0 - 4 Very Loose
Easily penetrated several inches by thumb.2 - 4 0.125 - 0.25 Soft 4 - 10 Loose
Can be penetrated several inches by thumb with
moderate effort.4 - 8 0.25 - 0.50 Medium Stiff 10 - 30 Medium Dense
Readily indented by thumb but penetrated only with
great effort.8 - 15 0.50 - 1.0 Stiff 30 - 50 Dense
Readily indented by thumbnail.15 - 30 1.0 - 2.0
Very Stiff > 50
Very Dense
Indented with difficulty by thumbnail.> 30 > 2.0 Hard
Term Soil Moisture Field Description
Dry Absence of moisture. Dusty. Dry to the touch.
Damp Soil has moisture. Cohesive soils are below plastic limit and usually moldable.
Moist Grains appear darkened, but no visible water. Silt/clay will clump. Sand will bulk. Soils are often at or near plastic
limit.
Wet
Visible water on larger grain surfaces. Sand and cohesionless silt exhibit dilatancy. Cohesive soil can be readily
remolded. Soil leaves wetness on the hand when squeezed. Soil is wetter than the optimum moisture content and
above the plastic limit.
Term PI Plasticity Field Test
Non-plastic 0 - 3 Cannot be rolled into a thread at any moisture.
Low Plasticity 3 - 15 Can be rolled into a thread with some difficulty.
Medium Plasticity 15 - 30 Easily rolled into thread.
High Plasticity > 30
Easily rolled and re-rolled into thread.
Term Soil Structure Criteria
Stratified Alternating layers at least ¼ inch thick.
Laminated Alternating layers less than ¼ inch thick.
Fissured Contains shears and partings along
planes of weakness.
Slickensided Partings appear glossy or striated.
Blocky Breaks into small lumps that resist further
breakdown.
Lensed Contains pockets of different soils.
Term Soil Cementation Criteria
Weak Breaks under light finger pressure.
Moderate Breaks under hard finger pressure.
Strong Will not break with finger pressure.
* SPT N-value in blows per foot (bpf)
** Undrained shear strength
DRAFT
Capped withgravel
Backfilled
with bentonite
chips
Groundwaterencountered
during drilling
SS-1-1
SS-1-2
SH-1-3
SS-1-4
SS-1-5
ASPHALTIC CONCRETE (±2 inches).
Dense silty CRUSHED ROCK (GM); grey-brown, moist,±2-inch minus angular rock, (base rock).
Medium stiff silty CLAY (CH); brown and iron-stained,moist, medium to high plasticity, (Willamette Silt).
Stiff below ±5 feet.
Field vane on SH-1-3: Su= 0.74 tsf at ±7.5 feet.
Very dense sandy GRAVEL, trace silt (GW); grey-brownand iron-stained, wet, fine to coarse sand, fine to coarsesubrounded to rounded gravel, (alluvium).
BOTTOM OF BORING
471.8
0.2
470.5
1.5
463.5
8.5
455.5
16.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
BORING LOG: BH-1Project No.:
Surface Elevation:
Date of Boring: November 20, 2023
Rosboro Project
Springfield, Oregon
BH-1
Page 1 of 1
472.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
6
10
67
65
6
10
67
65
DRAFT
Backfilledwith bentonitechips
No seepageor
groundwaterencountered
during drilling
S-2-1
SS-2-2
SS-2-3
SS-2-4
Dense CRUSHED GRAVEL (GP); grey, moist, up to ±1to 2-inch diameter subrounded to rounded gravel, (fill).
Stiff silty CLAY (CH); brown and iron-stained, wet,medium to high plasticity, (Willamette Silt).
Very dense sandy GRAVEL, trace silt (GW); grey-brown,wet, fine to coarse sand, fine to coarse subrounded torounded gravel, (alluvium).
BOTTOM OF BORING
466.0
7.0
463.5
9.5
461.5
11.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
1
2
3
4
5
6
7
8
9
10
11
BORING LOG: BH-2Project No.:
Surface Elevation:
Date of Boring: November 20, 2023
Rosboro Project
Springfield, Oregon
BH-2
Page 1 of 1
473.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
43
9
73
43
9
73
DRAFT
Capped withcrushed rock
Backfilledwith bentonitechips
Groundwaterencounteredduring drilling
SS-3-1
SH-3-2
SS-3-3
SS-3-4
SS-3-5
SS-3-6
ASPHALTIC CONCRETE (±4 inches).
Dense sandy GRAVEL (GP); grey, moist, ±2-inch minussubrounded to rounded gravel, (base rock).
Stiff silty CLAY (CH); brown to dark brown andiron-stained, moist, medium to high plasticity, (WillametteSilt).
Field vanes on SH-3-2: Su= 0.84 tsf at ±5 feet andSu= 0.46 tsf at ±7.5 feet.
Some fine sand below ±7 feet.
Sandy below ±11 feet.
Dense to very dense sandy GRAVEL, trace silt (GW);wet, fine to coarse sand, fine to coarse subrounded torounded gravel, (alluvium).
BOTTOM OF BORING
472.7
0.3
471.0
2.0
460.5
12.5
451.5
21.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
BORING LOG: BH-3Project No.:
Surface Elevation:
Date of Boring: November 20, 2023
Rosboro Project
Springfield, Oregon
BH-3
Page 1 of 1
473.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
13
15
13
69
33
13
15
13
69
33
DRAFT
Capped withcrushed rock
Backfilledwith bentonitechips
Groundwater
encountered
during drilling
SS-4-1
SS-4-2
SS-4-3
SS-4-4
SS-4-5
Dense CRUSHED ROCK (GP); grey, moist, ±2-inchminus angular rock, (fill).
±1-inch minus crushed rock below ±1.5 feet.
SILT, some debris (ML); grey, moist, low to mediumplasticity, debris consists of brick and concrete fragments,(fill).
Very stiff silty CLAY (CH); dark brown, moist, medium tohigh plasticity, (Willamette Silt).
Iron-stained from ±5 to 7 feet.
Stiff and dark grey below ±7 feet.
Very dense sandy GRAVEL, trace silt (GP); grey-brown,wet, fine to coarse sand, fine to coarse subrounded torounded gravel, (alluvium).
BOTTOM OF BORING
474.0
2.0
472.5
3.5
461.5
14.5
459.6
16.4
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
BORING LOG: BH-4Project No.:
Surface Elevation:
Date of Boring: November 20, 2023
Rosboro Project
Springfield, Oregon
BH-4
Page 1 of 1
476.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
30
19
10
9
96/11"
30
19
10
9
96/11"
DRAFT
Capped withcrushedgravel
Backfilledwith bentonitechips
Groundwater
encountered
during drilling
SS-5-1
SS-5-2
SS-5-3
SS-5-4
SS-5-5
Dense silty CRUSHED GRAVEL (GM); grey-brown,moist, low plasticity silt, ±2-inch minus, (fill).
Blue-grey with scattered wood fibers below ±2 feet.
Stiff silty CLAY (CH); dark brown, moist, medium to highplasticity, (Willamette Silt).
Iron-stained below ±6 feet.
Medium stiff to stiff below ±7 feet.
Very dense sandy GRAVEL, trace silt (GW); grey, wet,fine to coarse sand, fine to coarse subrounded to roundedgravel, (alluvium).
BOTTOM OF BORING
471.0
4.0
461.5
13.5
458.5
16.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
BORING LOG: BH-5Project No.:
Surface Elevation:
Date of Boring: November 20, 2023
Rosboro Project
Springfield, Oregon
BH-5
Page 1 of 1
475.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
31
12
9
6
91/11½"
31
12
9
6
91/11½"
ldh (1-10-2024)
DRAFT
Capped withAC coldpatch
Backfilledwith bentonitechips
Groundwaterencounteredduring drilling
SH-7-1
SS-7-2
SS-7-3
SS-7-4
SS-7-5
SS-7-6
ASPHALTIC CONCRETE (±5 inches).
Very dense CRUSHED ROCK (GP); grey, wet, ±3-inchminus angular rock, (base rock).
Medium stiff silty CLAY, scattered organics (CH);grey-brown, moist, medium to high plasticity, organicsconsist of wood fragments, (fill).Field vanes on SH-7-1: Su= 0.46 tsf at ±2.5 feet andSu= 0.30 tsf at ±4 feet.
Medium stiff silty CLAY (CH); brown and iron-stained,moist to wet, medium to high plasticity, (Willamette Silt).
Soft, some fine sand, and grey mottling below±10 feet.
Dense to very dense sandy GRAVEL, trace silt (GW);grey, wet, fine to coarse sand, fine to coarse roundedgravel, (alluvium).
BOTTOM OF BORING
474.6
0.4
473.0
2.0
471.0
4.0
464.0
11.0
453.5
21.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
BORING LOG: BH-7Project No.:
Surface Elevation:
Date of Boring: December 4, 2023
Rosboro Project
Springfield, Oregon
BH-7
Page 1 of 1
475.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
5
8
20
50/3"
43
5
8
20
50/3"
43
DRAFT
Capped withAC coldpatch
Backfilledwith bentonitechips
Groundwater
encountered
during drilling
SS-8-1
SH-8-2
SS-8-3
SS-8-4
SS-8-5
SS-8-6
ASPHALTIC CONCRETE (±8 inches).
Very dense sandy GRAVEL (GP); grey, wet, fine tocoarse sand, fine to coarse subrounded to roundedgravel, (base rock).
Soft to medium stiff silty CLAY, trace sand (CH); grey,wet, medium to high plasticity, fine sand, (fill).
Medium stiff silty CLAY (CH); brown, moist, medium tohigh plasticity, (Willamette Silt).
Field vanes on SH-8-2: Su= 0.72 tsf at ±5 feet andSu= 0.82 tsf at ±7.5 feet.
Stiff and iron-stained below ±7.5 feet.
Mottled grey and wet below ±10 feet.
Very dense sandy GRAVEL, trace silt (GW); grey, wet,fine to coarse sand, fine to coarse rounded gravel,(alluvium).
BOTTOM OF BORING
475.3
0.7
474.0
2.0
473.0
3.0
462.0
14.0
454.5
21.5
SPT
N-Value
Moisture (%)Groundwater
Log Depth
Depth
and
Comments
Core
Recovery (%)
RQD (%)
0 50 100
Elev.Backfill/
Installations/(ft)
Sample
Number
and
Location
Soil / Rock Description
2231110
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
BORING LOG: BH-8Project No.:
Surface Elevation:
Date of Boring: December 4, 2023
Rosboro Project
Springfield, Oregon
BH-8
Page 1 of 1
476.0 feet (Approx.)
Professional Geotechnical Services
Foundation Engineering, Inc.
7
11
14
60
54
7
11
14
60
54
DRAFT
Appendix C
Laboratory Test Results
Foundation Engineering, Inc.
Professional Geotechnical Services
DRAFT
Foundation Engineering, Inc.
Rosboro Project
Project No.: 2231110
Table 1C. Laboratory Test Results
Sample
Number
Sample
Depth
(feet)
Moisture
Content
(%)
LL PL PI USCS
Classification
SS-1-1 2.5 – 4.0 38.0 86 32 54 CH
SS-5-2 5.0 – 6.5 31.8 81 30 51 CH
SS-8-1 2.5 – 4.0 37.2 77 31 46 CH
Table 2C. Expansion Index of Soils (ASTM D4829)
Sample
Number
Sample
Depth (ft)
Initial
Initial
Reading
(mm)
Final
Reading
(mm)
Final
Moisture
Content
(%)
Expansion
Index Height
(in)
Moisture
Content
(%)
Dry
Density
(pcf)
Degree of
Saturation
(%)
S-1-1 2.5 –4.0 0.999 19.2 94.4 52.0 0.0000 0.04865 39.6 49
Table 3C. Field Vane Undrained
Shear Strength (SU) Test Results
Sample
Number
Test Depth
(feet)
Undrained Shear
Strength
(tsf)
SH-1-3 7.5 0.74
SH-3-2 5.0 0.84
7.5 0.46
SH-7-1 2.5 0.46
4.0 0.30
SH-8-2 5.0 0.72
7.5 0.82
DRAFT