HomeMy WebLinkAbout20260413_PJA26-0201_Geotech Report CERTERRA Materially BetterT"'
GEOTEST
Geotechnical Investigation
Reece CID Plant
5802 Cemetery Road
Arlington , WA 98223
Client Name: 2812 Architecture
Project Name: Reece CD Plant
Project Number: 10-251772-0
Date: September 5, 2025
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September 5, 2025
Project No. 10-251772-0
2812 Architecture
2812 Colby Avenue
Everett, WA 98201
Attention: Adam Clark
Regarding: Geotechnical Engineering Report
Reece CD Plant
5802 Cemetery Road
Arlington, WA
Dear Adam:
As requested, Certerra (formerly GeoTest Services, Inc.) is pleased to submit the following report summarizing the results
of our geotechnical evaluation for the proposed Reece CD Plant located at 5802 Cemetery Road in Arlington, Washington
(see Vicinity Map, Figure 1).This report has been prepared in general accordance with the terms and conditions established
in our services agreement dated July 1, 2025 and authorized by yourself.
We appreciate the opportunity to provide geotechnical services on this project and look forward to assisting you during the
construction phase. Should you have any further questions regarding the information contained within the report, or if we
may be of service in other regards, please contact the undersigned.
Respectfully,
Certerra
O of w qo ry
c
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Gerry D. Bautista, Jr., P.E.
Senior Geotechnical Engineer
Enclosure: Geotechnical Engineering Report
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TABLE OF CONTENTS
Purposeand Scope of Services.................................................................................................................1
ProjectDescription......................................................................................................................................1
SiteConditions ............................................................................................................................................1
SurfaceConditions................................................................................................................................................1
SubsurfaceSoil Conditions..................................................................................................................................2
GeneralGeologic Conditions...............................................................................................................................2
Groundwater...........................................................................................................................................................3
WebSoil Survey....................................................................................................................................................3
GeologicHazards........................................................................................................................................4
Seismic and Liquefaction Hazards......................................................................................................................4
Conclusions and Recommendations .........................................................................................................5
Site Preparation and Earthwork...........................................................................................................................6
Filland Compaction...............................................................................................................................................6
Reuse of On-Site Soil — Existing Fill...............................................................................................................6
Reuse of On-Site Soil — Processed or Recycled Materials.........................................................................6
Reuseof On-Site Soil — Native Soil................................................................................................................7
ImportStructural Fill.........................................................................................................................................7
Backfilland Compaction..................................................................................................................................7
WetWeather Earthwork........................................................................................................................................7
SeismicDesign Considerations...........................................................................................................................7
FoundationSupport...............................................................................................................................................8
AllowableBearing Capacity.............................................................................................................................8
FoundationSettlement.....................................................................................................................................8
FloorSupport.........................................................................................................................................................8
Foundationand Site Drainage.............................................................................................................................9
Resistanceto Lateral Loads.................................................................................................................................9
Temporary and Permanent Slopes...................................................................................................................10
Utilities...................................................................................................................................................................10
PavementSubgrade Preparation......................................................................................................................11
Stormwater Infiltration Potential ........................................................................................................................11
Conceptual Infiltration Results......................................................................................................................11
StormwaterTreatment...................................................................................................................................12
Geotechnical Consultation and Construction Monitoring..............................................................................12
Useof This Report.....................................................................................................................................13
References.................................................................................................................................................13
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Purpose and Scope of Services
The purpose of this evaluation is to establish general subsurface conditions beneath the site from which conclusions and
recommendations pertaining to project design can be formulated. Our scope of services includes the following tasks:
• Explore soil and groundwater conditions underlying the site by advancing five Test Pit Explorations (TP-1 through
TP-5) with a subcontracted tracked excavator to evaluate subsurface conditions.
• Perform a visual reconnaissance of the proposed development site and immediate vicinity to observe existing site
topographic and geologic conditions.
• Perform laboratory testing on representative samples to classify and evaluate the engineering characteristics of the
soils encountered.
• Provide a preliminary assessment of the on-site infiltration capability based on USDA textural classification per the
Stormwater Management Manual for Western Washington[Manual].
• Provide a written report containing a description of surface and subsurface conditions and exploration logs. Included
are findings and recommendations pertaining to site preparation and earthwork, including stripping depths,
subgrade preparation below the planned buildings, reuse of on-site soils, wet weather earthwork, and criteria for
selection, placement, and compaction of Structural Fill.
• Provide recommendations for foundation support of the planned structures including allowable bearing pressures,
bearing elevations, frost penetration depth, a discussion of potential foundation settlement (total and differential),
floor support, and general foundation design.
• Provide recommendations for lateral earth pressures including active and at-rest conditions, allowable passive soil
resistance, groundwater considerations, drainage recommendations, pavement design, temporary and permanent
slope inclinations, and utilities.
• Discuss Seismic Site Class considerations based on the 2021 International Building Code (IBC).
• Provide an assessment of geologically hazardous areas per the City of Arlington Municipal Code (AMC), Chapter
20.93.600, Geologically Hazardous Areas.
• Provide recommendations for geotechnical monitoring, materials testing, and consultation during construction.
Project Description
Based on our review of preliminary plans, we understand that the project will include the construction of a new, one-story,
"L"-shaped warehouse building to house a construction debris sorting facility with an approximate footprint of 33,000 square
feet. Construction will take place on the southeast corner of the existing Reece Construction property. The site is generally
flat, aside from soil and recycled material stockpiles across the site. It is anticipated that the building will be metal-framed
and utilize conventional foundations leading to moderate structural loads. Information regarding final elevations for the
proposed building were not known as of the writing of this report. The Arlington Airport borders the site to the west and
south, which may affect the height of the proposed building and the suitability of proposed stormwater elements, such as
detention ponds.
Preliminary information regarding stormwater elements, such as type and depth of facilities,was not known as of the writing
of this report.
Site Conditions
This section includes a description of the general surface and subsurface conditions observed at the project site during the
time of our field investigation. Interpretations of site conditions are based on the results and review of available information,
site reconnaissance, subsurface explorations, laboratory testing, and previous experience in the project vicinity.
Surface Conditions
The subject property consists of two parcels totalling 13.88 acres, in which both has historically been gravel pits since
between 1998 and 2000. Both parcels currently contain multiple buildings, warehouses, trailers, concrete pads, roadway
asphalt, and construction equipment. The proposed development will be located at the southeast corner of the southern
parcel (Parcel 31051500200700, approximately 9 acres). This area is currently being used as a storage area for stockpiles
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of asphalt, recycled concrete, and other assorted materials. The Arlington Municipal Airport borders the project site to the
south. The northern end of Runway 16 is located approximately 2,000 feet southwest of the project site.
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Images 1 (left)and 2(right): Site conditions from eastern end of project area. Images 1,2,and 3 were taken during our site visit of July
17,2025.
Subsurface Soil Conditions
Subsurface conditions were explored and documented by advancing five test pits (TP-1 through TP-5) on July 17, 2025.
Explorations were advanced and soils were described by a Certerra Geotechnical Technician working under the direction
of a Certerra Professional Geotechnical Engineer. Soils were classified in general accordance with the guidelines of the
American Society for Testing and Materials (ASTM) D2487 and D2488. Approximate locations of these explorations have
been plotted on the Site and Exploration Plan (Figure 2). A Soil Classification System and Key can be found as Figure 4,
detailed test pit logs are presented as Figures 5 through 7, and laboratory results as Figure 8.
Test pit explorations consisted of the excavation of shallow open pits with the use of a tracked excavator and operator
supplied by Reece Construction Company. Select grab samples were obtained at approximately 2-foot intervals or upon
changes in soil stratigraphy. Depths of the test pit explorations ranged from approximately 8 to 11 feet below the ground
surface (BGS).
The on-site soils consisted of approximately 1 to 1.5 feet of road base consisting of very dense, gray-brown to brown, dry to
damp, slightly silty, sandy gravel with brick debris. Underlying the road base in the TP-1, TP-3, and TP-4 locations was
uncontrolled fill soils consisting of dense, sandy gravel/gravelly sand, or hard, sandy silt extending to approximately 2.5 to 4
feet BGS. Below the road base and/or fill soils, Certerra observed native soils consisting of medium-dense to dense, sand
to very gravelly sand or very sandy gravel. These soils extended to the maximum explored depth of the test pits. The
explorations were terminated due to the limitations of the excavator that was available on site, except at the TP-4 location,
where the exploration was terminated due to caving of the native soils.
General Geologic Conditions
Geologic information for the project site was obtained from the Geologic map of the Arlington West 7.5-minute quadrangle,
Snohomish County, Washington (Minard, 1985), published by the United States Geological Survey. This map indicates that
the project site is underlain by Vashon Drift Recessional Outwash consisting of the Marysville Sand Member(map unit Qvrm).
The Marysville Sand Member consists of mostly well-drained, outwash sand with minor amounts of gravel. The older
Arlington Gravel Member(map unit Qvra) of the Vashon Drift Recessional Outwash is also mapped northeast of the project
site, underlying the Marysville Sand. Both deposits were encountered in our explorations. Deposits of the Arlington Gravel
consist of mostly well-drained and stratified sand and gravel deposits. Sediments of both soil types were deposited as valley
fill by meltwater flowing south from the stagnating and receding Vashon Glacier during the Pleistocene Epoch.
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Image 3:Soil stratigraphy in TP-3—road base and uncontrolled fill over gray/brown,very sandy gravel.
Our onsite explorations indicate that the encountered subsurface soil conditions are generally in accordance with the
mapped deposits. It should be noted that the published soil types are representative of regional conditions and some
variation between onsite soils and mapped geologic units should generally be anticipated. The native soils encountered in
our explorations are consistent with soils that we have encountered on nearby projects, including our recent work on the
Reece Construction property.
For the purposes of this report, Certerra has referred to the native soils as Marysville Sand and Arlington Gravel.
Groundwater
Groundwater associated with the regional groundwater table was not encountered during our explorations in July of 2025.
The groundwater conditions reported on the exploration logs are for the specific locations and dates indicated and therefore
may not be indicative of other locations and/or times. Groundwater levels are variable and groundwater conditions will
fluctuate depending on local subsurface conditions, precipitation, and changes in on-site and offsite use.
Based on a review of publicly available well log data from the Washington Department Ecology Well Log Viewer and
potentiometric surface maps in Newcomb (1952),the regional water table in the vicinity of the project area appears to be at
depths of generally 60 to 70 feet BGS in the vicinity of the site.
Web Soil Survey
According to the United States Department of Agriculture(USDA) Natural Resource Conservation Service(NRCS) Web Soil
Survey website, one relevant soil unit is present on the subject property, Everett very gravelly sandy loam, 0 to 8 percent
slopes. Please refer to Table 1 below for general characteristics of the mapped site soils. Based on their erosion "K" factor
assigned by the NRCS, the soils present on-site are considered to have a low susceptibility to erosion. The value of the
erosion factor"K" ranges from 0.02 to 0.69;the higher the value,the more susceptible the soil is to sheet and rill erosion by
water. Mapped site soils are generally consistent with the soils observed during our explorations.
The site soils have a Land Capability Classifications of "s". Soils classified as "s" indicates that soil limitations within the
rooting zone, such as gravels and low moisture-holding ability, is the dominant hazard or limitation affecting soil suitability
(USDA, 1961).The soils found within the project vicinity are considered to have a low susceptibility to erosion based on their
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K Factor ratings. The soil's vulnerability to sheet and rill erosion are also considered low based on the flat inclination that is
present within the proposed area of development. In our opinion,erosion may be managed during and following construction
using conventional best management practices.
Table 1:
USDA INIRCS Soil Classifications
SymbolMap Unit
Map Unit Name Everett very gravelly sandy loam, 0 to 8 percent slopes
Soil Description Very gravelly sandy loam/loamy sand to extremely gravelly
coarse sand
Landform Kames, moraines,eskers
Parent Material Sandy and gravelly glacial outwash
Land Capability 4s
Classification
Erosion K Factor,Whole 0.10
Soil
Geologic Hazards
As the subject property is located within the City of Arlington, Certerra reviewed Chapter 20.93 Part V (Geologically
Hazardous Areas) of the Arlington Municipal Code (AMC). Since the subject property is relatively flat with minor elevation
gradients, it is Certerra's opinion that the subject property does not contain hazards pertaining to erosion or landslides (i.e.,
not an Erosion Hazard or Steep Slope Hazard). However, the subject property is mapped as having a low to moderate
susceptibility to liquefaction. This is addressed in the next section.
Seismic and Liquefaction Hazards
Based on a review of information obtained from the Washington State Department of Natural Resources Geologic Information
Portal, the subject site is classified as having a low to moderate liquefaction susceptibility. However, this map only provides
an estimate of the likelihood that the soil will liquefy as a result of an earthquake and is meant as a general guide to delineate
areas prone to liquefaction.
Liquefaction is defined as a significant rise in porewater pressure within a soil mass caused by earthquake-induced cyclic
shaking. The shear strength of liquefiable soils is reduced during large and/or long duration earthquakes as the soil
consistency approaches that of semi-solid slurry. Liquefaction can result in significant and widespread structural damage if
not properly mitigated. Deposits of loose, granular soil below the groundwater table are most susceptible to liquefaction.
Damage caused by foundation rotation, lateral spreading, and other ground movements can result from soil liquefaction.
Based on our subsurface explorations,the site is underlain by native, medium-dense,very gravelly, sandy soils. Certerra did
not encounter the regional groundwater table during our explorations and a review of local well log data and published
potentiometric surface maps suggests that it is more than 60 feet BGS in the vicinity of the site. Due to these factors, it is
Certerra's opinion that the potential for liquefaction underlying the subject property is low.Thus, it is our opinion that the site
does not require mitigations to address liquefaction concerns.
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Project Location
Liquefaction Susceptibility
■High
Moderate to ngh
Low[o nlOdera'k
Lbw
Very low to low
Very bw
Befrc;k
Peat
WaNr roes:E—HERE,
Gamin,IMermap,
Image 4. Map showing liquefaction hazard susceptibility.Yellow depicts"low to moderate"susceptibility in the vicinity of the subject
property. (Source:Washington Geologic Information Portal.)
Conclusions and Recommendations
Based on the evaluation of the data collected during this investigation, it is our opinion that the subsurface conditions at the
site are suitable for the proposed development, provided the recommendations contained herein are incorporated into the
project design.
The site is generally flat and underlain by sandy gravel (road base) and medium dense to dense Marysville Sand and
Arlington Gravel. Approximately half of the test pits encountered uncontrolled fill consisting of dense, gravelly sand/sandy
gravel or hard silt. The native soils were encountered at approximately 1 to 4 feet BGS. In our opinion, the Marysville Sand
and Arlington Gravel soils are suitable for foundation support.
Existing fill, deleterious materials, organics, and loose/unsuitable portions of native soil should be removed from building
footprints to expose suitable undisturbed Marysville Sand or Arlington Gravel. The foundations should be supported by
undisturbed, firm, and unyielding native soils, or on properly placed and compacted Structural Fill over suitably prepared
native soils. For pavements, up to 2 feet of existing fill should be removed. The subgrades should then be compacted to a
firm and unyielding condition.A stabilization fabric or reinforcing grid may be considered if loose or soft pavement subgrade
conditions are encountered after stripping.The pavement excavation can then be filled to final grades using properly placed
and compacted Structural Fill.
Please note that no explorations were performed in the western half of the proposed building footprint due to the presence
of large stockpiles. In addition, no preliminary information regarding finish floor elevations for the building were available at
the time of this report. Thus, it will likely be necessary for Certerra to revisit the recommendations given in this report
(specifically, foundation recommendations) once the existing stockpiles have been removed and site stripping has taken
place. Qualified geotechnical personnel from Certerra should be on site during the stripping process to help determine the
required depth for overexcvavation to reveal competent native soils.Although no explorations were performed in the western
half of the proposed building footprint, we expect overexcavation depths similar to what we found in our explorations.
The native Marysville Sand and Arlington Gravel soils appear to be suitable for stormwater infiltration. Certerra has presented
preliminary design infiltration rates based on grain size analyses, per the SMMWW, in a subsequent section of this report.
A preliminary site development plan showing the proposed development area was available to us at the time of writing this
report. As a result, Certerra attempted to get data within the vicinity of the planned structures. It should be expected that
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additional design services, possibly paired with additional field work and collaboration with the project Civil Engineer, may
be needed to complete the stormwater design.
Site Preparation and Earthwork
The portions of the site proposed for foundations, floor slabs, and pavements should be prepared by removing existing
topsoil, deleterious material, and significant accumulations of organics. Based on our explorations, Certerra anticipates at
least 1 to 4 feet of removal at most locations to expose native Marysville Sand or Arlington Gravel. Given past site use, it
should be expected that variable depths of fill and/or construction debris will be present on the property. Subsurface soil
explorations suggest that between 1 and 4 feet of stripping will be needed at most locations. Finished site grades have not
been established, so it is currently unknown what finished building elevations will be. For pavements, up to 2 feet of existing
fill should be removed. A stabilization fabric or reinforcing grid maybe considered if loose or soft pavement subgrade
conditions are encountered after stripping. Depending on the soil conditions encountered after the stockpiles have been
removed, more stripping may be required in the area of the existing footprint.
Prior to placement of any foundation elements or Structural Fill, the exposed subgrade under all areas to be occupied by
soil-supported floor slabs, spread, or continuous foundations should be recompacted to a firm and unyielding condition.
Verification of compaction can be accomplished through proof rolling with a loaded dump truck, large self-propelled vibrating
roller, or similar piece of equipment applicable to the size of the excavation. The purpose of this effort is to identify loose or
soft soil deposits so that, if feasible,the soil disturbed during site work can be recompacted.
Proof rolling should be carefully observed by qualified geotechnical personnel. Areas exhibiting significant deflection,
pumping, or over-saturation that cannot be readily compacted should be overexcavated to firm soil. Alternatively, Dynamic
Cone Penetrometers or soil probing by a qualified Certerra representative can confirm firm and unyielding conditions if a
proof roll cannot be performed. Overexcavated areas should be backfilled with compacted granular material placed in
accordance with subsequent recommendations for Structural Fill. During periods of wet weather, proof rolling could damage
the exposed subgrade. Under these conditions, qualified geotechnical personnel should observe subgrade conditions to
determine if proof rolling is feasible.
Fill and Compaction
Structural Fill used to obtain final elevations for footings and soil-supported floor slabs must be properly placed and
compacted. In most cases, suitable, non-organic, predominantly granular soil may be used for fill material provided the
material is properly moisture conditioned prior to placement and compaction, and the specified degree of compaction is
obtained. Material containing topsoil, wood, trash, organic material, or construction debris is not suitable for reuse as
Structural Fill and should be properly disposed offsite or placed in non-structural areas.
Soils containing more than approximately 5 percent fines are considered moisture sensitive and are difficult to compact to
a firm and unyielding condition when over the optimum moisture content by more than approximately 2 percent. The
optimum moisture content is that which allows the greatest dry density to be achieved at a given level of compactive effort.
Reuse of On-Site Soil—Existing Fill
Existing fill soils were observed to extend to approximately 2.5 to 4 feet BGS in our explorations. The existing fill soils
contained indications of debris including brick and asphalt. Fill containing debris, or organics should be segregated and
removed from the site. It should be noted that the existing silt fill found in TP-1 also contained elevated fines content and are
considered moisture sensitive. Silty soil should only be reused if it can be placed at or near optimum moisture contents.
Reuse of On-Site Soil—Processed or Recycled Materials
These materials were stockpiled on or in proximity to the proposed building footprint area during our field investigation.
Based on our observations, we interpret that these materials should be suitable for use below floor slabs and drive paths
when compacted to Structural Fill standards. Certerra should evaluate specific materials for their intended use prior to
placement.
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Reuse of On-Site Soil—Native Soil
The on-site, native Marysville Sand and Arlington Gravel are suitable for reuse as structural fill when placed at or near
optimum moisture contents, as determined by ASTM D1557 and if allowed for in the project plans and specifications. The
near-surface, weathered soils may contain elevated silt contents and may be difficult to use during periods of wet weather.
The Contractor and Owner should be prepared to manage over-optimum moisture content soils. Moisture content of the site
soils may be difficult to control during periods of wet weather.
Import Structural Fill
Certerra recommends that imported Structural Fill consist of clean, well-graded sandy gravel, gravelly sand, or other
approved naturally occurring granular material (pit run)with at least 30 percent retained on the No.4 sieve, or a well-graded
crushed rock. Structural Fill for dry weather construction may contain up to 10 percent fines (that portion passing the U.S.
No. 200 sieve) based on the portion passing the U.S. No. 4 sieve. The use of an imported fill having more than 10 percent
fines may be feasible, but the use of these soils should generally be reviewed by the design team prior to the start of
construction.
Imported Structural Fill with less than 5 percent fines should be used during wet weather conditions. Due to wet site
conditions, soil moisture contents could be high enough that it may be difficult to compact even clean imported select
granular fill to a firm and unyielding condition. Soils with an over-optimum moisture content should be scarified and dried
back to a suitable moisture content during periods of dry weather or removed and replaced with drier Structural Fill.
Backfill and Compaction
Structural Fill should be placed in horizontal lifts. The Structural Fill must measure 8 to 10 inches in loose thickness and be
thoroughly compacted.All Structural Fill placed under load bearing areas should be compacted to at least 95 percent of the
maximum dry density,as determined using test method ASTM D1557.The top of the compacted Structural Fill should extend
outside all foundations and other structural improvements a minimum distance equal to the thickness of the fill. We
recommend that compaction be tested after placement of each lift in the fill pad.
Wet Weather Earthwork
If construction takes place during wet weather, Certerra recommends that Structural Fill consist of imported, clean, well-
graded sand or sand and gravel as described above. If fill is to be placed or earthwork is to be performed in wet conditions,
the contractor may reduce soil disturbance by:
• Limiting the size of areas that are stripped of topsoil and left exposed
• Accomplishing earthwork in small sections
• Limiting construction traffic over unprotected soil
• Sloping excavated surfaces to promote runoff
• Limiting the size and type of construction equipment used
• Providing gravel `working mats' over areas of prepared subgrade
• Removing wet surficial soil prior to commencing fill placement each day
• Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber-tired roller at the end of
each working day
• Providing up-gradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and
prevent water from ponding and damaging exposed subgrades
Seismic Design Considerations
The Pacific Northwest is seismically active, and the site could be subject to movement from a moderate or major earthquake.
Consequently, moderate levels of seismic shaking should be accounted for during the design life of the project, and the
proposed structure should be designed to resist earthquake loading using appropriate design methodology.
For structures designed using the seismic design provisions of the 2021 International Building Code, the Marysville Sand
and Arlington Gravel are classified as Site Class D according to ASCE 7-22. The Structural Engineer should select the
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appropriate design response spectrum based on Site Class D soil and the geographical location of the proposed
construction.
Foundation Support
Certerra recommends that existing topsoil, uncontrolled fill materials and loose, upper portions of the native soil be removed
from beneath the building foundation area(s) to expose medium-dense to dense, Marysville Sand or Arlington Gravel.
Certerra identified approximately 1 to 4 feet of road base and/or dense/hard, uncontrolled fill overlying weathered and non-
weathered gravelly sand/sandy gravel and sand. Certerra does not recommend that new foundations be placed on existing
uncontrolled fill. In all cases, new foundations must be placed on either firm and unyielding native soil or Structural Fill
overlying firm and unyielding native soil.
Due to large stockpiles occupying the western portion of the building footprint area during explorations, Certerra was not
able to perform explorations in these areas. However, we expect that overexcavation depths for the building footprint will be
similar (+/-4 feet). The Owner should expect some variability in overexcavation depths and have contingencies for deeper
overexcavation and replacement depths.
Continuous and isolated spread footings should be founded 18 inches (at minimum) below the lowest adjacent final grade
for freeze/thaw protection. The footings should be sized in accordance with the Structural Engineer's prescribed design
criteria and seismic considerations.
Allowable Bearing Capacity
Assuming the above foundation support criteria are satisfied, continuous or isolated spread footings founded directly on
native, Marysville Sand/Arlington Gravel, or on compacted Structural Fill placed directly over undisturbed native soils, may
be proportioned using a net allowable soil bearing pressure of 2,500 pounds per square foot(psf).
The"net allowable bearing pressure"refers to the pressure that can be imposed on the soil at foundation level.This pressure
includes all dead loads, live loads, the weight of the footing, and any backfill placed above the footing. The net allowable
bearing pressure may be increased by one-third for transient wind or seismic loads.
Foundation Settlement
Settlement of shallow foundations depends on foundation size and bearing pressure, as well as the strength and
compressibility characteristics of the underlying soil. If construction is accomplished as recommended and at the maximum
allowable soil bearing pressure, Certerra estimates the total settlement of building foundations to be less than one inch under
static conditions. Differential settlement between two adjacent load-bearing components supported on competent soil is
estimated to be less than one half the total settlement.
Floor Support
Conventional slab-on-grade floor construction is feasible for the planned site improvements. Floor slabs may be supported
on properly prepared native subgrade or on properly placed and compacted Structural Fill placed over properly prepared
firm and unyielding soil. Prior to placement of the Structural Fill, the native soil should be proof-rolled as recommended in
the Site Preparation and Earthwork section of this report.
Certerra recommends that interior concrete slab-on-grade floors be underlain with at least 6 inches of clean, compacted,
free-draining gravel. The gravel should contain less than 3 percent passing the U.S. Standard No. 200 sieve(based on a wet
sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The purpose of this gravel layer is to provide uniform
support for the slab, provide a capillary break, and act as a drainage layer. To help reduce the potential for water vapor
migration through floor slabs, a continuous 10-mil minimum thick polyethylene sheet with tape-sealed joints should be
installed below the slab to serve as an impermeable vapor barrier. The vapor barrier should be installed and sealed in
accordance with the manufacturer's instructions.
The American Concrete Institute (ACI) guidelines suggest that the slab may either be poured directly on the vapor barrier
or on a granular curing layer placed over the vapor barrier depending on construction conditions. Certerra recommends
that the Architect or Structural Engineer specify if a curing layer should be used. If moisture control within the building is
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critical, we recommend a representative of Certerra observe the vapor barrier to confirm that joints and penetrations have
been properly sealed.A Subgrade Modulus (k) of 250 pounds per cubic inch (pci) is recommended for use in the design of
concrete slab elements placed on suitably compacted near-surface soils and Structural Fill.
Exterior concrete slabs-on-grade, such as sidewalks, may be supported directly on undisturbed native soil or on properly
placed and compacted Structural Fill; however, long-term performance will be enhanced if exterior slabs are placed on a
layer of clean, durable, well-draining granular material.
Foundation and Site Drainage
Positive surface gradients should be provided adjacent to new foundation areas) to direct surface water away from the
building and toward suitable drainage facilities. Roof drainage should not be introduced into the perimeter footing drains but
should be separately discharged directly to the stormwater collection system or similar municipality-approved outlet.
Pavement and sidewalk areas, if present, should be sloped and drainage gradients should be maintained to carry surface
water away from the building(s)towards an approved stormwater collection system. Surface water should not be allowed to
pond and soak into the ground surface near buildings or paved areas during or after construction. Construction excavations
should be sloped to drain to sumps where water from seepage, rainfall,and runoff can be collected and pumped to a suitable
discharge facility.
To reduce the potential for groundwater and surface water to seep into interior spaces,Certerra recommends that an exterior
footing drain system be constructed around the perimeter of new building foundations as shown in the Conceptual Footing
and Wall Drain Section (Figure 3)of this report.The drain should consist of a perforated pipe measuring 4 inches in diameter
at minimum, surrounded by at least 12 inches of filtering media. The pipe should be sloped to carry water to an approved
collection system.
The filtering media may consist of open-graded drain rock wrapped in a nonwoven geotextile fabric such as Mirafi 140N (or
equivalent) or wrapped with a graded sand and gravel filter. For foundations supporting retaining walls, drainage backfill
should be carried up the back of the wall and be at least 12 inches wide. The drainage backfill should extend from the
foundation drain to within approximately 1 foot of the finished grade and consist of open-graded drain rock containing less
than 3 percent fines by weight passing the U.S. Standard No. 200 sieve(based on a wet sieve analysis of that portion passing
the U.S. Standard No. 4 sieve). The invert of the footing drainpipe should be placed at approximately the same elevation as
the bottom of the footing or 12 inches below the adjacent floor slab grade, whichever is deeper, so that water will be
contained.This process prevents water from seeping through walls or floor slabs.The drain system should include cleanouts
to allow for periodic maintenance and inspection.
Please understand that the above recommendations are intended to assist the Design Engineer and/or Architect in
development of foundation and site drainage parameters and are based on our experience with similar projects in the area.
The final foundation and site drainage plan that will be incorporated into the project plans is to be determined by the design
team.
Resistance to Lateral Loads
The lateral earth pressures that develop against retaining walls will depend on the method of backfill placement, degree of
compaction, slope of backfill, type of backfill material, provisions for drainage, magnitude and location of any adjacent
surcharge loads,and the degree to which the wall can yield laterally during or after placement of backfill. If the wall is allowed
to rotate or yield so the top of the wall moves an amount equal to or greater than about 0.001 to 0.002 times its height (a
yielding wall), the soil pressure exerted comprises the active soil pressure. When a wall is restrained against lateral
movement or tilting (a nonyielding wall), the soil pressure exerted comprises the at rest soil pressure. Wall restraint may
develop if a rigid structural network is constructed prior to backfilling or if the wall is inherently stiff.
Certerra recommends that yielding walls under drained conditions be designed for an equivalent fluid density of 35 pounds
per cubic foot (pcf), for granular, imported Structural Fill and native soils in active soil conditions. Nonyielding walls under
drained conditions should be designed for an equivalent fluid density of 55 pcf, for Structural Fill and native soils in at-rest
conditions. Design of walls should include appropriate lateral pressures caused by surcharge loads located within a
horizontal distance equal to or less than the height of the wall. For uniform surcharge pressures, a uniformly distributed
certerra.com 20527 6711 Avenue NE,Arlington,WA 98223 9
f CERTERRA Materially Better'""1 GEOTEST
lateral pressure equal to 35 percent and 50 percent of the vertical surcharge pressure should be added to the lateral soil
pressures for yielding and nonyielding walls, respectively. Certerra also recommends that a seismic surcharge of 8*H psf be
included where H is the wall height.The seismic surcharge should be modeled as a rectangular distribution with the resultant
applied at the midpoint of the wall.
Passive earth pressures developed against the sides of building foundations, in conjunction with friction developed between
the base of the footings and the supporting subgrade,will resist lateral loads transmitted from the structure to its foundation.
For design purposes, the passive resistance of well-compacted fill placed against the sides of foundations is equivalent to a
fluid with a density of 350 pcf.The recommended value includes a safety factor of about 1.5 and is based on the assumption
that the ground surface adjacent to the structure is level in the direction of movement for a distance equal to or greater than
twice the embedment depth. The recommended value also assumes drained conditions that will prevent the buildup of
hydrostatic pressure in the compacted fill. Retaining walls should include a drain system constructed in general accordance
with the recommendations presented in the Foundation and Site Drainage section of this report. In design computations,
the upper 12 inches of passive resistance should be neglected if the soil is not covered by floor slabs or pavement. If future
plans call for the removal of the soil providing resistance, the passive resistance should not be considered.
An allowable coefficient of base friction of 0.35, applied to vertical dead loads only, may be used between the underlying
imported granular Structural Fill and the base of the footing. If passive and frictional resistance are considered together, one
half the recommended passive soil resistance value should be used since larger strains are required to mobilize the passive
soil resistance as compared to frictional resistance. A safety factor of about 1.5 is included in the base friction design value.
Certerra does not recommend increasing the coefficient of friction to resist seismic or wind loads.
Temporary and Permanent Slopes
The contractor is responsible for construction slope configurations and maintaining safe working conditions, including
temporary excavation stability. All applicable local, state, and federal safety codes should be followed. All open cuts should
be monitored during and after excavation for any evidence of instability. If instability is detected,the contractor should flatten
the side slopes or install temporary shoring.
Temporary excavations in excess of 4 feet should be shored or sloped in accordance with Safety Standards for Construction
Work Part N, WAC 296-155-66403.
Marysville Sand is classified as a Type B soil.According to WAC 296-155-66401,Type B soils may be sloped as steep as 1:1
(Horizontal: Vertical). All soils encountered are classified as Type C soil in the presence of groundwater seepage. Type C
soils may be sloped as steep as 1.5:1 (Horizontal: Vertical). Flatter slopes or temporary shoring may be required in areas
where groundwater flow is present and unstable conditions develop.
Temporary slopes and excavations should be protected as soon as possible using appropriate methods to prevent erosion
from occurring during periods of wet weather.
Certerra recommends that permanent cut or fill slopes be designed for inclinations of 2HAV or flatter. Permanent cuts or
fills used in detention ponds, retention ponds,or earth slopes intended to hold water should be 3H:1 V or flatter.All permanent
slopes should be vegetated or otherwise protected to limit the potential for erosion as soon as practical after construction.
As the subject site is in close proximity to the Arlington Municipal Airport and is adjacent to the approach path to Runway
16, the project team should research what potential impacts (if any) that proposed detention ponds would have on airport
operations or be made aware of restrictions that would prevent the use of ponds in the area.
Utilities
Utility trenches must be properly backfilled and compacted to reduce cracking or localized loss of foundation, slab, or
pavement support. Excavations for new shallow underground utilities are expected to be placed within the native Marysville
Sand or Arlington Gravel.
Trench backfill in improved areas(beneath structures, pavements,sidewalks,etc.)should consist of Structural Fill as defined
in the Fill and Compaction section of this report. Outside of improved areas, trench backfill may consist of reused material
certerra.com 20527 6711 Avenue NE,Arlington,WA 98223 10
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provided the backfill can be compacted to the project specifications. Trench backfill should be placed and compacted in
general accordance with the recommendations presented in the Fill and Compaction section of this report.
Surcharge loads on trench support systems due to construction equipment, stockpiled material, and vehicle traffic should
be included in the design of any anticipated shoring system. The contractor should implement measures to prevent surface
water runoff from entering trenches and excavations. In addition, vibration as a result of construction activity and traffic may
cause caving of the trench walls.
The contractor is responsible for trench configurations. All applicable local, state, and federal safety codes should be
followed. All open cuts should be monitored by the contractor during excavation for any evidence of instability. If instability
is detected,the contractor should flatten the side slopes or install temporary shoring. If groundwater or groundwater seepage
is present, and the trench is not properly dewatered, the soil within the trench zone may be prone to caving, channelling,
and running. Trench widths may be substantially wider than under dewatered conditions.
Pavement Subgrade Preparation
Selection of a pavement section is typically a choice relative to a higher initial cost and lower long-term maintenance, or a
lower initial cost with more frequent maintenance. For this reason, we recommend that the Owner participates in the
selection of the proposed pavement sections planned for the site. Site grading plans should include provisions for sloping
of the subgrade soils in proposed pavement areas, so that passive drainage of the pavement section(s) can proceed
uninterrupted during the life of the project. The proposed pavement areas should be prepared as indicated in the Site
Preparation and Earthwork section of this report. We provide further detail for suitable subgrade preparation in the
Foundation Support and Slab on Grade support sections of this report. We can provide asphalt and concrete pavement
recommendations if it is planned for the project.
Stormwater Infiltration Potential
The presence of native, medium dense to dense, very sandy gravels to gravelly sands with generally low fines contents
exposed within our subsurface explorations appear to be suitable for infiltration at depths greater than 4 feet BGS. Dense,
low permeability uncontrolled fill was encountered near the surface and is expected to be encountered at variable depths
within the site. Silt lenses, if encountered, may present challenges during construction of the planned facilities. We
recommend these soils be removed from the footprint of the planned stormwater infiltration facilities.
In situ testing, such as Pilot Infiltration Testing, may be required to determine design level infiltration rates for the project.
Certerra is available to perform Pilot Infiltration Testing at a later date and provide design infiltration rates once the
Stormwater Management Plan has been developed and facility bottom elevations can be referenced.
Conceptual Infiltration Results
In order to assist with the project design, we are providing a preliminary infiltration rate using the Grain Size Analysis
method outlined in Volume V,Chapter 5.4 of the 2019 Department of Ecology's Stormwater Management Manual for Western
Washington. This rate is to be used in the conceptual sizing of the planned facilities and will need to be confirmed through
field testing. It should be noted that the grain size analysis method does not take into account the density of a given soil unit
or the effects of groundwater mounding.
From the explorations in the areas of interest, seven representative soil samples were selected from native soils and
mechanically tested for grain size method as referenced above. The total correction factor applied to the initial saturated
hydraulic conductivity (Ksat)values was 0.25 based on the below variables.
• Site variability and number of locations tested (CF,): 0.7
• Test Method—Grain Size Analysis (CFt): 0.4
• Degree of influent control to prevent siltation and bio-buildup (CFm): 0.9
Based on the grain size approach with the referenced correction factors incorporated, a preliminary infiltration rate of 10
inches per hour could be used in the conceptual sizing of the stormwater management facilities. This rate assumes that
facilities will be founded in the Marysville Sand or Arlington Gravel deposits encountered at depths greater than 4 feet BGS.
certerra.com 20527 671"Avenue NE,Arlington,WA 98223 11
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Infiltration facilities should not be founded in existing fill soils. As stated above, this rate is considered preliminary and
should not be used for final design without a reviewed by Certerra and/or confirmation of the rate through field
testing.This rate also assumes separation of at least 5 feet from the base of the facilities and any hydraulic restriction layer
is maintained. If this separation is not feasible a groundwater mounding analysis should be performed prior to completion of
the facility design.
At the time of this report, a specific infiltration facility design is not available. As such, it should be expected that multiple
iterations may be needed to initially size facilities and then determine the necessity of reductions to the presented infiltration
rate to account for groundwater mounding.
Stormwater Treatment
The stormwater facilities on-site may require some form of pollutant pretreatment with an amended soil prior to on-site
infiltration or offsite discharge. The reuse of on-site topsoil is often the most sustainable and cost-effective method for
pollutant treatment purposes.Cation exchange capacities,organic contents,and pH of site subsurface soils were also tested
to determine possible pollutant treatment suitability.
Cation exchange capacity, organic content, and pH tests were performed by Northwest Agricultural Consultants on two soil
samples collected from the project site.A summary of the laboratory test results is presented in Table 2 below.
Suitability for onsite pollutant treatment is determined in accordance with SSC-6 of the Manual. Soils with an organic content
of greater than or equal to 1 percent and a cation exchange capacity of greater than or equal to 5 meq/100 grams are
characterized as suitable for stormwater treatment. Based on the results shown in Table 2, the native Arlington Gravel and
Marysville Sand directly underlying the near-surface road base or uncontrolled fill is not suitable for stormwater treatment
due to the low cation exchange capacity, unless they are amended.
Table 2:
Cation Exchange Capacity, Organic Content, and .
Test Pit Sample Geologic Cation Exchange Organic
ID Depth Unit Capacity Content pH
0i grams)
TP-2 2.0 Arlington Gravel 3.0 1 1.09 6.6
TP-5 2.0 Arlington Gravel 4.5 10.26 6.3
On-site soils can be amended by mixing higher silt content soils or adding mulch (or other admixtures)to elevate the cation
exchange capacity and organic contents. On-site amended soil requires additional testing to confirm compliance with
ecological regulations. Certerra is available to perform additional laboratory testing as part of an expanded scope of services
if the soil is to be amended. Alternatively, the owner may elect to import amended soils with the desired properties for
planned treatment facilities.
Geotechnical Consultation and Construction Monitoring
Certerra recommends that we be involved in the project design review process. The purpose of the review is to verify that
the recommendations presented in this report are understood and incorporated in the design and specifications.
We also recommend that geotechnical construction monitoring services be provided. These services should include
observation by Certerra personnel during Structural Fill placement, compaction activities and subgrade preparation
operations to confirm that design subgrade conditions are obtained beneath the areas of improvement.
Periodic field density testing should be performed to verify that the appropriate degree of compaction is obtained. The
purpose of these services is to observe compliance with the design concepts, specifications, and recommendations of this
report. In the event that subsurface conditions differ from those anticipated before the start of construction, Certerra would
be pleased to provide revised recommendations appropriate to the conditions revealed during construction.
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Certerra is available to provide a full range of materials testing and special inspection during construction as required by the
local building department and the International Building Code. This may include specific construction inspections on
materials such as reinforced concrete, reinforced masonry,wood framing and structural steel.These services are supported
by our fully accredited materials testing laboratory.
Use of This Report
Certerra has prepared this report for the exclusive use of 2812 Architecture and their design consultants for specific
application to the design of the proposed Reece Construction Debris Sorting Facility located at development located at 5802
Cemetery Road in Arlington, Washington. Use of this report by others is at the user's sole risk. This report is not applicable
to other site locations. Our services are conducted in accordance with accepted practices of the geotechnical engineering
profession; no other warranty, express or implied, is made as to the professional advice included in this report.
Our site explorations indicate subsurface conditions at the dates and locations indicated. It is not warranted that these
conditions are representative of conditions at other locations and times. The analyses, conclusions, and recommendations
contained in this report are based on site conditions to the limited depth and time of our explorations, a geological
reconnaissance of the area,and a review of previously published geological information for the site. If variations in subsurface
conditions are encountered during construction that differ from those contained within this report, Certerra should be
allowed to review the recommendations and, if necessary, make revisions. If there is a substantial lapse of time between
submission of this report and the start of construction, or if conditions change due to construction operations at or adjacent
to the project site, we recommend that we review this report to determine the applicability of the conclusions and
recommendations contained herein.
The earthwork contractor is responsible to perform all work in conformance with all applicable WISHA/OSHA regulations.
Certerra is not responsible for job site safety on this project, and this responsibility is specifically disclaimed.
Attachments: Figure 1 Vicinity Map
Figure 2 Site and Exploration Plan
Figure 3 Typical Footing and Wall Drain Section
Figure 4 Soil Classification System and Key
Figures 5-7 Test Pit Exploration Logs
Figure 8 Grain Size Test Data
Attachment NW Agricultural Consultants Test Results
Attachment Report Limitations and Guidelines for its Use (3 Pages)
References
American Society of Civil Engineers, (2022). Minimum design loads and associated criteria for buildings and other structures:ASCE/SEI
7-22. Reston,Virginia:American Society of Civil Engineers.
American Society for Testing and Materials(ASTM). Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil
Classification System).ASTM D2487—17el.
American Society for Testing and Materials(ASTM). Standard Practice for Description and Identification of Soils(Visual-Manual
Procedures).ASTM D2488—17el.
Arlington (WA) Municipal Code—Chapter 20.93 Part V(Geologically Hazardous Areas),June 4,2025. Retrieved August 2025.
Gariepy, D.,Graul,C. Heye,A., Howie, D., Labib, F.&Song, K. (n.d.)2019. Stormwater Management Manual for Western Washington
(2019 SMMWW)(pp. 1-1108)(United States,Washington Department of Ecology).
GeoTest Services, Inc.,Geotechnical Engineering Report—Construction Office and Scale Relocation, 5802 Cemetery Road,Arlington,
Washington. Project No.20-0888, November 25,2020. Report prepared for Reece Construction Company.
certerra.com 20527 671"Avenue NE,Arlington,WA 98223 13
f CERTERRA Materially Better'""1 GEOTEST
Minard.J.P., 1985, Geologic map of the Arlington West 7.5-minute quadrangle, Snohomish County, Washington: U.S. Geological Survey
MF-1740,scale 1:24,000.
Newcomb, R.C., 1952,Ground-water resources of Snohomish County, Washington: U.S. Geological Survey,Water-Supply Paper 1135,
scale 1:62,500.
USDA Web Soil Survey. (August 27,2024). Retrieved August 2025, from
https.Ilwebsoilsurvey.sc.egov.usda.govIAppIWebSoilSurvey.aspx.
Washington State Department of Natural Resources-Online Web Services. Washington Geologic Information Portal. Retrieved in
August 2025.
certerra.com 20527 6711 Avenue NE,Arlington,WA 98223 14
VW Aff
544 Map Referenced from Google Terrain using QGIS 3.34.5-Prizren
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0 7.5 15 22.5 mi
Date: 8-20-2025 By: JV Scale: As Shown Project
VICINITY MAP 25-1772
CERTERRA REECE CD PLANT Figure
GEOTEST 5802 CEMETERY ROAD
ARLINGTON,WASHINGTON
Map Referenced from Google Hybrid using QGIS 3.34.5-Prizren
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br ? f 1'
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'� tea. .. 'r .�"• � c ~ S '"'�'� � `' t
V; TP-5 xJ TP-A' .
0 100 200 300 ft TP-# =Approximate Test Pit Location
009- =Subject Parcel Boundaries
Date: 8-20-2025 By: JV Scale: As Shown Project
SITE AND EXPLORATION PLAN 25-1772
CERTERRA REECE CD PLANT Figure
101� GEOTEST 5802 CEMETERY ROAD
ARLINGTON,WASHINGTON 2
CONCEPTUAL FOOTINGS WITH INTERIOR SLAB-ON-GRADE
' ' < Typical Framing
Compacted Low-Permeability Soil
(12 inch minimum)
Floor Slab
or Pavement •,•,',' , , , , , , , , , , , , , , , ,
(2 inch minimum)
. . . . . . . . . . . . . . . . . . .
, , , , , , , , , , , , , , , , ,
Slope to drain away
Vapor Barrier
from structure.
•.f:r:f:r:f:f:::r:;:r:r:r:r. . f f.;: .;.
_ — — ',',',' ti'ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•ti•
•+•+•�• ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti. .ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti.ti•tilti.l
Gravel Capillary Break
minimum,typically clear crushed)
Suitable Soil
/ +,+,+• .
•,•,• •. •. Free Draining Sand
+ +' and Gravel Fill
Approved Non-woven / •,•,'
Geotextile Filter Fabric + + + + + + + +
(18 inch minimum fabric lap) ' '
Suitable Soil
Drainage Material
(Drain Rock or Clear
Crushed Rock w/no fines) Appropriate Waterproofing
Applied to Exterior of Wall
Four Inch Diameter,Perforated,Rigid PVC Pipe
(Perforations oriented down directed to suitable discharge)
Notes:
Footings should be properly buried for frost protection in accordance with International Building
Code or local building codes (Typically 18 inches below exterior finished grades).
This figure is not intended to be representative of a design. This figure is intended to present
concepts that can be incorporated into a functional foundation drain designed by a Civil Engineer. In
all cases, refer to the Civil plan sheet for drain details and elevations.
This footing drain detail may need to be modified from this conceptual drawing to fit the dimensions
of the planned footing and slab configuration.
Date:8-20-2025 By: JV Scale: None Project
CONCEPTUAL FOOTING & WALL DRAIN SECTION 25-1772
CERTERRA REECE CD PLANT
1 GEOTEST 5802 CEMETERY ROAD Figure
ARLINGTON,WASHINGTON 3
Soil Classification System
Uscs
MAJOR GRAPHIC LETTER TYPICAL
DIVISIONS SYMBOL SYMBOL DESCRIPTIONSt't(2)
GRAVEL AND CLEAN GRAVEL o o o°o;o GW Well-graded gravel;gravel/sand mixture(s);little or no fines
GRAVELLY SOIL (Little or no fines) o,6 o�?o GP Poorly graded gravel;gravel/sand mixture(s);little or no fines
O 'N ° ° .
m y
.� (More than 50%of
coarse fraction retained GRAVEL WITH FINES GM Silty gravel;gravel/sand/silt mixture(s)
M a)W E o on No.4 sieve) (Appreciable amount of
z o N fines) GC Clayey gravel;gravel/sand/clay mixture(s)
(7 LO z $W Well-graded sand;gravelly sand;little or no fines
w SAND AND CLEAN SAND
CO c;t SANDY SOIL (Little or no fines)
QSP Poorly graded sand;gravelly sand;little or no fines
O 2 (More than 50%of
U_ m coarse fraction passed SAND WITH FINES SM Silty sand;sand/siltmixture(s)
through No.4 sieve) (Appreciable amount of
fines) SC Clayey sand;sand/clay mixture(s)
Inorganic silt and very fine sand;rock flour;silty or clayey fine
f6 ��', SILT AND CLAY ML sand or clayey silt with slight plasticity
.N Inorganic clay of low to medium plasticity;gravelly clay;sandy
0 E N (Liquid limit less than 50) C�' clay;silty clay;lean clay
W O o
z o z QL Organic silt;organic,silty clay of low plasticity
O C N
� 0ca0
C�7 r� SILT AND CLAY MH Inorganic silt;micaceous or diatomaceous fine sand
CH Inorganic clay of high plasticity;fat clay
LL 5 E (Liquid limit greater than 50)
OH Organic clay of medium to high plasticity;organic silt
HIGHLY ORGANIC SOIL PT Peat;humus;swamp soil with high organic content
GRAPHIC LETTER
OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS
PAVEMENT AC Or PC Asphalt concrete pavement or Portland cement pavement
ROCK RK Rock(See Rock Classification)
WOOD WD Wood,lumber,wood chips
DEBRIS O O O Dg I Construction debris,garbage
Notes: 1. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils(Visual-Manual Procedure),
as outlined in ASTM D 2488.Where laboratory index testing has been conducted,soil classifications are based on the Standard Test Method for Classification
of Soils for Engineering Purposes,as outlined in ASTM D 2487.
2. Soil description terminology is based on visual estimates(in the absence of laboratory test data)of the percentages of each soil type and is defined as follows:
Primary Constituent: >50%-"GRAVEL,""SAND,""SILT,""CLAY,"etc.
Secondary Constituents: >30%and<50%-"very gravelly,""very sandy,""very silty,"etc.
>12%and<30%-"gravelly,""sandy,""silty,"etc.
Additional Constituents: > 5%and<12%-"slightly gravelly,""slightly sandy,""slightly silty,"etc.
< 5%-"trace gravel,""trace sand,""trace silt,"etc.,or not noted.
Drilling and Sampling Key Field and Lab Test Data
SAMPLE NUMBER&INTERVAL SAMPLER TYPE
Code Description Code Description
Sample Identification Number a 3.25-inch O.D.,2.42-inch I.D.Split Spoon PP=1.0 Pocket Penetrometer,tsf
b 2.00-inch O.D.,1.50-inch I.D.Split Spoon TV=0.5 Torvane,tsf
Recovery Depth Interval c Shelby Tube PID=100 Photoionization Detector VOC screening,ppm
1� 14-- Sample Depth Interval d Grab Sample W=10 Moisture Content,%
J e Other-See text if applicable D=120 Dry Density,pcf
Portion of Sample Retained 1 300-lb Hammer,30-inch Drop -200=60 Material smaller than No.200 sieve,%
for Archive or Analysis 2 140-lb Hammer,30-inch Drop GS Grain Size-See separate figure for data
3 Pushed AL Atterberg Limits-See separate figure for data
4 Other-See text if applicable GT Other Geotechnical Testing
Groundwater CA Chemical Analysis
L7 Approximate water elevation at time of drilling(ATD)or on date noted. Groundwater
ATD levels can fluctuate due to precipitation,seasonal conditions,and other factors.
Reece CD Plant Figure
r CERTERRA 5802 Cemetery Road Soil Classification System and Key A
f GEOTEST /1
Arlington, Washington u1
TP-1
SAMPLE DATA SOIL PROFILE GROUNDWATER
o
E— a E -6 Excavation Method- Tracked Excavator
T
za, > v U N Ground Elevation(ft). —118
v E S E o M N Excavated By: Reece Construction Company
0 N 06 In H C7 D
0 GP- Very dense,gray-brown to brown,dry to
= d GM damp,slightly silty,sandy GRAVEL with brick
ML debris(Road Base) _ Groundwater not encountered.
2 ------- ----------J
= d Hard,light brown,damp,slightly gravelly,
sandy SILT with orange mottling,asphalt
debris(Uncontrolled Fill)
4 = d o Gp \ PP=>4.5tsf
6 0 \ Certerra observed a decrease in relative /
6 o 0 consistency to stiff to—very stiff below 3 feet._J
= d O o Medium dense,brown,damp,very sandy
= GRAVEL(Arlington_Gravel)
dW=5 SP
_J
g GS Medium dense,gray-brown,damp,slightly
gravelly SAND(Marysville Sand)
10 = d
Excavation terminated due to excavator
12 Test Pit Completed 07/31/25 restrictions.
Total Depth of Test Pit=11.0 ft.
TP-2
SAMPLE DATA SOIL PROFILE GROUNDWATER
o
E_ a E -6 Excavation Method. Tracked Excavator
T
_v v Y T Ground Elevation(ft -119
Ln
Y a cu Y a � Q O7
v E S E N Excavated By: Reece Construction Company
0 N Off N H CJ
0 GP- Very dense,gray-brown to brown,dry to
= d GM damp,slightly silty,sandy GRAVEL with brick
o GP debris(Road Base) Groundwater not encountered.
d Do 0 Dense,brown to dark brown,damp,very
Q O sandy GRAVEL with cobbles(Arlington
0 p Gravel)
4 = d G53 0,o Certerra observed an approximately 1-foot
0 o thick gravel layer at 3 feet.
o Certerra observed an increase in moisture
6 o a content below 4 feet.
= d o0
00
8 =
d oa
o0
00
10 = d SP Mediumdense,brown,moist,slightly
gravelly SAND(Marysville Sand)
Excavation terminated due to excavator
12 Test Pit Completed 07/31/25 restrictions.
Total Depth of Test Pit=11.0 ft.
Notes: 1.Stratigraphic contacts are based on field interpretations and are approximate.
2.Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3.Refer to"Soil Classification System and Key"figure for explanation of graphics and symbols.
4.Approximate elevations obtained from CalTopo interactive web portal.
Reece CD Plant Figure
UOTUT
r RA 5802 Cemetery Road Log of Test Pits
f GEOTEST
Arlington, Washington
TP-3
SAMPLE DATA SOIL PROFILE GROUNDWATER
o
E— a E -6 Excavation Method- Tracked Excavator
T
za, > v U N Ground Elevation(ft —119
v E S E o M N Excavated By: Reece Construction Company
0 N 06 In
0 GP- Very dense,gray-brown to brown,dry to
= d GM damp,slightly silty,sandy GRAVEL with brick
debris(Road Base) Groundwater not encountered.
2 o GP Dense,dark orange brown,damp,sandy
= d on GRAVEL with cobbles(Uncontrolled Fill)
OGP Medium dense,gray-brown,damp,very
4 = d 010 sandy GRAVEL with cobbles,trace boulders
00 (Arlington Gravel)
o°
°
o .
6 —Mir:: d q.a: Certerra observed a decrease in boulder
6 0. content below 6 feet.
o a.
8 D°o
R
= d W=4 O
GS o a
10
Excavation terminated due to excavator
Test Pit Completed 07/31/25 restrictions
Total Depth of Test Pit=10.0 ft.
12
TPA
SAMPLE DATA SOIL PROFILE GROUNDWATER
o
E_ a E -6 Excavation Method. Tracked Excavator
T
Ln
_v > v T Ground Elevation(ft "121
Y a cu Y a � Q O7
v E S E M N Excavated By: Reece Construction Company
In of !n H CJ D
0 GP- Very dense,gray-brown to brown,dry to
= d GM damp,slightly silty,sandy GRAVEL with brick
SM debris(Road Base) Groundwater not encountered.
------------------J
Dense,dark orange-brown,damp,silty,
2
= d gravelly SAND with scattered asphalt debris
(Uncontrolled Fill)
4 SP Medium dense to dense,gray-brown,damp,
= d very gravelly SAND with cobbles,trace
boulders(Arlington Gravel)
6 = d W=6
GS Certerra observed an increase in cobble
content below 6 feet.
8
Test Pit Completed 07/31/25 Excavation terminated due to caving.
Total Depth of Test Pit=8.0 ft.
Notes: 1.Stratigraphic contacts are based on field interpretations and are approximate.
2.Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3.Refer to"Soil Classification System and Key"figure for explanation of graphics and symbols.
4.Approximate elevations obtained from CalTopo interactive web portal.
CERReece CD Plant Figure
r UOTUT RA 5802 Cemetery Road Log of Test Pits G 1 GEOTEST
Arlington, Washington V
TP-5
SAMPLE DATA SOIL PROFILE GROUNDWATER
o
�
a E -6 Excavation Method- Tracked Excavator
T
z—a, > v U N Ground Elevation(ft -120
v E S E o M N Excavated By: Reece Construction Company
0 N 06 N H (7 D
° GP- Very dense,gray-brown to brown,dry to
= d GM damp,slightly silty,sandy GRAVEL with brick
GP- debris(Road Base) ,' Groundwater not encountered.
�--_LRoa ----------
2 = d D, c GM Dense,dark orange-brown,damp.slightly
silty,sandy GRAVEL th trace cobbles
_ _ (Weathered Arlington_Gravel)_________
4 = d W=5 SP Medium dense,gray-brown,damp,SAND
GS (Marysville Sand)
6
= d o GP Medium dense,gray brown,damp,gravelly
o,a. SAND with trace cobbles(Arlington Gravel)
8 b.o
= d o,o.
°a. Certerra observed a decrease in cobbles
10
d ° below 9 feet.
Excavation terminated due to excavator
Test Pit Completed 07/31/25 restrictions.
Total Depth of Test Pit=10.0 ft.
12
Notes: 1.Stratigraphic contacts are based on field interpretations and are approximate.
2.Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3.Refer to"Soil Classification System and Key"figure for explanation of graphics and symbols.
4.Approximate elevations obtained from CalTopo interactive web portal.
CERReece CD Plant Figure
r UOTUT RA 5802 Cemetery Road Log of Test Pits 7
f GEOTEST I
Arlington, Washington
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 4 112 3 4 6 810 1416 20 30 40 50 60 100 140 200
100
90
80
70
60
T
Q
50
ii
c
U
0040
30
20
10
IL
100 10 1 0.1 0.01 0.001
Grain Size in Millimeters
Cobbles Gravel Sand Silt or Clay
coarse fine coarse medium fine
Point Depth Classification ILL PL PI C,� Cu
• TP-1 7.5 Slightly gravelly SAND (SP) 1.09 2.47
m TP-2 4.0 Very sandy GRAVEL (GP) 0.64 18.00
A TP-3 9.0 Very sandy GRAVEL (GP) 2.59 24.45
* TP-4 6.0 Very gravelly SAND (SP) 0.56 20.84
O TP-5 4.0 SAND (SP) 1.08 2.21
Point Depth D D D D D %Coarse %Fine %Coarse %Medium %Fine %Fines
p 90 60 50 30 10 Gravel Gravel Sand Sand Sand
0 TP-1 7.5 2.773 0.431 0.374 0.286 0.175 0.0 8.4 2.6 29.6 56.1 3.3
m TP-2 4.0 17.299 9.085 5.404 1.716 0.505 5.4 47.0 15.0 25.3 4.8 2.4
A TP-3 9.0 15.572 8.246 6.27 2.682 0.337 0.0 60.1 14.9 13.2 7.3 4.4
* TP-4 6.0 13.027 3.218 1.946 0.529 0.154 0.0 32.2 17.4 23.6 19.8 7.0
O TP-5 4.0 1.77 0.398 0.353 0.278 0.18 0.0 3.7 5.2 25.5 63.6 1.9
C, = D3o2/(D60* D1o) To be well graded: 1 < C,< 3 and
C,, = D6o/D10 C, > 4 for GW or C, > 6 for SW
Reece CD Plant Figure
r CERTERRA 5802 Cemetery Road Grain Size Test Data Q.r GEOTEST CJ Arlington, Washington
Northwest Agricultural
Consultants
Z SW-F,11,Ave re e—. WA"I%
Report: 73513-1 S07D145O --&— 1,b4P,. ,om GEOTEST SERVICES INC
Date: 2025-08-03 741 MARINE DR
Project Name: Reece BELLINGHAM,WA 98225
Project Number: 10-251772-0
Sample Sulfate pH Resistivity OM CEC Chloride Moisture Sand Silt Clay Class
ID ma/kq S.U. ohm-m % me /100 mg/kg % % % %
TP-2 @ 2.0 6.6 1.09 3.0
TP-5 @ 2.0 6.3 1.58 4.5
Analyte Sulfate pH Resistivity OM CEC Chloride Moisture Sand Silt Clay Class
Method SM-4500 SO4 E SM 4500-H+B SM 2510 B ASTM D2974 EPA 9081 ASTM D512 Gravimetric Hydrometer Hydrometer Hydrometer Hydrometer
f CERTERRA
1 GEOTEST
REPORT LIMITATIONS AND GUIDELINES FOR ITS USE '
Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such
risks,you can manage them. The following information is provided to help:
Geotechnical Services are Performed for Specific Purposes, Persons, and Projects
At Certerra our geotechnical engineers and geologists structure their services to meet specific needs of our clients. A
geotechnical engineering study conducted for a civil engineer may not fulfill the needs of an owner,a construction contractor
or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering
report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineer who prepared
it.And no one—not even you—should apply the report for any purpose or project except the one originally contemplated.
Read the Full Report
Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely
on an executive summary. Do not read selected elements only.
A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors
Certerra's geotechnical engineers consider a number of unique, project-specific factors when establishing the scope of a
study. Typical factors include: the clients goals, objectives, and risk management preferences; the general nature of the
structure involved its size, and configuration; the location of the structure on the site; and other planned or existing site
improvements, such as access roads, parking lots, and underground utilities. Unless Certerra, who conducted the study
specifically states otherwise, do not rely on a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specific site explored, or
• completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect:
• the function of the proposed structure,as when it's changed,for example,from a parking garage to an office building,
or from a light industrial plant to a refrigerated warehouse,
• elevation, configuration, location, orientation, or weight of the proposed construction,
• alterations in drainage designs; or
• composition of the design team;the passage of time; man-made alterations and construction whether on or adjacent
to the site; or by natural alterations and events, such as floods, earthquakes or groundwater fluctuations; or project
ownership.
Always inform Certerra's geotechnical engineer of project changes—even minor ones—and request an assessment of their
impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do
not consider developments of which they were not informed.
Subsurface Conditions Can Change
This geotechnical or geologic report is based on conditions that existed at the time the study was performed. Do not rely
on the findings and conclusions of this report, whose adequacy may have been affected by: the passage of time; by man-
made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or
1 Information in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(asfe.org)
f CERTERRA
f GEOTEST
groundwater fluctuations. Always contact Certerra before applying the report to determine if it is still relevant. A minor
amount of additional testing or analysis will help determine if the report remains applicable.
Most Geotechnical and Geologic Findings are Professional Opinions
Our site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples
are taken. Certerra's engineers and geologists review field and laboratory data and then apply their professional judgment
to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ—sometimes
significantly — from those indicated in your report. Retaining Certerra who developed this report to provide construction
observation is the most effective method of managing the risks associated with anticipated or unanticipated conditions.
A Report's Recommendations are Not Final
Do not over-rely on the construction recommendations included in this report. Those recommendations are not final,
because geotechnical engineers or geologists develop them principally from judgment and opinion. Certerra's geotechnical
engineers or geologists can finalize their recommendations only by observing actual subsurface conditions revealed during
construction. Certerra cannot assume responsibility or liability for the report's recommendations if our firm does not perform
the construction observation.
A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation
Misinterpretation of this report by other design team members can result in costly problems. Lower that risk by having
Certerra confer with appropriate members of the design team after submitting the report. Also, we suggest retaining
Certerra to review pertinent elements of the design teams plans and specifications. Contractors can also misinterpret a
geotechnical engineering report. Reduce that risk by having Certerra participate in pre-bid and preconstruction
conferences, and by providing construction observation.
Do not Redraw the Exploration Logs
Our geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs
and laboratory data. To prevent errors of omissions,the logs included in this report should never be redrawn for inclusion in
architectural or other design drawings. Only photographic or electronic reproduction is acceptable; but recognizes that
separating logs from the report can elevate risk.
Give Contractors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface
conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete
geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, consider advising the
contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited;
encourage them to confer with Certerra and/or to conduct additional study to obtain the specific types of information they
need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional
study. Only then might you be in a position to give contractors the best information available,while requiring them to at least
share some of the financial responsibilities stemming from unanticipated conditions. In addition, it is recommended that a
contingency for unanticipated conditions be included in your project budget and schedule.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that geotechnical engineering or geology is far less
exact than other engineering disciplines. This lack of understanding can create unrealistic expectations that can lead to
disappointments, claims, and disputes. To help reduce risk, Certerra includes an explanatory limitations section in our
f CERTERRA
f GEOTEST
reports. Read these provisions closely. Ask questions and we encourage our clients or their representative to contact our
office if you are unclear as to how these provisions apply to your project.
Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report
The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to
perform a geotechnical or geologic study. For that reason, a geotechnical engineering or geologic report does not usually
relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated containments, etc. If you have not yet obtained your own environmental information, ask your
geotechnical consultant for risk management guidance. Do not rely on environmental report prepared for some one else.
Obtain Professional Assistance to Deal with Biological Pollutants
Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant
amounts biological pollutants from growing on indoor surfaces. Biological pollutants includes but is not limited to molds,
fungi, spores, bacteria and viruses. To be effective, all such strategies should be devised for the express purpose of
prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional biological pollutant
prevention consultant. Because just a small amount of water or moisture can lead to the development of severe biological
infestations, a number of prevention strategies focus on keeping building surfaces dry. While groundwater,water infiltration,
and similar issues may have been addressed as part of this study, the geotechnical engineer or geologist in charge of this
project is not a biological pollutant prevention consultant;none of the services preformed in connection with this geotechnical
engineering or geological study were designed or conducted for the purpose of preventing biological infestations.