DNS BLD2021-1385+Geotechnical_Report+10.6.2021_2.34.44_PM+2448457Geotechnical Engineering Report
Port Administration and Maintenance Building
471 Admiral Way
Edmonds, Washington
October 4, 2021
Prepared for
Port of Edmonds
336 Admiral Way
Edmonds, Washington 98020
LANDAU
ASSOCIATES
155 NE 100th St, Ste 302
Seattle, WA 98125
206.631.8680
Landau Associates
Geotechnical Engineering Report
Port Administration and Maintenance Building
471 Admiral Way
Edmonds, Washington
This document was prepared by, or under the direct supervision of, the undersigned, whose seal is
affixed below. _&AJLV _
Name: Sean Gertz, PE
Washington/No. 20100325
Date: October 4, 2021
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Document prepared by: - Sean Gertz, PE
Project Manager
4 Document reviewed by: L,) Steven R. Wright, PE
Quality Reviewer
Date: October 4, 2021
Project No.: 0173039.010.011
File path: \\edmdata0l\projects\173\039.010\R\Signature Page.docx
Project Coordinator: MCS
LANDAU
ASSOCIATES
Landau Associates
TABLE OF CONTENTS
Page
1.0
INTRODUCTION
..............................................................................................................................1-1
1.1
Project Description.............................................................................................................1-1
1.2
Scope of Services................................................................................................................1-1
2.0
SITE CONDITIONS...........................................................................................................................2-1
2.1
Geologic Setting..................................................................................................................2-1
2.2
Surface Conditions..............................................................................................................2-1
2.3
Subsurface Explorations.....................................................................................................2-1
2.3.1
Soil Conditions.................................................................................................2-2
2.3.2
Groundwater Conditions..................................................................................2-2
3.0
CONCLUSIONS AND RECOMMENDATIONS....................................................................................3-1
3.1
Seismic Considerations.......................................................................................................3-1
3.1.1
Site Classification and Seismic Design Parameters
...........................................3-1
3.1.2
Liquefaction and Lateral Spreading..................................................................3-1
3.2
Earthwork and Grading......................................................................................................3-2
3.2.1
Site Preparation...............................................................................................3-2
3.2.2
Engineered Fill Materials.................................................................................3-3
3.2.3
Reuse of Site Soils............................................................................................3-3
3.2.4
Wet Weather Earthwork Considerations..........................................................3-4
3.2.5
Subgrade Preparation......................................................................................3-4
3.2.6
Temporary Construction Dewatering...............................................................3-5
3.3
Utility Construction............................................................................................................3-5
3.3.1
Temporary Excavations....................................................................................3-5
3.3.2
Pipe Foundation Support.................................................................................3-6
3.3.3
Pipe Bedding and Trench Backfill.....................................................................3-6
3.4
Flexible Pavement Design...................................................................................................3-7
3.5
Stormwater Infiltration Considerations.............................................................................3-7
3.6
Foundations........................................................................................................................3-8
3.6.1
Rammed Aggregate Piers.................................................................................3-8
3.6.2
Shallow Foundation Support............................................................................3-9
3.6.3
Slab -On -Grade Support..................................................................................3-10
3.6.4
Foundation Settlement..................................................................................3-10
3.6.5
Foundation and Site Drainage........................................................................3-10
3.7
Lateral Earth Pressures on Below -Grade Walls................................................................3-11
4.0
REVIEW OF DOCUMENTS AND CONSTRUCTION OBSERVATIONS
.................................................4-1
5.0
USE OF THIS REPORT......................................................................................................................5-1
6.0
REFERENCES
...................................................................................................................................6-1
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and Maintenance Building iii
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FIGURES
Figure Title
1 Vicinity Map
2 Site and Exploration Plan
TABLES
Table Title
1 20181nternational Building Code Seismic Design Parameters
2 Engineered Fill Materials
3 Recommended Soil Parameters for Design of Temporary Shoring
APPENDICES
Appendix Title
A Field Explorations
B Laboratory Soil Testing
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LIST OF ABBREVIATIONS AND ACRONYMS
ACI.......................................................................................American Concrete Institute
ASTM.................................................................................................ASTM International
bgs................................................................................................. below ground surface
ft....................................................................................................................... foot/feet
H:V..................................................................................................horizontal to vertical
IBC........................................................................................ International Building Code
LAI............................................................................................... Landau Associates, Inc.
NAVD 88............................................................North American Vertical Datum of 1988
pcf................................................................................................. pounds per cubic foot
Port....................................................................................................... Port of Edmonds
psf.............................................................................................. pounds per square foot
WAC............................................................................ Washington Administrative Code
WSDOT............................................... Washington State Department of Transportation
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1.0 INTRODUCTION
This report summarizes the results of geotechnical engineering services provided by Landau
Associates, Inc. (LAI) in support of the Port of Edmonds (Port; project owner)
Administration/Maintenance Building project, located at 471 Admiral Way in Edmonds, Washington
(site; Figure 1).
This report has been prepared with information provided by the Port and CG Engineering, Inc. (project
civil engineer) and with data collected during LAI's 2017 critical areas review and 2021 geotechnical
field exploration and laboratory testing programs.
1.1 Project Description
The Port proposes to develop the site with a multi -story administration and maintenance building.
The building will measure 100 feet (ft) long by 70 ft wide and will have an area of approximately 6,650
square feet. Other proposed site improvements include utility upgrades and the addition of paved
parking areas. The Port may install infiltration trenches and rain gardens to manage stormwater
generated on site.
1.2 Scope of Services
LAI provided the following geotechnical services in accordance with the scope outlined in Professional
Services Agreement No. 2021-380, dated April 22, 2021:
• Reviewed readily available geologic maps and geotechnical reports for the site and the
surrounding area.
• Coordinated the clearance of underground utilities.
• Advanced one mud rotary boring into very dense subsurface soils at the proposed building
location.
• Collected representative soil samples to characterize site subsurface conditions.
• Completed geotechnical laboratory testing and engineering analyses on select soil samples
obtained from the boring.
• Developed geotechnical conclusions and recommendations to support design of the proposed
improvements.
• Prepared this report, which includes:
— a site and exploration plan (Figure 2). The plan shows the approximate locations of
relevant site features and past and present borings advanced by LAI.
— summary boring logs and laboratory test results.
— a discussion of near -surface soil and groundwater conditions observed at the site.
— seismic design considerations in accordance with the 2018 International Building Code
(IBC).
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— geotechnical recommendations for site earthwork and grading, including criteria for
stripping depth, subgrade preparation, construction dewatering, reuse of site
materials as structural fill, and structural fill placement and compaction.
— geotechnical recommendations for utility construction, including criteria for trench
excavation and temporary shoring, pipe foundation support, pipe bedding, initial
backfill materials, and trench backfill compaction.
— pavement design recommendations.
— an assessment of the feasibility of infiltrating stormwater on site.
— geotechnical design recommendations for shallow foundation support of the
proposed structure, including allowable soil bearing capacity, lateral resistance
criteria, minimum footing dimensions, slab -on -grade support, and settlement
estimates.
a discussion of ground improvement methods that can be used to limit settlement of
the proposed building.
— site and foundation drainage considerations.
— recommendations for geotechnical construction monitoring.
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2.0 SITE CONDITIONS
The following sections describe the geologic setting of the site and the surface and subsurface
conditions observed during LAI's field investigation. Interpretations of site conditions are based on
LAI's review of available geologic and geotechnical information and on the results of the subsurface
explorations and laboratory testing.
2.1 Geologic Setting
The site is located in the Central Puget Lowland, a wide, low-lying region between the Cascade Range
to the east and the Olympic Mountains to the west. The area was covered by ice sheets during the
Pleistocene Epoch. Surficial deposits in the vicinity of the site primarily consist of fill (Minard 1983),
likely the result of historical infilling along the Edmonds waterfront, where native marsh was partially
filled to promote commercial and industrial development.
Based on the results of its geologic data review, LAI infers that the fill is underlain by sediments of the
Whidbey Formation, typically dense, bedded, medium- to coarse -grained sand (Minard 1983).
Outcroppings of the Whidbey Formation are present along the lower bluffs of Puget Sound and may
measure up to 160 ft thick in the vicinity of the site. Compressible wetland deposits may be present
between the fill unit and the Whidbey Formation.
2.2 Surface Conditions
The site currently is used to stockpile bark mulch and other soils; it is generally level with little to no
vegetation. The site is bordered by Admiral Way to the west and BNSF Railway to the east.
Surrounding development includes a marina and associated facilities, restaurants, and commercial
retail spaces.
2.3 Subsurface Explorations
LAI has completed two field investigations to characterize subsurface soil and groundwater conditions
at the site. The first investigation was completed on June 8, 2017 and included one hollow -stem auger
boring (B-1) advanced 26.5 ft below ground surface (bgs). Findings were used to prepare a critical
areas report for the Port's Marine Retail Development project (LAI 2017). The second investigation
was completed on May 4, 2021 and included a mud rotary boring (B-2) advanced 36.5 ft bgs. The
approximate locations of the explorations are shown on Figure 2.
LAI personnel monitored the explorations, collected representative soil samples, and maintained
detailed logs of the subsurface soil and groundwater conditions observed. Copies of the logs and a
description of the field exploration program are provided in Appendix A.
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Samples were transported to LAI's soils laboratory for further examination and classification. Findings
are summarized in Appendix B.
2.3.1 Soil Conditions
The soil conditions in boring B-1 consisted of asphalt pavement underlain by an approximately
7-ft-thick layer of medium dense to dense sand. Approximately 5 ft of very soft to soft silt with
organics was observed beneath the sand. The silt was underlain by dense to very dense sand with
gravel; this unit extended to the maximum depth explored (26.5 ft).
The soil conditions in boring B-2 consisted of 11.5 ft of very loose to loose sand with variable silt
content. An approximately 6-inch-thick silt lens was observed at 7 ft bgs, and an approximately
3-inch-thick, organic silt lens was observed at 11.25 ft bgs. The organic silt layer was underlain by
medium dense to very dense sand with variable silt content; this unit extended to the maximum
depth explored (36.5 ft).
2.3.2 Groundwater Conditions
During LAI's June 2017 field investigation, groundwater was observed at approximately 9 ft bgs in
boring B-1. Boring B-2 was advanced using the mud rotary technique, which does not allow for
groundwater observation.
As part of its geotechnical study, LAI reviewed groundwater monitoring data collected for the
Jacobsen's Marine Facility project, located immediately north of the site (LAI 2007). Approximate
depths -to -groundwater were measured on August 30, September 1, September 6, October 3, and
November 11, 1995. The highest groundwater level (7.9 ft bgs, approximately 5.1 ft North American
Vertical Datum of 1988 [NAVD 88]) was recorded on November 11.
The groundwater conditions reported herein are for the specific locations and dates indicated and
may not be representative of other locations and/or times. Groundwater conditions will vary
depending on local subsurface conditions, weather conditions, tidal fluctuations, and other factors.
Groundwater levels are expected to fluctuate seasonally, with maximum levels occurring during late
winter and early spring.
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3.0 CONCLUSIONS AND RECOMMENDATIONS
Based on the results of LAI's field investigations and geotechnical engineering analyses, subsurface
conditions at the site are suitable for the proposed improvements, provided the following
recommendations are incorporated into the project design.
3.1 Seismic Considerations
The site is located in the seismically active Pacific Northwest and could be subject to ground shaking
from a moderate to major earthquake. Consequently, moderate seismic motion should be anticipated
during the design life of the project, and the proposed improvements should be designed to resist
seismic loading.
3.1.1 Site Classification and Seismic Design Parameters
LAI understands that the proposed structure will be designed in accordance with 20181BC standards.
The parameters in Table 1 can be used to compute seismic base shear forces (2017 ICC). A site -specific
ground motion hazard analysis was not performed; as a result, the long -period coefficient presented
in Table 1 is based on an exception in Section 11.4.8 of the American Society of Civil Engineers' (ASCE)
Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16).
Table 1. 2018International Building Code Seismic Design Parameters
Spectral response acceleration at short period (Ss) 1.285g
Spectral response acceleration at 1-second period (Si) 0.452g
Site class D(a)
Site coefficient (Fa) 1.0
Site coefficient (F.) 1.848(b)
(a) The site includes potentially liquefiable soils and is categorized by the American Society of Civil Engineers (ASCE; 2017)
as Site Class F. The ASCE provides an exception for structures with a fundamental period of vibration equal to or less than
0.5 second. LAI recommends that ground improvement activities are completed at the site to improve the engineering
properties of site soil. LAI recommends the use of Site Class D if the fundamental period of vibration of the proposed
structure is equal to or less than 0.5 second and ground improvement activities are completed at the site.
(b) When using the coefficient Fv = 1.848, observe the Exception 2 requirements for a ground motion hazard analysis.
Requirements are detailed in Section 11.4.8 of the ASCE's Minimum Design Loads and Associated Criteria for Buildings and
Other Structures (ASCE/SEI 7-16). The coefficient should be used only to calculate T,.
Fa, F = short -period (0.2-second period) and long -period (1.0-second period) site coefficients, respectively
g = force of gravity
S,, S1 = spectral response accelerations at 0.2- and 1.0-second periods, respectively.
3.1.2 Liquefaction and Lateral Spreading
Liquefaction is a seismic hazard in which the strength and stiffness of soil is reduced by earthquake
shaking, causing the soil to behave, temporarily, like a liquid. Liquefaction often occurs in loose,
granular soils and non -plastic silts located below the groundwater table, during or shortly after a
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strong seismic event. In LAI's opinion, site soils are susceptible to liquefaction and liquefaction -
induced settlement. A design -level earthquake could result in differential and liquefaction -induced
settlement on the order of 1.5 inches each.
Seismically induced soil liquefaction can result in lateral spreading. Lateral spreading typically occurs
on sloping ground or free faces underlain by loose soils and a shallow groundwater table. During a
large seismic event, blocks of overburden soil may slide over lower, liquefied soil layers, displacing
down slope. The site includes potentially liquefiable soils and areas of vertical relief. As such, site soils
may be susceptible to lateral spreading. Using the empirical method developed by Youd et al. (2002),
LAI estimates that approximately 2 to 6 inches of lateral spreading could occur at the site as a result of
the design earthquake.
LAI understands that the proposed administration and maintenance building will be a Risk Category II
structure with no concrete or masonry wall systems. The design team has indicated that the span
between bearing points (L) will be 27 ft. Per the ASCE (2017), deep foundations are required where
estimated lateral spreading displacements are greater than the values identified in Table 12.13-2 (18
inches for Risk Category II structures). Structures may be supported on shallow foundations, provided
the estimated liquefaction -induced differential settlement is below the limits established in Table
12.13-3 (0.010L, 3.24 inches for this structure), and the structure is designed in accordance with
Section 12.13.9.2.1 (ASCE 2017).
Though a structure designed in accordance with Section 12.13.9.2.1 (ASCE 2017) can be supported on
shallow foundations, ground improvement, designed by a specialty contractor, is recommended to
improve the static foundation performance of the structure. LAI anticipates that ground improvement
will also help to reduce liquefaction and lateral spreading hazards at the site.
3.2 Earthwork and Grading
Earthwork will likely consist of clearing, grubbing, and stripping areas designated for improvement
and preparing building, pavement, and utility subgrades.
3.2.1 Site Preparation
Existing vegetation should be cleared or grubbed in accordance with Section 2-01 of the Washington
State Department of Transportation's 2021 Standard Specifications for Road, Bridge, and Municipal
Construction (2021 WSDOT Standard Specifications). Material generated during clearing and grubbing
should be disposed of at an approved offsite location. Sod, topsoil, and organic -rich soils should be
stripped to expose underlying inorganic soil. Stripped material is not considered suitable for reuse as
structural fill and should be disposed of off site or spread in areas of the site where several inches of
postconstruction settlement would be tolerable.
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3.2.2 Engineered Fill Materials
Table 2 includes a list of engineered fill materials and their recommended applications. All fill
materials, except Gravel Backfill for Pipe Zone Bedding and Bank Run Gravel for Trench Backfill, should
be placed and compacted in accordance with Section 2-03.3(14)C, Method C of the 2021 WSDOT
Standard Specifications. Gravel Backfill for Pipe Zone Bedding should be placed and compacted in
accordance with Section 7-08.3(1)C of the 2021 WSDOT Standard Specifications. Pipe zone backfill and
backfill above the pipe zone should be placed in accordance with Section 7-08.3(3) of the 2021
WSDOT Standard Specifications. The maximum dry density and optimum moisture content can be
determined using ASTM International (ASTM) standard test method D1557, Standard Test Methods
for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-Ibf/ft3 (2,700 kN-
m/m3))•
Table 2. Engineered Fill Materials
Engineered Fill Type
Granular Fill
Structural Fill
Top Course
Base Course
Gravel Backfill for Drains
Gravel Backfill for Pipe Zone
Bedding
Specification
Gravel Borrow — WSDOT
Specification 9-03.14(1)
Select Borrow — WSDOT
Specification 9-03.14(2)
Crushed Surfacing Top Course —
WSDOT Specification 9-03.9(3)
Crushed Surfacing Base Course —
WSDOT Specification 9-03.9(3)
WSDOT Specification 9-03.12(4)
WSDOT Specification 9-03.12(3)
Bank Run Gravel for Trench Backfill WSDOT Specification 9-03.19
Application
• Imported fill material
• Wet weather working platform
• Replacement of overexcavated,
unsuitable material
• Site subgrade repair
• Upper 2 inches of crushed surfacing
beneath pavement
• Crushed surfacing beneath pavement
• Footing drain backfill
• Pipe zone fill
• Pipe zone bedding
• Utility subgrade repair
• Trench backfill above pipe zone
WSDOT Specification = Washington State Department of Transportation 2021 Standard Specifications for Road, Bridge, and
Municipal Construction
3.2.3 Reuse of Site Soils
Soil generated from cuts and/or excavations is expected to consist primarily of sand with silt and
sandy silt to silt with organics. Some soils with a high fines content are moisture sensitive; less silty
material may be reused with proper moisture conditioning.
Highly organic site soils should not be placed beneath footings or pavements or behind retaining
walls; these soils are not recommended for reuse as utility trench backfill. Excavated material that is
not suitable for reuse should be disposed of at an approved offsite location or placed in landscaped
areas, where several inches of postconstruction settlement would be tolerable. If reused, site soil
should meet the applicable requirements specified in Table 2.
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3.2.4 Wet Weather Earthwork Considerations
As noted, site soils generally are considered moisture sensitive. Completing earthwork during periods
of wet weather or in wet conditions could result in soil disturbance and damaged subgrades. The
contractor should take measures to prevent excessive soil erosion and ground destabilization from
occurring during earthwork activities.
If earthwork is performed during wet weather or in wet conditions, the allowable fines in structural fill
should be reduced to 5 percent or less by dry weight, based on the fraction passing the %-inch sieve.
Granular fill may be used to provide a stable working platform. If wet weather earthwork is
unavoidable, LAI recommends:
• Performing earthwork in small sections.
• Sloping excavated surfaces to promote runoff.
• Restricting construction traffic to areas of the site surfaced with materials that are not
susceptible to wet weather disturbance.
• Removing wet surficial soil daily. Soil should be removed before fill is placed.
• Sealing the soil surface with a smooth drum or rubber -tired roller to reduce the extent to
which soil becomes wet or unstable.
• Track -walking sloped ground at the end of each workday to check that grouser marks are
on -contour.
• Providing upgradient perimeter ditches or low earthen berms and using temporary sumps to
collect runoff and prevent ponding.
3.2.5 Subgrade Preparation
Existing pavement, topsoil, organic and man-made debris, and other deleterious material should be
stripped from all areas designated for improvement. LAI recommends that stripping extend
approximately 6 to 12 inches bgs. Before structural fill is placed, the upper 12 inches of subgrade
should be compacted to at least 95 percent of the maximum dry density, determined in accordance
with ASTM standard test method D1557.
The compacted subgrade should be proof -rolled with a loaded dump truck; a self-propelling, vibrating
roller; or an equivalent piece of equipment. Proof -rolling should be performed in the presence of a
qualified civil or geotechnical engineer, who is familiar with the site and can check for soft/and or
disturbed areas. If proof -rolling reveals loose and/or disturbed subgrade, LAI recommends moisture -
conditioning and recompacting the subgrade or removing and replacing loose subgrade with properly
compacted structural fill. Overexcavation of unsuitable subgrade material should be completed in
accordance with Section 2-03.3(14)E of the 2021 WSDOT Standard Specifications.
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3.2.6 Temporary Construction Dewatering
During LAI's June 2017 field investigation, groundwater was observed at approximately 9 ft bgs. In
nearby explorations, completed in support of the Jacobsen's Marine Facility project, groundwater was
observed at depths as shallow as 7.9 ft bgs (approximately 5.1 ft NAVD 88). Depending on the
locations and depths of the excavations, temporary construction dewatering may be required.
Dewatering should extend to a depth of at least 2 ft below the base of the excavation.
Open sump pumping may be sufficient to dewater excavations that extend to the groundwater table.
Wells or well points may be necessary in excavations that extend below the groundwater table. Well
points are a viable option for lowering groundwater to a depth of 17 ft below the pump elevation. The
contractor should be responsible for the design, installation, monitoring, and maintenance of required
dewatering system(s). If wells or well points are necessary, a registered professional engineer or
hydrogeologist should prepare a dewatering plan; prior to implementation, the plan should be
submitted for the design team's review and comment. The plan should include provisions for limiting
the effects of dewatering-induced settlement on existing structures in the vicinity of the site.
3.3 Utility Construction
The following sections include geotechnical recommendations for design and construction of
underground utilities.
3.3.1 Temporary Excavations
Utility excavations extending through fill deposits are likely to encounter loose to medium dense sand
or soft silt. While not observed in LAI's explorations, cobbles, boulders, debris, and other deleterious
materials could be encountered in the fill. The contractor should be prepared to manage such
unsuitable material.
Trench excavation should be completed in accordance with the requirements in Section 7-08.3(1)A of
the 2021 WSDOT Standard Specifications. The contractor should be responsible for actual trench
configurations and the maintenance of safe working conditions, including temporary excavation
stability. All applicable local, state, and federal safety codes should be followed. Temporary
excavations in excess of 4 ft should be shored or sloped in accordance with Safety Standards for
Construction Work, Part N (Chapter 296-155 of the Washington Administrative Code [WAC]). In the
absence of groundwater seepage, Type C soils are likely to be encountered within the trench zone.
The prescriptive maximum allowable excavation slope for Type C soils is 1% horizontal to 1 vertical
(1%1-1:1V). If groundwater seepage is present, flatter slopes, temporary shoring, and/or dewatering
may be required.
Trench boxes are a worker safety device that provide lateral support of adjacent soil. Where a trench
box is used to support excavations, one or both sides of the trench may cave against the box,
especially if the soil is not properly dewatered. Caving may extend along the sides of the trench a
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distance equal to the depth of the trench box. The potential for caving can be reduced by routing
stormwater away from the excavation and limiting traffic and vibrations near the trench. Precautions
should be taken to minimize disturbance of utility subgrades, foundation materials, and surrounding
soil. Trench boxes should meet the requirements in WAC Chapter 296-155.
Additional bracing or sheeting may be required where the edge of the trench is separated from
settlement -sensitive structures or utilities by a distance less than 1.5 times the trench depth. If
needed to support trench walls, a temporary bracing system should be designed by a structural
engineer licensed in the State of Washington.
The parameters in Table 3 can be used to design temporary shoring. Temporary shoring typically
consists of steel plates with internal bracing. Surcharge loads, exerted by construction equipment,
stockpiled material, and traffic, should be included in the temporary shoring design. Prior to
construction, the design should be submitted for the design team's review and comment.
Table 3. Recommended Soil Parameters for Design of Temporary Shoring
Moist Unit Weight Cohesion Internal Angle of Friction
(pcf) (psf) (degrees)
120 0 30
pcf = pounds per cubic foot
psf = pounds per square foot
3.3.2 Pipe Foundation Support
Based on the conditions observed in LAI's explorations, utility foundation soils will likely consist of
very loose to medium dense sand or soft silt (fill). Provided utility subgrades are prepared as
recommended in Section 3.2.5, the sand fill is anticipated to provide adequate foundation support of
the proposed utilities. Very soft silt and organic silt are not anticipated to provide adequate
foundation support. If these soils are encountered near the bottom of utility trench excavations, they
should be overexcavated and replaced with Backfill for Pipe Zone Bedding. The backfill should be
placed and compacted in accordance with the recommendations in Section 3.2.2
Exposed foundation soils could be disturbed by construction activities. If disturbed by excavation
and/or foot traffic, the trench bottom should be overexcavated to expose undisturbed foundation
soil.
3.3.3 Pipe Bedding and Trench Backfill
Buried utility pipes should be bedded in accordance with the requirements in Section 7-08 of the 2021
WSDOT Standard Specifications. Utility trenches should be backfilled with Bank Run Gravel for Trench
Backfill, as described in Section 3.2.2. Pipe zone backfill should meet the requirements in Section
7-08.3(3) of the 2021 WSDOT Standard Specifications.
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Some site soils are considered moisture sensitive and are not recommended for reuse as trench
backfill.
3.4 Flexible Pavement Design
Based on the results of LAI's field investigations, flexible pavements could be designed using a
California bearing ratio of approximately 10 percent. LAI assumes that pavements will be constructed
on subgrades prepared as recommended in Section 3.2.5.
Pavement sections should be constructed on a subgrade that has been scarified to a depth of 1 ft bgs
and recompacted to at least 95 percent of the maximum dry density. Adequate compaction may be
difficult to achieve in fill soils that exhibit a high fines content. If construction will be completed
during the wet season or in wet conditions, pavement subgrades should be overexcavated and
replaced with at least 1 ft of structural fill, placed and compacted as described in Section 3.2.2.
Traffic loading information was not available at the time of this writing. When developing pavement
design recommendations, LAI assumed a design load of 100,000 equivalent single -axle loads; a
terminal serviceability index (Pt) of 2.5; and a level of reliability of 90 percent. LAI also assumed that
pavements would be subject to light vehicle traffic. A thicker pavement section will be required if
heavy vehicle traffic is anticipated. Based on these assumptions, LAI recommends that pavement
sections consist of 3 inches of asphalt concrete over 6 inches of crushed surfacing base course. If
traffic loading information becomes available, LAI should be asked to provide updated pavement
design recommendations.
Asphalt concrete should be Class B aggregate material or hot -mix asphalt class % inch, PG64-22
binder, conforming to the requirements in Section 5-04 of the 2021 WSDOT Standard Specifications.
The asphalt should be compacted to at least 91 percent of the Rice density. Base course material
should be compacted to at least 95 percent of the maximum dry density, determined in accordance
with ASTM standard test method D1557. Compacted base course should meet the requirements for
Crushed Surfacing Base Course in Section 9-03.9(3) of the 2021 WSDOT Standard Specifications. To
facilitate fine grading of the surface, the upper 2 inches of crushed surfacing should consist of Crushed
Surfacing Top Course, as described in Section 3.2.2. Prevention of road -base saturation is essential for
pavement durability; efforts should be made to limit the amount of water entering the base course.
3.5 Stormwater Infiltration Considerations
The Port is considering constructing stormwater management facilities at the site. Based on the
conditions observed in LAI's explorations, stormwater infiltration may be feasible at certain locations;
however, the silty soils observed in borings B-1 and B-2 are considered hydraulically restricting.
Furthermore, relatively shallow groundwater was observed in boring B-1 (9 ft bgs) and in nearby
borings completed in support of the Jacobsen's Marine Facility project (7.9 ft bgs, approximately 5.1 ft
NAVD 88).
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-7 October 4, 2021
Landau Associates
An initial infiltration rate was developed for near -surface soils at the boring B-1 and B-2 locations. The
infiltration rate was developed using the Soil Grain Size Analysis Method — Detailed Approach outlined
in the Washington State Department of Ecology's 2012 Stormwater Management Manual for Western
Washington, As Amended in December 2014 and in Appendix B of the Edmonds Stormwater
Addendum (2017). Based on the results of LAI's soil grain size analysis, near -surface site soils have an
estimated initial infiltration rate (Ksat;n;t;ai) of approximately 0.001 inches per hour. Correction factors
should be applied to the infiltration rate to account for site variability and number of test locations,
the test method used, and the degree of influent control to prevent siltation and bio buildup. In LAI's
opinion, onsite stormwater infiltration is not feasible.
3.6 Foundations
LAI understands that the proposed structure will be supported on continuous and isolated spread
footings with column loads of 40 to 150 kips, and slabs -on -grade will be installed in maintenance and
administration areas. Compressible wetland deposits are present beneath fill soils, and relatively large
amounts of static settlement are anticipated.
To mitigate static settlement, LAI recommends that ground improvement is completed beneath the
proposed building footprint. The use of rammed aggregate piers is a viable ground improvement
method for the proposed structure. Alternatively, the structure may be supported on a mat
foundation. LAI's preliminary analyses indicate that, if supported by a mat foundation, the structure
would experience up to 3 inches of static settlement.
The following sections include recommendations for ground improvement. If the structure will be
supported on a mat foundation, LAI should be contacted to provide additional recommendations.
3.6.1 Rammed Aggregate Piers
If rammed aggregate piers will be used to improve foundation soils, the proposed building could be
supported on conventional shallow foundations. A specialty contractor should design the piers for
site -specific soil conditions and project requirements; the contractor should also prepare
specifications for pier installation. Prior to pier installation, the specifications and design should be
submitted for the structural and geotechnical engineers' review and approval. In LAI's opinion, an
allowable bearing capacity of approximately 1,500 pounds per square foot (psf) is feasible for
improved ground.
Pier spacing and depth would be informed by building performance requirements. Based on LAI's
discussions with a local ground improvement contractor (Geopier Northwest, Inc.), footings and
slabs -on -grade may be supported by drilled GP30 piers, with compacted quarry spalls installed at the
bottom of the piers. Piers would likely measure 24 inches in diameter, have an average depth of
approximately 12 ft, and be spaced approximately 8 ft on center.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-8 October 4, 2021
Landau Associates
Rammed aggregate piers should be installed prior to excavating the foundation subgrade. After the
piers are installed, foundation excavations may be cut to finished grade. Before formwork is installed,
the exposed piers should be compacted with hand -operated, vibratory equipment.
3.6.2 Shallow Foundation Support
Foundation support of the proposed structure may be provided by continuous or isolated spread
footings founded on properly prepared, improved ground. Bearing soil disturbed during foundation
excavation should be properly recompacted or removed. All soil directly below footings should be
compacted to at least 95 percent of the maximum dry density (ASTM standard test method D1557)
before placement of forms, reinforcing steel, and concrete. All continuous and isolated spread
footings should have minimum widths of 18 and 24 inches, respectively, and should be founded a
minimum of 18 inches below the lowest adjacent final grade.
Assuming the above criteria are satisfied, continuous or isolated spread footings founded directly on
improved ground may be proportioned using a maximum net allowable soil bearing pressure of 1,500
psf. The term "net allowable bearing pressure" refers to the pressure that can be imposed on the soil
at foundation level; it results from the total of all dead plus live loads, exclusive of the weight of the
footing or any overlying backfill. The net allowable bearing pressure may be increased by one-third for
transient forces, such as those induced by wind or seismic loads. Following installation of rammed
aggregate piers, footing subgrades should be prepared as recommended in Section 3.2.5.
Passive earth pressures that develop 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 walls or the sides of foundations may be considered equivalent to a
fluid with a density of 260 pcf. This value includes a safety factor of approximately 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 value is also
based on the assumption that drained conditions will prevent the buildup of hydrostatic pressure in
compacted fill. In design computations, the upper 12 inches of passive resistance should be neglected
if the soil will not be covered by floor slabs or pavement. If future plans call for removal of the soil
providing resistance, the passive resistance should not be considered.
An allowable coefficient of friction of 0.33, applied to vertical dead loads only, may be used to
calculate the resistance to sliding at the base of foundation elements bearing on undisturbed native
soil or well -compacted granular/structural fill. If passive and frictional resistance are considered
together, one-half of the recommended passive soil resistance value should be used, as larger strains
are required to mobilize the passive soil resistance. The base friction design value includes a safety
factor of approximately 1.5. LAI does not recommend increasing the coefficient of friction to resist
seismic or wind loads.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-9 October 4, 2021
Landau Associates
3.6.3 Slab -On -Grade Support
LAI understands that slabs -on -grade within the equipment maintenance and administration areas will
also be supported by rammed aggregate piers. Ground improvement -supported slab -on -grade floor
construction is considered feasible, provided the subgrade is properly prepared following installation
of the rammed aggregate piers. Pier -supported slabs can be designed in accordance with guidance
from Geopier Northwest (2016). LAI recommends using a subgrade modulus, k, of 50 pounds per cubic
inch to represent the stiffness of unimproved, native site soils.
Following installation of the rammed aggregate piers, slab -on -grade subgrades should be prepared as
recommended in Section 3.2.5. At least 4 inches of Crushed Surfacing Base Course, as described in
Section 3.2.2, should be placed beneath slab -on -grade floors to act as a capillary break layer. A
condensation barrier, such as visqueen, should be placed beneath slab -on -grade floors to prevent
condensation on the bottom of the floor slab and wicking through the floor slab. The condensation
barrier should consist of a minimum 10-millimeter membrane with tape -sealed joints. The American
Concrete Institute (ACI; 2019) guidelines recommend placing 4 inches of compacted granular material,
such as Crushed Surfacing Top Course, over the barrier to facilitate curing of the concrete floor slab
and to protect the vapor barrier. The ACI no longer recommends using sand as a protective layer. If
moisture control within the building is critical, the condensation barrier should be inspected to verify
that all openings have been properly sealed.
3.6.4 Foundation Settlement
Foundations supported by properly installed rammed aggregate piers, bearing in the underlying dense
to very dense Whidbey Formation, are expected to experience less than 1 inch of total settlement.
Differential settlement between adjacent, ground improvement -supported foundations is expected to
be less than % inch.
3.6.5 Foundation and Site Drainage
LAI recommends constructing an exterior footing drainage system around the perimeter of building
foundations to prevent buildup of hydrostatic pressure against subterranean walls. The drain should
consist of a minimum 4-inch-diameter, perforated pipe, surrounded by at least 12 inches of filtering
media. The filtering media may consist of open -graded drain rock, wrapped in a non -woven geotextile
fabric (such as Mirafi° 140N, Synthetic Industries 351, or equivalent). Drainage backfill should contain
less than 3 percent by weight passing the U.S. Standard No. 200 sieve, based on a wet sieve analysis of
the portion passing the U.S. Standard No. 4 sieve.
The drain should be sloped to carry water to a suitable collection and discharge system. To prevent
the accumulation or seepage of water, 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. The footing drain should discharge to an approved drain system and
should include cleanouts to allow for periodic maintenance and inspection.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-10 October 4, 2021
Landau Associates
Positive surface gradients, adjacent to the proposed structure, should be used to direct surface water
away from the foundation, toward suitable discharge facilities. Roof drainage should be discharged
directly to the stormwater-collection system or another appropriate outlet. During and after
construction, surface water should not be allowed to pond and soak into the ground near the
buildings.
3.7 Lateral Earth Pressures on Below -Grade Walls
The magnitude of lateral earth pressures that develop against subterranean walls will depend on:
• the inclination of adjacent slopes;
• backfill type, placement, and degree of compaction;
• degree of wall restraint;
• drainage provisions;
• magnitude and location of adjacent surcharge loads; and
• the degree to which the wall can yield laterally during or after placement of backfill.
An at -rest soil pressure is exerted when a wall is restrained against lateral movement or tilting. Such
wall restraint may develop if a rigid structural network is constructed prior to backfilling or if the wall
is inherently stiff or otherwise restrained from rotating. In contrast, active soil pressure will be
exerted if the top of a subsurface structure or wall is allowed to rotate or yield a distance equal to at
least 0.001 times the height of the structure or wall.
For drained, active soil conditions, non -restrained (yielding) walls with level backfill should be
designed with an equivalent fluid density of 34 pcf, and restrained (non -yielding) walls with an
equivalent fluid density of 54 pcf. For undrained soil conditions, yielding walls with level backfill
should be designed to resist an equivalent fluid density of 80 pcf, and non -yielding walls an equivalent
fluid density of 90 pcf. The equivalent fluid densities recommended for use in undrained soil
conditions include hydrostatic pressure.
When developing recommendations for active and at -rest earth pressures, LAI assumed that the
backfill placed against below -grade walls would consist of properly compacted structural fill with no
adjacent surcharge loads. If surcharge loads will occur within a horizontal distance equal to or less
than the wall height, the walls should be designed to withstand the additional horizontal pressure. A
uniformly distributed lateral pressure, 0.43 times the surcharge pressure, should be included for rigid
walls. A uniformly distributed lateral pressure, 0.27 times the surcharge pressure, should be included
for walls free to rotate during loading. A minimum surcharge pressure of 250 psf should be assumed
when estimating the additional load on walls adjacent to parking areas and roadways.
Dynamic lateral earth pressures should be included in the design of below -grade walls. For
non -restrained (yielding) walls with a level backslope, a lateral pressure distribution of 14H (where H
is the vertical height of the wall in feet) should be added to the static lateral earth pressure. The
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-11 October 4, 2021
Landau Associates
recommended lateral earth pressure is based on the assumption that the wall will be free to rotate
and translate a small amount during a strong motion earthquake. For restrained (non -yielding) walls
with a level backslope, a lateral pressure distribution of 40H should be included in the design. LAI
should be contacted for additional recommendations if the project will include walls with a non -level
backslope.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 3-12 October 4, 2021
Landau Associates
4.0 REVIEW OF DOCUMENTS AND CONSTRUCTION
OBSERVATIONS
LAI should be asked to review geotechnical portions of the project plans and specifications to evaluate
their consistency with the recommendations presented in this report. LAI also recommends that
geotechnical monitoring, testing, and consultation be provided during construction to confirm that
the conditions encountered are consistent with those indicated by its explorations, to provide
expedient recommendations should conditions differ from those anticipated, and to evaluate whether
geotechnical construction activities comply with project plans/specifications and the
recommendations contained in this report.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 4-1 October 4, 2021
Landau Associates
5.0 USE OF THIS REPORT
Landau Associates has prepared this report for the exclusive use of the Port of Edmonds and its design
consultants for specific application to the Port Administration/Maintenance Building project in
Edmonds, Washington. No other party is entitled to rely on the information, conclusions, and
recommendations included in this document without the express written consent of Landau
Associates. Reuse of the information, conclusions, and recommendations provided herein for
extensions of the project or for any other project, without review and authorization by Landau
Associates, shall be at the user's sole risk. Landau Associates warrants that, within the limitations of
scope, schedule, and budget, its services have been provided in a manner consistent with that level of
skill and care ordinarily exercised by members of the profession currently practicing in the same
locality, under similar conditions as this project. Landau Associates makes no other warranty, either
express or implied.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 5-1 October 4, 2021
Landau Associates
6.0 REFERENCES
ACI. 2019. Building Code Requirements for Structural Concrete (ACI 318-19). American Concrete
Institute. June.
ASCE. 2017. Minimum Design Loads and Associated Criteria for Buildings and Other Structures
(ASCE/SEI 7-16). American Society of Civil Engineers, Structural Engineering Institute.
ASTM. 2017. Annual Book of ASTM Standards. In: Soil and Rock (1). West Conshohocken, PA: ASTM
International.
Ecology. 2014. 2012 Stormwater Management Manual for Western Washington, as Amended in
December 2014. Washington State Department of Ecology.
Edmonds, City of. 2017. Addendum to Edmonds Community Development Code Chapter 18.30
(Edmonds Storm water Addendum). June 8.
Geopier Northwest, Inc. 2016. Technical Bulletin No. 10. Structural Design Considerations for
Uniformly -Loaded Floor Slabs Supported by Rammed Aggregate Pier° Elements. January.
ICC. 2017. 2018International Building Code. International Code Council. September 13.
LAI. 2007. Report: Geotechnical Engineering Services, Jacobsen's Marine Facility, Edmonds,
Washington. Landau Associates, Inc. December 5.
LAI. 2017. Wetland/Waterway Critical Areas Assessment, Port of Edmonds Marine Retail Property,
Edmonds, Washington. Landau Associates, Inc. June 21.
LNI. 2020. Construction Work. Chapter 296-155 WAC; Part N. Excavation, Trenching, and Shoring.
Washington State Department of Labor and Industries. Effective October.
Minard, J.P. 1983. Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles,
Washington. Department of the Interior, US Geological Survey.
WSDOT. 2020. M41-10: Standard Specifications for Road, Bridge, and Municipal Construction. 2021
Edition. Washington State Department of Transportation. September 9.
Youd, T.L., C.M. Hansen, and S.F. Bartlett. 2002. Revised Multilinear Regression Equations for
Prediction of Lateral Spread Displacement. Journal of Geotechnical and Geoenvironmental
Engineering. 128(12).
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building 6-1 October 4, 2021
Puget Sound
Project Location
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Miles
Data Source: Esri 2012
Port Administration and
LANDAU Maintenance Building
ASSOCIATES Edmonds, Washington
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Port Administration and Figure
Maintenance Building Site and Exploration Plan
Edmonds, Washington
APPENDIX A
Field Explorations
APPENDIX A
FIELD EXPLORATIONS
Landau Associates, Inc. (LAI) and its drilling subcontractor, Holocene Drilling, Inc., have completed two
field investigations to characterize subsurface soil and groundwater conditions at the site. The first
investigation was completed on June 8, 2017 and included one hollow -stem auger boring advanced
26.5 feet (ft) below ground surface (bgs). The second investigation was completed on May 4, 2021 and
included one mud rotary boring advanced 36.5 ft bgs. The boring locations were identified using
existing infrastructure as a field reference (Figure 2). The ground surface elevation was not
determined at either exploration location.
LAI personnel monitored the explorations, obtained representative soil samples, maintained a
detailed record of the subsurface soil and groundwater conditions observed, and described the soil by
visual and textural examination. Each representative soil type was described using the soil
classification system shown on Figure A-1, in general accordance with ASTM International standard
test method D2488, Standard Practice for Description of Soils (Visual -Manual Procedures).
The summary boring logs on Figures A-2 and A-3 represent LAI's interpretation of site subsurface
conditions. The stratigraphic contacts shown on the logs represent the approximate boundaries
between soil types; actual transitions may be more gradual. The soil and groundwater conditions
depicted are for the specific locations and dates reported and may not be representative of other
locations and/or times.
Disturbed soil samples were obtained at select intervals using a 1.5-inch-inside-diameter split -spoon
sampler. A 140-pound automatic hammer, falling approximately 30 inches, was used to drive the
sampler 18 inches (or a portion thereof) into the undisturbed soil. The number of blows required to
drive the sampler for the final 12 inches of soil penetration (or a portion thereof) is noted on the
boring logs, adjacent to the appropriate sample notation.
Samples were transported to LAI's soils laboratory for further examination and testing. Test results
and a discussion of testing procedures are presented in Appendix B.
Upon completion of drilling and sampling, the boreholes were decommissioned in general accordance
with the requirements in Washington Administrative Code 173-160.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building A-1 October 4, 2021
MAJOR
DIVISIONS
Soil Classification System
uscs
GRAPHIC LETTER
SYMBOL SYMBOL')
TYPICAL
DESCRIPTIONS 121(3)
GRAVEL AND
CLEAN GRAVEL
"'
p; :o: ;a:
GW
Well -graded ravel; ravel/sand mixture(s); little or no fines
9 9 9
J N
N
O m'�
GRAVELLY SOIL
(Little or no fines)
Poorly graded ravel; ravel/sand mixtures little or no fines
Y9 9 9 mixture(s);
o. o o.
GP
GRAVEL WITH FINES
GM
❑ 6 >0
(More than 50% of
Silty gravel; gravel/sand/silt mixture(s)
w E 'v,
coarse fraction retained
(Appreciable amount of
Qo 0
N
on No. 4 sieve)
fines)
GC
Clayey gravel; gravel/sand/clay mixture(s)
e
(� � z
SAND AND
CLEAN SAND
$W
Well -graded sand; gravelly sand; little or no fines
w m C
u) L m
SANDY SOIL
(Little or no fines)
Poorly graded sand; gravelly sand; little or no fines
$P
�t
SAND WITH FINES
$M
< o 6
00
(More than 50% of
fraction
Silty sand; sand/silt mixture(s)
g @
coarse passed
(Appreciable amount of
SC
—
through No. 4 sieve)
fines)
Clayey sand; sand/clay mixture(s)
ML
Inorganic silt and veryfine sand; rock flour; silty or clayey fine
sand or clayey silt with slight
po t �,
N
`,'
SILT AND CLAY
plasticity
Inorganic clay of low to medium plasticity; gravelly clay; sandy
C L
uy
L0@
(Liquid limit less than 50)
clay; silty clay; lean clay
>
Z E y
OL
Organic silt; organic, silty clay of low plasticity
- n o
MH
Inorganic silt; micaceous or diatomaceous fine sand
E m N
SILT AND CLAY
uj @
CH
Inorganic clay of high plasticity; fat clay
z°
Z E
L�
(Liquid limit greater than 50)
Organic clay of medium to high plasticity; organic silt
OH
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
DB
Construction debris, garbage
Notes: 1. USCS letter symbols correspond to symbols used by the Unified Soil Classification System and ASTM classification methods. Dual letter
symbols (e.g., SP-SM for sand or gravel) indicate soil with an estimated 5-15% fines. Multiple letter symbols (e.g., ML/CL) indicate borderline
or multiple soil classifications.
2. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils
(Visual -Manual Procedure), 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.
3. 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.
> 15% and < 30% - "gravelly," "sandy," "silty," etc.
Additional Constituents: > 5% and < 15% - "with gravel," "with sand," "with silt," etc.
< 5% - "with trace gravel," "with trace sand," "with trace silt," etc., or not noted.
4. Soil density or consistency descriptions are based on judgement using a combination of sampler penetration blow counts, drilling or
excavating conditions, field tests, and laboratory tests, as appropriate.
Drilling and Sampling Key
Field and Lab Test Data
SAMPLER TYPE
SAMPLE NUMBER & INTERVAL
Code
Description
Code
Description
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
Sample Identification Number
TV = 0.5
Torvane, tsf
c
Shelby Tube
F___
PID = 100
Photoionization Detector VOC screening, ppm
d
Grab Sample
Recovery Depth Interval
W = 10
Moisture Content, %
e
Single -Tube Core Barrel
1 1 ~ Sample Depth Interval
D = 120
Dry Density, pcf
f
Double -Tube Core Barrel
J
-200 = 60
Material smaller than No. 200 sieve, %
g
2.50-inch O.D., 2.00-inch I.D. WSDOT
Portion of Sample Retained
GS
Grain Size - See separate figure for data
h
3.00-inch O.D., 2.375-inch I.D. Mod. California for Archive or Analysis
AL
Atterberg Limits - See separate figure for data
i
Other - See text if applicable
GT
Other Geotechnical Testing
1
300-lb Hammer, 30-inch Drop
CA
Chemical Analysis
2
140-lb Hammer, 30-inch Drop
Groundwater
3
Pushed
4
Vibrocore (Rotosonic/Geoprobe)
Approximate water level at time of drilling (ATD)
5
Other - See text if applicable
1 Approximate water level at time after drilling/excavation/well
Port Administration and Figure
LANDAU Maintenance Building Soil Classification System and Key /� �I
ASSOCIATES Edmonds, Washington A_ I
0
M
n
B-1
SAMPLE DATA
SOIL PROFILE
o
Drilling Method: Hollow -Stem Auger
�
a>
*6T
a o
E
Ground Elevation (ft): Not Determined
z
O 2>
o
4:
co0)
m
>
U V!
L a a)
o w in —
0-n
m
a
E U)
U)
Logged By: SMG Date: 06/08/17
0
rn
AC
Asphalt pavement (3-inch thickness)
SID
(ASPHALT)
SM
Gray, gravelly SAND with silt (medium
dense, moist to wet)
(FI LL)
L
W=9
1 b2 28 -200 = 6
4
W=15 '
2 b2 18 GS
6
ML Gray -brown SILT with organics
8 3 b2 2 Sand lens at 11.4 ft (very soft to soft, moist
to wet)
(ALLUVIUM)
10
4 b2 3 W = 55
AL
12
SP Gray, fine to coarse SAND with gravel,
W = 16 trace silt (dense to very dense, wet)
5 b2 34 -200 = 5 (WHIDBEY FORMATION)
14
6 b2 54
16
18
20
Notes: 1. Stratigraphic contacts are based on field interpretations and are approbmate.
2. Reference to the text of this report is necessary fora proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key' figure for explanation of graphics and symbols.
Port Administration and
LAI Project No: 0173039.010
Moisture Content (%)
Plastic Liquid
Limit I�� Limd
20 40 60 80
- SPT N-Value -
A Klb Standard N-Value A
3
20 40 60 80
z
X Fines Content (%) X
0
20 40 60 80
LALANDAU Maintenance Building Log of Boring B-1
ASSOCIATES Edmonds, Washington
A
•
0
M
0
M
n
SAMPLE DATA
E
a)
0-
z�
~
°
_
L
0
N
0
O N
w cn xs
N
rn
m
0
7
b2
831
g..
8 E I I b2 1 56
Boring Completed 06/08/17
Total Depth of Boring = 26.5 ft.
B-1
SOIL PROFILE
a
Drilling Method: Hollow -Stem Auger
0
E
Ground Elevation (ft): Not Determined
t>>1
U
U!
fl
rn
U)
Logged By: SMG Date: 06/08/17
SP
Gray, fine to coarse SAND with gravel,
trace silt (dense to very dense, wet)
(WHIDBEY FORMATION)
LAI Project No: 0173039.010
Moisture Content (%)
Plastic Liquid
Limit I�� Limd
20 40 60 80
- SPT N-Value -
A Klb Standard N-Value A
3 20 40 60 80
z X Fines Content (%) X
0 20 40 60 80
83/
40
Notes: 1. Stratigraphic contacts are based on field interpretations and are approbmate.
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.
Port Administration and
LALANDAU Maintenance Building Log of Boring B-1
ASSOCIATES Edmonds, Washington
Figure
A-2
(2 of 2)
0
M
0
M
n
B-2
SAMPLE DATA
SOIL PROFILE
o
Drilling Method: Mud Rotary
a>
o
a
T
o
E
Ground Elevation (ft): Not Determined
z
O N>
o
LL
m
m
0)
U
>
V!
3
-O
o
a)
w in —
Q
Un
m
C)
a)U)
fl.
fn
Logged By: BCS Date: 05/04/21
j
2
rn
0
SP
Tan, fine to medium SAND with trace
gravel (loose, moist)
(FILL)
2
Z
a)
N
0
S-1
b2
8
°
z
4
0
3
c
2
SW-
Gray, gravelly SAND with silt (loose, moist)
S-2
b2
8
=
W 19
SM
6
GS
ML
Gray, sandy SILT with trace gravel (soft,
S-3B
b2
8
W =24
—
SP'
moist)
`-----------------
8
SM
Grayish -black SAND with gravel, silt (very
S-3A
W = 23
'.
loose to loose, wet)
GS
10
S-4
b2
2
W = 63
'.
S-413
W = 101
OL
Grayish -brown ORGANIC SILT (very soft,
SP_
moist to wet)
12
SM
(ALLUVIUM)
Blackish -gray, gravelly SAND with silt
(medium dense, wet)
(WHIDBEY FORMATION)
�-14
S-5 b2 24 W = 14
16 GS
GS-1 J] d W = 5
18
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.
Port Administration and
LALANDAU Maintenance Building Log of Boring B-2
ASSOCIATES Edmonds, Washington
LAI Project No: 0173039.010
Moisture Content (%)
Plastic Liquid
Limit Limit
20 40 60 80
- SPT N-Value -
A Klb Standard N-Value A
20 40 60 80
X Fines Content (%) X
20 40 60 80
• A
1011
Figure
A-3
(1 of 2)
0
M
0
M
n
B-2
LAI Project No: 0173039.010
SAMPLE DATA
SOIL PROFILE
Moisture Content (%)
Plastic Liquid
Limit Limit
20 40 60 80
a>
o
a
o
Drilling Method: Mud Rotary
A
- SPT N-Value
T
o
E
E
Ground Elevation (ft): Not Determined
?
o Klb -Standard N-Value A
o
@
)
t>
@
3
20 40 60 80
L
m o iv
_
0-
i°
N
L
a
U)
a
C
z
X Fines Content (%) X
a)
2 m
m
°
a
m
U)
Loed By: BCS Date: 05/04/21
Logged
0
o
w u) os
rn
m
C9
0
20 40 60 80
20
SP-
Blackish -gray, gravelly SAND with silt
SM
(medium dense, wet)
-
S-61
b2
33
(WHIDBEY FORMATION)
- A
-with gravel
-
-dense
22
(D
Z
a)
N
0
O
Z
iu
24
m
c
2
SP
Uight gray, very gravelly, fine tc coarse
SAND with trace silt (very dense, wet)
S-7
b2
60
-
26
........... :................ :.......
28
-
30
SP-
Uight gray, very gravelly SAND with silt
SM
(dense, wet)
-
S-8
b2
50
-
32
-
34
-
S-9
b2
48
- a
36
Boring Completed 05/04/21
Total Depth of Boring = 36.5 ft.
40
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.
Port Administration and Figure
LALANDAU Maintenance Building Log of Boring B-2 A-3
ASSOCIATES Edmonds, Washington (2 of 2)
APPENDIX B
Laboratory Soil Testing
APPENDIX B
LABORATORY SOIL TESTING
Samples obtained from the borings were transported to Landau Associates, Inc.'s soils laboratory for
further examination and testing. Laboratory tests were performed in accordance with the ASTM
International (ASTM) standard test methods noted below.
Natural Moisture Content
Natural moisture content determinations were completed in general accordance with ASTM standard
test method D2216. The results of the moisture content determinations are shown as "W = xx" in the
"Test Data" column on Figures A-2 and A-3.
Grain Size Analysis
Grain size analyses were completed in general accordance with ASTM standard test method D422.
Samples selected for grain size analysis are designated with a "GS" in the "Test Data" column on
Figures A-2 and A-3. The test results are presented on Figure B-1.
U.S. Standard No. 200 Wash Sieve
To provide an indication of the fines content of site soils, select samples were washed over a
U.S. Standard No. 200 sieve in general accordance with ASTM standard test method C117. Samples
selected for U.S. Standard No. 200 washes are designated with a "-200 = xx" in the "Test Data" column
on Figures A-2 and A-3.
Atterberg Limit Test
An Atterberg limits test was completed in general accordance with ASTM standard test method
D4318. The purpose of the test was to determine the liquid limit, plastic limit, and plasticity i ndex of
fine-grained site soils. The sample selected for the Atterberg limits test is designated with an "AL" in
the "Test Data" column on Figure A-2. The test results are presented on Figure B-2.
Geotechnical Engineering Report 0173039.010.011
Port Administration and Maintenance Building B-1 October 4, 2021
173039.01 10/3/21 C:\USERS\MSKINNER\DESKTOP\0173039.010.GPJ GRAIN SIZE FIGURE STRAIGHT LINE
U.S. Sieve Opening in Inches
U.S. Sieve Numbers
Hydrometer
6 4 3 2 1.5
1
1/2 3/8 3 4
6 810 1416 20 30 40 5060 100 140 200
100
90
80
70
L
60
50
Q)
40
o_
30
20
10
0
100
10
1 0.1
0.01 0.001
Grain Size in Millimeters
Cobbles
Gravel
Sand
Silt or Clay
Coarse
Fine
Coarse Medium Fine
Symbol Exploration Sample
Depth
Natural
Port Administration and
Figure
LANDAU
ASSOCIATES
Maintenance Building
Edmonds, Washington
Grain Size Distribution
-�I B
I
Number
Number
(ft)
o
Moisture (/o)
Soil Description
Unified Soil
Classification
•
B-1
S-2
5.0
15
Gravelly SAND with silt
SP-SM
m
B-2
S-2
5.0
19
Gravelly, fine to coarse SAND with silt
SW-SM
A
B-2
S-3A
8.0
23
Fine to coarse SAND with gravel and silt
Gravelly, fine to coarse SAND with silt
SP-SM
*
B-2
S-5
15.0
14
SP-SM
0
60
50
40
a
20
10
0
CL CH
CL-ML M or OL MH or OH
0 10 20 30 40 50 60 70 80 90 100 110
Liquid Limit (LL)
ATTERBERG LIMIT TEST RESULTS
Natural
Exploration
Sample
Liquid
Plastic
Plasticity
Symbol
Number
Number
Depth
Limit
Limit
Index
Moisture
Soil Description
(ft)
(%)
(%)
(%)
(%)
•
B-1
S-4
10.0
43
27
16
55
SILT with organics
ASTM D 4318 Test Method
LANDAU
LA ASSOCIATES
Port Administration and
Maintenance Building
Edmonds, Washington
Plasticity Chart
t
Soil
ation
Figure
B-2