HomeMy WebLinkAbout20250430_PWD3985_Geotech Addendum iIrth
December 10, 2024 Earth Solutions NW LLC
Updated December 16, 2024
ES-10152 Ceotechnical Engineering, Construction
Observation/Testing and Environmental Services
Harmony at Arlington, LLC
2033 East Lake Sammamish Place Southeast
Sammamish, Washington 98075
Attention: Saeed Abtahi
Subject: Geotechnical Addendum
Harmony at Arlington
7417 — 204t" Street Northeast
Arlington, Washington
Dear Saeed:
As requested, Earth Solutions NW, LLC (ESNW) has prepared this report and geotechnical
addendum for the proposed residential development. In preparing this addendum, an earlier May
2024 geotechnical study prepared by PBS (Project No. 73672.000) was reviewed. Based on our
review, we are in general agreement with the findings of the PBS report. However, for design
purposes, the recommendations provided in this addendum report should be assumed for the
project civil, structural, and geotechnical design documents. In this respect, and in accordance
with your request, ESNW is assuming the role of geotechnical engineer of record for the project.
Project Description
The subject property is roughly 4.38 acres and abuts the west side of State Route 9 (see attached
Plate 1 — Vicinity Map). Access to the development will be established off of 204t" Street NE,
located just south of the subject property. The site is largely devoid of vegetation, and overall
topography throughout the planned development area is relatively flat. We understand current
plans propose construction of a 60-unit townhome complex with related site infrastructure
improvements. Building structures to accommodate the townhome units are expected to be 3-
stories and constructed of relatively lightly loaded wood framing. Grading activities propose fill
placement of roughly 4-feet across the site to establish future road grade and building pad
elevations. Geologic mapping of the area (Minard 1985) identifies Marysville Sand (Qvrm)
deposits throughout the site and surrounding areas. Subsurface data previously acquired at the
site (by others) generally confirms the presence of sands and gravels at-depth across the site.
The Subsurface Exploration Plan (Plate 2) provided as an attachment to this report illustrates the
approximate locations of the test sites where borings and test pits were conducted by PBS. For
reference, the boring and test pit logs completed by PBS are also provided as attachments to this
report. With respect to stormwater, infiltration is currently proposed. As such, stormwater designs
currently propose a series of rock filled galleries positioned throughout the site and designed to
infiltrate collected stormwater into the native sand deposits at-depth.
15365 NE 9011 Street, Suite 100 Redmond,WA 98052 • (425)449-4704
3130 Varney Lane, Suite 105 Pasco,WA 99301 • (509)905-0275
esnw.com
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 2
Updated December 16, 2024
Site Preparation
Initial earthwork will primarily involve site stripping and subsequent filling of the site to establish
finish subgrade elevations. Based on current plans, we expect fill placement of up to roughly two
feet above current grades will be necessary to achieve design grades.
Temporary Erosion Control
Temporary construction entrances and drive lanes should consist of at least 6 to 12 inches of
quarry spalls underlain by a non-woven filter fabric. Silt fencing should be installed as appropriate
along the site perimeter. Soil stockpiles and exposed earth surfaces should be covered or
otherwise protected to reduce soil erosion. Temporary approaches for controlling surface water
runoff should be established prior to beginning earthwork activities. Additional Best Management
Practices (BMPs), as specified by the project civil engineer and indicated on the plans, should be
incorporated into construction activities. BMPs will likely require upkeep and/or modification
during construction and should be coordinated with the site erosion control lead, where
applicable.
Excavations and Slopes
Based on the identified subsurface condition, the following allowable temporary slope inclinations
as a function of horizontal to vertical (H:V), are recommended for the project. The applicable
Federal Occupation Safety and Health Administration and Washington Industrial Safety and
Health Act soil classifications are also provided:
• Native sand and gravel deposits 1.5H:1V (Type C)*
• New structural fill 1.5H:1V (or flatter)
It should be noted that steeper temporary excavations may be feasible based on the excavation depth and
exposed soil condition. In any case, the engineer must confirm acceptability prior to proceeding with excavations
that exceed the state and federal standards for temporary slope layback.
In-situ and Imported Soil
The near surface in-situ sand and gravel outwash deposits possess a varying degree of fines,
and may be characterized as possessing a moderate sensitivity to moisture. Overall, however,
the native soils are expected to becomes increasingly"clean"with depth. As such, the native soils
are generally expected to be suitable for use as structural fill throughout the site. Imported soil
intended for use as structural fill should be evaluated by ESNW during construction. The imported
soil must be workable to the optimum moisture content, as determined by the Modified Proctor
Method (ASTM D1557), at the time of placement and compaction. During wet weather conditions,
imported soil intended for use as structural fill should consist of a well-graded, granular soil with
a fines content of 5 percent or less (where the fines content is defined as the percent passing the
Number 200 sieve, based on the minus three-quarter-inch fraction).
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 3
Updated December 16, 2024
Structural Fill
Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway,
permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and
compacted during site grading activities should meet the following specifications and guidelines:
• Structural fill material Granular soil
• Moisture content At or slightly above optimum
• Relative compaction (minimum) 95 percent (Modified Proctor)
• Loose lift thickness (maximum) 12 inches
Foundations
It should be noted that standard conventional foundations are considered acceptable for support
of the new building structures. As such, special consideration with respect to foundation support
for this project (i.e. mat foundations) are deemed unnecessary for the development.
Based on current plans, up to roughly 4-feet of fill will be placed across the site to establish design
subgrade elevations. As such, subgrade exposed at foundation grade for the new buildings is
expected to consist of compacted structural fill. In any case, subgrade surfaces for support of
future foundations must exhibit a well compacted and "dense" condition. The engineer (or his
representative) should observe and confirm acceptability of subgrade surfaces along future
foundation alignments during the course of foundation work for the project. As necessary,
supplement recommendations may be provided by the engineer to ensure a "dense" and suitable
foundation subgrade is established below future building foundations.
Assuming the above, the following recommendations are provided for foundation design:
• Allowable soil bearing capacity 2,500 psf
• Footing Embedment 18 inches (min.)
• Passive earth pressure 350 pcf (equivalent fluid)
• Coefficient of friction 0.40
A one-third increase in the allowable soil bearing capacity may be assumed for short-term wind
and seismic loading conditions. The above passive pressure and friction values include a factor-
of-safety of 1.5. With structural loading as expected, total settlement in the range of one inch and
differential settlement of about one-half inch is anticipated. Most settlement should occur during
construction when dead loads are applied.
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 4
Updated December 16, 2024
As emphasized above, an ESNW representative should be present onsite at the time of
foundation subgrade preparation to confirm acceptability of the bearing surface. If necessary,
supplement recommendations may be provided by the engineer to ensure a suitable bearing
surface is established at the building foundation subgrade.
Slab-on-Grade Floors
Slab-on-grade floors for the proposed structures should be supported on well-compacted, firm,
and unyielding subgrades. Unstable or yielding areas of the subgrade should be recompacted or
overexcavated and replaced with suitable structural fill prior to slab construction. An ESNW
representative should be requested to observe slab-on-grade subgrade conditions prior to
placement of capillary break sections and concrete slab formwork.
A capillary break consisting of a minimum of four inches of free-draining crushed rock or gravel
should be placed below the slab. The free-draining crushed rock or gravel material should have
a fines content of 5 percent or less (defined as the percent passing the No. 200 sieve, based on
the minus three-quarter-inch fraction). In areas where slab moisture is undesirable, installation of
a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of
a material specifically designed to function as a vapor barrier and should be installed in
accordance with the manufacturer's specifications.
Retaining Walls
Where applicable, building and site retaining walls accommodating grade transitions must be
designed to resist earth pressures and applicable surcharge loads. The following values may be
used for retaining wall design:
• Active earth pressure (unrestrained condition) 35 pcf (equivalent fluid)
• At-rest earth pressure (restrained condition) 55 pcf
• Traffic surcharge* (passenger vehicles) 70 psf (rectangular distribution)
• Passive earth pressure 350 pcf (equivalent fluid)
• Coefficient of friction 0.40
• Seismic surcharge 8H psf**
Where applicable.
** Where H equals the retained height(in feet).
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 5
Updated December 16, 2024
The above design parameters are based on a level backfill condition and level grade at the wall
toe. Revised design values will be necessary if sloping grades are to be used above or below
retaining walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other
loads should be included in the retaining wall design. Retaining walls should be backfilled with a
free-draining material that extends along the height of the wall and a distance of at least 18 inches
behind the wall. The upper 12 inches of the wall backfill may consist of a less permeable soil, if
desired.
Drainage should be provided behind retaining walls such that hydrostatic pressures do not
develop. If drainage is not provided, hydrostatic pressures should be included in the wall design.
A perforated drainpipe should be placed along the base of the wall and connected to an
appropriate discharge location. A typical retaining wall drainage detail is provided on Plate 3
(Retaining Wall Drainage Detail).
Seismic Design
The 2021 International Building Code (2021 IBC) recognizes ASCE 7-16 (formally known as the
Minimum Design Loads for Buildings and Other Structures manual) for seismic design,
specifically with respect to earthquake loads. Based on the soil conditions identified at the test
locations, the parameters and values provided below are recommended for seismic design per
the 2018 IBC.
Parameter Value
Site Class D*
Mapped short period spectral response acceleration, Ss (g) 1.039
Mapped 1-second period spectral response acceleration, S1 (g) 0.371
Short period site coefficient, Fa 1.084
Long period site coefficient, Fv 1.929
Adjusted short period spectral response acceleration, SMs (g) 1.127
Adjusted 1-second period spectral response acceleration, Smi (g) 0.716
Design short period spectral response acceleration, SDS (g) 0.751
Design 1-second period spectral response acceleration, SD1 (g) 0.477
The liquefaction susceptibility of the site is characterized as low. In any case, the proposed building structures
are expected to have a fundamental period of less than 0.5 sec. As such, even under a Site Class F
characterization (liquefiable), the site structures could still be designed using a Site Class D classification per the
exceptions provided in ASCE 7-16.
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 6
Updated December 16, 2024
Based on the identified subsurface soil and groundwater condition, site susceptibility to
liquefaction (post-construction) is characterized as low. A non-liquefiable "crust" exists across the
site to depths of roughly 25 to 35 feet. Although liquefaction of the soil units located within the
groundwater table environment below these depths is possible, settlements induced by
liquefaction within these deeper units are not expected to impact foundation support of throughout
the future building sites. In any case, differential settlement induced as a result of a liquefaction
event at-depth would be expected to be less than one-inch over a distance of roughly 30 feet. As
such, provided the recommendations of this addendum report as they pertain to foundation
subgrade preparation are adhered to during construction, additional measures to mitigate
liquefaction induced settlements at the site are deemed unnecessary for the project.
Drainage
Finish grades should be designed to direct surface water away from structures and slopes.
Grades adjacent to buildings should be sloped away from the building exterior at a gradient of 2
percent for a horizontal distance of at least 10 feet. Where pavement areas are present at the
building exteriors, the slope may be reduced to 1 percent. In our opinion, foundation drains should
be installed along building perimeter footings (see Plate 4 — Footing Drain Detail).
Infiltration Evaluation
As previously established, outwash sands and gravels reside at-depth throughout the site and
surrounding areas. Based on the subsurface data collected at the test sites, these outwash
deposits become increasingly "clean" with depth. Given the relative absence of groundwater,
such conditions present a favorable environment for stormwater infiltration. Current plans
propose infiltration of the site stormwater through the use of rock-filled galleries positioned
throughout the site. Infiltration testing conducted by PBS confirmed generally good rates of
infiltration at depths of roughly 5-feet below current grades. Based on the results of the PBS
testing, allowable rates of ranging between 10.5 and 12.0 inches per hour were recommended
for design. Based on discussions with the civil design team, an allowable infiltration rate of 12
inches per hour was assumed for the current design. As such, and based on our review, the
following recommendations are provided for infiltration design purposes, and are considered
acceptable from a geotechnical standpoint:
• Design Infiltration Rate 12 in./hr.
• Receptor Soil Clean Outwash
The geotechnical engineer (or his representative) should observe and document excavation and
related construction of the proposed infiltration galleries. Specifically, suitability of the receptor
soils at the base of the proposed facilities should be confirmed by our staff. If necessary,
supplement recommendations may be provided by the engineer at the time of construction to
ensure that the facilities are positioned within the clean outwash deposits.
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 7
Updated December 16, 2024
Utility Support and Trench Backfill
The soils observed at the subsurface locations are generally suitable for support of utilities. In
general, the onsite soils are expected to be suitable for reuse as backfill over future utility
alignments. Given the sand and gravel nature of the native soil deposits, moisture conditioning
of the backfill through the addition of water will likely be necessary during placement and
compaction. Such efforts to moisture condition the backfill will help mitigate future settlement of
the backfill zone. The utility trench backfill should be placed and compacted to the specifications
of structural fill provided in this report, or to the applicable requirements of presiding jurisdiction.
It should also be noted that the presiding jurisdiction may require use of"select" backfill materials
within their right-of-way alignments.
Preliminary Pavement Sections
The performance of site pavements is largely related to the condition of the underlying subgrade.
To ensure adequate pavement performance, the subgrade should be in a firm and unyielding
condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement
areas should be compacted to the specifications detailed in the Site Preparation and Earthwork
section of this report. Soft, wet, or otherwise unsuitable subgrade areas may still exist after base
grading activities. Areas of unsuitable or yielding subgrade conditions may require remedial
measures, such as overexcavation and replacement with structural fill or thicker crushed rock
sections, prior to pavement.
For relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the
following sections may be considered for preliminary design:
• Two inches of hot-mix asphalt (HMA) placed over four inches of crushed rock base (CRIB),
or;
• Two inches of HMA placed over three inches of asphalt-treated base (ATB).
Heavier traffic areas generally require thicker pavement sections depending on site usage,
pavement life expectancy, and site traffic. For preliminary design purposes, the following
pavement sections for occasional truck traffic and access roadways may be considered:
• Three inches of HMA placed over six inches of CRIB, or;
• Three inches of HMA placed over four and one-half inches of ATB.
A representative of ESNW should be requested to observe subgrade conditions prior to
placement of CRIB or ATB. As necessary, supplemental recommendations for achieving
subgrade stability and drainage can be provided. If on-site roads will be constructed with an
inverted crown, additional drainage measures may be recommended to assist in maintaining road
subgrade and pavement stability.
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 8
Updated December 16, 2024
Final pavement design recommendations, including recommendations for heavy traffic areas,
access roads, and frontage improvement areas, can be provided once final traffic loading has
been determined. Road standards utilized by the governing jurisdiction may supersede the
recommendations provided in this report. The HMA, ATB, and CRB materials should conform to
WSDOT specifications. All soil base material should be compacted to a relative compaction of 95
percent, based on the laboratory maximum dry density as determined by ASTM D1557.
Limitations
This addendum report has been prepared for the exclusive use of Harmony at Arlington, LLC and
their representatives. The recommendations and conclusions provided in this addendum report
are professional opinions consistent with the level of care and skill that is typical of other members
in the profession currently practicing under similar conditions in this area. A warranty is not
expressed or implied. Variations in the soil and groundwater conditions observed at the test
locations may exist, and may not become evident until construction. ESNW should reevaluate
the conclusions in this addendum report if variations are encountered.
Additional Services
ESNW should have an opportunity to review the final design with respect to the geotechnical
recommendations provided in this report. ESNW should also be retained to provide testing and
consultation services during construction.
Earth Solutions NW, LLC
Harmony at Arlington, LLC ES-10152
December 10, 2024 Page 9
Updated December 16, 2024
We trust this addendum report meets your current needs. If you have any questions regarding
the content of this report, or if additional information is required, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
A' CO
W
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S�ONA.�-
12/16/2024
Raymond A. Coglas, P.E.
Senior Principal Engineer
Attachments: Plate 1 —Vicinity Map
Plate 2 — Subsurface Exploration Plan
Plate 3 — Retaining Wall Drainage Detail
Plate 4 — Footing Drain Detail
Subsurface Exploration Logs (by Others)
cc: Land Technologies, Inc.
Attention: Merle Ash
Earth Solutions NW, LLC
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Snohomish County, Washington
OpenStreetMap.org Vicinity Map
Harmony at Arlington
Arlington, Washington
NOTE:This plate maycontain areas ofcolor.ESNWcannotbe Drawn MRS Date 12/09/2024 PrOj. No. 10152
responsible for any subsequent misinterpretation of the information
resulting from black&White reproductions of this plate. Checked RAC Date Dec. 2024 Plate 1
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LEGEND NORTH
TP-1 I Approximate Location of
■ — PBS Test Pit, Proj. No.
73672.000, Feb. 2019
B-1 Approximate Location of
— • — PBS Boring, Proj. No.
;4 Ii
73672.000, Feb. 2019
NOT-TO - SCALE
Subject Site
Existing Building 117'�Earth
Solutions
NOTE:The graphics shown on this plate are not intended for design Geotechnical Firgineering,Construction
proposes or precise scale measurements,but only to illustrate the
approximate test locations relative to the approximate locations of
existing and/or proposed site features.The infomuationillustrated Subsurface Exploration Plan
is largely based on data provided by the client at the timeofour Harmony at Arlington
study.ESNWcannotbe responsible for subsequent design changes Arlington, Washington
or interpretation ofthe data by others.
NOTE:This plate may contain areas of color.ESNWcannotbe Drawn MRS Date 12/09/2024 Proj. No. 10152
responsible for any subsequent misinterpretation of theinfomration Checked RAC Date Dec. 2024 Plate 2
resulting from black&white reproductions of this plate.
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NOTES: (Surround in Drain Rock)
• Free-draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No. 4 sieve should be
25 to 75 percent.
• Sheet Drain may be feasible in lieu SCHEMATIC ONLY- NOT TO SCALE
of Free-draining Backfill, per ESNW NOT A CONSTRUCTION DRAWING
recommendations.
• Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
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Harmony at Arlington
Arlington, Washington
Drawn MRS Date 12/10/2024 Proj. No. 10152
Checked RAC Date Dec. 2024 Plate 3
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NOTES:
• Do NOT tie roof downspouts
to Footing Drain.
SCHEMATIC ONLY- NOT TO SCALE
• Surface Seal to consist of NOT A CONSTRUCTION DRAWING
12" of less permeable, suitable
soil. Slope away from building.
LEGEND:
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Surface Seal: native soil or
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Footing Drain Detail
Harmony at Arlington
Arlington, Washington
Drawn MRS Date 12/10/2024 Proj. No. 10152
Checked RAC Date Dec. 2024 Plate 4
Table A-2
Imo. Key To Test Pit and Boring Log Symbols
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SAMPLING DESCRIPTIONS
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LOG GRAPHICS
Soil and Rock Sampling Symbols Instrumentation Detail
Lithology Boundary: "- - - "'Ground Surface
• : / separates distinct units
(i.e., Fill,Alluvium, Sample Well CaD
Bedrock)at Recovery Sample Well Seal
approximate depths Interval Well PiDe
o°c inciated Piezometer
O Soil-type or Material-type
o -- Change Boundary: separates soil 4 Well Screen
v' '- Sampler
and material changes within the Type Piezometer
_-_-_ same lithographic unit at
approximate depth indicated Bottom of Hole
Geotechnical Testing Acronym Explanations
PP Pocket Penetrometer HYD Hydrometer Gradation
TOR Torvane SIEV Sieve Gradation
DCP Dynamic Cone Penetrometer DS Direct Shear
ATT Atterberg Limits DD Dry Density
PL Plasticity Limit CBR California Bearing Ratio
LL Liquid Limit RES Resilient Modulus
PI Plasticity Index VS Vane Shear
P200 Percent Passing US Standard No. 200 Sieve bgs Below ground surface
OC Organic Content MSL Mean Sea Level
CON Consolidation HCL Hydrochloric Acid
UC Unconfined Compressive Strength
Details of soil and rock classification systems are available on request. Rev.oz/zoi7
HARMONY AT ARLINGTON BORING B-1
ARLINGTON,WASHINGTON
PBS
PBS PROJECT NUMBER: APPROX.BORING B-1 LOCATION:
TAN APEX COMPANY 73672.000 (See Site Plan)
Lat:--- Long:---
a p A UNCORRECTED N-VALUE
v MATERIAL DESCRIPTION x z w 4-DYNAMIC CONE INSTALLATION AND
DEPTH c9 w a PENETROMETER COMMENTS
FEET NOTE: Lines representing the interface between soil/rock units of w w a 2 •MOISTURE CONTENT%
C7 differing description are appropmate only,inferred where p H Q uai ®RQD% ®CORE REC% Surface Conditions:Gravel
between samples,and may indicate gradual transition. cn 0 50 100
0.0 :. Very dense, brown,silty GRAVEL(GM)with
sand; low plasticity;fine to coarse sand;fine to
coarse,subrounded gravel; moist
a 54
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5.0 a
0 :
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Medium dense, brown,silty SAND (SM); 75 �M zs
non-plastic;fine to medium sand;trace,fine U) '
gravel; moist
10.0
v 29
15.0 Dense, brown,well-graded SAND(SW-SM) 50 ;33;
with silt; non-plastic;fine to coarse sand;trace, to
fine gravel; moist
20.0 18
becomes medium dense �19
to
25'0 Medium dense,dark brown, poorly graded ZS.o 19
SAND(SP-SM)with silt; non-plastic;fine sand; rn 4
a moist
w
0
Z
a
a
30.0 P200 17 P200=8%
o becomes wet
w U) : 4 •:
31.5
Final depth 31.5 feet bgs; boring backfilled with
bentonite. Groundwater not measured at time
of exploration due to mud rotary drilling.
N
a
35.0
S
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m
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2 40.0 c9 o so 100
DRILLING METHOD:Mud Rotary-Tricone BIT DIAMETER:3 7/8 inches FIGURE Al
m DRILLED BY:Holt Services,Inc. HAMMER EFFICIENCY PERCENT:90
LOGGED BY:M.Bagley LOGGING COMPLETED:2/2 612 0 1 9 Page 1 of 1
HARMONY AT ARLINGTON BORING B-2
ARLINGTON,WASHINGTON
PBS
PBS PROJECT NUMBER: APPROX.BORING B-2 LOCATION:
TAN APEX COMPANY 73672.000 (See Site Plan)
Lat:--- Long:---
a p A UNCORRECTED N-VALUE
v MATERIAL DESCRIPTION x z W 4-DYNAMIC CONE
DEPTH x C0 W CL
o o-
PENETROMETER INSTALLATION AND
FEET NOTE: Lines representing the interface between soil/rock units of W(L w J
a •MOISTURE CONTENT% COMMENTS
C7 differing description are appropmate only,inferred where p H Q U)i ®RQD% ®CORE REC% Surface Conditions:Gravel
between samples,and may indicate gradual transition. < 0 50 100
0.0 Dense, brown,clayey SAND(SC); medium Flush monument
plasticity;fine to coarse sand; moist
FILL
A2
0 2-inch diameter
Dense,gray-brown,well-graded SAND �� PVC pipe
(SW-SC)with clay and gravel; non-plastic;fine
5.0 to coarse sand;fine to coarse,subrounded so 64 Bentonite
gravel; moist �N
Dense, brown with gray mottles,well-graded
P�.. 9 Y 9 p°
SAND(SW-SM)with silt and gravel;
non-plastic;fine to coarse sand;fine to coarse, 36
P�. subrounded gravel; moist ��
10.0 'V becomes medium dense ;23;
to
'6f Filter sand
q
q
15.0 — -- ———— -- -- 1s.o 2-inch diameter
Medium dense, light brown, poorly graded 49 slotted PVC screen
SAND(SP-SM)with silt; non-plastic;fine to
medium sand;trace,fine gravel; moist `: 03i01/19
20.0 becomes dark brown;wet P200 : 15 P200=7%
Bentonite
25.0
a 14
N �U)
N
W
F
Q
F
Z
a
0 30.o becomes olive-brown � 23:
W �(n •
Final depth 31.5 feet bgs. Piezometer installed 31.5
to 20 feet bgs; boring backfilled with bentonite
from 20 to 31.5 feet bgs. Groundwater not
measured at time of exploration due to mud
rotary drilling.
35.0
S
a
v
m
c�
0 40.0 1 0 50 100
c�
DRILLING METHOD:Mud Rotary-Tricone BIT DIAMETER:3 7/8 inches FIGUREA2
Om DRILLEDBY:Holt Services,Inc. HAMMER EFFICIENCY PERCENT:90
LOGGED BY:M.Bagley LOGGING COMPLETED:2/25/2019 Page 1 of 1
HARMONY AT ARLINGTON BORING B-3
ARLINGTON,WASHINGTON
PBS
PBS PROJECT NUMBER: APPROX.BORING B-3 LOCATION:
BAN APEX COMPANY 73672.000 (See Site Plan)
Lat:--- Long:---
a p A UNCORRECTED N-VALUE
v MATERIAL DESCRIPTION x z w O DYNAMIC CONE INSTALLATION AND
DEPTH a(9 w a PENETROMETER COMMENTS
FEET a- FNOTE: Lines representing the interface between soil/rock units of w w a 2 •MOISTURE CONTENT%
0 differing description are approximate only,inferred where p H U) ®RQD% ®CORE REC% Surface Conditions:Gravel
between samples,and may indicate gradual transition. < 0 50 100
0.0 GRAVEL FILL(-6 inches) 0.5
Dense, brown,silty SAND(SM); non-plastic;
fine to medium sand; moist
3.5 8
Dense,gray, poorly graded SAND(SP-SM)
d • with silt and gravel; non-plastic;fine to coarse
5.0 sand;fine to coarse, rounded gravel; moist N 27
becomes medium dense, brown-gray;fine toA.
o medium sand
.v •
19
P rn
——— 9.5
10.0 Very dense, brown poorly graded SAND
(SP-SM)with silt; non-plastic;fine to medium I 10.5 �� A5
Isand_moist________________1
o Very dense, brown-gray, poorly graded
GRAVEL(GP-GM)with silt and sand;
non-plastic;fine to medium sand;fine to I 13.3
Ico_arse, rounded gravel; moist to wet
15.0 Medium dense, brown,well-graded SAND P200 21 : P200=a°io
(SW-SM)with silt; non-plastic;fine to coarse A
sand; moist
20.0 Medium dense, brown, poorly graded SAND zo.o ��0 19
O (SP-SM)with silt and gravel;fine to medium
sand;fine, rounded gravel; moist to wet
:v •
wW
25.0 — P200 20 P200=7%
Medium dense, brown poorly graded SAND
(SP-SM)with silt; non-plastic;fine to medium �� Ae
sand;wet
w
0
Z
a
a
30.0 24
d °'
0 �:
a
a
0
m
a
q 35.0 P200 1 s P200=8%
�U) •
m
cD
0 40.0 0 50 100
DRILLING METHOD:Mud Rotary-Tricone BIT DIAMETER:3 7/8 inches
°m DRILLED BY:Holt Services,Inc. HAMMER EFFICIENCY PERCENT:90 FIGURE A3
LOGGED BY:D.Eibert LOGGING COMPLETED:2/25/2019 Pagel oft
HARMONY AT ARLINGTON BORING B-3
ARLINGTON,WASHINGTON
P 135 (continued)
PBS PROJECT NUMBER: APPROX.BORING B-3 LOCATION:
TAN APEX COMPANY 73672.000 (See Site Plan)
Lat:--- Long:---
a p A UNCORRECTED N-VALUE
v MATERIAL DESCRIPTION x z w 4-DYNAMIC CONE INSTALLATION AND
DEPTH c9 w a PENETROMETER COMMENTS
FEET NOTE: Lines representing the interface between soil/rock units of w w a 2 •MOISTURE CONTENT%
C7 differing description are appropmate only,inferred where p H Q uai ®RQD% ®CORE REC% Surface Conditions:Gravel
between samples,and may indicate gradual transition. v 0 50 100
40.0Medium dense, brown poorly graded SAND
1s
(SP-SM)with silt; non-plastic;fine to medium A:
sand;wet
45.0 P200 19 : P200=11
�� L
becomes gray
50.0
N 18
�c
55.0 P200
co :21: P200=9%
60.0
26
tu)
:•:
65.0 P200 22: P200=8%
N
F Rig chatter
a
0
z
a
0 70.o becomes dense •32:
0 71.5 [U)
Final depth 71.5 feet bgs; boring backfilled with
bentonite. Groundwater not measured at time
of exploration due to mud rotary drilling.
N
a
�? 75.0
v
Y
m
t7
OJ 80.0 1 0 50 100
C7
DRILLING METHOD:Mud Rotary-Tricone BIT DIAMETER:3 7/8 inches FIGUREA3
m DRILLED BY:Holt Services,Inc. HAMMER EFFICIENCY PERCENT:90
LOGGED BY:D.Eibert LOGGING COMPLETED:2/25/2019 Page 2 of 2
HARMONY AT ARLINGTON BORING B-4
ARLINGTON,WASHINGTON
PBS
PBS PROJECT NUMBER: APPROX.BORING B-4 LOCATION:
TAN APEX COMPANY 73672.000 (See Site Plan)
Lat:--- Long:---
a p A UNCORRECTED N-VALUE
v MATERIAL DESCRIPTION x z W 4-DYNAMIC CONE
DEPTH x C0 W CL PENETROMETER INSTALLATION AND
FEET NOTE: Lines representing the interface between soil/rock units of W(L w J a a •MOISTURE CONTENT% COMMENTS
C7 differing description are appropmate only,inferred where p H Q U)i ®RQD% ®CORE REC% Surface Conditions:Gravel
between samples,and may indicate gradual transition. < 0 50 100
0.0 ; Dense,dark brown,silty SAND(SM)with Flush monument
gravel; low plasticity;fine to coarse sand;fine to
coarse,subrounded gravel; moist
33; 2-inch diameter
v) PVC pipe
Bentonite
5.0 — —— ——— —— —— 5° 2 : : =
Medium dense, brown,well-graded SAND P200 20 P200 7%
�N ;�
P�. (SW-SM)with silt and gravel; non-plastic to low rn
plasticity;fine to coarse sand;fine,subrounded
gravel; moist
a6p I? 28
4 U)
1 03/26/24
10.0 Medium dense, brown, poorly graded SAND o.o 19
(SP-SM)with silt; non-plastic;fine to medium 4
sand; moist Filter sand
15.0 2-inch diameter
becomes dark brown 21: slotted PVC screen
v)
t 03/01/19
20.0
�� 15
to
Bentonite
25.0 P2oo 18 P200=8%
becomes moist to wet
N
W
F
Q
Z
!r
a
30.0 24
d °O
31.5
Final depth 31.5 feet bgs; boring backfilled with
bentonite. Piezometer installed to 20 feet bgs;
boring backfilled with bentonite from 20 to 31.5
feet bgs. Groundwater not measured at time of
exploration due to mud rotary drilling.
35.0
S
a
v
m
0
0 40.0 1 0 50 100
c�
DRILLING METHOD:Mud Rotary-Tricone BIT DIAMETER:3 7/8 inches FIGUREA4
m DRILLED BY:Holt Services,Inc. HAMMER EFFICIENCY PERCENT:90
LOGGED BY: Bagley LOGGING COMPLETED:2/2 612 0 1 9 Page 1 of 1
HARMONY AT ARLINGTON
ARLINGTON,WASHINGTON TEST PITS
PBS
_ PBS PROJECT NUMBER: TEST PIT LOCATION:
BAN APEX COMPANY 73672.000 (See Site Plan)
U w p -0- DYNAMIC CONE
DEPTH 2 0 MATERIAL DESCRIPTION 7 z a s m STATICROMETER COMMENTS
IN Q O NOTE: Lines representing the interface between soil/rock units of w U) Q 2i PENETROMETER
FEET 0Y J differing description are approximate only,inferred where 0 H U) < 0 MOISTURE
C7 between samples,and may indicate gradual transition. CONTENT%
TP-1 0 25 50
o.o ; Brown,silty SAND(SM)with gravel and o:o
cobbles; low plasticity; medium sand;coarse,
subrounded gravel; moist
2.0 ———— -- — 2=0
Light brown, poorly graded SAND(SP)with 2 0
gravel and cobbles;fine to medium sand;
coarse,subrounded gravel; moist Infiltration testing
4.0 ———— — — —— 4_0 completed at 5 feet
Light brown,well-graded SAND(SW)with 4.0 bgs
cobbles;fine to coarse sand; moist P200 ®� P200=1%
W
6.0
8.0
10.0 10.0
Final depth 10.0 feet bgs;test pit backfilled with 10.0
excavated material to existing ground
surface.Groundwater not encountered at time
12.0 of exploration.
14.0
Date Completed:2/27/2019 Elevation:--- Final Depth: 10 feet bgs Latitude:--- Longitude:---
TP.o 0 25 50
Brown,silty SAND(SM)with gravel, cobbles, u0.0
.0
and roots; non-plastic;fine to medium sand;
coarse,subrounded gravel; moist
2.0
————————————————————— 2—
Light brown, poorly graded SAND(SP)with 2.s
gravel and cobbles;fine to medium sand; Infiltration testing
4,0 coarse,subrounded gravel; moist completed at 5 feet
____ ________________ 4_5 bgs
Brown to light brown,well-graded SAND(SW) 4.5 P200 P200=1%
with cobbles;fine to coarse sand; moist ®� •
0 6.0
0
a
a
Q 8.0
0
m
a
10.0 10.0
Final depth 10.0 feet bgs;test pit backfilled with 10.0
excavated material to existing ground
? surface.Groundwater not encountered at time
12.0 of exploration.
w
a 14.0
w
a
°o Date Completed:2/27/2019 Elevation:--- Final Depth: 10 feet bgs Latitude:--- Longitude:---
EXCAVATION METHOD:Komatsu 170LC with 36"Bucket LOGGED BY:M. Bagley FIGURE A5
w EXCAVATED BY:Taylor's Excavators Inc. Pagel of