160514KEA_R 10-12-16 New Retail Building.pdfa s s o c i a t e d
e a r t h s c i e n c e s
incorporated
Subsurface Exploration, Geologic Hazard, and
Preliminary Geotechnical Engineering Report
NEW RETAIL BUILDING
Edmonds, Washington
Prepared For:
BEHAR COMPANY
October 12, 2016
Project No. KE160514A
a s s o c i a t e d
earth sciences
i n c o r p o r a t e d
October 12, 2016
Project No. KE160514A
Behar Company
Commercial Real Estate Services
1000 Second Avenue, Suite 3230
Seattle, Washington 98104
Attention: Mr. Matt Steiner, Vice President
Subject: Subsurface Exploration, Geologic Hazard,
and Preliminary Geotechnical Engineering Report
New Retail Building
Edmonds, Washington
Dear Mr. Steiner:
We are pleased to present these copies of our report for the referenced project. This report
summarizes the results of our subsurface exploration, geologic hazards, and geotechnical
engineering studies, and offers preliminary recommendations for the design and development
of the proposed project. Our report is preliminary since project plans were under development
at the time this report was written. We should be allowed to review the recommendations
presented in this report and modify them, if needed, once final project plans have been
formulated.
We have enjoyed working with you on this study and are confident that the recommendations
presented in this report will aid in the successful completion of your project. If you should have
any questions, or if we can be of additional help to you, please do not hesitate to call.
Sincerely,
ASSOCIATED EARTH SCIENCES, INC.
Kirkland, Washington
Stephen A. iebert, P.E.
Associate Geotechnical Engineer
SAS/Id - KE160514A2 - Projects\20160514\KE\WP
Kirkland Office 1 911 Fifth Avenue I Kirkland, WA 98033 P 1425.827.7701 F 1425.827,5424
Everett Office 12911 % Hewitt Avenue, Suite 2 1 Everett, WA 98201 P 1425.259.0522 F 1425.827.5424
Tacoma Office 1 1552 Commerce Street, Suite 102 1 Tacoma, WA 98402 P 1 253.722.2992 F 1 253.722.2993
www.aesgeo.com
SUBSURFACE EXPLORATION, GEOLOGIC HAZARD,
AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
NEW RETAIL BUILDING
Edmonds, Washington
Prepared for:
Behar Company
Commercial Real Estate Services
1000 Second Avenue, Suite 3230
Seattle, Washington 98104
Prepared by:
Associated Earth Sciences, Inc.
911 51h Avenue
Kirkland, Washington 98033
425-827-7701
Fax: 425-827-5424
October 12, 2016
Project No. KE160514A
Subsurface Exploration, Geologic Hazard, and
New Retail Building Preliminary Geotechnical Engineering Report
Edmonds, Washington Project and Site Conditions
I. PROJECT AND SITE CONDITIONS
1.0 INTRODUCTION
This report presents the results of our subsurface exploration, geologic hazards, and
preliminary geotechnical engineering study for the proposed retail building in Edmonds,
Washington. Our recommendations are preliminary in that the project is still in the conceptual
design phase. Recommendations in this report are based on review of a topographic survey
dated February 12, 2014 and written information provided to us by the Behar Company
(Behar). The site location is shown on the "Vicinity Map," Figure 1. The approximate locations
of the exploration borings completed for this study are shown on the "Site and Exploration
Plan," Figure 2. Interpretive logs of the subsurface explorations and laboratory test results
completed for this study are included in the Appendix.
1.1 Purpose and Scope
The purpose of this study was to provide preliminary geotechnical engineering
recommendations to be utilized in the design of the project. This study included a review of
selected available geologic literature, advancing three hollow -stem auger soil borings, and
performing geologic studies to assess the type, thickness, distribution, and physical properties
of the subsurface sediments and shallow ground water. Geotechnical engineering studies were
completed to establish recommendations for site preparation, structural fill, foundations, floor
support, drainage, and pavement. Feasibility of storm water infiltration was also evaluated.
This report summarizes our fieldwork and offers recommendations based on our present
understanding of the project. We recommend that we be allowed to review the
recommendations presented in this report and revise them, if needed, when a project design
has been finalized.
1.2 Authorization
Our work was completed in general accordance with our scope of work and cost proposal dated
September 22, 2016. This report has been prepared for the exclusive use of the Behar
Company, and their agents, for specific application to this project. Within the limitations of
scope, schedule, and budget, our services have been performed in accordance with generally
accepted geotechnical engineering and engineering geology practices in effect in this area at
the time our report was prepared. No other warranty, express or implied, is made.
2.0 PROJECT AND SITE DESCRIPTION
The site is occupied by an existing one-story commercial building with associated asphalt paving
located at 22019 State Route 99 (SR-99). Site topography is relatively flat and bounded by
similar one-story commercial buildings with asphalt -paved surface parking on the north, south,
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and east sides, and SR-99 to the west. We understand that the site development plans will
include demolition of the existing building and construction of a new one-story retail building
roughly 6,000 square feet in size in approximately the same location. We also understand that
on -site storm water infiltration is being considered for this project.
3.0 SUBSURFACE EXPLORATION
Our subsurface exploration program completed for this project consisted of advancing three
hollow -stem auger soil borings. The conclusions and recommendations presented in this report
are based on the explorations completed for this study. The locations and depths of the
explorations were completed within site and budget constraints.
3.1 Exploration Borings
The exploration borings were completed by advancing hollow -stem auger tools with a
truck -mounted drill rig. During the drilling process, samples were obtained at generally 2.5- to
5-foot-depth intervals. The exploration borings were continuously observed and logged by a
representative from our firm. The exploration logs presented in the Appendix are based on the
field logs, drilling action, and observation of the samples collected.
Disturbed but representative samples were obtained by using the Standard Penetration Test
(SPT) procedure in accordance with American Society for Testing and Materials (ASTM) D-1586.
This test and sampling method consists of driving a standard, 2-inch outside -diameter,
split -barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free -falling a
distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the
number of blows required to drive the sampler the final 12 inches is known as the Standard
Penetration Resistance ("N") or blow count. If a total of 50 is recorded within one 6-inch
interval, the blow count is recorded as the number of blows for the corresponding number of
inches of penetration. The resistance, or N-value, provides a measure of the relative density of
granular soils or the relative consistency of cohesive soils; these values are plotted on the
attached exploration boring logs. The samples obtained from the split -barrel sampler were
classified in the field and representative portions placed in watertight containers. The samples
were then transported to our laboratory for further visual classification and laboratory testing,
as needed.
Subsurface conditions at the project site were inferred from the field explorations
accomplished for this study, visual reconnaissance of the site, and review of selected applicable
geologic literature. Because of the nature of exploratory work below ground, interpolation of
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subsurface conditions between field explorations is necessary. It should be noted that differing
subsurface conditions may sometimes be present due to the random nature of deposition and
the alteration of topography by past grading and/or filling. The nature and extent of any
variations between the field explorations may not become fully evident until construction.
4.1 Stratigraphy
Existing Asphalt
Existing surficial asphalt paving was encountered at all exploration locations and ranged from
1.5 to 4 inches in thickness.
Fill
Existing fill was observed in all three exploration borings advanced for this study to depths of
7.5 to 10 feet below existing ground surface. The thickness of the existing fill observed at each
exploration location is depicted on Figure 2. The observed existing fill typically consists of
moist, very loose to loose, silty to very silty sand with variable amounts of gravel. Variable
amounts of charcoal debris and other organic material were observed in exploration borings
E13-2 and EB-3. Existing fill on this site is unsuitable for structural support, however it may be
possible to reuse provided debris and organics are removed and proper moisture -conditioning
is achieved in structural fill applications.
Vashon Lodgement Till
Underlying the existing fill, exploration borings E13-1 and E13-2 encountered dense to very dense,
silty sand with variable amounts of gravel interpreted as Vashon lodgement till. Lodgement till
was deposited at the base of an active ice sheet and was subsequently compacted by the
weight of the overlying glacial ice. Lodgement till typically possesses high -strength and
low -compressibility attributes that are favorable for support of moderate to heavy foundation
loads, with proper preparation. Lodgement till is silty and moisture -sensitive. As a result
during wet weather it can be difficult to reuse as structural fill and subgrades can be disturbed
by construction equipment.
Vashon Advance Outwash
Underlying the existing fill, exploration boring E13-3 encountered typically dense to very dense,
silty, interbedded sand with some gravel interpreted as Vashon advance outwash. Advance
outwash was deposited by meltwater streams from an advancing ice sheet. Advance outwash
is suitable for support of structural loads when prepared as recommended in this report. The
advance outwash encountered in the boring contained a significant fine-grained fraction, and
may be difficult to reuse as structural fill during wet weather.
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Published Geologic Map
Review of the regional geologic map titled Geologic Map of the Edmonds East and Part of the
Edmonds West Quadrangles, Washington by James P. Minard (1983), indicates that the area of
the subject site is underlain by the Vashon lodgement till and Vashon advance outwash contact.
Our interpretation of the sediments encountered at the subject site is in general agreement
with the regional geologic map.
4.2 Hydrology
We did not encounter ground water in our exploration borings. The oxidized staining observed
at the contact between the fill and lodgement till in our explorations suggests that ground
water may perch within the fill, and be present during the wetter winter and spring months,
similar to interflow. Interflow occurs when surface water percolates down through the surficial
weathered or higher -permeability sediments and becomes perched atop underlying, lower -
permeability sediments. It should be noted that the occurrence and level of ground water
seepage at the site may vary in response to such factors as changes in season, precipitation,
and site use.
4.3 Laboratory Testing
Two laboratory grain -size analyses were performed in accordance with ASTM D-422 on
representative selected samples of the Vashon advance outwash collected during our
subsurface exploration. The grain -size analysis test results are included in the Appendix.
We understand infiltration testing for this site is dictated by the City of Edmonds' Stormwater
Supplement in combination with the Washington State Department of Ecology's (Ecology's)
Stormwater Management Manual for Western Washington (Ecology Manual). The City's
supplement requires that preliminary infiltration rates be based on U.S. Department of
Agriculture (USDA) textural analysis. Based on our explorations completed for this study,
correlations with the USDA textural analysis are not appropriate for the soils encountered at
this site because they have been glacially consolidated. Our infiltration feasibility
recommendations are presented later in this report.
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Edmonds, Washington Geologic Hazards and Mitigations
II. GEOLOGIC HAZARDS AND MITIGATIONS
The following discussion of potential geologic hazards is based on the geologic, and ground and
surface water conditions, as observed and discussed herein. The discussion will be limited to
seismic and erosion issues.
5.0 SEISMIC HAZARDS AND MITIGATIONS
Earthquakes occur regularly in the Puget Lowland. The majority of these events are small and
are usually not felt by people. However, large earthquakes do occur, as evidenced by the 1949,
7.2-magnitude event; the 2001, 6.8-magnitude event; and the 1965, 6.5-magnitude event. The
1949 earthquake appears to have been the largest in this region during recorded history and
was centered in the Olympia area. Evaluation of earthquake return rates indicates that an
earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period.
Generally, there are three types of potential geologic hazards associated with large seismic
events at this site: 1) surficial ground rupture, 2) liquefaction, and 3) ground motion. The
potential for each of these hazards to adversely impact the proposed project is discussed
below.
5.1 Surficial Ground Rupture
Generally, the largest earthquakes that have occurred in the Puget Sound area are sub -crustal
events with epicenters ranging from 50 to 70 kilometers in depth. Earthquakes that are
generated at such depths usually do not result in fault rupture at the ground surface. Current
research indicates that surficial ground rupture is possible in areas close to the Southern
Whidbey Island Fault Zone, the closest mapped fault to the project. Although our current
understanding of this fault zone is limited and is an active area of research, the site lies more
than 5 miles from the currently understood limits of this fault zone. Therefore, based on
current information, the risk of damage to the planned development as a result of surface
rupture due to faulting is low, in our opinion.
5.2 Liquefaction
Liquefaction is a process through which unconsolidated soil loses strength as a result of
vibrations, such as those which occur during a seismic event. During normal conditions, the
weight of the soil is supported by both grain -to -grain contacts and by the fluid pressure within
the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the
grain -to -grain contact, increase the pore pressure, and result in a temporary decrease in soil
shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is
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supported by pore pressure alone. Liquefaction can result in deformation of the sediment and
settlement of overlying structures. Areas most susceptible to liquefaction include those areas
underlain by non -cohesive silt and sand with low relative densities, accompanied by a shallow
water table.
The subsurface conditions encountered at this site pose little risk of liquefaction due to the
relatively high density of the native soils and lack of shallow ground water. No detailed
liquefaction analysis was completed as part of this study, and none is warranted, in our opinion.
5.3 Ground Motion/Seismic Site Class (2015 International Buildina Code
Structural design of the building should follow 2015 International Building Code (IBC) standards.
We recommend that the project be designed in accordance with Site Class "C" as defined in IBC
Table 20.3-1 of American Society of Civil Engineers (ASCE) 7 — Minimum Design Loads for
Buildings and Other Structures.
6.0 EROSION HAZARDS AND MITIGATIONS
Project plans should include implementation of temporary erosion controls in accordance with
local standards of practice. Erosion control methods should include limiting earthwork to
seasonally drier periods, typically April 1 to October 31, use of perimeter silt fences, and straw
mulch in exposed areas. During construction, surface water should be collected as close as
possible to the source to minimize silt entrainment that could require treatment or detention
prior to discharge. Timely implementation of permanent drainage control measures should
also be a part of the project plans, and will help reduce erosion and generation of silty surface
water onsite.
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III. PRELIMINARY DESIGN RECOMMENDATIONS
7.0 INTRODUCTION
Our exploration indicates that, from a geotechnical engineering standpoint, the proposed
project is feasible provided the recommendations contained herein are properly followed. Very
loose to loose existing fill was observed in all three explorations advanced around the existing
building. It is unclear based on our subsurface explorations if the fill is present beneath the
existing building. While onsite we did not observe any evidence of building settlement which
suggests that some mitigation of fill may have occurred within the building footprint. We
understand that the new building will be situated in roughly the same location as the existing
building, however the actual footprint was not available at the time our report was prepared.
Existing fill on this site is not suitable for support of new foundations and is also not suitable for
infiltration. The surficial fill is underlain at depth by dense to very dense glacially consolidated
lodgement till and advance outwash sediments that are suitable for structural support. The
depth to suitable support soils observed in our explorations ranges from 7.5 to 10 feet below
existing grade as shown on Figure 2.
Where existing fill is found at the time of construction within the footprint of the new building
we recommend that it be excavated beneath foundations and replaced with compacted,
controlled structural fill, as discussed in the "Structural Fill" section in this report. Beneath floor
slabs, we recommend a thickness of at least 2 feet of new structural fill. The following report
sections provide additional recommendations regarding site preparation, grading, foundations,
floor support, drainage, paving, and infiltration feasibility.
8.0 SITE PREPARATION
Erosion and surface water control should be established around the clearing limits to satisfy
local requirements. Consideration should be given to keeping existing paving in place for use
during construction even if long-term plans call for pavement removal. Existing structures,
foundations, paving, buried utilities, and any other deleterious materials should be removed
where they are located below planned construction areas. All disturbed soils resulting from
demolition activities should be removed to expose underlying undisturbed native sediments
and replaced with structural fill, as needed. All excavations below final grade made for
demolition activities should be backfilled, as needed, with structural fill.
Once demolition has been completed, existing fill should be addressed. The observed fill depth
in our exploration borings was up to approximately 10 feet below existing grade. We
recommend that existing fill below the new foundation be removed to expose underlying
native sediments suitable for structural support. Removal of existing fill should extend laterally
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beyond the edge of the footing a distance equal to the depth of overexcavation. The required
depth of removal should be determined in the field based on actual conditions encountered
during excavation. Planned foundation grade should be restored using compacted structural fill.
8.1 Temporary Cut Slopes
In our opinion, stable construction slopes should be the responsibility of the contractor and
should be determined during construction. For estimating purposes, however, temporary,
unsupported cut slopes can be planned at 1.5H:1V (Horizontal:Vertical) in unsaturated existing
fill. Temporary slopes of 1H:1V can be planned in unsaturated lodgement till and advance
outwash sediments.
These slope angles are for areas where ground water seepage is not present at the faces of the
slopes. If ground or surface water is present when the temporary excavation slopes are
exposed, flatter slope angles may be required. As is typical with earthwork operations, some
sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In
addition, WISHA/OSHA regulations should be followed at all times.
8.2 Site Disturbance
Most of the on -site soils contain fine-grained material, which makes them moisture -sensitive
and subject to disturbance when wet. The contractor must use care during site preparation
and excavation operations so that the underlying soils are not softened. If disturbance occurs,
the softened soils should be removed and the area brought to grade with structural fill.
8.3 Wet Weather Construction
The existing fill material and the native sediments at this site contain substantial silt and are
considered highly moisture -sensitive. Care should be taken to seal all earthwork areas during
mass grading at the end of each workday by grading all surfaces to drain and sealing them with
a smooth -drum roller. Stockpiled soils that will be reused in structural fill applications should
be covered whenever wet weather is possible.
If winter construction is expected, existing paving should be used for construction staging if at
all possible. In areas of exposed soil crushed rock fill could be used to provide construction
staging areas. The stripped subgrade should be observed by the geotechnical engineer, and
should then be covered with a geotextile fabric, such as Mirafi 50OX or equivalent. Once the
fabric is placed, we recommend using a crushed rock fill layer at least 10 inches thick in areas
where construction equipment will be used.
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8.4 Frozen Subgrades
If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to
thaw and then be recompacted prior to placing subsequent lifts of structural fill or foundation
components. Alternatively, the frozen material could be stripped from the subgrade to reveal
unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil
should not be reused as structural fill until allowed to thaw and adjusted to the proper
moisture content, which may not be possible during winter months.
9.0 STRUCTURAL FILL
All references to structural fill in this report refer to subgrade preparation, fill type, placement,
and compaction of materials, as discussed in this section. If a percentage of compaction is
specified under another section of this report, the value given in that section should be used.
For backfill of buried utilities in the right-of-way, the backfill should be placed and compacted in
accordance with the City of Edmonds codes and standards.
After stripping, planned excavation, and any required overexcavation have been performed to
the satisfaction of the geotechnical engineer/engineering geologist, the surface of the exposed
ground should be recompacted to a firm and unyielding condition. If the subgrade contains too
much moisture, adequate recompaction may be difficult or impossible to obtain, and should
probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed
with washed rock or quarry spalls to act as a capillary break between the new fill and the wet
subgrade. Where the exposed ground remains soft and further overexcavation is impractical,
placement of an engineering stabilization fabric may be necessary to prevent contamination of
the free -draining layer by silt migration from below.
After recompaction of the exposed ground is tested and approved, or a free -draining rock
course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as
non -organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts,
with each lift being compacted to 95 percent of ASTM D-1557. The top of the compacted fill
should extend horizontally outward a minimum distance of 3 feet beyond the locations of the
perimeter footings or roadway edges before sloping down at a maximum angle of 2H:1V.
The contractor should note that any proposed fill soils should be evaluated by Associated Earth
Sciences, Inc. (AESI) prior to their use in fills. This would require that we have a sample of the
material at least 72 hours in advance to perform a Proctor test and determine its field
compaction standard.
Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater
than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered
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moisture -sensitive. The lodgement till soils and advance outwash sediments are estimated to
contain substantially more than 5 percent fine-grained material. Use of moisture -sensitive soil
in structural fills should be limited to favorable dry weather and dry subgrade conditions.
Construction equipment traversing the site when the soils are wet can cause considerable
disturbance.
If fill is placed during wet weather or if proper compaction cannot be obtained, a select, import
material consisting of a clean, free -draining gravel and/or sand should be used. Free -draining
fill consists of non -organic soil, with the amount of fine-grained material limited to 5 percent by
weight when measured on the minus No. 4 sieve fraction, and at least 25 percent retained on
the No. 4 sieve.
Existing fill soils observed in one of our explorations contained variable amounts of organic
material. Excavated existing fill could be reused in structural fill applications provided organic
material is removed and moisture content is suitable for required compaction. The lodgement
till and advance outwash soils we encountered in our explorations ranged in moisture content
from moist to very moist and are interpreted to be above their optimum moisture content for
compaction purposes. In order to reuse excavated on -site soils in structural fill applications, it
will likely be necessary to moisture -condition wet site soils by aeration and drying during
favorable dry weather conditions. Alternatives to drying site soils include using imported
granular soils suitable for use in structural fill, or treating wet soils with Portland cement.
10.0 FOUNDATIONS
Spread footings may be used for building support when founded directly on suitable native
sediments or on new structural fill underlain by suitable native sediments as described in the
"Site Preparation" section of this report. We recommend that an allowable foundation soil
bearing pressure of 3,000 pounds per square foot (psf) be used for design of shallow
foundations. Perimeter footings should be buried at least 18 inches into the surrounding soil
for frost protection. However, all footings must penetrate to the prescribed bearing stratum,
and no footing should be founded in or above organic or loose soils or above existing fill. All
footings should have a minimum width of 18 inches.
It should be noted that the area bound by lines extending downward at 1H:1V from any footing
must not intersect another footing or intersect a filled area that has not been compacted to
at least 95 percent of ASTM D-1557. In addition, a 1.5H:1V line extending down from any
footing must not daylight because sloughing or raveling may eventually undermine the footing.
Thus, footings should not be placed near the edge of steps or cuts in the bearing soils.
Anticipated settlement of footings founded as described above should be on the order of
inch or less. However, disturbed soil not removed from footing excavations prior to footing
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placement could result in increased settlements. All footing areas should be inspected by AESI
prior to placing concrete to verify that the design bearing capacity of the soils has been attained
and that construction conforms to the recommendations contained in this report. Such
inspections may be required by the governing municipality. Perimeter footing drains should be
provided as discussed under the "Drainage Considerations" section of this report.
10.1 Passive Resistance and Friction Factors
Lateral loads can be resisted by friction between the foundation and the natural glacial soils or
supporting structural fill soils, and by passive earth pressure acting on the buried portions of
the foundations. The foundations must be backfilled with structural fill and compacted to
at least 95 percent of the maximum dry density to achieve the passive resistance provided
below. We recommend the following allowable design parameters:
• Passive equivalent fluid = 300 pounds per cubic foot (pcf)
• Coefficient of friction = 0.30
10.2 Drainage Considerations
Foundation drains should be placed at the base of footing elevation. Drains should consist of
rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed gravel. The drains should
be constructed with sufficient gradient to allow gravity discharge away from the proposed
building. Roof and surface runoff should not discharge into the footing drain system, but
should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to
walls should be sloped downward away from the proposed structure to achieve surface
drainage.
11.0 FLOOR SUPPORT
Slab -on -grade floors may be used over medium dense to very dense native soils, or over at least
2 feet of structural fill placed as recommended in the "Site Preparation" and "Structural Fill"
sections of this report. Slab -on -grade floors should be cast atop a minimum of 4 inches of
washed pea gravel or washed crushed "chip" rock with less than 3 percent passing the U.S. No.
200 sieve to act as a capillary break. The floors should also be protected from dampness by
covering the capillary break layer with an impervious moisture barrier at least 10 mils in
thickness.
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12.0 PAVEMENT RECOMMENDATIONS
We anticipate that project plans will also include removal of existing asphalt paving around the
existing building and replacement with new asphalt paving. We recommend that all new
pavement be supported on a subgrade that has been compacted to a firm and non -yielding
condition. All subgrades should be proof -rolled to identify any soft areas prior to placement of
base course. Soft areas should be overexcavated and replaced with structural fill.
For parking and driveway areas, we recommend a pavement section consisting of 3 inches of
Class %-inch Hot Mix Asphalt (HMA) underlain by 4 inches of Crushed Surfacing Base Course
(CSBC). Alternatively, Asphalt Treated Base (ATB) or Class %-inch HMA could be used for
construction access followed by repair of any construction damage and final surfacing. If this
alternative is used, we recommend a minimum of 2 inches of CSBC to serve as a working
surface and a minimum of 3 inches of ATB. Final surfacing should consist of 2 inches of Class %-
inch HMA after any construction damage has been repaired.
13.0 INFILTRATION FEASIBILITY AND RECOMMENDATIONS
The site is mostly underlain by undocumented fill from ground surface to depths of 7.5 to
10 feet. The fill is not considered suitable for shallow infiltration due to unknowns in vertical
and lateral extent of the fill, both in regards to fines content and debris.
The Vashon advance outwash deposits encountered beneath the fill and lodgement till may be
suitable for infiltration. Grain -size analyses were performed on two samples of advance
outwash for this study. The outwash was silty and glacially consolidated. In our opinion,
correlations with the USDA soil textural triangle (City of Edmonds' Stormwater Supplement) are
not appropriate for finer -grained glacially consolidated sediments. Glacial consolidation can
reduce permeability by a factor of 3 to 10.
In our opinion, shallow infiltration is not feasible. However deeper infiltration strategies may
be feasible within the advance outwash. Deeper infiltration evaluation was beyond the scope
of this study and would require additional subsurface exploration.
14.0 PROJECT DESIGN AND CONSTRUCTION MONITORING
Our report is preliminary since project plans were not finalized at the time this report was
written. We recommend that AESI perform a geotechnical review of the plans prior to final
design completion. In this way, we can confirm that our earthwork and foundation
recommendations have been properly interpreted and implemented in the design.
October 12, 2016 ASSOCIATED EARTH SCIENCES, INC.
DDV/Id-KE160514A2-Projects �20160514�KE�WP Page 12
Subsurface Exploration, Geologic Hazards,
New Retail Building and Preliminary Geotechnica/ Engineering Report
Edmonds, Washington Preliminary Design Recommendations
We are also available to provide geotechnical engineering and monitoring services during
construction. The integrity of the foundation system depends on proper site preparation and
construction procedures. In addition, engineering decisions may have to be made in the field in
the event that variations in subsurface conditions become apparent. Construction monitoring
services are not part of this current scope of work. If these services are desired, please let us
know, and we will prepare a cost proposal.
We have enjoyed working with you on this study and are confident that these
recommendations will aid in the successful completion of your project. If you should have any
questions or require further assistance, please do not hesitate to call.
Sincerely,
ASSOCIATED EARTH SCIENCES, INC.
Kirkland, Washington N k
OL�
r,
S�J
V-
Daniel D. Voth
Staff Geologist
Matthe A. Miller, P.E.
Principal Engineer
Attachments: Figure 1: Vicinity Map
Figure 2: Site and Exploration Plan
Appendix: Exploration Logs
Laboratory Test Results
Stephen A. Siebert, P.E.
Associate Geotechnical Engineer
October 12, 2016
DDV/Id - KE160514A2 - Projects k20160514 �KE� WP
ASSOCIATED EARTH SCIENCES, INC.
Page 13
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DATA SOURCES/REFERENCES:
a USGS: 24K SERIES TOPOGRAPHIC MAPS
E SNOHOMISH CO: STREETS, CITY LIMITS, PARCELS 2016
e LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE
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' , Cop rl'ghtOO 2013 Natonal,Geographlc;;Soclety,-cubed'
a s s o c i a t e d
N earth sciences
An c o r p o r a t e d
,DDD 2000 VICINITY MAP
FEET
NEW RETAIL BUILDING
NOTEREPRO UCTIOND WHITE
OFTHIS EDMONDS, WASHINGTON
REPRODUCTION OF THIS COLOR
ORIGINAL MAY REDUCE ITS
EFFECTIVENESS AND LEAD TO PROJ NO. DATE: FIGURE:
INCORRECT INTERPRETATION KE160514A 10/16 1
w
W
CB
_<�__TOP=P3.36
6" INy(W)=351.88
D/A
N
A
15 30
I /7 %% %% %% %r%%i
FEET
� y
r
1
1 r
1 /
4" INV(W)=351.30 \
\ Q EB-3 r
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1-STORY
CONC. BI
BUILDINC
/ 03 �I ' r 18,934 SC
> EXISTING
STUCCO
BUILDING
U G 0 EB-2
DRAIN
6,184 SQ. FT. ` 10'/ r�TOP=347.71
DRAIN
TOP=351.28 /I /
EB-1
7.5'
e / C
'� r
r 351
- ��z
350
CB
TOP=3
\
"so
CONC.
�44'47
A,
❑
� 1
LEGEND:
Q EB EXPLORATION BORING
X.X' DEPTH OF EXISTING FILL
rK.�rrrmanrra:�aasl
NOTE: LOCATION AND DISTANCES SHOWN ARE APPROXIMATE.
NOTES:
1. BASE MAP REFERENCE: ALTA SURVEY, BEHAR SURVEY
SCAN, RITE AID EDMONDS, 2/12/2014
IBLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS I
EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION.
a s s o c i a t e d
earth sciences
incorporated
SITE AND EXPLORATION PLAN
NEW RETAIL BUILDING
EDMONDS, WASHINGTON
PROJ NO. DATE: FIGURE:
KE160514A 10/16 2
APPENDIX
Exploration Logs
Laboratory Test Results
U
EZ
°o
Well -graded gravel and
Terms Describing Relative Density and Consistency
o p o o
OW
g ravel with sand, little to
2)
Density SPT blows/foot
w
o
no fines
Very Loose 0 to 4
Coarse-4 to 10
o o o
0 o
0 0
o o o
GP
Poorly -graded gravel
0)Loose
>
U)
c>
o o
- v,
o
�,o
w
Grained Soils Medium Dense 10 to 30 Test Symbols
0
0
o 0 0 0 o
and gravel with sand,
Dense 3o to 50
little to no fines
Very Dense >50 G = Grain Size
M = Moisture Content
° 0°
0
Silty gravel and silty
6
Z
C
LO o
Consistency SPT(2�blows/foot
Y A= Atterberg Limits
c a
S
GM
gravel with sand
Very Soft 0 to 2 C = Chemical
Fine -
v
~ `
.Soft
° 0
° 0
2 to 4 DID =Dry Density
Grained Soils
c
E
0
.i
Medium Stiff 4 to 8 K = Permeability
g
o
Stiff 8 to 15
Clayey gravel and
Very Stiff 15 to 30
N
NI
GC
clayey gravel with sand
Hard >30
o
L
Component Definitions
o
Well -graded sand and
t
Descriptive Term Size Range and Sieve Number
m
SW
sand with gravel, little
Boulders Larger than 12"
o
Li
u
e
to no fines
Cobbles 3" to 12"
m
;n a�
_
eveeeveeee
Gravel 3" to No. 4 (4.75 mm)
Poorly -graded sand
con
c i °'
A
SP
and sand with gravel,
Coarse Gravel 3" to 3/4"
Fine Gravel 3/4to No. 4 75 mm
" 4 (� )
4)
c
cn
o v
N o
little to no fines
Sand No. 4 (4.75 mm) to No. 200 (0.075 mm)
0 z
Coarse Sand No. 4 (4.75 mm) to No. 10 (2.00 mm)
6
o y
�
SM
Silty Sand and
Medium Sand No. 10 (2.00 mm) to No. 40 (0.425 mm)
silty sand with
Fine Sand No. 40 (0.425 mm) to No. 200 (0.075 mm)
N
v
c N
o a
tp.-::'::.
gravel
Silt and Clay Smaller than No. 200 (0.075 mm)
(3) Estimated Percentage
Moisture Content
Na
sc
Clayey sand and
co
NI
clayey sand with gravel
Component Percentage by Weight
Dry - Absence of moisture,
Trace <5
dusty, dry to the touch
Slightly Moist - Perceptible
Silt, sandy silt, gravelly silt,
moisture
o
ML
silt with sand or gravel
Some 5 to <12
Moist - Damp but no visible
u7
c
T w
Modifier 12 to <30
water
Clay Of low to medium
o
`—°
(silty, sandy, gravelly)
Very Moist - Water visible but
d
CL
plasticity; silty, sandy, or
not free draining
z
•=
gravelly clay, lean clay
Very modifier 30 to <50
Wet -Visible free water, usual) Y
NE
(silty, sandy, gravelly)
from below water table
0-
a
==
Organic clay or silt of low
Symbols
E
—
OL
plasticity
Blows/6" or
0
Sampler portion of 6"
Cement grout
o
Type /
i
surface seal
Elastic silt, clayey silt, silt
2.0" OD Sampler Type
o
o
�,
MH
with micaceous or
Split Spoon p Description (4)
Bentonite
seal
�
o
or fine sand or
Sampler p 3.0" OD Split -Spoon Sampler -
:-= Filter pack with
A
o
silt
(SPT) 3.25" OD Split -Spoon Ring Sampler (4)
. -
; .
:: blank casing
Clay of high plasticity,
v�
U o
c
CH
sandy or gravelly Clay, fat
Bulk sample 3.0" OD Thin -Wall Tube Sampler
section
Screened casing
12
E
J
clay with sand or ravel
Y g
(including Shelby tube)
_ or Hydrotip
= with filter pack
U
c
Grab Sample
End cap
c
9
j %
Organic clay or silt of
0 Portion not recovered
Jmedium
to high
(1) (4)
Percentage by dry weight Depth of ground water
plasticity
(2) (SPT) Standard Penetration Test
ASTM D 1586 1 ATD = At time of drilling
(3) ( ) Q Static water level (date)
In General Accordance with
w
Peat, muck and other
rn
_0
c
a, 0
PT
highly organic soils
Standard Practice for Description (e) Combined USCS symbols used for
and Identification of Soils (ASTM D-2488) fines between 5% and 12%
Classifications of soils in this report are based on visual field and/or laboratory observations, which include density/consistency, moisture condition, grain size, and
g plasticity estimates and should not be construed to imply field or laboratory testing unless presented herein. Visual -manual and/or laboratory classification
3 methods of ASTM D-2487 and D-2488 were used as an identification guide for the Unified Soil Classification System.
T
O!
° a s s o c i a t e d
earth sciences EXPLORATION LOG KEY FIGURE Al
N
o i n c o r p o r a t e d
a
asaccIat9d
Exploration Lo
e a r t h s c i e n c e s
Project Number
Exploration Number
Sheet
incorporated
KE160514A
EB-1
1of1
Project Name New Retail Building Ground Surface Elevation (ft) 352
Location Edmonds, WA Datum Unknown
Driller/Equipment EDI / B-61 Date Start/Finish 10/5/16,10/5/16
Hammer Weight/Drop 140# / 30" Hole Diameter (in) inr hPs
Q
a
o
>
J
ifl
N
Blows/Foot
n
S m
m
E
°
`m
❑
T rn
DESCRIPTION
o
"
m
3:
m
°
10 20 30 40
Asphalt - 3 inches
Fill
Very loose, very moist to wet, dark brown, silty, gravelly, fine to coarse SAND
0
S-1
(SM).
0
1
1
5
Very loose, moist, oxidized gray, silty, fine to coarse SAND, some gravel (SM).
0
S 2
1
-
2
1
S-3
14
21
A43
Vashon Lodgement Till
Dense, moist, gray, silty, fine to medium SAND, some gravel; diamict (SM).
22
10
Very dense, very moist, gray, silty, gravelly, fine to medium SAND; diamict
14
S-4
(SM).
40
75
35
15
S-5
As above.
0/
50/
"
20
S-6
-
As above.
0/1„
50/
"
Bottom of exploration boring at 21.5 feet
No ground water encountered.
25
30
35
Sampler Type (ST):
2" OD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: DV
3" OD Split Spoon Sampler (D & M) Ring Sample Water Level() Approved by: .1HS
Grab Sample 0 Shelby Tube Sample 1 Water Level at time of drilling (ATD)
asaccIat9d
Exploration Lo
e a r t h s c i e n c e s
Project Number
Exploration Number
Sheet
incorporated
KE160514A
EB-2
1of1
Project Name New Retail Building Ground Surface Elevation (ft) 352
Location Edmonds, WA Datum Unknown
Driller/Equipment EDI / B-61 Date Start/Finish 10/5/16,10/5/16
Hammer Weight/Drop 140# / 30" Hole Diameter (in) inr hPs
Q
a
o
>
J
ifl
N
Blows/Foot
n
S m
m
E
°
`m
❑
T rn
DESCRIPTION
o
"
m
3:
m
°
10 20 30 40
Asphalt - 1 1/2 inches
Fill
Dense, moist, gray, very silty, fine to coarse SAND, some gravel; blow counts
14
S-1
overstated due to rock (SM).
16
A3
19
5
Loose, moist, gray, silty, fine to coarse SAND, some gravel (SM).
7
S 2
5
-
B
3
Loose, moist, dark brown, very silty, fine to medium SAND, some gravel, some
4
S-3
charcoal and organics (SM).
3
A6
3
10
5
Vashon Lodgement Till
TS-4
Very dense, very moist, mottled gray, silty, gravelly, fine to coarse SAND;
23
52
diamict (SM).
29
15
Dense, moist, oxidized gray, silty, gravelly, fine to medium SAND; diamict (SM).
12
S-5
16
A42
26
20
S-6
Becomes very dense. No recovery.
0/ „
50/
"
Bottom of exploration boring at 21.5 feet
No ground water encountered.
25
30
35
Sampler Type (ST):
2" OD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: DV
3" OD Split Spoon Sampler (D & M) Ring Sample Water Level() Approved by: .1HS
Grab Sample 0 Shelby Tube Sample 1 Water Level at time of drilling (ATD)
asaccIat9d
Exploration Lo
e a r t h s c i e n c e s
Project Number
Exploration Number
Sheet
incorporated
KE160514A
EB-3
1of1
Project Name New Retail Building Ground Surface Elevation (ft) 352
Location Edmonds, WA Datum Unknown
Driller/Equipment EDI / B-61 Date Start/Finish 10/5/16,10/5/16
Hammer Weight/Drop 140# / 30" Hole Diameter (in) inr hPs
Q
a
o
>
J
ifl
N
Blows/Foot
n
S m
m
E
°
`m
❑
T rn
DESCRIPTION
o
"
m
3:
m
°
10 20 30 40
Asphalt - 4 inches
Fill
Loose, moist, dark brown, silty, fine to coarse SAND, some gravel, trace
2
S-1
organics (SM).
3
A5
2
5
Loose, moist, mottled gray to dark brown, gravelly, very silty, fine to coarse
3
S-2
-
SAND (SM).
3
AB
5
5
Vashon Advance Outwash
S-3
Dense, slightly moist, gray, silty, fine to medium SAND, some gravel;
17
A34
occasional silty, fine sand interbeds (SP-SM).
17
10
_
As above.
13
S 4
19
4
27
15
S-5
Very dense, moist, gray, silty, fine to coarse SAND, some gravel; fine to
339 „
50/
"
medium sand is major constituent; diamict (SM).
20
S-g
Very dense, slightly moist to moist, gray, silty, fine to medium SAND, some
42 „
50/
"
gravel, interbedded with zones of diamict (SP-SM).
Bottom of exploration boring at 21.5 feet
No ground water encountered.
25
30
35
Sampler Type (ST):
2" OD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: DV
3" OD Split Spoon Sampler (D & M) Ring Sample Water Level() Approved by: .1HS
Grab Sample 0 Shelby Tube Sample 1 Water Level at time of drilling (ATD)
a s s o c i a t e d
0 i earth sciences
n c o r p o r a t e
GRAIN SIZE ANALYSIS - MECHANICAL ASTM D422
Project Name Project Number Date Sampled Date Tested Tested By
New Retail Buiding KE160514A 10/6/2016 10/7/2016 MS
Sample Source Sample No. Depth (ft) Soil Description
Onsite EB-3 10 silty SAND, some gravel (SM)
Total Sample Dry Wt. (g) Moisture Content (%) D10 (mm) Reference Specification
533.5 5 <0.01
U.S. Sieve Opening in Inches U.S. Sieve Numbers Hydrometer
4 3 2 1.5 1 3/4 1/2 3/8 3.5 4 6 8 10 14 16 20 30 40 50 60 100 140 200 270 400 500 635
100
90
80
70
v
0 30
20
10
0 1 II I I 1 1. 1 1 1II I I I 1 11 1 1I' I
100 10 1 0.1 0.01
Diameter (mm) ---@-- EB-3 - - - Ref. Spec.
Gravel Sand
conb. Silt or Clay
Coarse Fine coarse Medium Fine
Sieve No.
Diam.
(mm)
Cum. Wt.
Ret. (g)
% Ret.
by Wt.
% Passing
by Wt.
%Specs. Pass. by Wt.
Min
Max
3
76.1
0.0
100.0
2.5
64
0.0
100.0
2
50.8
0.0
100.0
1.5
38.1
0.0
100.0
1
25.4
0.0
100.0
3/4
19
0.0
100.0
3/8
9.51
37.8
7.1
92.9
#4
4.76
60.9
11.4
88.6
#8
2.38
77.7
14.6
85.4
#10
2
81.6
15.3
84.7
#20
0.85
108.4
20.3
79.7
#40
0.42
181.3
34.0
66.0
#60
0.25
289.5
54.3
45.7
#100
0.149
391.5
73.4
26.6
#200
0.074
401.9
75.3
24.7
#270
0.053
403.4
1 75.6
24.4
Kirkland Office 1911 Fifth Avenue I Kirkland, WA 98033 P 1425.827.7701 F 1425.827.5424
Everett Office 12911 Y: Hewitt Avenue, Suite 2 1 Everett, WA 98201 P 1425.259.0522 F 1425.252.3408
Tacoma Office 1 1552 Commerce Street, Suite 102 1 Tacoma, WA 98402 P 1253.722.2992 F 1253.722.2993
www.aesgeo.com
a s s o c i a t e d
0 i earth sciences
n c o r p o r a t e I'
GRAIN SIZE ANALYSIS - MECHANICAL ASTM D422
Project Name Project Number Date Sampled Date Tested Tested By
New Retail Buiding KE160514A 10/6/2016 10/7/2016 MS
Sample Source Sample No. Depth (ft) Soil Description
Onsite EB-3 20 silty SAND, some gravel (SM)
Total Sample Dry Wt. (g) Moisture Content (%) D10 (mm) Reference Specification
330.5 6 <0.01
U.S. Sieve Opening in Inches U.S. Sieve Numbers Hydrometer
4 3 2 1.5 1 3/4 1/2 3/8 3.5 4 6 8 10 14 16 20 30 40 50 60 100 140 200 270 400 500 635
100
�J F
90
80
70
v
0 30
20
10
0 ! ' !
100 10 1 0.1 0.01
Diameter (mm) --@-- EB-3 - - - Ref. Spec.
Gravel Sand
conb. Silt or Clay
Coarse Fine Coarse Medium Fine
Sieve No.
Diam.
(mm)
Cum. Wt.
Ret. (g)
% Ret.
by Wt.
% Passing
by Wt.
%Specs. Pass. by Wt.
Min
Max
3
76.1
0.0
100.0
2.5
64
0.0
100.0
2
50.8
0.0
100.0
1.5
38.1
0.0
100.0
1
25.4
0.0
100.0
3/4
19
0.0
100.0
3/8
9.51
8.8
2.7
97.3
#4
4.76
23.6
7.1
92.9
#8
2.38
37.6
11.4
88.6
#10
2
42.3
12.8
87.2
#20
0.85
63.9
19.3
80.7
#40
0.42
104.1
31.5
68.5
#60
0.25
159.3
48.2
51.8
#100
0.149
209.8
63.5
36.5
#200
0.074
236.6
71.6
28.4
#270
0.053
240.6
1 72.8
27.2
Kirkland Office 1911 Fifth Avenue I Kirkland, WA 98033 P 1425.827.7701 F 1425.827.5424
Everett Office 12911 Y: Hewitt Avenue, Suite 2 1 Everett, WA 98201 P 1425.259.0522 F 1425.252.3408
Tacoma Office 1 1552 Commerce Street, Suite 102 1 Tacoma, WA 98402 P 1253.722.2992 F 1253.722.2993
www.aesgeo.com