Perrinville Microbrewery Remodel Draft Infiltration Report 2015-09-02.pdfCobalt
Geosciences
Infiltration Evaluation
Proposed Commercial
Development
18502 — 76th Avenue West
Edmonds, Washington
September 2, 2015
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
Table of Contents
i.o INTRODUCTION..............................................................................................................1
2.0 PROJECT DESCRIPTION...............................................................................................1
3.0 SITE DESCRIPTION........................................................................................................1
4.o FIELD INVESTIGATION................................................................................................2
4.1.1 Site Investigation Program....................................................................................2
5.o SOIL AND GROUNDWATER CONDITIONS...............................................................2
5.1.1 Area Geology.........................................................................................................2
5.1.2 Soil Conditions......................................................................................................2
5.1.3 Groundwater.........................................................................................................3
6.o GEOLOGIC HAZARDS....................................................................................................3
6.1 Landslide Hazard..................................................................................................3
6.2 Erosion Hazard.....................................................................................................4
6.3 Seismic Hazard......................................................................................................4
7.o DISCUSSION....................................................................................................................5
7.1.1 General..................................................................................................................5
8.o RECOMMENDATIONS...................................................................................................5
8.1.1 Site Preparation.....................................................................................................5
8.1.2 Temporary Excavations.........................................................................................6
8.1.3 Erosion and Sediment Control...............................................................................6
8.1.4 Infiltration............................................................................................................. 7
8.1.7 Utilities.................................................................................................................8
8.1.8 Groundwater Influence on Construction................................................................8
8.1.9 Pavement Recommendations................................................................................8
9.o CONSTRUCTION FIELD REVIEWS...........................................................................10
1o.o CLOSURE....................................................................................................................10
LIST OF APPENDICES
Appendix A — Statement of General Conditions
Appendix B — Figures; Vicinity Map, Site Plan, Test Pit Logs
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
i.o Introduction
In accordance with your authorization, Cobalt Geosciences has completed an Infiltration Evaluation for
the proposed commercial development located at 18502 — 76th Avenue West in Edmonds, Washington
(Figure 1).
The purpose of the investigation was to identify subsurface conditions and to provide recommendations
for aspects of earthwork construction along with infiltration rates for stormwater management system
design.
The scope of work consisted of a site investigation followed by analyses to prepare this report.
Recommendations presented herein pertain to various earthwork aspects of the proposed development,
including erosion control, utilities, drainage, infiltration, and pavement recommendations.
2.0 Project Description
The proposed development includes remodeling of the existing building, landscaping improvements,
parking and drive area re -grading and surfacing, and outdoor plaza construction. Stormwater
management will include shallow infiltration trenches and/or rain gardens located north and west of the
building.
We anticipate that site grading may include cuts and fills on the order of 2 feet or less for parking lot
grading and infiltration trench placement.
3.0 Site Description
The site is located at 18502 — 76+h Avenue West in Edmonds, Washington (Figure 1). The site consists of
one irregularly shaped parcel (No. 00434600001o602) with a total area of approximately 40,500 square
feet.
The central portion of the property is developed with a wood framed single story building with a footprint
of 1,890 square feet. The building is surrounded by gravel parking and drive areas with local asphalt
pavements which slope gently toward the north.
The western portion of the property consists of a relatively steep slope that extends downward toward the
west. The slope is approximately 50 feet in height overall and has slope magnitudes of 30 to 8o percent.
The slope area is vegetated with deciduous and evergreen trees, blackberry vines, ferns, and other
herbaceous vegetation.
The overall property is bordered to the north by Olympic View Drive, to the south by commercial
developments, to the east by 76th Avenue West, and to the west by a slope area and residential properties.
1
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
4.o Field Investigation
4.1.1 Site Investigation Program
The geotechnical field investigation program was completed on August 25, 2015 and included excavating
three test pits at or near proposed infiltration trench locations.
The soils encountered were logged in the field and are described in accordance with the Unified Soil
Classification System (USCS).
A Cobalt Geosciences field representative conducted the explorations, collected disturbed soil samples,
classified the encountered soils, kept a detailed log of each test pit, and observed and recorded pertinent
site features.
The results of the test pits are presented on the exploration logs in Figure 3.
5.o Soil and Groundwater Conditions
5.1.1 Area Geology
The site lies within the Puget Lowland. The lowland is part of a regional north -south trending trough that
extends from southwestern British Columbia to near Eugene, Oregon. North of Olympia, Washington,
this lowland is glacially carved, with a depositional and erosional history including at least four separate
glacial advances/retreats. The Puget Lowland is bounded to the west by the Olympic Mountains and to
the east by the Cascade Range. The lowland is filled with glacial and non -glacial sediments consisting of
interbedded gravel, sand, silt, till, and peat lenses.
The Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles,
Snohomish and King Counties, Washington, indicates that the site is underlain by Esperance Sand.
Esperance Sand, sometimes known as Vashon Advance Outwash or Undiffentiated Outwash in many new
publications and maps, consists of stratified sands with minor amounts of gravel to areas of relatively
coarse gravel with variable amounts of sand.
5.1.2 Soil Conditions
Details of the encountered soil conditions are presented on the test pit logs (Figure 3). The detailed soil
description on these logs should be referred to in preference to the generalized description provided
below.
Test Pits TP-1 through TP-3
All of the test pits encountered several inches of gravel underlain by 1 to 2 feet of medium dense, silty -
sand to poorly graded sand with variable amounts of gravel. These materials were underlain by loose to
medium dense, poorly graded sand with gravel, which extended to the termination depths of the test pits.
Medium dense to dense soil conditions were encountered generally below 4.5 feet below existing grades.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
5.1.3 Groundwater
At the time of our investigation, groundwater was not encountered in any of the explorations. Light
volumes of perched groundwater could develop above finer grained areas of the native soils or within
areas of undocumented fill. We would expect any groundwater to be encountered during the winter
months and in deeper excavations.
Water table elevations often fluctuate over time. The groundwater level will depend on a variety of factors
that may include seasonal precipitation, irrigation, land use, climatic conditions and soil permeability.
Water levels at the time of the field investigation may be different from those encountered during the
construction phase of the project.
6.o Geologic Hazards
6.1 Landslide Hazard
Per the City of Edmonds Community Development Code (23.80.020), landslide hazard areas are areas
potentially subject to landslides based on a combination of geologic, topographic, and hydrologic factors.
They include areas susceptible because of any combination of bedrock, soil, slope (gradient), slope aspect,
structure, hydrology, or other factors. Within Edmonds, landslide hazard areas specifically include:
i. Areas of ancient or historic failures in Edmonds which include all areas within the earth
subsidence and landslide hazard area as identified in the 1979 report of Robert Lowe Associates
and amended by the 1985 report of GeoEngineers, Inc.;
2. Any area with a slope of 40 percent or steeper and with a vertical relief of io or more feet except
areas composed of consolidated rock.
3. Any area potentially unstable as a result of rapid stream incision or stream bank erosion; and
4. Any area located on an alluvial fan, presently subject to, or potentially subject to, inundation by
debris flow or deposition of stream -transported sediments.
During our field assessment, we observed the relatively steep slope area located in the west portion of the
site, extending west of the site. The slope extends downward toward the east with the toe of the slope
located near the gravel parking lot. The slope is approximately 50 feet in height and has slope magnitudes
ranging from approximately 30 to 8o percent. This slope is vegetated with evergreen and deciduous trees
with a variety of underbrush.
Overall, the steep slope area appears stable at this time with no evidence of severe erosion, exposed soils,
curved tree trunks, hummocky terrain, or other signs of landslide activity. The native soils that underlie
this area are generally medium dense or firmer and do not appear to have ongoing issues related to
landslide activity.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
6.1 Erosion Hazard
Per the City of Edmonds Community Development Code (23.80.020), erosion hazard areas include sites
containing soils that may experience severe to very severe erosion. These soils include, but are not limited
to, the following when they occur on slopes of 15 percent or greater:
a. Alderwood soils (15 to 25 percent slopes);
b. Alderwood/Everett series (25 to 70 percent slopes);
c. Everett series (15 to 25 percent slopes);
2. Any area with slopes of 15 percent or greater and impermeable soils interbedded with
granular soils and springs or ground water seepage; and
3. Areas with significant visible evidence of ground water seepage, and which also include
existing landslide deposits regardless of slope.
The Natural Resources Conservation Services (NRCS) maps for Snohomish County indicate that the site is
underlain by Alderwood-Everett gravelly sandy loam soils. These materials commonly have a very high to
severe erosion potential in a disturbed state when they are present in slope areas greater than 15 percent
magnitude. The site itself is nearly level and these soils under these sloping conditions have a slight to
moderate erosion potential in a disturbed state.
It is our opinion that soil erosion potential at this project site can be reduced through landscaping and
surface water runoff control. Typically erosion of exposed soils will be most noticeable during periods of
rainfall and may be controlled by the use of normal temporary erosion control measures, such as silt
fences, hay bales, mulching, control ditches and diversion trenches. The typical wet weather season, with
regard to site grading, is from October 31st to April ist. Erosion control measures should be in place before
the onset of wet weather.
6.2 Seismic Hazard
The overall subsurface profile corresponds to a Site Class D as defined by Table 1613.5.2 of the 2012
International Building Code (2012 IBC). A Site Class D applies to an overall profile consisting of dene to
very dense soils within the upper too feet.
We referenced the U.S. Geological Survey (USGS) Earthquake Hazards Program Website to obtain values
for Ss, S,, FQ, and F,,. The USGS website includes the most updated published data on seismic conditions.
The site specific seismic design parameters and adjusted maximum spectral response acceleration
parameters are as follows:
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
PGA (Peak Ground Acceleration, in percent of g)
SS 127.90% of g
S, 50.20% of g
FA 1.00
Fv 1.50
Additional seismic considerations include liquefaction potential and amplification of ground motions by
soft/loose soil deposits. The liquefaction potential is highest for loose sand with a high groundwater table.
The dense soil deposits that underlie the site have a low potential for liquefaction.
7.o DISCUSSION
7-m General
The near surface native soils include loose to medium dense poorly graded sand with trace silt and
variable amounts of gravel which become denser with depth. These materials are overlain by variable
composition and thicknesses of fill materials.
The native soils are suitable for shallow infiltration trenches or rain gardens. We should observe trench
excavation to ensure soil conditions are encountered as anticipated.
The near surface soils are suitable for new asphalt pavement support or continued gravel parking lot
support. We should observe a proofroll of the subgrade using a loaded dump truck prior to asphalt
placement.
8.o Recommendations
8.1.1 Site Preparation
Trees, shrubs and other vegetation should be removed prior to stripping of surficial organic -rich soil.
Based on observations from the site investigation program, it is anticipated that the stripping depth may
range from 4 to 12 inches where topsoil is present. The excavated material is not suitable as fill material
within the proposed building envelope but could be used as fill material in non -settlement sensitive areas
such as landscaping regions. In these non -settlement sensitive areas, the fill should be placed in
maximum 12 inch thick lifts that should be compacted to at least 90 percent of the modified proctor
(ASTM D 1557 Test Method) maximum dry density.
The site soils generally consist of poorly graded sand with silt and gravel. These materials are generally
considered suitable for use as structural fill provided they are within 3 percent of the optimum moisture
content. It should be noted that these materials are typically suitable for structural fill during the summer
months and some soils may be moisture sensitive if they have higher fines content. Cobbles larger than 6
inches in diameter should be removed prior to compaction.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
Imported structural fill should consist of a sand and gravel mixture with a maximum grain size of 3 inches
and less than 5 percent fines (material passing the U.S. Standard No. 200 Sieve). Structural fill should be
placed in maximum lift thicknesses of 12 inches and should be compacted to a minimum of 95 percent of
the modified proctor maximum dry density, as determined by the ASTM D 1557 test method.
8.1.2 Temporary Excavations
Based on our understanding of the project, we anticipate that the grading could include local cuts on the
order of approximately 2 feet or less. If there are any excavations that extend deeper than 4 feet below
existing elevations, they should be sloped no steeper than 1H:1V (Horizontal:Vertical) in native soils. If an
excavation is subject to heavy vibration or surcharge loads, we recommend that the excavations be sloped
no steeper than I.51-1:IV, where room permits.
Temporary cuts should be in accordance with the Washington Administrative Code (WAC) Part N,
Excavation, Trenching, and Shoring. Temporary slopes should be visually inspected daily by a qualified
person during construction activities and the inspections should be documented in daily reports. The
contractor is responsible for maintaining the stability of the temporary cut slopes and reducing slope
erosion during construction.
Temporary cut slopes should be covered with visqueen to help reduce erosion during wet weather, and the
slopes should be closely monitored until the permanent retaining systems or slope configurations are
complete. Materials should not be stored or equipment operated within io feet of the top of any
temporary cut slope.
Soil conditions may not be completely known from the geotechnical investigation. In the case of
temporary cuts, the existing soil conditions may not be completely revealed until the excavation work
exposes the soil. Typically, as excavation work progresses the maximum inclination of temporary slopes
will need to be re-evaluated by the geotechnical engineer so that supplemental recommendations can be
made. Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be
adjustable, to deal with unanticipated conditions, so that the project can proceed and required deadlines
can be met.
If any variations or undesirable conditions are encountered during construction, we should be notified so
that supplemental recommendations can be made. If room constraints or groundwater conditions do not
permit temporary slopes to be cut to the maximum angles allowed by the WAC, temporary shoring
systems may be required. The contractor should be responsible for developing temporary shoring
systems, if needed. We recommend that Cobalt Geosciences and the project structural engineer review
temporary shoring designs prior to installation, to verify the suitability of the proposed systems.
8.1.3 Erosion and Sediment Control
Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to wetlands,
streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures
should be implemented and these measures should be in general accordance with local regulations. At a
minimum, the following basic recommendations should be incorporated into the design of the erosion
and sediment control features for the site:
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
• Schedule the soil, foundation, utility, and other work requiring excavation or the disturbance of the
site soils, to take place during the dry season (generally May through September). However, provided
precautions are taken using Best Management Practices (BMP's), grading activities can be completed
during the wet season (generally October through April).
• All site work should be completed and stabilized as quickly as possible.
• Additional perimeter erosion and sediment control features may be required to reduce the possibility
of sediment entering the surface water. This may include additional silt fences, silt fences with a
higher Apparent Opening Size (AOS), construction of a berm, or other filtration systems.
• Any runoff generated by dewatering discharge should be treated through construction of a sediment
trap if there is sufficient space. If space is limited other filtration methods will need to be
incorporated.
8.1.4 Infiltration
We understand that stormwater runoff will be directed into infiltration trenches or rain gardens north and
west of the building.
We conducted in situ infiltration tests using the small scale pilot infiltration test (PIT) method in
excavations in the areas of the proposed trenches (TP-1 and TP-3). The testing was performed in general
accordance with PIT procedures detailed in the 2012 Stormwater Design Manual for Western Washington
(SDMWW) for Pilot Infiltration Testing (Volume III, Page 3-77).
The generalized PIT method includes excavating a level area at the elevation of the proposed infiltration
system several square feet in area, pre-soaking the test area, and conducting constant head testing until
the system achieves a steady state rate. Once the rate has stabilized, the water flow is stopped and
measurements continue to evaluate the infiltration rate until all of the water has infiltrated. Once
performed, the test areas are excavated to determine whether groundwater mounding has occurred at
deeper levels and to verify that groundwater is not present within 5 feet of the bottom of facility
elevations.
The measured and factored soil infiltration rates based on small scale PIT procedures are presented in the
following table:
Test
Test pit
Elevation
Observed Infiltration
Number
(Feet Below
Rate
Factored Infiltration Rate
Grade)
TP-i
2.5
17.5 in/hr
3.93 in/hr
TP-3
2.0
16.8 in/hr
3.78 in/hr
As indicated above, our field testing yielded un-factored infiltration rates of 17.5 and 16.8 inches per hour
in Test Pits TP-1 and TP-3, respectively.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
After application of appropriate safety factors for effluent control (o.9), site variability (0.5), and small
scale testing (0.5), the design infiltration rates for the two tested areas are 3.93 and 3.78 inches/hour.
Below variable thicknesses of undocumented fill, the native soil conditions within the site area appear to
be relatively homogeneous, consisting of poorly graded sand with trace silt and variable amounts of
gravel, which become denser with depth.
We recommend removing any undocumented fill from the infiltration trench areas during construction.
These soils may be replaced with native poorly graded sands or clean washed or angular rock (5/8 inch to
2 inches in size). We should verify soil conditions during construction and provide additional
recommendations as needed.
8.1.7 Utilities
Utility trenches should be excavated according to accepted engineering practices following OSHA
(Occupational Safety and Health Administration) standards, by a contractor experienced in such work.
The contractor is responsible for the safety of open trenches. Traffic and vibration adjacent to trench
walls should be reduced; cyclic wetting and drying of excavation side slopes should be avoided.
Depending upon the location and depth of some utility trenches, groundwater flow into open excavations
could be experienced, especially during or shortly following periods of precipitation.
In general, sandy soils were encountered at shallow depths in the explorations at this site. These soils
have low cohesion and have a tendency to cave or slough in excavations. Shoring or sloping back trench
sidewalls is required within these soils.
All utility trench backfill should consist of imported structural fill or suitable on site soils. Utility trench
backfill placed in or adjacent to buildings and exterior slabs should be compacted to at least 95 percent of
the maximum dry density based on ASTM Test Method D1557. The upper 5 feet of utility trench backfill
placed in pavement areas should be compacted to at least 95 percent of the maximum dry density based
on ASTM Test Method D1557. Below 5 feet, utility trench backfill in pavement areas should be compacted
to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. Pipe bedding
should be in accordance with the pipe manufacturer's recommendations.
The contractor is responsible for removing all water -sensitive soils from the trenches regardless of the
backfill location and compaction requirements. Depending on the depth and location of the proposed
utilities, we anticipate the need to re -compact existing fill soils below the utility structures and pipes. The
contractor should use appropriate equipment and methods to avoid damage to the utilities and/or
structures during fill placement and compaction procedures.
&L.8 Groundwater Influence on Construction
At the time of our investigation, groundwater was not encountered in any of the explorations. Based on
the soil conditions and area geology, we do not expect groundwater to be encountered during construction
at this site. Light amounts of perched groundwater could be encountered in deeper utility excavations
during the wetter months of the year.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
8.1.9 Pavement Recommendations
The near surface subgrade soils generally consist of silty -sand with variable amounts of gravel to poorly
graded sand with gravel. These soils are rated as good for pavement subgrade material. We estimate that
the subgrade will have a California Bearing Ratio (CBR) value of 10 and a modulus of subgrade reaction
value of k = 200 pci, provided the subgrade is prepared in general accordance with our recommendations.
We recommend that at a minimum, the upper 12 inches of the on -site soils be moisture conditioned (as
necessary) and re -compacted to prepare for the construction of pavement sections. A proofroll using a
fully loaded dump truck should be performed and observed by Cobalt Geosciences to verify proper
subgrade soil conditions prior to base course placement.
The subgrade should be compacted to at least 95 percent of the maximum dry density as determined by
ASTM Test Method D1557. In place density tests should be performed to verify proper moisture content
and adequate compaction. The recommended flexible and rigid pavement sections are based on design
CBR and modulus of subgrade reaction (k) values that are achieved, only following proper subgrade
preparation. It should be noted that subgrade soils that have relatively high silt contents may be highly
sensitive to moisture conditions. The subgrade strength and performance characteristics of a silty
subgrade material may be dramatically reduced if this material becomes wet.
Based on our knowledge of the proposed project, we expect the traffic to range from light duty (passenger
automobiles) to heavy duty (delivery trucks). The following tables show the recommended pavement
sections for light duty and heavy duty use.
ASPHALTIC CONCRETE (FLEXIBLE) PAVEMENT
LIGHT DUTY
Asphaltic Concrete
Aggregate Base*
Compacted Subgrade* **
2.0 in.
6.o in.
12.0 in.
* 95% compaction based on ASTM Test Method D1557
** A proof roll may be performed in lieu of in place density tests
HEAVY DUTY
Asphaltic Concrete
Aggregate Base*
Compacted Subgrade* **
3.0 in.
6.o in.
12.0 in.
* 95% compaction based on ASTM Test Method D1557
**A proof roll may be performed in lieu of in place density tests
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
PORTLAND CEMENT CONCRETE (RIGID) PAVEMENT
Min. PCC Depth
Aggregate Base*
Compacted Subgrade*
**
6.o in.
6.o in.
12.0 in.
* 95% compaction based on ASTM Test Method D1557
**A proof roll may be performed in lieu of in place density tests
The asphaltic concrete depth in the flexible pavement tables should be a surface course type asphalt, such
as Washington Department of Transportation (WSDOT) Y2 inch HMA. The rigid pavement design is
based on a Portland Cement Concrete (PCC) mix that has a 28 day compressive strength of 4,000 pounds
per square inch (psi). The design is also based on a concrete flexural strength or modulus of rupture of
550 psi. Aggregate base should generally consist of 4 to 6 inches of WSDOT Base Course overlain by 2
inches of WSDOT Top Course (1-1/4" crushed and 5/8" crushed respectively).
9.o Construction Field Reviews
Cobalt Geosciences should be retained to provide part time field review during construction in order to
verify that the soil conditions encountered are consistent with our design assumptions and that the intent
of our recommendations is being met. This will require field and engineering review to:
■ Monitor and test structural fill placement and soil compaction
■ Observe proofroll or soil compaction of soil subgrades prior to asphalt pavement (if proposed)
■ Confirm soil conditions and infiltration characteristics at stormwater system locations
Geotechnical design services should also be anticipated during the subsequent final design phase to
support the structural design and address specific issues arising during this phase. Field and engineering
review services will also be required during the construction phase in order to provide a Final Letter for
the project.
lo.o Closure
This report was prepared for the exclusive use of Mr. Greg Payne and his appointed consultants. Any use
of this report or the material contained herein by third parties, or for other than the intended purpose,
should first be approved in writing by Cobalt Geosciences.
The recommendations contained in this report are based on assumed continuity of soils with those of our
test holes, and assumed structural loads. Cobalt Geosciences should be provided with final architectural
and civil drawings when they become available in order that we may review our design recommendations
and advise of any revisions, if necessary.
P.O. Box 82243, Kenmore, WA 98028
INFILTRATION EVALUATION
EDMONDS, WASHINGTON
September 2, 2015
Use of this report is subject to the Statement of General Conditions provided in Appendix A. It is the
responsibility of Mr. Greg Payne, who is identified as "the Client" within the Statement of General
Conditions, and its agents to review the conditions and to notify Cobalt Geosciences should any of these
not be satisfied.
Respectfully submitted,
Cobalt Geosciences
Original signed by: Original signed by:
Phil Haberman, P.G., P.E.G. Sean Caraway, P.E.
Principal Engineering Geologist Senior Geotechnical Engineer
PH/sc
P.O. Box 82243, Kenmore, WA 98028
APPENDIX A
Statement of General Conditions
Statement of General Conditions
USE OF THIS REPORT: This report has been prepared for the sole benefit of the Client or its agent and
may not be used by any third parry without the express written consent of Cobalt Geosciences and the
Client. Any use which a third party makes of this report is the responsibility of such third party.
BASIS OF THE REPORT: The information, opinions, and/or recommendations made in this report are
in accordance with Cobalt Geosciences present understanding of the site specific project as described by
the Client. The applicability of these is restricted to the site conditions encountered at the time of the
investigation or study. If the proposed site specific project differs or is modified from what is described in
this report or if the site conditions are altered, this report is no longer valid unless Cobalt Geosciences is
requested by the Client to review and revise the report to reflect the differing or modified project specifics
and/or the altered site conditions.
STANDARD OF CARE: Preparation of this report, and all associated work, was carried out in
accordance with the normally accepted standard of care in the state of execution for the specific
professional service provided to the Client. No other warranty is made.
INTERPRETATION OF SITE CONDITIONS: Soil, rock, or other material descriptions, and
statements regarding their condition, made in this report are based on site conditions encountered by
Cobalt Geosciences at the time of the work and at the specific testing and/or sampling locations.
Classifications and statements of condition have been made in accordance with normally accepted
practices which are judgmental in nature; no specific description should be considered exact, but rather
reflective of the anticipated material behavior. Extrapolation of in situ conditions can only be made to
some limited extent beyond the sampling or test points. The extent depends on variability of the soil, rock
and groundwater conditions as influenced by geological processes, construction activity, and site use.
VARYING OR UNEXPECTED CONDITIONS: Should any site or subsurface conditions be
encountered that are different from those described in this report or encountered at the test locations,
Cobalt Geosciences must be notified immediately to assess if the varying or unexpected conditions are
substantial and if reassessments of the report conclusions or recommendations are required. Cobalt
Geosciences will not be responsible to any party for damages incurred as a result of failing to notify Cobalt
Geosciences that differing site or sub -surface conditions are present upon becoming aware of such
conditions.
PLANNING, DESIGN, OR CONSTRUCTION: Development or design plans and specifications
should be reviewed by Cobalt Geosciences, sufficiently ahead of initiating the next project stage (property
acquisition, tender, construction, etc), to confirm that this report completely addresses the elaborated
project specifics and that the contents of this report have been properly interpreted. Specialty quality
assurance services (field observations and testing) during construction are a necessary part of the
evaluation of sub -subsurface conditions and site preparation works. Site work relating to the
recommendations included in this report should only be carried out in the presence of a qualified
geotechnical engineer; Cobalt Geosciences cannot be responsible for site work carried out without being
present.
APPENDIX B
Figures: Vicinity Map, Site Plan
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p geaCc�A - �a 0qegjppL K 0�
JL 122*22.000 W 122*21.000' W 122'20.000'W WGS84 122-19.000' W
0 .5 1 TN MN
MILES
IM0 0 low 2WO MM 4M - 5w 160 A
NATIONAL
L GEOGRAPHIC b 0 KlLommRs FEET I
1000 0 MFTERS 1 08/27/15
PBox 82243
18502 - 76th Avenue West VICINITY MAP Ken.O. more, WA 98028
Edmonds, Washington Cobalt (2o6) 331-1097
1 FIGURE i Geosciences cobaltgeopgmail.com
1
— -r
TP-2
3,1150
I �1 4 S
Olympic View Dr. 0
I 1.400sf1ii \\
LM
Footprint of Existing Bldg —
1,890 sf
� I
-350 sf
� IIII—III
::� L�j �E—]��� 7,875 sf paving
------------
TP-1 N
Not to Scale Approximate Test Pit Location A
18502 - �76th Avenue West SITE PLAN K Boxnmo e, WA 98028
Edmonds, Washington Cobalt (2o6) 331-1097
FIGURE 2 Geosciences cobaltgeoggmail.com
Test Pit TP-1
18502 - 76th Avenue West
Edmonds, Washington
0-0.5' Gravel
0.5-2.0' Silty SAND with gravel (SM)
Medium dense, fine to medium sand with
gravel,yellowish brown, dry to moist (Fill).
2.0-7.0' Poorly graded SAND with gravel (SP)
Loose to dense, fine to medium grained
sand with gravel and trace silt, yellowish
brown to grayish brown, moist. (Outwash)
End of Test Pit 7.0'
No Groundwater
Test Pit TP-2
0-0.5' Topsoil/Gravel
0.5-1.5' Silty SAND with gravel (SM)
Medium dense, fine to medium sand with
gravel,yellowish brown, dry to moist (Fill).
1.5-8.o' Poorly graded SAND with gravel (SP)
Loose to dense, fine to medium grained
sand with gravel and trace silt, yellowish
brown to grayish brown, moist. (Outwash)
End of Test Pit 8.o'
No Groundwater
Test Pit TP-3
0-0.5' Topsoil/Gravel
0.5-1.0' Silty SAND with gravel (SM)
Medium dense, fine to medium sand with
gravel,yellowish brown, dry to moist (Fill?).
1.o-8.o' Poorly graded SAND with gravel (SP)
Loose to dense, fine to medium grained
sand with gravel and trace silt, yellowish
brown to grayish brown, moist. (Outwash)
End of Test Pit 8.o'
No Groundwater
TEST PIT LOGS
Cobalt
FIGURE 3 kiGeosciences
P.O. Box 82243
Kenmore, WA 98028
(2o6) 331-1097
cobaltgeo (& gmail. com