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Geotechnical Engineering Report -
Addendum
__________________________________________________________________________
Chick-fil-A Restaurant #04249 – Parking Lot Expansion
Renton, King County, Washington
October 29, 2021
Terracon Project No. 81185084
Prepared for:
Chick-fil-A, Inc.
Irvine, California
Prepared by:
Terracon Consultants, Inc.
Mountlake Terrace, Washington
Terracon Consultants, Inc. 21905 64t h Ave. W, Suite 100 Mountlake Terrace, WA 98043
P (425) 771 3304 F (425) 771 3549 terracon.com
REPORT COVER LETTER TO SIGN
October 29, 2021
Chick-fil-A, Inc.
15635 Alton Parkway Suite 350
Irvine, California 92618
Attn: Ms. Beth Witt
P: (714) 595-6463
E: beth.witt@cfacorp.com
Re: Geotechnical Engineering Report Addendum
Chick-fil-A Restaurant #04249 – Parking Lot Expansion
351 Rainier Avenue South
Renton, King County, Washington
Terracon Project No. 81185084
Dear Ms. Beth Witt:
We have completed the Geotechnical Engineering services for the above referenced project. This
study was performed in general accordance with Terracon Master Services Agreement dated
March 31, 2005. This report presents the findings of the subsurface exploration and provides
geotechnical recommendations concerning earthwork and pavement for the proposed project.
We appreciate the opportunity to be of service to you on this project. If you have any questions
concerning this report or if we may be of further service, please contact us.
Sincerely,
Terracon Consultants, Inc.
Eric D. Kunz, P.E. David A. Baska, Ph.D., P.E.
Senior Principal Senior Engineering Consultant
National Account Manager: Josh Schilling
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REPORT TOPICS
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 2
GEOTECHNICAL OVERVIEW ....................................................................................... 3
EARTHWORK ................................................................................................................ 4
PAVEMENTS .................................................................................................................. 7
GENERAL COMMENTS ............................................................................................... 10
Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced
section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the
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ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
PHOTOGRAPHY LOG
SITE LOCATION AND EXPLORATION PLANS
EXPLORATION RESULTS
SUPPORTING INFORMATION
Note: Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
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EXECUTIVE SUMMARY
Topic 1 Overview Statement 2
Project
Description
Expanded asphalt paved parking lot and concrete entry drives to be located
immediately north of the existing Chick-fil-A restaurant located at 361 Rainier
Avenue South, Renton, WA
Expected traffic for pavement areas:
■ 300 autos/light trucks per day
■ Up to 5 medium-duty delivery/trash trucks and 1 tractor-trailer per week
Geotechnical
Characterization
Areas of existing fill extending to up to 3 feet below ground surface, underlain by
alluvial deposits composed primarily of silt, sand, and gravel that are loose and soft
to medium stiff in the top 7 ½ feet.
Groundwater was not encountered.
Earthwork
■ Demolition of the existing development should include the complete
removal of existing buried utilities within the building area, the existing
pavement section should be removed and catch basins or buried utilities
that will not be reused as a part of the proposed site development should
be removed or grouted in-place.
■ Any material proposed to be used for engineered fill should be tested &
approved
■ Fines are sensitive to moisture variation and movement.
Pavements
For subgrade prepared as noted in Earthwork with 2 feet of over-excavation, we
have provided CFA’s standard pavement sections.
General
Comments
This section contains important information about the limitations of this geotechnical
engineering report.
1. If the reader is reviewing this report as a pdf, the topics above can be used to access the appropriate section
of the report by simply clicking on the topic itself.
2. This summary is for convenience only. It should be used in conjunction with the ent ire report for design
purposes.
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INTRODUCTION
Geotechnical Engineering Report
Chick-fil-A Restaurant #04249 – Parking Lot Expansion
351 Rainier Avenue South
Renton, King County, Washington
Terracon Project No. 81185084
October 29, 2021
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed Chick-fil-A restaurant #04249 parking lot expansion to be
located at Renton, King County, Washington. The purpose of these services is to provide
information and geotechnical engineering recommendations relative to:
■ Subsurface soil conditions ■ Demolition considerations
■ Groundwater conditions ■ Pavement design and construction
■ Site preparation and earthwork
The geotechnical engineering Scope of Services for this project included the advancement of
three test borings to depths of approximately 7 ½ feet below existing site grades.
Maps showing the site and boring locations are shown in the Site Location and Exploration
Plan sections, respectively. The results of the laboratory testing performed on soil samples
obtained from the site during the field exploration are included on the boring logs in the
Exploration Results section.
SITE CONDITIONS
The following description of site conditions is derived from our site visit in association with the
field exploration and our review of publicly available geologic and topographic maps.
Item Description
Parcel Information
The project is located at 351 Rainier Avenue South Renton, King County,
Washington
Latitude: 47° 28.74' N, Longitude: 122° 13.03' W
See Site Location
Existing
Improvements
Existing asphalt parking lot and concrete aprons, existing building formerly
occupied by Firestone.
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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Item Description
Current Ground
Cover Asphalt paved parking lot with concrete aprons
Existing Topography The site is relatively flat based on review of USGS quadrangle maps and
information from Google Earth Pro.
Geology According to the published geologic maps reviewed, the site is underlain by
alluvial deposits composed primarily of silt, sand, and gravel
PROJECT DESCRIPTION
Our understanding of the project conditions is as follows:
Item Description
Project Description
Expanded asphalt paved parking lot and concrete entry drives to be located
immediately north of the existing Chick-fil-A restaurant located at 361
Rainier Avenue South, Renton, WA
Grading/Slopes Grading plan not provided at the time of this report
Below-Grade Structures None anticipated
Free-Standing Retaining
Walls None anticipated
Pavements
No specific traffic information has been provided to us. Without this
information, we plan to use the following traffic volumes for design of the
pavement:
■ Autos/Light Trucks: 300 vehicles per day
■ Medium duty trucks and Trash Collection Vehicles: 5 vehicles per
week
■ Tractor-trailer trucks: 1 vehicle per week
The pavement design period is 20 years.
GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
We have developed a general characterization of the subsurface soil and groundwater conditions
based upon our review of the data and our understanding of the geologic setting and planned
construction. The following table provides our geotechnical characterization.
The geotechnical characterization forms the basis of our geotechnical calculations and evaluation
of site preparation, foundation options and pavement options. As noted in General Comments,
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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the characterization is based upon widely spaced exploration points across the site, and variations
are likely.
Stratum Approximate Depth to
Bottom of Stratum (feet) Material Description Consistency/Density
Surface 0.3 Asphalt Pavement N/A
Surface 0.3 to ½ Aggregate base course N/A
1 1 to 3 Fill: Silty Sand trace gravel N/A
2 3 to 7½ Alluvial Deposits: Silt, Silt with sand Soft to medium stiff
Conditions encountered at each boring location are indicated on the individual boring logs shown
in the Exploration Results section and are attached to this report. Stratification boundaries on
the boring logs represent the approximate location of changes in native soil types; in situ, the
transition between materials may be gradual.
Groundwater Conditions
The borings were observed during drilling for the presence and level of groundwater.
Groundwater was not observed in the borings while drilling. However, this does not necessarily mean
the borings terminated above groundwater.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff
and other factors not evident at the time the borings were performed. Therefore, groundwater
levels during construction or at other times in the life of the structure may be higher or lower than
the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be
considered when developing the design and construction plans for the project
GEOTECHNICAL OVERVIEW
About half of the site is cover with asphalt pavements and concrete aprons overlying about 2 to 3
feet of sandy silty fill /possible fill. The fill soils are underlain by high moisture content, loose to
medium stiff silt and silt with sand.
The near-surface silty sand could become unstable with typical earthwork and construction traffic,
especially after precipitation events. Effective drainage should be established early in the
construction sequence and maintained after construction to avoid potential issues. If possible, the
grading should be performed during the warmer and drier time of the year. If grading is performed
during the winter months, the risk for possible overexcavation and replacement of unstable
subgrade will increase. Additional site preparation recommendations including subgrade
improvement and fill placement are provided in the Earthwork section.
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A flexible pavement system and a rigid pavement system are recommended for this site. The
Pavements section addresses the design of pavement systems.
The General Comments section provides an understanding of the report limitations.
EARTHWORK
Earthwork will include demolition of existing structures, excavations and fill placement. The
following sections provide recommendations for use in the preparation of specifications for the
work. Recommendations include critical quality criteria as necessary to render the site in the state
considered in our geotechnical engineering evaluation for pavements.
Site Preparation
All large-area subgrades should be proof-rolled with an adequately loaded vehicle such as a fully-
loaded tandem-axle dump truck. The proof-rolling should be performed under the observation of
the Geotechnical Engineer. Areas excessively deflecting under the proof-roll should be delineated
and subsequently addressed by recommendations from the Geotechnical Engineer.
Following removal of unsuitable soils and selected overexcavation, the subgrade should be proof-
rolled with an adequately loaded vehicle such as a fully loaded tandem axle dump truck. The
proof-rolling should be performed under the observation of the Geotechnical Engineer. Areas
excessively deflecting under the proof-roll should be delineated and subsequently addressed by
the Geotechnical Engineer. Such areas should either be removed or replaced by tested and
approved structural fill. Excessively wet or dry material should either be removed or moisture
conditioned and recompacted.
In pavement areas, the following procedure should be followed. Over-excavation should extend
to 2 feet below the bottom of the pavement section (i.e., asphalt surface course and aggregate
base). Geotextile, such as Mirafi 500x, should be placed directly on the subgrade to provide
separation between the soft subgrade and the structural fill. Above the geotextile, place and
compact 2 feet of structural fill in two lifts. The first lift should be 18 inches thick followed by a 6
inch thick lift.
Given the wet, very soft and loose consistency of the material underlying the structural fill,
dynamic compaction may lead to excessive movements or “pumping” of the subgrade. A
Geotechnical Engineer should be present to observe compaction and if movement in the native
soils below the structural fill is observed, static compaction techniques should be employed.
Fill Material Types
Fill required to achieve design grade should be classified as structural fill and general fill.
Structural fill is material used below, or within 5 feet of structures, pavements or constructed
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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slopes. General fill is material used to achieve grade outside of these areas. Earthen materials
used for structural and general fill should meet the following material property requirements:
Soil Type 1 USCS Classification Acceptable Location for Placement
General Fill
WSDOT 9-03.14(2) for
Select Borrow2
All locations across the site. Appropriate for utility trench
backfill, outside of pipe bedding zone.
Dry Weather only.
Structural Fill
WSDOT 9-03.14(1) for
Gravel Borrow with
exception of no more
than 5% passing the
No. 200 sieve by weight
if placed during wet
weather2
All locations across the site.
Wet Weather and Dry Weather acceptable.
Crushed
Aggregate Base
Course (CAB)
WSDOT 9-03.9(3) for
Crushed Surfacing
(Base Course and Top
Course sizes)
All locations across the site. Recommended for finished
base course materials for pavements.
Wet Weather and Dry Weather acceptable.
1. Controlled, compacted fill should consist of approved materials that are free of organic matter and debris.
Frozen material should not be used, and fill should not be placed on a frozen subg rade. A sample of each
material should be submitted to the geotechnical engineer evaluation.
2. With Geotechnical Engineer’s approval, the fines content (percent passing the #200 sieve) may be
increased to allow use of on-site soils that otherwise meet Select Borrow criteria, provided these soils can
be compacted to a dense and unyielding condition and provided that completed fill areas are protected from
additions of moisture and other causes of subgrade degradation.
Fill Compaction Requirements
Structural and general fill should meet the following compaction requirements.
Item Structural Fill General Fill
Maximum Lift
Thickness
8 inches or less in loose thickness when
heavy, self-propelled compaction
equipment is used; 4 to 6 inches in loose
thickness when hand-guided equipment
(i.e. jumping jack or plate compactor) is
used.
See specific recommendations for
Pavement sections in Site Preparation
Same as Structural Fill
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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Item Structural Fill General Fill
Minimum
Compaction
Requirements 1
95% of maximum dry density within the 2
feet of finished pavement subgrade; 92%
of maximum dry density more than 2 feet
below finished pavement subgrade
Same as Structural Fill
Water Content
Range 1
-2% to +2% of optimum As required to achieve min.
compaction requirements
1. Maximum density and optimum water content as determined by the modified Proctor test (ASTM D 1557).
Utility Trench Backfill
Utility trenching should conform to all applicable federal, state, and local regulations, such as
OSHA and WISHA, for open excavations.
All trenches should be wide enough to allow for compaction around the haunches of the pipe, or
material such as pea gravel (provided this is allowed by the pipe manufacturer) should be used
below the spring line of the pipes to eliminate the need for mechanical compaction in this portion
of the trenches. We recommend that utility trench excavations be completed using a smooth
excavation bucket (without teeth) to reduce the potential for subgrade disturbance. If water is
encountered in the excavations, it should be removed prior to fill placement.
Materials, placement and compaction of utility trench backfill should be in accordance with the
recommendations presented in Fill Material Types and Fill Compaction Requirements
sections of this report. In our opinion, the initial lift thickness should not exceed one foot unless
recommended by the manufacturer to protect utilities from damage by compacting equipment.
Light, hand-operated compaction equipment in conjunction with thinner fill lift thicknesses may be
utilized on backfill placed above utilities if damage resulting from heavier compaction equipment
is of concern.
Earthwork Construction Considerations
After initial proofrolling and compaction, unstable subgrade conditions could develop during
general construction operations, particularly if the soils are wetted and/or subjected to repetitive
construction traffic. Upon completion of filling and grading, care should be taken to maintain the
subgrade moisture content prior to construction of pavements. Construction traffic over the
completed subgrade should be avoided to the extent practical. The site should also be graded to
prevent ponding of surface water on the prepared subgrades or in excavations. If the subgrade
should become desiccated, saturated, or disturbed, the affected material should be removed, or
these materials should be scarified, moisture conditioned, and re-compacted prior to pavement
construction.
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
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As a minimum, all temporary excavations should be performed in accordance with OSHA 29 CFR,
Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable
local, and/or state regulations.
Construction site safety is the sole responsibility of the contractor who controls the means,
methods, and sequencing of construction operations. Under no circumstances shall the
information provided herein be interpreted to mean Terracon is assuming responsibility for
construction site safety, or the contractor's activities; such responsibility shall neither be implied
nor inferred.
Construction Observation and Testing
The earthwork efforts should be monitored under the observation of the Geotechnical Engineer.
Monitoring should include documentation of adequate removal of any vegetation, existing fill and
top soil, proofrolling and mitigation of areas delineated by the proofroll to require mitigation. Each
lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by
the Geotechnical Engineer prior to placement of additional lifts.
In addition to the documentation of the essential parameters necessary for construction, the
continuation of the Geotechnical Engineer into the construction phase of the project provides
the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions,
including assessing variations and associated design changes.
PAVEMENTS
General Pavement Comments
Pavement designs are provided for the traffic conditions and pavement life conditions as noted in
Project Description and in the following sections of this report. A critical aspect of pavement
performance is site preparation. Pavement designs noted in this section must be applied to the
site which has been prepared as recommended in the Earthwork section.
Design Considerations
The standard equivalent single-axle load (ESAL) was estimated using 1993 Guideline for Design
of Pavement Structures by the American Association of State Highway and Transportation
Officials (AASHTO-1993). The assumed traffic loading for flexible and rigid pavement areas on a
per day basis are:
■ 300 passenger cars/pick-up trucks and vans/recreational vehicles per day
■ 5 delivery trucks and garbage/dumpster trucks per week
■ 1 tractor-trailer truck per week
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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A 20-year design life is assumed. If traffic volumes will exceed the assumed values, Terracon
should be notified in order to provide pavement sections designed for higher levels of traffic.
Pavement Design Parameters
Design of Asphaltic Concrete (AC) pavements are based on the 1993 AASHTO guidelines.
Minimum recommended pavement section thicknesses are presented below:
Minimum AC Pavement Section (inches)
Layer Thickness (inches) Compaction/Material
Specification
Compacted Subgrade 1
24 inches of
structural fill placed
and compacted in
two lifts of 18 and 6
inches
95% of Modified Proctor Maximum Dry Density; -2
to +2% Optimum Moisture Content
Crushed Aggregate Base 6 WSDOT: 9-03.9(3) Base Course
Asphalt Thickness 4 WSDOT: 9-03.8(2) ½-inch HMA
PG64-22 asphalt binder
1. May vary based on observations following proof-rolling.
We recommend that Portland cement concrete (PCC, rigid) pavement be used for entrance and
exit sections, or other areas where extensive wheel maneuvering or repeated loading are
expected. The minimum thickness of PCC pavement should be 6 inches and underlain by a
minimum of 6 inches of crushed aggregate base course (use WSDOT 9.03.9(3)). The 28-day
unconfined compressive strength should be at least 4,000 psi. Adequate reinforcement and
number of longitudinal and transverse control joints should be placed in the rigid pavement in
accordance with ACI requirements. Although not required for structural support, the base course
layer is recommended to help reduce potentials for slab curl, shrinkage cracking, subgrade
“pumping” through joints, and provide a workable surface. Proper joint spacing will also be
required to prevent excessive slab curling and shrinkage cracking. All joints should be sealed to
prevent entry of foreign material and dowelled where necessary for load transfer.
The minimum pavement sections outlined above were determined based on the laboratory test
results and post-construction traffic loading conditions. These pavement sections do not account
for heavy construction traffic during development. A partially constructed structural section that is
subjected to heavy construction traffic can result in pavement deterioration and premature
distress or failure. Our experience indicates that this pavement construction practice can result in
pavements that will not perform as intended. Considering this information, several alternatives
Geotechnical Engineering Report
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
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are available to mitigate the impact of heavy construction traffic prior to pavement construction.
These include using thicker sections to account for the construction traffic after paving; using
some method of soil stabilization to improve the support characteristics of the pavement
subgrade; routing heavy construction traffic around paved areas; or delaying paving operations
until as near the end of construction as is feasible.
Additional Pavement Design Considerations
Subgrade
As recommended in the Earthwork section, over-excavation in the pavement areas should
extend to 2 feet below the bottom of the pavement section, including the aggregate base. A
geotextile, such as Mirafi 500x should be installed at the base of the excavation to provide
separation between the soft subgrade and the structural fill. Above the geotextile, structural fill
should be placed in two lifts of 18 inches and 6 inches. Each lift can be compacted with a vibratory
roller under the observation of a geotechnical engineer. If movement of the subgrade is observed
during dynamic compaction, static compaction methods should be employed and we may
recommend that the 24 inches of structural fill be placed in a single lift.
Landscape Islands
Openings in the pavement surface, such as landscape islands, are sources for water infiltration into
the surrounding pavement section and subgrade. Water can collect in the islands and migrate into
the underlying subgrade soils, thereby degrading support of the pavement. This is especially
applicable for islands with raised concrete curbs, irrigated vegetation, and near surface soils with
low permeability.
The following should be considered as minimum recommendations in the design and construction
of pavements:
1. Provide a minimum 2% grade in the ground surface away from the edge of pavements.
2. Provide a minimum 2% cross slope for the subgrade and pavement surface to promote
proper surface drainage.
3. Install pavement drainage at the perimeter of areas where frequent wetting, such as from
irrigation or other sources of water, is anticipated.
4. Seal cracks promptly.
5. Seal landscaped areas near pavements to reduce moisture migration to subgrade soils.
6. Place compacted low-permeability backfill against the exterior side of the curb and gutter.
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Pavement Drainage
Pavements should be sloped to provide rapid drainage of surface water. Water allowed to pond on
or adjacent to the pavements could saturate the subgrade and contribute to premature pavement
deterioration. In addition, the pavement subgrade should be graded to provide positive drainage
within the granular base section.
We recommend drainage be included at the bottom of the aggregate layer at the storm structures
to aid in removing water that may enter this layer. Drainage could consist of small diameter weep
holes excavated around the perimeter of the storm structures. The weep holes should be
excavated at the elevation of the aggregate and soil interface. The excavation should be covered
with No. 57 stone which is encompassed in Mirafi 140 NL or approve equivalent which will aid in
reducing fines from entering the storm system.
Preventive Maintenance
Preventative maintenance should be planned and provided as a part of an asphalt pavement
management program. These maintenance activities are intended to slow the rate of pavement
deterioration and to preserve the pavement investment. Preventative maintenance consists of
both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance
(e.g. surface sealing for asphalt pavements). This type of maintenance is usually the first priority
when implementing a planned pavement maintenance program. Even with periodic maintenance,
some movements and related cracking may still occur and require repair.
Pavement Construction Considerations
Where subgrades for replacement pavement sections have been prepared, we recommend
subgrades be thoroughly proof-rolled with a loaded tandem axle dump truck to verify a firm and
stable surface prior to final grading and placement of aggregate base. Particular attention should
be paid to high traffic areas and to areas where backfilled trenches are located. Areas where
unsuitable conditions are encountered should be repaired by removing and replacing the affected
material with properly compacted Structural Fill. All pavement subgrade areas should be moisture
conditioned and properly compacted in accordance with the recommendations in this report
immediately prior to placement of the pavement section materials. In areas of prepared subgrade,
the contractor should limit traffic to equipment necessary to construct the pavement section.
Heavily loaded vehicles operating on these surfaces may cause significant damage, resulting in
deterioration and reduction in pavement life.
GENERAL COMMENTS
Our analysis and opinions are based upon our understanding of the project, the geotechnical
conditions in the area, and the data obtained from our site exploration. Natural variations will occur
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Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
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between exploration point locations or due to the modifying effects of construction or weather.
The nature and extent of such variations may not become evident until during or after construction.
Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide
observation and testing services during pertinent construction phases. If variations appear, we
can provide further evaluation and supplemental recommendations. If variations are noted in the
absence of our observation and testing services on-site, we should be immediately notified so
that we can provide evaluation and supplemental recommendations.
Our Scope of Services does not include either specifically or by implication any environmental or
biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of
pollutants, hazardous materials or conditions. If the owner is concerned about the potential for
such contamination or pollution, other studies should be undertaken.
Our services and any correspondence or collaboration through this system are intended for the
sole benefit and exclusive use of our client for specific application to the project discussed and
are accomplished in accordance with generally accepted geotechnical engineering practices with
no third-party beneficiaries intended. Any third-party access to services or correspondence is
solely for information purposes to support the services provided by Terracon to our client.
Reliance upon the services and any work product is limited to our client, and is not intended for
third parties. Any use or reliance of the provided information by third parties is done solely at their
own risk. No warranties, either express or implied, are intended or made.
Site characteristics as provided are for design purposes and not to estimate excavation cost. Any
use of our report in that regard is done at the sole risk of the excavating cost estimator as there
may be variations on the site that are not apparent in the data that could significantly impact
excavation cost. Any parties charged with estimating excavation costs should seek their own site
characterization for specific purposes to obtain the specific level of detail necessary for costi ng.
Site safety, and cost estimating including, excavation support, and dewatering
requirements/design are the responsibility of others. If changes in the nature, design, or location
of the project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
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ATTACHMENTS
Geotechnical Engineering Report
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
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EXPLORATION AND TESTING PROCEDURES
Field Exploration
Exploration ID Type of Exploration Boring Depth (feet) Planned Location
B-9 Boring 7 ½ Proposed parking lot
B-10 Boring 7 ½ Proposed parking lot
B-11 Boring 7 ½ Proposed parking lot
Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. A Terracon representative also used field
measurements from existing site features to mark the boring locations prior to drilling operations.
Approximate elevations were obtained by interpolation from the Google Earth terrain model.
Subsurface Exploration Procedures: We advanced the borings with a truck-mounted drill rig
using continuous-flight augers. Samples were obtained at depth intervals of 2.5 ft in all borings.
The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch
penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT
resistance values, also referred to as N-values, are indicated on the boring logs at the test depths.
Borings were backfilled with bentonite in accordance with Washington Department of Ecology
requirements after their completion. Pavements were patched with cold-mix asphalt and/or pre-
mixed concrete, as appropriate.
The sampling depths, penetration distances, and other sampling information was recorded on the
field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory
for testing and classification by a Geotechnical Engineer. Our exploration team prepared field
boring logs as part of the drilling operations. These field logs included visual classifications of the
materials encountered during drilling and our interpretation of the subsurface conditions between
samples. Final boring logs were prepared from the field logs. The final boring logs represent the
Geotechnical Engineer's interpretation of the field logs and include modifications based on
observations and tests of the samples in our laboratory.
Laboratory Testing
The project engineer reviewed the field data and assigned various laboratory tests to better
understand the engineering properties of the various soil strata. Procedural standards noted
below are for reference to methodology in general. In some cases, variations to methods are
applied because of local practice or professional judgment. Standards noted below include
reference to other, related standards. Such references are not necessarily applicable to describe
the specific test performed.
Geotechnical Engineering Report
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2
■ ASTM D2488 Description and Identification of Soils (Visual-Manual Procedure)
■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture)
Content of Soil and Rock by Mass
Responsive ■ Resourceful ■ Reliable
SITE LOCATION AND EXPLORATION PLANS
Contents:
Site Location Plan
Exploration Plan
SITE LOCATION
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
Note to Preparer: This is a large table with outside borders. Just click inside the table
above this text box, then paste your GIS Toolbox image.
When paragraph markers are turned on you may notice a line of hidden text above and
outside the table – please leave that alone. Limit editing to inside the table.
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it as desired, but try to keep to a single line of text to avoid reformatting the page.
SITE LOCATION
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION PLAN
Chick-fil-A Restaurant #04249 – Parking Lot Expansion ■ Renton, King County, Washington
October 29, 2021 ■ Terracon Project No. 81185084
Note to Preparer: This is a large table with outside borders. Just click inside the table
above this text box, then paste your GIS Toolbox image.
When paragraph markers are turned on you may notice a line of hidden text above and
outside the table – please leave that alone. Limit editing to inside the table.
The line at the bottom about the general location is a separate table line. You can edit
it as desired, but try to keep to a single line of text to avoid reformatting the page.
EXPLORATION PLAN
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
EXPLORATION RESULTS
Contents:
Boring Logs (B-9 through B-11)
3-1-1
N=2
3-1-2
N=3
ASPHALT
AGGREGATE BASE COURSE
FILL - SILTY SAND WITH GRAVEL (SM), gray, moist, loose
SILT WITH SAND (ML), brown and reddish brown, wet, soft
Boring Terminated at 7.5 Feet
0.3
0.6
3.0
7.5
22.5+/-
22.5+/-
20+/-
15.5+/-
4
10
S-1
S-2
13
38
Stratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 81185084 CHICK-FIL-A #0424_BS_10282021.GPJ TERRACON_DATATEMPLATE.GDT 10/29/21DEPTH (Ft.)1
2
3
4
5
6
7 WATER LEVELOBSERVATIONSFIELD TESTRESULTSLOCATION See Exploration Plan
Latitude: 47.4790° Longitude: -122.2175°GRAPHIC LOGDEPTH ELEVATION (Ft.)
Approximate Surface Elev.: 23 (Ft.) +/-
Page 1 of 1
Advancement Method:
Hollow Stem Auger
Abandonment Method:
Boring backfilled with bentonite
Surface capped with Cold-Mix Asphalt
Notes:
Project No.: 81185084
Drill Rig: Truck-mounted
BORING LOG NO. B-9
Chick-fil-A, Inc.CLIENT:
Irvine, CA
Driller: EDI
Boring Completed: 10-18-2021
PROJECT: Chick-fil-A #04249 Renton
Elevations were interpolated from google Earth.
See Exploration and Testing Procedures for a
description of field and laboratory procedures
used and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
351 Rainier Ave S.
Renton, WA
SITE:
Boring Started: 10-18-2021
21905 64th Ave W, Ste 100
Mountlake Terrace, WA
WATER LEVEL OBSERVATIONS
Groundwater not encountered RECOVERY (In.)SAMPLE IDWATERCONTENT (%)PERCENT FINESSAMPLE TYPE
2-2-2
N=4
3-4-2
N=6
ASPHALT
AGGREGATE BASE COURSE
FILL - SILTY SAND (SM), trace gravel, gray brown, wet, loose
SILT WITH SAND (ML), brown and reddish brown, moist, medium
stiff
SILT (ML), brown and gray, wet, medium stiff
Boring Terminated at 7.5 Feet
0.3
0.6
3.0
6.0
7.5
22.5+/-
22.5+/-
20+/-
17+/-
15.5+/-
6
14
S-1
S-2
23
38
Stratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 81185084 CHICK-FIL-A #0424_BS_10282021.GPJ TERRACON_DATATEMPLATE.GDT 10/29/21DEPTH (Ft.)1
2
3
4
5
6
7 WATER LEVELOBSERVATIONSFIELD TESTRESULTSLOCATION See Exploration Plan
Drill Rig: Truck-mounted
BORING LOG NO. B-10
Chick-fil-A, Inc.CLIENT:
Irvine, CA
Driller: EDI
Boring Completed: 10-18-2021
PROJECT: Chick-fil-A #04249 Renton
Elevations were interpolated from google Earth.
See Exploration and Testing Procedures for a
description of field and laboratory procedures
used and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
351 Rainier Ave S.
Renton, WA
SITE:
Boring Started: 10-18-2021
21905 64th Ave W, Ste 100
Mountlake Terrace, WA
WATER LEVEL OBSERVATIONS
Groundwater not encountered RECOVERY (In.)Latitude: 47.4791° Longitude: -122.2174°GRAPHIC LOGDEPTH ELEVATION (Ft.)
Approximate Surface Elev.: 23 (Ft.) +/-
Page 1 of 1
Advancement Method:
Hollow Stem Auger
Abandonment Method:
Boring backfilled with bentonite
Surface capped with Cold-Mix Asphalt
Notes:
Project No.: 81185084 SAMPLE IDWATERCONTENT (%)PERCENT FINESSAMPLE TYPE
15-3-3
N=6
1-3-4
N=7
ASPHALT
AGGREGATE BASE COURSE
FILL - SILTY SAND (SM), trace gravel, gray brown, wet
SILT WITH SAND (ML), brown and gray, wet, medium stiff
Boring Terminated at 7.5 Feet
0.3
0.6
2.5
7.5
22.5+/-
22.5+/-
20.5+/-
15.5+/-
18
12
S-1
S-2
31
30
Stratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 81185084 CHICK-FIL-A #0424_BS_10282021.GPJ TERRACON_DATATEMPLATE.GDT 10/29/21DEPTH (Ft.)1
2
3
4
5
6
7 WATER LEVELOBSERVATIONSFIELD TESTRESULTSLOCATION See Exploration Plan
Latitude: 47.4791° Longitude: -122.2171°GRAPHIC LOGDEPTH ELEVATION (Ft.)
Approximate Surface Elev.: 23 (Ft.) +/-
Page 1 of 1
Advancement Method:
Hollow Stem Auger
Abandonment Method:
Boring backfilled with bentonite
Surface capped with Cold-Mix Asphalt
Notes:
Project No.: 81185084
Drill Rig: Truck-mounted
BORING LOG NO. B-11
Chick-fil-A, Inc.CLIENT:
Irvine, CA
Driller: EDI
Boring Completed: 10-18-2021
PROJECT: Chick-fil-A #04249 Renton
Elevations were interpolated from google Earth.
See Exploration and Testing Procedures for a
description of field and laboratory procedures
used and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
351 Rainier Ave S.
Renton, WA
SITE:
Boring Started: 10-18-2021
21905 64th Ave W, Ste 100
Mountlake Terrace, WA
WATER LEVEL OBSERVATIONS
Groundwater not encountered RECOVERY (In.)SAMPLE IDWATERCONTENT (%)PERCENT FINESSAMPLE TYPE
SUPPORTING INFORMATION
Contents:
General Notes
Unified Soil Classification System
UNIFIED SOIL CLASSIFICATION SYSTEM
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse-Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction
retained on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E GW Well-graded gravel F
Cu 4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F, G, H
Fines classify as CL or CH GC Clayey gravel F, G, H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E SW Well-graded sand I
Cu 6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G, H, I
Fines classify as CL or CH SC Clayey sand G, H, I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic: PI 7 and plots on or above “A”
line J
CL Lean clay K, L, M
PI 4 or plots below “A” line J ML Silt K, L, M
Organic: Liquid limit - oven dried 0.75 OL Organic clay K, L, M, N
Liquid limit - not dried Organic silt K, L, M, O
Silts and Clays:
Liquid limit 50 or more
Inorganic: PI plots on or above “A” line CH Fat clay K, L, M
PI plots below “A” line MH Elastic Silt K, L, M
Organic: Liquid limit - oven dried 0.75 OH Organic clay K, L, M, P
Liquid limit - not dried Organic silt K, L, M, Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve.
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded
gravel with silt, GW -GC well-graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW -SM well-graded
sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay.
E Cu = D60/D10 Cc =
6010
2
30
DxD
)(D
F If soil contains 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name.
I If soil contains 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains 30% plus No. 200 predominantly sand, add
“sandy” to group name.
M If soil contains 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI 4 and plots on or above “A” line.
O PI 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
UNIFIED SOIL CLASSIFICATION SYSTEM