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Home My WebLink AboutEX06_GeotechnicalReport2021 REPORT COVER PAGE RED 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 RECEIVED 01/07/2022 AVanGordon PLANNING DIVISION EXHIBIT 6 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 Responsive ■ Resourceful ■ Reliable 1 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 GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com. 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 i 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 Responsive ■ Resourceful ■ Reliable 1 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 2 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, DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 3 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 4 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 5 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 6 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 7 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 8 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 9 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 10 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 11 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 Responsive ■ Resourceful ■ Reliable ATTACHMENTS DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 1 of 2 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 Responsive ■ Resourceful ■ Reliable SITE LOCATION AND EXPLORATION PLANS Contents: Site Location Plan Exploration Plan DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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. 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. SITE LOCATION DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 EXPLORATION RESULTS Contents: Boring Logs (B-9 through B-11) DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 TYPEDocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 TYPEDocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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 TYPEDocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 SUPPORTING INFORMATION Contents: General Notes Unified Soil Classification System DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 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. DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286 UNIFIED SOIL CLASSIFICATION SYSTEM DocuSign Envelope ID: F94832C8-5168-46AD-9392-B611DC851286