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HomeMy WebLinkAboutRS_Geotechnical_Report_071825_v1ECS Southwest, LLP Geotechnical Engineering Report Proposed Valvoline Instant Oil Change NE 4th Street and Whitman Court NE Renton, Washington ECS Project Number 80:1171 July 18, 2025 Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page i TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................. 1 1.0 INTRODUCTION ............................................................................................................ 2 2.0 PROJECT INFORMATION ............................................................................................... 3 2.1 SITE INFORMATION ........................................................................................................... 3 2.2 PROPOSED CONSTRUCTION .............................................................................................. 3 3.0 FIELD EXPLORATION AND LABORATORY TESTING .......................................................... 4 3.1 SUBSURFACE CHARACTERIZATION .................................................................................... 5 3.2 GROUNDWATER OBSERVATIONS ...................................................................................... 5 3.3 INFILTRATION TESTING...................................................................................................... 6 3.4 LABORATORY TESTING ...................................................................................................... 7 3.4.1 PID Testing ................................................................................................................ 7 4.0 DESIGN RECOMMENDATIONS ...................................................................................... 7 4.1 BUILDING/STRUCTURE DESIGN ......................................................................................... 7 4.1.1 Undocumented Fill ................................................................................................... 7 4.1.2 Foundations .............................................................................................................. 8 4.1.3 Floor Slabs ............................................................................................................... 11 4.1.4 Below Grade Retaining Walls ................................................................................. 11 4.2 GEOLOGIC HAZARDS ....................................................................................................... 13 4.2.1 Seismic Site Classification ....................................................................................... 13 4.2.2 Liquefaction ............................................................................................................ 14 4.2.3 Faulting ................................................................................................................... 14 4.3 PAVEMENT DESIGN ......................................................................................................... 14 4.3.1 Design Traffic Loading............................................................................................. 14 4.3.2 Subgrade Characteristics ........................................................................................ 14 4.3.3 Minimum Material Thicknesses .............................................................................. 15 4.3.4 Concrete Pavements ............................................................................................... 15 4.3.5 Construction Traffic ................................................................................................ 15 5.0 SITE CONSTRUCTION RECOMMENDATIONS ................................................................ 16 5.1 SUBGRADE PREPARATION ............................................................................................... 16 5.1.1 Stripping and Grubbing ........................................................................................... 16 5.1.2 Proofrolling ............................................................................................................. 16 5.2 EARTHWORK OPERATIONS .............................................................................................. 17 5.2.1 Excavation Considerations ...................................................................................... 17 5.2.2 Engineered Fill Materials ........................................................................................ 18 5.2.3 Compaction ............................................................................................................. 18 5.3 FOUNDATIONS ................................................................................................................ 19 5.4 UTILITY INSTALLATIONS ................................................................................................... 20 6.0 CLOSING .................................................................................................................... 20 APPENDICES Appendix A – Diagrams •Site Location Diagram •Boring Location Diagram(s) •Subsurface Cross-Sections(s) Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page ii Appendix B – Field Operations •Reference Notes •Exploration Procedures •Boring Logs Appendix C – Laboratory Testing •Laboratory Testing Summary Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 1 EXECUTIVE SUMMARY This executive summary is intended as a very brief overview of the primary geotechnical conditions that are expected to affect design and construction. Information gleaned from the executive summary should not be utilized in lieu of reading the entire geotechnical report. •Soil Findings: The surface cover consisted of 2 inches of asphalt material over 10 to 12 inches of ABC stone at soil boring locations B-07 and I-01 through I-04. It was not encountered at the remaining boring locations. Possible fill was encountered beneath the surface cover or at the surface, at depths ranging from approximately 1.5 to 8 feet, consisting of various granular soils with densities ranging from loose to very dense. Below the fill, natural granular soils extended to the boring termination depths, with SPT N-values generally increasing with depth, indicating medium-dense to very dense conditions. However, a very loose zone was identified in boring B-02 between 8 and 11.75 feet. It is the intent of this report is to remove any possible fill below the shallow foundations and allow stable fill to remain beneath the slabs or pavement, provided it is observed to be stable during the proof-roll observation during the construction phase. The possible fill could remain below the footings if documentation of its placement is provided or explorations during construction determine it is suitable. •Building Foundation: The proposed building with basement can be supported by a mat foundation bearing on compacted engineered fill or suitable natural soils beneath the mat base layer, which consists of gravel. The mat should be designed using allowable soil bearing pressure of 2,000 psf. •Apron Foundation: The street level apron can be supported on monolithic turndown slab with a net allowable bearing pressure of 3,000 psf bearing on compacted engineered fill or suitable natural soils. •Dumpster Foundation: The dumpster enclosure can be supported as conventional spread footing consisting of column or wall footings designed for a net allowable bearing pressure of 3,000 psf bearing on compacted engineered fill or suitable natural soils. •Seismic Site Class: Based on the N-values measured in the borings and experience in the area, a Seismic Site Class CD designation is appropriate for seismic design of the proposed building. •Liquefaction Potential: Based on the conditions encountered and our experience, it is our opinion that the liquefaction potential is low at the site and that no mitigation measures are required. •Drains and Waterproofing: Based on the anticipated basement grades, the below-grade walls will require waterproofing, as well as foundation and wall drains. The mat should be waterproofed across its bottom and up the sides to the top of the below-grade retaining walls. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 2 1.0 INTRODUCTION The purpose of this study was to provide geotechnical information for the design of a Valvoline Instant Oil Change Building in Renton, Washington. The recommendations developed for this report are based on project information supplied by Valvoline Company. Our services were provided in accordance with Proposal No. 80:1656-GP, dated May 21, 2025, as authorized by Laura Orr on June 6, 2025, and the associated change order for infiltration testing authorized via email by Hayley Fourney on June 11, 2025. This report contains the procedures and results of our subsurface exploration and laboratory testing programs, review of existing site conditions, engineering analyses, and recommendations for the design and construction of the project. The report includes the following items: a.A site location diagram and a boring location diagram. b.Boring logs prepared in accordance with the standard practice for geotechnical engineering. c.Laboratory test results. d.A review of the published geologic conditions and their relevance to the planned development. e.A subsurface characterization based on the field exploration and laboratory tests performed. f.Recommended allowable soil bearing pressure(s) for conventional shallow foundations (spread footings) and estimates of predicted foundation settlement. g.Recommendations for slab-on-grade design and construction, including recommendations for subgrade materials and design modulus of subgrade reaction. h.Design and construction recommendations for building retaining walls, including lateral earth pressures, sliding resistance coefficients, and allowable bearing pressures. i.Recommendations for seismic site classification in accordance with the 2021 International Building Code. j.Recommendations for design and construction of the pavements, including a recommended California Bearing Ratio (CBR) design value, and recommended pavement section thicknesses based on assumed 18-kip Equivalent Single Axle Loads (ESALs). k.Recommendations for subgrade preparation and earthwork, including excavation considerations, engineered fill material, and engineered fill placement. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 3 2.0 PROJECT INFORMATION This report is based on the following sources of information: •Review the provided Conceptual Site Plan (Sheet No: CSP, with boring locations) dated May 21, 2025, ALTA/NSPS Land Title Survey dated January 28, 2025, and Aerial Site Location and Photos Package all received via email dated May 21, 2025. •Google Earth aerial photos dated between 1990 and 2025. •Geologic Map of Washington State by J Eric. Schuster (2005). 2.1 SITE INFORMATION The project site is located in the southwest quadrant of the intersection of NE 4th Street and Whitman Court NE in Renton, Washington. Based on Google Earth imagery, the site appears to have been graded and asphalt-paved sometime between 2015 and 2016. Prior to this, the site remained undeveloped, with possibly some minor grading work. Based on our site reconnaissance, there is an existing wetland area just west of the site. The wetland was overgrown and appeared to contain a small amount of water at the bottom, which was approximately 10 feet below the general site grade at the time of the site walk. The location of the site is shown on Figure 2.1.1 and indicated on the Site Location Diagram in Appendix A. Figure 2.1.1. Site Location 2.2 PROPOSED CONSTRUCTION Based on our review of the Conceptual Site Plan and our previous experience with similar Valvoline sites, we understand the proposed construction will include a Valvoline Instant Oil Change development. Based on the provided information, a summary of our understanding of the proposed project is provided below in the following Project Description table. Approximate Site Location Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 4 PROJECT DESCRIPTION AND PROPOSAL BASIS Building Project Items The proposed development will include construction of following: •A single story with basement, Instant Oil change building structure for Valvoline, measuring ± 1,508 square feet in plan area •Dumpster enclosure •Customer parking areas & two access driveways to service bays Building Construction Types Single Story with below grade basement supported by mat slab Building area ± 1,508 square feet Existing Grade Change within Project Site It appears that there is approximately a 2-foot grade change across the project site within the proposed area of construction based on land survey information. Finished Floor Elevations 10 to 12 feet below existing site grade Estimated Max. Mat Contact Stress 2,000 psf Estimated Max. Street Level Apron Load 1 kip per liner foot Dumpster Enclosure Estimated Max. Column Load 10 Kips Estimated Max. Design Wall Load 1 kip per liner foot Estimated Maximum Design Floor Load 25 Pounds per square foot (psf) Pavement Pavement for Parking 9 car parking spaces Access Driveway Two entrances are proposed: one from Vashon Court NE on the south side, and the other from NE 4th Street on the north side. Design Traffic Load Not Provided Based on the current and proposed grades, we anticipate that cut and fill depths will be less than 2 feet for general site grading. The Valvoline standard pavement sections for a 20-year design life include: •Asphalt Section: 1½-inch asphalt surface course with a polymer-modified asphalt binder over a 2½-inch asphalt base course on an 8-inch-thick compacted aggregate subbase course. If our understanding of the proposed construction is inaccurate or if more details regarding the proposed construction become available, please inform ECS so that we can revise our recommended scope of geotechnical services to better suit the project requirements. 3.0 FIELD EXPLORATION AND LABORATORY TESTING Our exploration procedures are explained in greater detail in Appendix B including the insert titled Subsurface Exploration Procedure: Standard Penetration Testing (SPT) and Wall, Ring-Lined, Split Barrel, Drive Sampling of Soils. Our scope of work included drilling eleven (11) borings to depths ranging from 4 to 20 feet: six (6) within the proposed building footprint, one (1) within the proposed dumpster pad area, and four (4) in the proposed green areas for infiltration testing. The borings were located with a mobile phone GPS unit and/or measuring from existing site features. Their approximate locations are shown on the Boring Location Diagram in Appendix A. The elevations on Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 5 the boring logs referenced in the report were obtained from the land survey information and should be considered approximate. 3.1 SUBSURFACE CHARACTERIZATION The following sections provide generalized characterizations of the site geology and soil conditions. Please refer to the boring logs in Appendix B for more detailed information. According to the Geologic Map of Washington, the site is situated in an area characterized by Pleistocene till and outwash composed of clay, silt, sand, gravel, cobbles, and boulders deposited by or originating from continental glaciers. Locally, the area may also include peat, nonglacial sediment, modified land, and artificial fill. The surface cover consisted of 2 inches of asphalt material over 10 to 12 inches of ABC stone at soil boring locations B-07 and I-01 through I-04. It was not encountered at the remaining boring locations. Beneath the surface cover or from the surface, possible fill was encountered at depths ranging from approximately 1.5 to 8 feet below existing grades. This material consisted of granular soils, including poorly graded sand with clay, clayey sand, poorly graded sand, poorly graded sand with silt, and silty sand, with varying amounts of gravel. The density of the fill appeared to range from loose to very dense. The shallow infiltration borings, I-01 through I-03, were terminated within this layer. The possible fill may be part of the grading work observed on Google Earth historical aerial imagery. Below the possible fill, natural granular soils were encountered extending to the termination depths of the borings. These soils consisted of silty sand, clayey sand, poorly graded sand, silty gravel, poorly graded sand with clay, and clayey gravel. Most of the sand layers contained varying amounts of gravel. In general, the Standard Penetration Test (SPT) N-values increased with depth, indicating densities ranging from medium dense to very dense. However, a zone of very loose soil was encountered in boring B-02 between depths of 8 and 11.75 feet. 3.2 GROUNDWATER OBSERVATIONS At the time of drilling, groundwater was encountered at four of the seven soil boring locations (B- 01, B-03, B-04, and B-05) at depths ranging from 11 to 18.5 feet below existing grades. During classification, some soil samples collected above the groundwater depths as shallow as 8.5 feet were observed to be wet, suggesting the presence of perched water conditions or groundwater fluctuations. It should be noted that perched zones can significantly affect water table depth measurements, particularly depending on seasonal variations. If more accurate groundwater level readings are desired, ECS recommends installing monitoring wells. Water levels in open excavations may require several hours to several days to stabilize depending on the permeability of the soils. Groundwater levels at the site may be subject to seasonal conditions, recent rainfall, drought or temperature effects, surface water runoff, construction activities, and other factors. Clays are generally not conducive to the presence of groundwater; however, gravels, sands and silts, and open fractures and solution features; where present, can Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 6 store and transmit “perched” groundwater flow or seepage. Therefore, groundwater conditions should be observed just prior to the start of construction. 3.3 INFILTRATION TESTING The infiltration testing locations were selected and drilled to a depth of 4 feet below existing grade, as per the civil engineer’s recommendation. A 2-inch PVC pipe (slotted at the bottom 6 inches) was placed in each hole, and sand or pea gravel was placed in the annulus between the pipe and the wall of the hole in the bottom 1 foot. The remaining depth was backfilled with spoils from the drilling work. Test locations I-01 through I-03 exhibited a faster rate of infiltration compared to I-04, which contained very dense soils. At location I-04, the soil was saturated by maintaining an approximately constant head of 12 inches from the bottom for 4 hours. However, at locations I-01 through I-03, water infiltrated almost immediately, and a constant head could not be maintained. Therefore, saturation at these locations was achieved by pouring a relatively large quantity of water to ensure the soil reached saturation conditions. After saturation, the infiltration rate at I-04 was measured using at least eight consecutive readings or until stable readings were observed. A head of 6 inches from the bottom was maintained, with each reading taken at 5-minute intervals, followed by topping off to 6 inches before taking the next reading. At the remaining locations, due to the relatively high infiltration rates, a constant head of 6 inches was maintained during a 5-gallon pour of water. The time required for the pour was recorded to calculate the infiltration rate. Testing was continued for at least eight consecutive readings or until stable readings were observed. Infiltration Test Results Locations Soil Type at Test Depth Infiltration Rate (min/in) I-01 Medium Dense, Clayey Sand ~0.028 I-02 Medium Dense , Poorly Graded Sand with Silt ~0.014 I-03 Medium Dense, Poorly Graded Sand ~0.0073 I-04 Very Dense, Poorly Graded Sand with Clay ~1.38 We recommend applying a factor of safety of 2 to the measured infiltration rate for design purposes. Additionally, soil and groundwater conditions should be verified at the time of construction to confirm whether the in-situ conditions are consistent with those observed during this study. This verification may also include infiltration testing if the infiltration rate is critical to Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 7 the system's performance. Should the location or depth of the storm drain systems differ from the current design, we also recommend conducting additional infiltration testing to ensure suitability. 3.4 LABORATORY TESTING Each sample was visually classified on the basis of texture and plasticity in accordance with ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedures). After identification and classification, the samples were grouped in the major zones noted on the boring logs in Appendix B. The group symbols for each soil type are indicated in parentheses along with the soil descriptions. The stratification lines between strata on the logs are approximate; in situ, the transitions may be gradual. Additionally, percent passing the No. 200 sieve and moisture content were performed on representative samples. The laboratory results are summarized in Appendix C. 3.4.1 PID Testing Each soil sample was subjected to headspace screening using a photo-ionization detector (PID). Headspace vapor measurements were taken in the laboratory on recovered split samples to estimate the volatile organic compound (VOC) content using a Rae Systems Mini-Rae® PID. A PID is a type of gas detector that uses ultraviolet (UV) light to ionize chemicals in the air, allowing for the detection and measurement of various VOCs and other gases. All of the soil samples were screened, and the results were below the detection limit. 4.0 DESIGN RECOMMENDATIONS 4.1 BUILDING/STRUCTURE DESIGN 4.1.1 Undocumented Fill Possible fill was encountered at depths ranging from approximately 1.5 to 8 feet below existing grades. At the time of this report, no documentation regarding the placement or compaction of the fill was available; therefore, all fill is considered undocumented. The fill may be part of the grading work observed on Google Earth historical aerial imagery. Undocumented fill soils can vary significantly in consistency, density, compressibility, and other characteristics. They may also contain buried debris or other unsuitable materials that were not discovered during our site investigation. Therefore, it is the intent of this report is to remove any possible fill below the shallow foundations and allow stable fill to remain beneath the slabs or pavement, provided it is observed to be stable during the proof-roll observation in the construction phase. The possible fill could remain below the footings if documentation of its placement is provided or explorations during construction determine it is suitable. Such explorations could include hand augers, dynamic cone penetrometer (DCP) testing, and/or test pits. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 8 4.1.2 Foundations Building Foundation Provided subgrades are prepared as discussed herein and based on the assumed design foundation load, the proposed building with basement can be supported by a mat foundation. The design of the mat foundations should utilize the following parameters: Design Parameters Allowable Bearing Pressure 2,000 psf Acceptable Bearing Soil Material (Underneath Base Layer) Engineered fill or Approved Native Soils Minimum Bottom of Foundation Embedment Below Finished Basement Grade (1) Nominal Depth Minimum Mat Base Layer Thickness (2) 6 inches gravel Modulus of Subgrade Reaction (k1) (Plate Load Test Basis) 100 pci Estimated Total Settlement (3) Less than 1 inch Estimated Differential Settlement (4) ½ inch or less across the width of the foundation Notes: 1.Embedment depths consider bearing capacity, frost penetration, and expansive soils considerations. 2.To distribute foundation loading into the subgrade soil more uniformly, the mat foundation should be directly supported by aminimum 6-inch-thick layer of gravel (Mat Base Layer). 3.Settlement is based on the assumed uniform contact stress of 2,000 psf over approximately 30.67’x49.17’ mat foundation. It should be noted that contact stress should not exceed the allowable bearing capacity recommended herein. If final stress is different, ECS must be contacted to update foundation recommendations and settlement calculations. 4.Based on the variability in soil borings. Differential settlement can be re-evaluated once the foundation plans are more complete. The possible fill will be penetrated during basement excavation. Soft soil encountered at B-02 between depths of 8 and 11.75 feet may require undercutting, depending on the final elevation of the foundation bottom. If soft or unsuitable soils are encountered at the footing bearing elevations, the unsuitable soils should be undercut and removed. Any undercut should be backfilled with compacted, engineered fill or lean concrete (with a strength of f’c ≥ 1,000 psi at 28 days) up to the original design bottom of the mat base layer. If the fill is below the water table, the engineered fill should be free draining gravel with less than 5% passing the no. 200 sieve (fines). For resistance to lateral loads, a coefficient of friction is recommended between the base of the foundation elements and underlying soils. In addition, for footings cast directly against excavation sidewalls, a passive resistance may be used to resist lateral forces for undisturbed soils. The passive resistance should be neglected in the upper 12 inches unless the ground immediately in front of the footing is covered with concrete or other impervious pavement. The recommended lateral resistance values are ultimate values, and a suitable factor of safety should be used in design. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 9 * The groundwater was encountered as shallow as 8.5 feet based on visual classification. If the basement excavation encounters groundwater, the effective unit weight calculation should account for subtracting the unit weight of water (63 pcf). Where utility trenches or other excavations are located adjacent to foundations, the bottom of the footing should be located below an imaginary 1:1 (horizontal to vertical) plane upward from the nearest bottom edge of the utility trench. Footing excavations should have firm bottoms and be free from slough prior to mat base placement. The foundation excavations should be observed by a geotechnical engineer or their representative prior to placement of mat base to observe the exposed ground conditions. The mat should be waterproofed across its bottom and up the mat sides to the top of the below grade retaining walls. The below grade retaining walls should be provided with wall drains near the bottom of the mat. Street Level Apron Slabs Provided subgrades are prepared as discussed herein and based on the assumed design load, the proposed street level aprons can be supported as monolithic turn down slabs. The design of the turn down slab should utilize the following parameters: Design Parameters Net Allowable Bearing Pressure (1) 3,000 psf Acceptable Bearing Soil Material Engineered fill or Approved Native Soils Minimum Turn Down Width 8 inches Minimum Turn Down Embedment Depth (below finished exterior grades) (2) 30 inches Climatic Rating (Cw) 30 Modulus of Subgrade Reaction (k1) 100 pci Estimated Total Settlement (3) Less than 1 inch Estimated Differential Settlement (3) ½ inch or less in 50 feet Notes: 1.Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above the base of thefoundation. 2.For bearing capacity, frost penetration, and expansive soils considerations. 3.Based on assumed maximum wall load of 1 klf. If final loads are different, ECS must be contacted to update foundation recommendations and settlement calculations. Depth (ft) Sliding Friction Coefficient [Concrete on Soil] (µ) Soil Angle of Internal Friction (ø) Effective Unit Weight (γ’ pcf) Coefficient of Passive Earth Pressure (Kp) To 15 0.40 32o 130/67* 3.00 Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 10 The turndown slab should be considered similar to foundations. This means that if existing fill, soft or unsuitable soils are encountered at the footing bearing elevations, the unsuitable soils should be undercut and removed. Any undercut should be backfilled with compacted, engineered fill or lean concrete (with a strength of f’c ≥ 1,000 psi at 28 days) up to the original design bottom of the footing elevation. The original footing shall then be constructed on top of the backfill material. At the time of construction, further evaluation of the possible fill soils is necessary to determine if undercutting of these materials is required. Where utility trenches or other excavations are located adjacent to foundations, the bottom of the footing should be located below an imaginary 1:1 (horizontal to vertical) plane upward from the nearest bottom edge of the utility trench. Footing excavations should have firm bottoms and be free from slough prior to concrete or reinforcement placement. The foundation excavations should be observed by a geotechnical engineer or their representative prior to placement of concrete or reinforcing steel to observe the exposed ground conditions. Dumpster Enclosure Foundation Provided subgrades are prepared as discussed herein, and based on the assumed design foundation loads, the proposed dumpster enclosure can be supported by conventional shallow spread footing foundations. These include individual column footings or continuous wall footings. The design of the shallow foundations should utilize the following parameters: Design Parameter Column Footing Wall Footing Net Allowable Bearing Pressure (1) 3,000 psf 3,000 psf Acceptable Bearing Soil Material Engineered fill or Approved Native Soils Minimum Width 24 inches 18 inches Minimum Footing Embedment Depth (below slab or finished grade) [Interior/Exterior] (2) 24/30 inches 24/30 inches Estimated Total Settlement (3) Less than 1 inch Less than 1 inch Estimated Differential Settlement (4) Less than 0.5 inches between columns Less than 0.5 inches over 50 feet Notes: (1)Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above the base of the foundation. (2)For bearing, expansive soils, and frost penetration requirements.(3)Based on assumed structural loads (10kips/1klf). If final loads are different, ECS must be contacted to update foundationrecommendations and settlement calculations. (4)Based on anticipated variability in borings. Differential settlement can be re-evaluated once the foundation plans are more complete. If existing fill, soft or unsuitable soils are encountered at the footing bearing elevations, the unsuitable soils should be undercut and removed. Any undercut should be backfilled with Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 11 compacted, engineered fill or lean concrete (with a strength of f’c ≥ 1,000 psi at 28 days) up to the original design bottom of the footing elevation. The original footing shall then be constructed on top of the backfill material. At the time of construction, further evaluation of the possible fill soils is necessary to determine if undercutting of these materials is required. For resistance to lateral loads, a coefficient of friction of 0.4 is recommended between the base of the foundation elements and underlying soils. In addition, for footings cast directly against excavation sidewalls, a passive resistance equal to an equivalent fluid applying 300 pcf pressure may be used to resist lateral forces for undisturbed soils. The passive resistance should be neglected in the upper 12 inches unless the ground immediately in front of the footing is covered with concrete or other impervious pavement. The recommended lateral resistance values are ultimate values, and a suitable factor of safety should be used in design. Where utility trenches or other excavations are located adjacent to foundations, the bottom of the footing should be located below an imaginary 1:1 (horizontal to vertical) plane upward from the nearest bottom edge of the utility trench. Footing excavations should have firm bottoms and be free from slough prior to concrete or reinforcing steel placement. The foundation excavations should be observed by a geotechnical engineer or their representative prior to placement of reinforcing steel or concrete to observe the exposed ground conditions. 4.1.3 Floor Slabs Provided subgrades and engineered fills are prepared as discussed herein, the proposed floor slabs can be constructed as Ground Supported Slabs (or Slab-On-Grade). It appears that the slabs will bear on existing fill or newly compacted fill. We recommend that a 4-in base course layer of gravel or crushed stone be provided below the slab. Provided a base course moisture break layer is implemented in the slab section, the slabs may be designed using a modulus of subgrade reaction of 150 psi/in. Ground-supported slabs should be isolated from the foundations and foundation-supported elements of the structure so that differential movement between the foundations and slab will not induce excessive shear and bending stresses in the floor slab. Where the structural configuration does not allow the use of a free-floating slab, the slab should be designed with adequate reinforcement and load transfer devices to avoid overstressing of the slab. 4.1.4 Below Grade Retaining Walls As the proposed building includes basement, the below grade walls should be designed and constructed in accordance with the following recommendations. Lateral Earth Pressures: Retaining walls should be designed to withstand the lateral earth pressures exerted by the backfill. The pressure diagram is triangular. It is anticipated that retaining walls associated with the building structure, such as for below-grade basement walls, will be rigid walls restrained from rotation by the floor slab. For rigid walls, the "At Rest" (Ko) soil condition should Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 12 be used in the wall design and evaluation. For cantilever walls that are free to rotate, the “Active” (Ka) soil condition should be used. In the design of these retaining wall structures, the following soil parameters can be utilized. The critical zone is defined as the area between the back of the retaining wall structure and an imaginary line projected upward and rearward from the bottom back edge of the wall footing at a 45-degree angle. The structural engineer should use the following recommended soil properties for wall design. Retaining Wall Backfill in the Critical Zone – Granular Engineered Fill Soil Parameter Recommended Value Soil Classification SILTY SAND (SM), CLAYEY SAND (SC), or more granular Fines Content Max. 20%<#200 Sieve Retained Soil Moist Unit Weight (γ) 120 pcf Cohesion (C) 50 psf Angle of Internal Friction (φ) 32° Coefficient of At-Rest Earth Pressure (Ko) 0.47 Coefficient of Active Earth Pressure (Ka) 0.30 We recommend that all permanent below grade walls be designed to also withstand lateral earth pressures from surcharge loads due to adjacent pavements, buildings, structures, slopes, equipment, or materials. Retaining Wall Backfill: The backfill should be placed and compacted in accordance with the recommendations for engineered fill given in this report. Samples of proposed retaining wall backfill should be submitted by the contractor and tested by ECS prior to beginning construction activities to verify that the soils proposed meet or exceed those specified in the geotechnical report and retaining wall design. Tests should include classification, Standard/Modified Proctor compaction, and shear strength (remolded direct shear and/or remolded triaxial shear). The use of proper retaining wall backfill material, placement, and compaction, should be observed and tested by ECS or third-party testing firm at the time of construction. Wall Drains: All below-grade building retaining walls should be properly drained so that hydrostatic pressures do not build up behind the walls and the backfill soils do not become saturated and soften. (Proper drainage and backfill compaction are required to prevent excessive mat slab settlement near the walls.) Wall drains can consist of a 12-inch-wide zone of free draining gravel, such as No. 57 Stone, employed directly behind the wall and separated from the soils beyond with a non-woven filter fabric. Alternatively, the wall drain can consist of a suitable geocomposite drainage board material. The wall drain should be hydraulically connected to the foundation drain. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 13 The wall foundation drains should be connected to the stormwater system. Below grade retaining walls should be waterproofed. 4.2 GEOLOGIC HAZARDS 4.2.1 Seismic Site Classification The 2021 Washington State Building Code (WBC), that is based on International Building Code 2021, requires site classification for seismic design based on the upper 100 feet of a soil profile. The methods utilized in classifying sites are based on shear wave velocity measurements or correlations to shear wave velocity from suitable geotechnical parameters such as standard penetration test (SPT) blow counts, shear strength, overburden pressure, void ratio, or cone penetration test (CPT) test resistance. The seismic site class definitions for the average of shear wave velocity in the upper 100 feet of the soil profile are shown in the following table: SEISMIC SITE CLASSIFICATION Site Class Soil Profile Name Shear Wave Velocity, Vs, (ft./s) A Hard Rock >5,000 B Medium Hard Rock 3,000-5,000 BC Soft Rock 2,100-3,000 C Very Dense Sand or Hard Clay 1,450-2,100 CD Dense Sand or Very Stiff Clay 1,000-1,450 D Medium Dense Sand or Stiff Clay 700-1,000 DE Loose Sand or Medium Stiff Clay 500-700 E Very Loose Sand or Soft Clay <500 Based on the Site Class Definitions, correlations between SPT blow counts, and our experience, it is our opinion the site soil and rock can be characterized as Site Class CD. The deepest boring drilled at the project site extended to a depth of 20 feet beneath the existing ground surface, whereas WBC site classifications are based on characterization of the upper 100 feet of the soil profile. The Site Class definition should not be confused with the Seismic Design Category designation which the Structural Engineer typically assesses. In addition to the seismic site classification, ECS has determined the design spectral response acceleration parameters following the IBC methodology. The Mapped Reponses were estimated from the ASCE 7 Hazard Tool https://asce7hazardtool.online/ and ASCE 7-22 using the following coordinates: lat. 47.488231°, long. -122.16195°. The design responses for the short (0.2 sec, SDS) and 1-second period (SD1) are noted at the far-right end of the following table. GROUND MOTION PARAMETERS [ASCE 7-22 Design Code] Period (sec) Mapped Spectral Response Accelerations (g) Maximum Spectral Response Acceleration Adjusted for Site Class (g) Design Spectral Response Acceleration (g) 0.2 SS 1.58 SMS 1.75 SDS 1.16 1.0 S1 0.55 SM1 0.94 SD1 0.62 Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 14 4.2.2 Liquefaction When a saturated soil with little to no cohesion liquefies during a major earthquake, it experiences a temporary loss of shear strength as a result of a transient rise in excess pore water pressure generated by strong ground motion. Flow failure, lateral spreading, differential settlement, loss of bearing, ground fissures, and sand boils are evidence of excess pore pressure generation and liquefaction. Based on the presence of primarily medium-dense to very dense soils encountered within the maximum explored depth of 20 feet, and the planned undercutting of any localized very loose soils beneath the foundations, it is our opinion that the liquefaction potential is low. 4.2.3 Faulting There are no mapped active faults extending through the project site. The nearest mapped fault to the site, which is considered active, is the Seattle Fault Zone approximately 1.75 miles to the north of the site according to USGS Quaternary Fault and Fold Database of the Unites Staes. 4.3 PAVEMENT DESIGN We understand the proposed construction will include paved parking lots mainly for passenger cars and light trucks. 4.3.1 Design Traffic Loading Design traffic loading information for the pavements has not been provided to us. Based on our experience with similar projects, we assume that the proposed private pavements will be subjected to the average daily traffic of cars and light trucks, and additional delivery, garbage and recycling trucks (less than 150,000 ESALs in 20 years). The civil engineer, developer, owner, and/or user should verify these assumptions and notify ECS if the actual pavement design traffic loading conditions exceed or are significantly less than these assumed values. If the project will include any public pavements (WSDOT or local municipality), we need the projected average daily traffic, % dual axle trucks, and % tractor trailer trucks in order to provide recommended pavement sections for the public pavements. 4.3.2 Subgrade Characteristics Pavement subgrades should consist of firm, stable, compacted low plasticity soil. Their stability should be evaluated at the time of construction. Based on our experience with soils similar to those encountered, a design CBR value of 8 is recommended for this project. The pavement design assumes subgrades consist of suitable materials evaluated by ECS and placed and compacted to specifications as highlighted in section 5.2.3. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 15 4.3.3 Minimum Material Thicknesses Based on our analysis, the typical Valvoline asphalt section, as shown below, is adequate for asphalt paved areas. The following minimum pavement sections may be used by the civil engineer to develop the pavement design drawings for the project, provided the civil engineer is in agreement with ECS’ design traffic loading assumptions and estimates. The contractor should bid and construct the project in accordance with the civil design drawings, not the recommendations given in this report. These recommendations are not contract drawings nor specifications. Asphalt Pavement Section Recommendations Pavement Type Material Designation Layer Thickness (in) Flexible Asphalt Surface Course 1.5 Asphalt Intermediate Course 2.5 Aggregate Base Course 8 Concrete Pavement Section Recommendations Pavement Type Material Designation Concrete Pavement, Plain Jointed (in.) Rigid Portland Cement Concrete (4000 psi, air-entrained) 6 Aggregate Base Course 6 It is recommended to follow WSDOT Standard Specifications for Road, Bridge, and Municipal Construction for the asphalt binders and aggregate grading of asphalt mix, as well as for aggregate base course or reclaimed asphalt pavement aggregate. 4.3.4 Concrete Pavements Concentrated front-wheel loads are frequently imposed on pavements in trash dumpster and truck loading dock areas. This type of loading typically results in rutting and scuffing of bituminous pavements and ultimately pavement failures and costly repairs. Therefore, we recommend that the pavements in trash pickup and loading dock aprons areas utilize the aforementioned Portland Cement Concrete (PCC) pavement section. It may be prudent to use rigid pavement sections in all areas planned for heavy truck traffic. The Portland cement concrete pavement section should consist of air-entrained Portland cement concrete having a minimum 28-day compressive strength of 4,000 psi. The rigid pavement section should be provided with construction joints and saw-cut control joints at appropriate intervals per Portland Cement Association (PCA) requirements. The construction joints should be reinforced with dowels to transfer loads across the joints. Wire mesh should be included to control shrinkage cracking of the concrete. 4.3.5 Construction Traffic It is important to note that the design sections do not account for construction traffic loading. An incomplete pavement section without the final 1 inch of surface course asphalt can be used for Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 16 temporary construction traffic, such as concrete trucks and tractor trailer material delivery trucks. Please note, however, that damage to the asphalt already placed is likely to occur in localized areas, and it should be repaired by removal and replacement with new asphalt at or near the end of construction, prior to placement of the surface course. It should also be noted that these design recommendations may not satisfy the local municipality or Washington State Department of Transportation guidelines. Any roadways constructed for public use and to be dedicated to the local municipality or State for repair and maintenance must be designed in accordance with the local municipality or State requirements. 5.0 SITE CONSTRUCTION RECOMMENDATIONS 5.1 SUBGRADE PREPARATION In a dry and undisturbed state, the soil at the site will provide good subgrade support for fill placement and construction operations. However, when wet, some of the soils will degrade quickly with disturbance from contractor operations. Therefore, the contractor should carefully plan his operation to reduce exposure of the subgrade to weather and construction equipment traffic and provide and maintain good site drainage during earthwork operations to help maintain the integrity of the surficial soils. Erosion and sedimentation should be controlled per sound engineering practice and current jurisdictional requirements. 5.1.1 Stripping and Grubbing Subgrade preparation should consist of stripping all vegetation, asphalt, gravel, rootmat, topsoil, and any other soft or unsuitable materials from the proposed construction areas. A geotechnical engineer or their representative should be called on to verify that unsuitable surficial materials have been completely removed prior to the placement of engineered fill or construction of structures and pavements. Appropriate diligence should be exercised to properly backfill removed below grade structures. Abandoned subsurface utilities should be removed and or grouted a sufficient distance from the proposed building to prevent the conduit of water beneath the proposed structure. 5.1.2 Proofrolling After removing unsuitable surface materials, cutting to the proposed grade, and prior to the placement of any engineered fill or other construction materials, the exposed subgrade should be examined by a geotechnical engineer or their representative. The exposed subgrade should be proofrolled with construction equipment having a minimum axle load of 10 tons (e.g., fully loaded tandem-axle dump truck). The areas subject to proofrolling should be traversed by the equipment in two perpendicular (orthogonal) directions with overlapping passes of the vehicle under the observation of a geotechnical engineer or their representative. This procedure is intended to assist in identifying any shallow depth yielding materials. In the event that yielding or “pumping” subgrade is identified by the proofrolling, those areas should be repaired prior to the placement of any subsequent engineered fill or other construction Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 17 materials. Methods of repair of unstable subgrade, such as undercutting or moisture conditioning or chemical stabilization, should be discussed with ECS to determine the appropriate procedure with regard to the existing conditions causing the yielding. 5.2 EARTHWORK OPERATIONS 5.2.1 Excavation Considerations Excavation Safety: All excavations and slopes should be made and maintained in accordance with OSHA excavation safety standards. The contractor is solely responsible for designing and constructing stable, temporary excavations and slopes and should shore, slope, or bench the sides of the excavations and slopes as required to maintain stability of both the excavation sides and bottom. The contractor’s responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. ECS is providing this information solely as a service to our client. ECS is not assuming responsibility for construction site safety or the contractor’s activities; such responsibility is not being implied and should not be inferred. Construction Dewatering: Based on the borings we performed, experience with groundwater fluctuations on similar sites, and anticipated design grades, temporary excavations will likely encounter groundwater. The contractor shall make their own assessment of temporary dewatering needs based upon the limited subsurface groundwater information presented in this report. Soil sampling is not continuous, and thus soil and groundwater conditions may vary between sampling intervals (typically 5 feet). If the contractor believes additional subsurface information is needed to assess dewatering needs, they should obtain such information at their own expense. ECS makes no warranties or guarantees regarding the adequacy of the provided information to determine dewatering requirements; such recommendations are beyond our scope of services. If dewatering is necessary, we recommend that the groundwater be lowered at least 2 feet below the excavation depth to maintain stability. Dewatering systems are a critical component of many construction projects. Dewatering systems must be selected, designed, and maintained by a qualified and experienced (specialty or other) contractor familiar with the geotechnical and other aspects of the project. The failure to properly design and maintain a dewatering system for a given project can result in delayed construction, unnecessary foundation subgrade undercuts, detrimental phenomena such as ‘running sand’ conditions, internal erosion (i.e., ‘piping’), the migration of ‘fines’ down-gradient towards the dewatering system, localized settlement of nearby infrastructure, foundations, slabs-on-grade and pavements, etc. Water discharged from any site dewatering system shall be discharged in accordance with all local, state, and federal requirements. Excavatibility: Based on the assumed excavation depths for mass grading, footings, and utilities, we anticipate that the materials to be excavated will consist of primarily medium-dense to very dense natural soils, which can be removed with conventional earth excavation equipment such as track-mounted backhoes, loaders, or bulldozers. However, hard excavation should be anticipated. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 18 5.2.2 Engineered Fill Materials Product Submittals: At least one week prior to placement of engineered fill, if necessary, representative bulk samples (about 50 pounds) of on-site and/or off-site borrow should be submitted for laboratory testing, which will include Atterberg limits, natural moisture content, grain-size distribution, and moisture-density relationships for compaction. Import materials should be tested prior to being hauled to the site to determine if they meet project specifications. Engineered Fill Materials: Materials for use as engineered fill should consist of inorganic soils classified as SM, SC, SW, SP, GW, GM and GC, or a combination of these group symbols, per ASTM D 2487. Rock fragments should generally be less than 3 inches in maximum dimension and should be blended with soil. Engineered fill below the water table should consist of free draining gravel with less than 5 percent passing No. 200 sieve (fines). Poor Quality Materials: Poor quality fill materials include materials which do not satisfy the requirements for engineered fill materials, such as: high plasticity clay (CH) or elastic silt (MH), topsoil, organic materials, debris, and debris-laden fill. Lean clay (CL) and silt (ML) are also poor quality fill materials due to the difficulty in achieving appropriate compaction to support structures. If CL or ML are to be used as engineered fills, moisture conditioning (drying or wetting) may be necessary to facilitate proper compaction. On-Site Borrow Suitability: The on-site soils primarily consist of granular soils suitable for use as engineered fill for the project. If the client chooses to use the poor-quality materials, they will require careful moisture control, in order to achieve compaction and stability. Any soils excavated from below the water table will require significant drying to achieve the recommended moisture content and minimum compaction. Soils above the water table may also be relatively dry at the time of construction and require wetting to achieve the recommended moisture content and minimum compaction. 5.2.3 Compaction Fill Compaction: Engineered fill should be placed in maximum 8-inch loose lifts. In confined areas such as utility trenches, portable compaction equipment and thin lifts of 4 inches to 6 inches may be required to achieve specified degrees of compaction. Engineered fill should be moisture conditioned as necessary to within -3 and +3 % of the soil’s optimum moisture content. Moisture conditioning options include spraying and mixing in water to excessively dry soils, scarifying and drying of excessively wet soils, and adding lime to excessively wet soils. Engineered fill should be compacted with suitable equipment to a dry density of at least 95% of the maximum modified proctor dry density (as per ASTM D1557) below building and pavements and 90% for the remainder of the project. ECS should be retained to observe and test the placement and compaction of engineered fill. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 19 Fill Placement Considerations: Proper drainage should be maintained during the earthwork phases of construction to reduce ponding of water which can degrade the subgrade soils. Exposed soil subgrades should be protected at the end of each working day by sloping to drain and sealing with a smooth-drum roller to reduce infiltration of precipitation and surface water. Where fill materials will be placed to widen existing embankment fills, or placed up against sloping ground, the soil subgrade should be scarified, and the new fill benched or keyed into the existing material. Fill material should be placed in horizontal lifts. When free draining gravel is placed below the water table, a separation fabric (woven or non-woven) should be placed between the gravel and surrounding soils to stop migration of soils into the gravel. Moisture Conditioning: Drying and compaction of wet soils is typically difficult during typically cooler, wetter months of the year (typically November through March). During the cooler and wetter periods of the year, delays and additional costs should be anticipated. At these times, reduction of soil moisture may need to be accomplished by a combination of mechanical manipulation and the use of chemical additives, such as lime or cement, in order to lower moisture contents to levels appropriate for compaction. Alternatively, removal and replacement with drier, off-site materials may be necessary. Subgrade Protection: Measures should also be taken to limit site disturbance, especially from rubber-tired heavy construction equipment, and to control and remove surface water from development areas, including structural and pavement areas. It would be advisable to designate and cover haul roads and construction staging areas to limit the areas of disturbance and to prevent construction traffic from excessively degrading subgrade soils. Haul roads and construction staging areas should be covered with ABC to protect those subgrades. 5.3 FOUNDATIONS Protection of Foundation Excavations: Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time. Therefore, foundation concrete should be placed the same day that excavations are made or shortly thereafter. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, the contractor should consider placement of a 1 to 3-inch thick “mud mat” of “lean” concrete on the bearing soils before the placement of reinforcing steel. Footing Subgrade Observations: It will be important to have a geotechnical engineer or their representative observe the foundation subgrade prior to placing foundation concrete, to confirm the bearing soils are as anticipated. If existing fill, very loose sand, very soft to soft silt/clay, or otherwise unsuitable or yielding soils are observed at the footing bearing elevations, they should be undercut and removed. Any undercut excavation should be backfilled with engineered fill, free draining stone wrapped in woven geotextile, flowable fill, or lean concrete (f’c ≥ 1,000 psi at 28 days) up to the original design bottom of footing elevation. The footing should be constructed on top of the engineered fill, free draining stone wrapped in woven geotextile, hardened flowable fill, or hardened lean concrete. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 20 Slab Subgrade Verification: A geotechnical engineer or their representative should be called on to observe exposed subgrades within the expanded building limits prior to engineered fill placement to assure that adequate subgrade preparation has been achieved. Proofrolling using a drum roller or loaded dump truck should be performed in their presence at that time. Once subgrades have been determined to be firm and stable, engineered fill can be placed. If there will be a significant time lag between the site grading work and final grading of concrete slab areas prior to the placement of the design floor slab section materials, a geotechnical engineer or their representative should be called on to verify the condition of the prepared soil subgrade. Prior to final floor slab section construction, the soil subgrade may require scarification, moisture conditioning, and re-compaction to restore stable conditions. 5.4 UTILITY INSTALLATIONS The soils encountered in our exploration are expected to be generally suitable for support of utility pipes. The pipe subgrades should be observed and probed for stability by a geotechnical engineer or their representative. Loose or deleterious materials encountered should be removed and replaced with suitable compacted General Fill, or pipe stone bedding material. The backfill materials should be placed in lifts not to exceed 8 inches loose measure, or 6 inches compacted measure. Thinner lifts may be required when using handheld compaction equipment. Compacted backfill should be free of topsoil, roots, ice, or any other material designated by a geotechnical engineer or their representative as unsuitable. The backfill should be moisture conditioned, placed, and compacted in accordance with the recommendations of this report. 6.0 CLOSING ECS has prepared this report of findings, evaluations, and recommendations to guide geotechnical- related design and construction aspects of the project. The description of the proposed project is based on information provided to ECS. If any of this information is inaccurate, either due to our interpretation of the documents provided or site or design changes that may occur later, ECS should be contacted immediately in order that we can review the report in light of the changes and provide additional or alternate recommendations as may be required to reflect the proposed construction. We recommend that ECS be allowed to review the project’s plans and specifications pertaining to our work so that we may ascertain consistency of those plans/specifications with the intent of the geotechnical report. Field observations, monitoring, and quality assurance testing during earthwork and foundation installation are an extension of and integral to the geotechnical design recommendation. We recommend that the owner retain these quality assurance services and that ECS be allowed to continue our involvement throughout these critical phases of construction to provide general consultation as issues arise. ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in this report. Geotechnical Engineering Report – Proposed Valvoline Instant Oil Change July 18, 2025 ECS Project No. 80:1171 Page 21 The analysis and recommendations submitted in this report are based upon the data obtained from the soil borings and tests performed at the locations as indicated on the Boring Location Diagram and other information referenced in this report. This report does not reflect any variations, which may occur between the borings. In the performance of the subsurface exploration, specific information is obtained at specific locations at specific times. However, it is a well-known fact that variations in subsurface conditions exist on most sites between boring locations and also such situations as groundwater levels vary from time to time. The nature and extent of variations may not become evident until the course of construction. If variations then appear evident, after performing on-site observations during the construction period and noting characteristics and variations, a reevaluation of the recommendations for this report will be necessary Appendix A - Drawings and Reports Site Location Diagram Boring Location Diagram(s) Subsurface Cross-Section(s) 7/15/2025 Service Layer Credits: World Boundaries and Places: Sources: Esri, HERE, Garmin, FAO, NOAA, USGS, ©² ENGINEER SCALE PROJECT NO. SHEET DATE 1 80:1171 1" = 800' SS Valvoline Instant Oil Change NE 4th Street and Whitman Court NE, Renton, Washington Valvoline Renton SITE LOCATION DIAGRAM I-04 I-03 I-02 I-01 B-07 B-06 B-05 B-04 B-03 B-02 B-01 7/15/2025 Service Layer Credits: 4th St_modified:² ENGINEER SCALE PROJECT NO. SHEET DATE Legend Approximate Infiltration Boring Locations - I Approximate Building and Dumpster Pad Boring Locations - B Approximate Cross-Section Location 2 80:1171 1" = 30' SS Valvoline Instant Oil Change NE 4th Street and Whitman Court NE, Renton, Washington Valvoline Renton BORING LOCATION DIAGRAM Appendix B – Field Operations Reference Notes Exploration Procedures Boring Logs REFERENCE NOTES FOR BORING LOGS MATERIAL1,2 1Classifications and symbols per ASTM D 2488-17 (Visual-Manual Procedure) unless noted otherwise. 2To be consistent with general practice, “POORLY GRADED” has been removed from GP, GP-GM, GP-GC, SP, SP-SM, SP-SC soil types on the boring logs. 3Non-ASTM designations are included in soil descriptions and symbols along with ASTM symbol [Ex: (SM-FILL)]. 4Typically estimated via pocket penetrometer or Torvane shear test and expressed in tons per square foot (tsf). 5Standard Penetration Test (SPT) refers to the number of hammer blows (blow count) of a 140 lb. hammer falling 30 inches on a 2 inch OD split spoon sampler required to drive the sampler 12 inches (ASTM D 1586). “N-value” is another term for “blow count” and is expressed in blows per foot (bpf). SPT correlations per 7.4.2 Method B and need to be corrected if using an auto hammer. 6The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in granular soils. In clay and cohesive silts, the determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally employed. 7Minor deviation from ASTM D 2488-17 Note 14. 8Percentages are estimated to the nearest 5% per ASTM D 2488-17. Reference Notes for Boring Logs (09-02-2021).doc © 2021 ECS Corporate Services, LLC. All Rights Reserved COHESIVE SILTS & CLAYS UNCONFINED COMPRESSIVE STRENGTH, QP4 <0.25 0.25 - <0.50 0.50 - <1.00 1.00 - <2.00 2.00 - <4.00 4.00 - 8.00 >8.00 SPT5 (BPF) CONSISTENCY7 (COHESIVE) GRAVELS, SANDS & NON-COHESIVE SILTS SPT5 DENSITY <5 5 - 10 11 - 30 31 - 50 >50 Very Loose Loose Medium Dense Dense Very Dense WATER LEVELS6 RELATIVE AMOUNT7 Trace With Adjective (ex: “Silty”) COARSE GRAINED (%)8 <5 FINE GRAINED (%)8 <5 DRILLING SAMPLING SYMBOLS & ABBREVIATIONS PARTICLE SIZE IDENTIFICATION DESIGNATION PARTICLE SIZES Hollow Stem Auger Power Auger (no sample) Bulk Sample of Cuttings Wash Sample Shelby Tube Sampler Split Spoon SamplerSS ST WS BS PA HSA RQD PM MC RC REC Boulders Cobbles Gravel: Sand: Silt & Clay (“Fines”) Fine Medium Coarse Fine Coarse 0.074 mm to 0.425 mm (No. 200 to No. 40 sieve) <0.074 mm (smaller than a No. 200 sieve) 0.425 mm to 2.00 mm (No. 40 to No. 10 sieve) 2.00 mm to 4.75 mm (No. 10 to No. 4 sieve) 4.75 mm to 19 mm (No. 4 sieve to ¾ inch) ¾ inch to 3 inches (19 mm to 75 mm) 3 inches to 12 inches (75 mm to 300 mm) 12 inches (300 mm) or larger >50 31 - 50 16 - 30 9 - 15 5 - 8 2 - 4 <2 Very Hard Hard Very Stiff Stiff Firm Soft Very Soft ASPHALT CONCRETE GRAVEL TOPSOIL VOID BRICK AGGREGATE BASE COURSE GW GP GM GC SW SP SM SC ML MH CL CH OL OH PT WELL-GRADED GRAVEL gravel-sand mixtures, little or no fines POORLY-GRADED GRAVEL gravel-sand mixtures, little or no fines SILTY GRAVEL gravel-sand-silt mixtures CLAYEY GRAVEL gravel-sand-clay mixtures WELL-GRADED SAND gravelly sand, little or no fines POORLY-GRADED SAND gravelly sand, little or no fines SILTY SAND sand-silt mixtures CLAYEY SAND sand-clay mixtures SILT non-plastic to medium plasticity ELASTIC SILT high plasticity LEAN CLAY low to medium plasticity FAT CLAY high plasticity ORGANIC SILT or CLAY non-plastic to low plasticity ORGANIC SILT or CLAY high plasticity PEAT highly organic soils WL (First Encountered) WL (Completion) WL (Seasonal High Water) WL (Stabilized) FILL POSSIBLE FILL PROBABLE FILL ROCK FILL AND ROCK 25 - 45 10 - 20 30 - 45 10 - 25 RD Pressuremeter Test Rock Bit Drilling Rock Core, NX, BX, AX Rock Sample Recovery % Rock Quality Designation % Modified California Sampler - -- • - - - • -- • - • - — - SUBSURFACE EXPLORATION PROCEDURE: THICK, WALL, RING-LINED, SPLIT BARREL, DRIVE SAMPLING OF SOILS ASTM D 3550 Thick wall, split barrel drive sampling of soils is used to obtain representative samples of soil for laboratory testing. The middle barrel section is split barrel design containing ring liners. Penetration resistance data may be recorded. The procedures are similar to the Standard Penetration Testing, or SPT, method. Thes method is often used in the arid southwest regions of the US where unsaturated soils are too difficult to sample using the thin-wall tube (ASTM D 1587). Variations of the sampler may be called Dames and Moore, Modified California, or Ring Sampler •Involves driving a hollow tube (split-spoon) into the ground by dropping a 140-lb hammer a height of 30-inches at desired depth •Auger is advanced* and an additional SPT is performed •Samples taken at depths where relatively un- disturbed samples are needed. •Obtain 1.38 to 2.88-inch diameter soil sample *Drilling Methods May Vary— The predominant drilling methods used for SPT are open hole fluid rotary drilling and hollow-stem auger drilling. Procedure: CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-01 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488231 LONGITUDE: -122.161950 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 Fines%MC% 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 S-07 SS SS SS SS MC SS SS 18 18 18 18 18 18 17 8 8 12 12 10 15 15 END OF BORING AT 19.92 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - grayish brown, moist. (SP) POORLY GRADED SAND WITH GRAVEL - grayish brown, moist, medium dense to dense. (SM) SILTY SAND WITH GRAVEL - grayish brown, wet, dense. (SC) CLAYEY SAND WITH GRAVEL - grayish brown, wet, very dense. (SM) SILTY SAND WITH GRAVEL - grayish brown, wet, very dense. 390.0 385.0 380.0 375.0 18-14- 14 (28) 4-5-7 (12) 20-15- 18 (33) 10-20- 18 (38) 45, 28, 40 (68) 6-38 - 50 (88) 5-18- 50/5 (68/11) 68 28 12 33 38 88 74 3.6 7.0 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):8.5 Ft BORING STARTED:06/25/2025 CAVE IN DEPTH:Not Observed WL (Compleon):18.5 Ft BORING COMPLETED:06/25/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-19.92') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-02 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488360 LONGITUDE: -122.161939 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 SS SS SS SS SS SS 18 18 18 18 9 18 14 12 14 4 7 14 END OF BORING AT 20 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - dark brown, moist, dense. POSSIBLE FILL - (SM) SILTY SAND WITH GRAVEL - brown, moist, dense. (GM) SILTY GRAVEL - brown, moist, very loose. (SC) CLAYEY SAND WITH GRAVEL - brownish gray, contains slight roots, moist, very dense. (SP) POORLY GRADED SAND WITH GRAVEL - brownish gray, wet, very dense. 390.0 385.0 380.0 375.0 35-28- 13 (41) 18-11- 16 (27) 38-17- 21 (38) 1-1-2 (3) 25-50/3 (50/3) 42-28- 35 (63) 41 27 38 3 50.3 63 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):18.5 Ft BORING STARTED:06/27/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/27/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-20') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-03 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488271 LONGITUDE: -122.162035 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 SS SS SS SS SS SS 18 18 18 18 17 17 10 8 8 10 12 15 END OF BORING AT 19.92 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - dark brown, moist. (SC) CLAYEY SAND WITH GRAVEL - brown, moist, medium dense. (SM) SILTY SAND WITH GRAVEL - grayish brown, moist, dense. (GM) SILTY GRAVEL - grayish brown, wet, medium dense. (SC) CLAYEY SAND WITH GRAVEL - grayish brown, wet, very dense. (SM) SILTY SAND WITH GRAVEL - grayish brown, wet, very dense. 390.0 385.0 380.0 375.0 19-9-5 (14) 14-7-7 (14) 4-16-28 (44) 7-10-18 (28) 4-15- 50/5 (65/11) 20-42- 50/5 (92/11) 14 14 44 28 65.11 92.11 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):8.5 Ft BORING STARTED:06/26/2025 CAVE IN DEPTH:Not Observed WL (Compleon):12 Ft BORING COMPLETED:06/26/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-19.92') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-04 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488318 LONGITUDE: -122.162031 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 Fines%MC% 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 S-07 SS SS SS SS SS MC SS 18 18 18 18 18 12 18 12 12 15 14 16 12 17 END OF BORING AT 20 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - grayish brown, moist. (SC) CLAYEY SAND WITH GRAVEL - brown, moist, dense. (SM) SILTY SAND WITH GRAVEL - brown, moist, dense. (GM) SILTY GRAVEL - brown, moist, medium dense. (SP-SC) POORLY GRADED SAND WITH CLAY AND GRAVEL - dark gray, wet, very dense. (SM) SILTY SAND WITH GRAVEL - dark gray, wet, very dense. 390.0 385.0 380.0 375.0 20-11-5 (16) 26-13- 20 (33) 15-13- 19 (32) 25-9-12 (21) 24-36- 50 (86) 20, 50 (50) 16-30- 50 (80) 50 16 33 32 21 86 80 10.1 9.0 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):13.5 Ft BORING STARTED:06/26/2025 CAVE IN DEPTH:Not Observed WL (Compleon):11 Ft BORING COMPLETED:06/26/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-20') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-05 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488233 LONGITUDE: -122.162086 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 S-07 SS SS SS SS MC SS SS 18 18 18 18 18 12 17 8 6 12 3 18 10 15 END OF BORING AT 19.92 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - grayish brown, moist. (SM) SILTY SAND WITH GRAVEL - grayish brown, moist, dense. (GM) SILTY GRAVEL - grayish brown, moist to wet, very dense. (SC) CLAYEY SAND WITH GRAVEL - grayish brown, wet, very dense. 390.0 385.0 380.0 375.0 21-8-6 (14) 4-9-10 (19) 12-25- 25 (50) 13-45- 45 (90) 13, 38, 40 (78) 25-50/6 (50/6) 24-40- 50/5 (90/11) 78 14 19 50 90 50.6 90.11 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):10.5 Ft BORING STARTED:06/26/2025 CAVE IN DEPTH:Not Observed WL (Compleon):11.5 Ft BORING COMPLETED:06/26/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-19.92') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-06 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488362 LONGITUDE: -122.162081 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP 5 10 15 S-01 S-02 S-03 S-04 S-05 S-06 S-07 SS SS MC SS SS SS SS 18 18 18 18 18 8 5 15 12 15 4 12 8 0 END OF BORING AT 18.92 Ft POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - brown, contains slight roots, moist. POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - brown, moist, loose. (SC) CLAYEY SAND WITH GRAVEL - brown, moist. (GM) SILTY GRAVEL - grayish brown, moist to wet, dense to very dense. 390.0 385.0 380.0 375.0 6-14-9 (23) 6-4-4 (8) 4, 6, 20 (26) 18-12- 20 (32) 6-18-23 (41) 42-50/2 (50/2) 50/5 (50/5) 26 23 8 32 41 50.2 50.5 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):8.5 Ft BORING STARTED:06/26/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/26/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-18.92') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: B-07 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488351 LONGITUDE: -122.162147 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP 5 10 S-01 S-02 S-03 S-04 S-05 SS SS SS SS SS 18 18 18 18 11 2 12 9 4 6 END OF BORING AT 14.42 Ft Asphalt Thickness [2.00"]. ABC Stone Thickness [12.00"]. POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - brown, moist. (SP) POORLY GRADED SAND WITH GRAVEL - grayish brown, moist, very dense. (SM) SILTY SAND WITH GRAVEL - grayish brown, moist, very dense. (GC) CLAYEY GRAVEL - grayish brown, wet, very dense. 390.0 385.0 380.0 13-7-4 (11) 3-4-8 (12) 9-35-33 (68) 30-42- 28 (70) 11-50/5 (50/5) 11 12 68 70 50.5 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):13.5 Ft BORING STARTED:06/27/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/27/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-14.42') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: I-01 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488336 LONGITUDE: -122.161805 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP S-01 S-02 SS SS 18 18 15 7 END OF BORING AT 4 Ft Asphalt Thickness [2.00"]. ABC Stone Thickness [10.00"]. POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - dark grayish brown, moist, dense to medium dense. 390.0 15-15- 21 (36) 15-12-8 (20) 36 20 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):Dry BORING STARTED:06/25/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/25/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-4') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: I-02 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488166 LONGITUDE: -122.161743 STATION:SURFACE ELEVATION: 392 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP S-01 S-02 SS SS 18 18 12 6 END OF BORING AT 4 Ft Asphalt Thickness [2.00"]. ABC Stone Thickness [12.00"]. POSSIBLE FILL - (SP-SM) POORLY GRADED SAND WITH SILT AND GRAVEL - brown, moist, medium dense. 390.0 9-13-13 (26) 9-10-10 (20) 26 20 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):Dry BORING STARTED:06/25/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/25/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-4') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: I-03 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488060 LONGITUDE: -122.161924 STATION:SURFACE ELEVATION: 392 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP S-01 S-02 SS SS 18 18 16 15 END OF BORING AT 4 Ft Asphalt Thickness [2.00"]. ABC Stone Thickness [12.00"]. POSSIBLE FILL - (SC) CLAYEY SAND WITH GRAVEL - dark grayish brown, moist, dense. POSSIBLE FILL - (SP) POORLY GRADED SAND WITH GRAVEL - dark grayish brown, moist, medium dense. 390.0 42-32- 10 (42) 5-8-10 (18) 42 18 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):Dry BORING STARTED:06/25/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/25/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-4') GEOTECHNICAL BOREHOLE LOG CLIENT: Valvoline Instant Oil Change PROJECT NO.: 80:1171 BORING NO.: I-04 SHEET: 1 OF 1 PROJECT NAME: Valvoline Renton DRILLER/CONTRACTOR: Holt Services, Inc. SITE LOCATION: NE 4th Street and Whitman Court NE, Renton, Washington, 98059 LOSS OF CIRCULATION LATITUDE: 47.488087 LONGITUDE: -122.162329 STATION:SURFACE ELEVATION: 391 BOTTOM OF CASING DE P T H ( F T ) SA M P L E N U M B E R SA M P L E T Y P E SA M P L E DI S T A N C E ( I N ) SA M P L E RE C O V E R Y ( I N ) DESCRIPTION OF MATERIAL ST R A T I G R A P H Y WA T E R L E V E L S EL E V A T I O N ( F T ) BL O W S / 6 " (T C P / M C / S P T - N VA L U E ) * 0 20 40 60 80 100 RQD%REC% 0 10 20 30 40 50 TCP ModCal SPT 0 20 40 60 80 100 0 1 2 3 4 5QP S-01 S-02 SS SS 18 18 18 17 END OF BORING AT 4 Ft Asphalt Thickness [2.00"]. ABC Stone Thickness [12.00"]. POSSIBLE FILL - (SP-SC) POORLY GRADED SAND WITH CLAY AND GRAVEL - dark gray, moist, very dense. (SP-SC) POORLY GRADED SAND WITH CLAY AND GRAVEL - dark gray, moist, very dense. 390.0 25-35- 50 (85) 25-48- 28 (76) 85 76 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL WL (First Encountered):Dry BORING STARTED:06/25/2025 CAVE IN DEPTH:Not Observed WL (Compleon):Dry BORING COMPLETED:06/25/2025 HAMMER TYPE:Automac WL (Seasonal High Water):EQUIPMENT:LOGGED BY:DRILLING METHOD: WL (Stabilized):CME-85 GP Hollow Stem Auger (0'-4') GEOTECHNICAL BOREHOLE LOG Appendix C – Laboratory Testing Laboratory Testing Summary S-02 7.0 3.6 S-05 9.0 10.1 Project: Client: Laboratory Testing Summary Sample Location Sample Number Depth (ft)^MC (%) Soil Type Atterberg Limits **Percent Passing No. 200 Sieve Moisture - Density CBR (%) #Organic Content (%)LL PL PI <Maximum Density (pcf) <Optimum Moisture (%)0.1 in.0.2 in. B-01 3.5-5.0 B-04 13.5-15.0 Notes:See test reports for test method, ^ASTM D2216-19, *ASTM D2488, **ASTM D1140-17, #ASTM D2974-20e1 < See test report for D4718 corrected values Definitions:MC: Moisture Content, Soil Type: USCS (Unified Soil Classification System), LL: Liquid Limit, PL: Plastic Limit, PI: Plasticity Index, CBR: California Bearing Ratio, OC: Organic Content Valvoline Renton Project No.:80:1171 Approved by Date Received Valvoline Instant Oil Change Date Reported:7/7/2025 Office / Lab Address Office Number / Fax GPuppala SSuresh SSuresh 7/1/2025 ECS Southwest LLP - Salt Lake City 2355 South 1070 West Suite A West Valley City, UT 84119 (385) 330-2270 Tested by Checked by SP SP-SC