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Home My WebLink AboutRS_Geotechnical_Report_240607_v1 STRIDE Bus Rapid Transit South Renton Transit Center (SRTC) Site Plan Review, Conditional Use Permit, Master Site Plan Review, and Lot Line Adjustment Application Attachment 28a Geotechnical Report June 2024 Prepared by the 75$160,77$/)250 3KRQH)D[ 6(17%<6DQGL:LVH )RXUWK$YHQXH6XLWH_6HDWWOH:$ 5(0$5.663(&,$/,16758&7,2161RQH '$7( 0DUFK72 %ODNH-RQHV )520 5RE*RUPDQ:63352-(&7123 7$6.12 352-(&71$0( ,%XV5DSLG7UDQVLW%57DQG%XV%DVH1RUWK6281'75$16,75()(5(1&( $( FF :HDUHSOHDVHGWRVXEPLWWKHIROORZLQJILQDO3KDVHGHOLYHUDEOH $('6RXWK5HQWRQ7UDQVLW&HQWHU*HRWHFKQLFDO5HFRPPHQGDWLRQV5HSRUW ,I\RXKDYHDQ\TXHVWLRQVRUFRQFHUQVSOHDVHFRQWDFWXV I-405 corridor South Renton Transit Center Geotechnical Recommendation Report March 2022 Stride program: I-405 corridor Page i | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Consultant Quality Control Form Version Title Date Originator/ Drafted by Reviewed by Approved by Notes, as required 0 South Renton Transit Center Geotechnical Recommendation Report – Draft 11/22/2021 Matteo Montesi (WSP) Elizabeth Lundquist (WSP) Ed Reynolds (tech edit) Sandra Wise (QA/QC) Rob Gorman (WSP) For ST review 1 South Renton Transit Center Geotechnical Recommendation Report 3/21/2022 Michelle Cline (WSP) Elizabeth Lundquist (WSP) Ed Reynolds (tech edit) Rob Gorman (WSP) Addressed ST comments Stride program: I-405 corridor Page ii | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Summary Purpose This Geotechnical Recommendation Report (GRR) documents procedures and presents the findings of the preliminary geotechnical investigation conducted for the proposed improvements at the South Renton Transit Center (SRTC) for the Sound Transit I-405 Bus Rapid Transit (BRT) project. The additional borings performed for this phase of work encountered similar subsurface conditions to those reported during prior phases of this project across much of the site. In addition, boring SB-2 encountered bedrock at about 75 feet below ground surface. The subsurface investigation program is deemed sufficient for the features covered in this report. Nevertheless, additional subsurface investigations may be required to support the design of the proposed parking structure (not covered in this report). The subsurface conditions are generally characterized by a surficial layer of fills over alluvial deposits. The alluvial deposits are generally very loose and loose in the upper portion while they become denser at depth. Interbedded layers of peats and highly organic soils were encountered in most borings. WSP concurs with HWA’s previous assessment that liquefaction poses a significant hazard at the site. Up to 40 feet of potentially liquefiable soils may be present at the site, which may experience up to 2 feet of liquefaction-induced settlement. Ground improvement mitigation measures and deep foundations are likely cost prohibitive for small structures. The proposed bus shelters are recommended to be supported on slabs-on-grade with a maximum allowable bearing pressure of 1,000 psf. The bearing pressure is limited due to the presence of very loose and loose alluvial deposits as well as compressible peats and highly organics soils. Flexible pavement will be used in the parking garage access areas and interim parking lot. Rigid pavement will be used for the bus lanes and layover area. A discussion of pavement design, including recommended thickness, is presented in this report. Due to soft subgrade conditions and shallow groundwater, it is recommended to place geosynthetics over properly prepared subgrade prior to placing pavement materials. This report has been prepared for the exclusive use of Sound Transit for the design and construction of the bus shelter foundations, pavements, and retaining walls considered for the SRTC site as part of the Sound Transit I-405 BRT project. The findings, conclusions, and recommendations presented in this report are applicable only to the specific project study elements and locations described and are not intended to apply to any other design elements or locations. All subsequent users shall accept any and all liability resulting from any use or reuse of the data, opinions, and recommendations without the prior written consent of WSP. Stride program: I-405 corridor Page iii | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Table of Contents 1INTRODUCTION ......................................................................................................................... 1 1.1Background ........................................................................................................... 1 1.2Purpose and Scope of Work ................................................................................. 1 1.3Site Description and Existing Facilities .................................................................. 3 1.4Proposed Improvements ....................................................................................... 3 2GEOTECHNICAL INVESTIGATION PROGRAM ..................................................................... 3 2.1Existing Geotechnical Data ................................................................................... 3 2.2Borehole Investigation ........................................................................................... 3 2.3Geophysical Surveys ............................................................................................. 4 2.4Laboratory Testing ................................................................................................ 4 3SITE CONDITIONS ..................................................................................................................... 5 3.1General Geologic Conditions ................................................................................ 5 3.2Subsurface Conditions .......................................................................................... 5 3.3Groundwater .......................................................................................................... 6 4GEOTECHNICAL RECOMMENDATIONS ................................................................................ 6 4.1Preliminary Seismic Design Parameters ............................................................... 6 4.2Liquefaction and Seismic Settlement .................................................................... 7 4.3Foundation Recommendations for Bus Shelters ................................................... 7 4.4Recommendations for Earth Retaining Structures ................................................ 8 4.5Pavement Design and Recommendations ............................................................ 8 4.6Site Preparation and Grading .............................................................................. 10 4.7Temporary Excavations ....................................................................................... 11 4.8Structural Fill and Compaction ............................................................................ 11 4.9Groundwater Control ........................................................................................... 11 5REFERENCES .......................................................................................................................... 12 Stride program: I-405 corridor Page iv | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Figures Figure 1-1I-405 Bus Rapid Transit Project ............................................................................ 2 Tables Table 2-1Design Seismic Coefficients per AASHTO ............................................................ 4 Table 4-1Preliminary Seismic Design Coefficients ............................................................... 6 Table 4-2Design ESALs (20-year Design Life) ..................................................................... 9 Table 4-3Recommended Flexible Pavement Sections ......................................................... 9 Table 4-4Recommended Rigid Pavement Section ............................................................... 9 Appendices Appendix A Detailed Figures: Appendix B Existing Geotechnical Information by Others Appendix C Boring Logs Appendix D Geophysical Survey Report Appendix E Laboratory Test Results Appendix F Pavement Design Data and Calculations Stride program: I-405 corridor Page v | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Acronyms and Abbreviations BRT bus rapid transit GRR Geotechnical Recommendation Report PE preliminary engineering SRTC South Renton Transit Center WSDOT Washington State Department of Transportation Stride program: I-405 corridor Page 1 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 1 INTRODUCTION 1.1 Background WSP USA (WSP) was retained by Sound Transit to provide engineering design services for the I-405 Bus Rapid Transit (BRT) project located in Washington state. The I-405 BRT project would provide BRT service along the I-405 corridor spanning 37 miles between the cities of Lynwood and Burien. The proposed project alignment and stations are presented in Figure 1-1. This project stage involves preliminary engineering (PE) design of BRT elements, including BRT stations and park-and-ride facilities. The I-405 BRT project also includes two new parking garages: one at the Totem Lake/Kingsgate Park-and-Ride site and one at the South Renton Transit Center (SRTC) site. At this time, final design and construction of both parking garages have been delayed. This report covers the SRTC site and the associated bus shelter and any retaining structures that may be needed. 1.2 Purpose and Scope of Work The purpose of this Geotechnical Recommendation Report (GRR) is to provide the required geotechnical information and design recommendations in support of the proposed SRTC improvements as part of the I-405 BRT project. This report provides preliminary geotechnical design recommendations pertaining to bus shelters, retaining walls, seismic considerations, and pavements. WSP scope of work included the following: x Field investigation: Perform seven (7) borings between 32 and 105 feet deep with periodic sampling (Section 2.2) x Geophysical Testing: Perform suspension hole logging in two borings (Section 2.3) x Laboratory testing: Perform geotechnical laboratory tests on selected soil samples (Section 2.4) x Geotechnical engineering analyses x Preparation of this report The information provided in this report is based on the boring log and laboratory testing of the recently drilled boring, existing geotechnical data, and published literature. Stride program: I-405 corridor Page 2 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Figure 1-1 I-405 Bus Rapid Transit Project Stride program: I-405 corridor Page 3 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 1.3 Site Description and Existing Facilities The SRTC site is located in the city of Renton, Washington, and is located between Rainier Avenue S., S Grady Way, and Lake Avenue S. The site is generally level with the majority of the site paved with an asphalt parking lot. Four existing building structures are present at the site at the time of the subsurface investigation and are planned to be demolished before any project elements are constructed. In the southern portion of the site (adjacent to S Grady Way), there is an existing Puget Sound Energy power line easement. In the eastern portion of the site (adjacent to Lake Avenue S) there is an existing Seattle City Light power line easement. Along the south boundary, the easement is approximately 100 feet wide. In the eastern portion of the site, the easement is approximately 200 feet wide. Prior to the start of construction, Sound Transit will coordinate with Puget Sound Energy, Seattle City Light, and other utility providers as needed to ensure construction activities would not interfere with their facilities and service. There are a few trees on the site primarily confined to the borders of the site and landscaped areas. The site is sparsely vegetated with small trees and landscaping at the edges of the site bordering S Grady Way and Rainier Avenue S. 1.4 Proposed Improvements The proposed improvements for the site may include a new parking garage, bus shelters, and earth retaining structures. The new parking garage is not part of this report and is therefore not discussed herein. When this report was prepared, the final locations and details of bus shelters and earth retaining structures were unknown. 2 GEOTECHNICAL INVESTIGATION PROGRAM 2.1 Existing Geotechnical Data During the project’s conceptual engineering phase, HWA completed a geotechnical investigation for this project at the SRTC site and summarized their findings in a Geotechnical Data Report dated 2020 (HWA, 2020). The HWA field investigation consisted of four (4) borings to depths varying between 45 and 81.5 feet below ground surface. A monitoring well was installed as part of the HWA investigation program, and laboratory tests on selected samples were also performed. Relevant information from previous geotechnical investigations is presented in Appendix B. 2.2 Borehole Investigation A geotechnical investigation program was performed at the SRTC site in July and August 2021, which included seven (7) borings advanced between 32 and 105 feet below the ground surface. This field investigation supplements previous field investigations performed by HWA during an earlier phase of the project. The results of HWA’s investigation are provided in the I-405 Bus Rapid Transit Project – Parking Garages Geotechnical Data Report (HWA, 2020). The drilling and sampling for the current investigations were performed by Holt Services, Inc. using a truck- mounted CME 85 drill rig equipped with a 5-inch outer diameter drilling system. All boring locations were cleared by requesting the One Call service as well as by utilizing a private geophysical subcontractor. The borings were advanced using rotary wash drilling techniques. Stride program: I-405 corridor Page 4 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 The approximate boring locations are presented in the Geotechnical Exploration Plan (Appendix A, Figure A-4). A geotechnical engineer from WSP coordinated the field exploration activities and was present full time to log the borehole and collect samples for further examination and laboratory testing. Soil samples were obtained using Standard Penetration Test (SPT, ASTM D1586) samplers at 2.5-foot intervals in the top 15 feet and at 5-foot depth intervals thereafter. Modified California sampler (3.25-inch outer diameter) and Shelby tube samplers were also used to obtain relatively undisturbed and undisturbed samples, respectively. Borings were backfilled with a bentonite mix, except for borings SB-1 and SB-2 where monitoring wells were installed. The excess soil cuttings were tested and disposed offsite by the drilling subcontractor. Boring logs are presented in Appendix C. 2.3 Geophysical Surveys Downhole geophysical surveys were conducted in borings SB-1 and SB-2. At both locations, shear wave data were measured in the boring at 2.5-foot intervals, and compressional wave data were measured at 5-foot intervals. Boring SB-1 near the northeast corner of the existing building was completed at a depth of 105 feet and the deepest data point is at 103.75 feet. Boring SB-2 is located near the southeast corner, completed at a depth of 70 feet with the deepest data point at 68.75 feet. Presentation of the field methodology and results of the geophysical surveys is provided in Appendix D. 2.4 Laboratory Testing A laboratory test program was conducted to confirm field classifications and obtain additional information on selected physical and mechanical properties of the materials encountered in the boreholes. Geotechnical laboratory testing was performed by HWA Geosciences of Bothell, Washington. Table 2-1 presents a summary of the laboratory tests that were performed. The laboratory test results are provided in Appendix E. Table 2-1 Design Seismic Coefficients per AASHTO Laboratory Test Standard Quantity Moisture Content ASTM D2216 25 Organic Content ASTM D2974 2 Unit Weight ASTM D2937 3 Passing #200 Sieve ASTM D1140 10 Particle Size Analysis ASTM D6913/D7928 4 Atterberg Limits ASTM D4318 10 Direct Shear ASTM D3080 1 Specific Gravity ASTM D854 2 One Dimensional Consolidation ASTM D2435 3 Stride program: I-405 corridor Page 5 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 3 SITE CONDITIONS 3.1 General Geologic Conditions The site is mapped as Quaternary alluvial deposits (Qa) by Schuster (2015). Qa is generally described as “loose, stratified to massively bedded fluvial silt, sand, and gravel: typically well rounded and moderately to well sorted; locally includes sandy to silty estuarine deposits” and is typically unconsolidated. This geologic unit was identified in the borings conducted by HWA and WSP. 3.2 Subsurface Conditions Based on the findings of the most recent subsurface investigation performed by WSP and the previous investigation at the site performed by HWA, the subsurface soils at the SRTC site generally consist of 5 to 10 feet of very loose to medium dense fill soils over alluvial deposits. The alluvial deposits are mostly coarse grained, very loose to loose in the upper portion. They become dense to very dense at a depth of approximately 20 to 45 feet below ground surface. Hydrocarbon odors were observed in the fill soils. Organic materials (including peat deposits) up to 20 feet were encountered in various borings. Bedrock was encountered in boring SB-2 at a depth of approximately 75 feet below ground surface. A brief description of these strata encountered in WSP borings is presented below. The artificial fill is characterized by a thickness up to 10 feet and consists of very loose to medium dense silty sands (SM) and poorly graded sands (SP). Uncorrected SPT N-values vary between 2 and 24. A layer of very loose to loose alluvium lies underneath the artificial fill. The thickness of this layer varies between 5 and 25 feet and consists mainly of silty sands (SM) and poorly graded sands (SP) and silts with varying plasticity (ML and MH). Uncorrected SPT N-values vary between 0 and 9. A layer of organics (PT, OH, OL) was encountered in borings RW-10, RW-11, RW-12, SB-1, SH4 and SH-5. The thickness of this stratum varies between 5 and 25 feet with uncorrected SPT N-values between 0 and 5. Dense to very dense alluvial deposits were encountered in all borings following the organics (or the looser alluvial deposits where organics were not present). Aside from boring SB-2, where the dense alluvial deposits were penetrated and the boring terminated into bedrock, this stratum was not fully penetrated and therefore its full thickness is unknown. At borings SB-1, the thickness is 40 feet. This stratum is also coarse grained with a larger presence of gravelly material and consists mainly of silty sands (SM), poorly graded sands (SP), and well graded gravels (GW). Uncorrected SPT N-values are in the 27 to 77 range, with occasional refusal. It is noted that this layer occasionally includes interbedded looser deposits, such as the one encountered in boring SB-2 at the depth of 50 to 60 feet below ground surface, and is characterized by uncorrected SPT N-values less than 10. Stride program: I-405 corridor Page 6 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 3.3 Groundwater Groundwater was not measured in the WSP borings due to the rotary wash method utilized in the boring. Based on the HWA GDR and direct push sampling performed at the site, groundwater was observed at about 5 feet below ground surface. Groundwater levels at the site are subject to variations in groundwater basin management, seasonal variation, nearby construction, irrigation, and other artificial and natural influences. 4 GEOTECHNICAL RECOMMENDATIONS 4.1 Preliminary Seismic Design Parameters Recommendations for seismic design parameters are in accordance with the Sound Transit Design Criteria that require a site classification based on AASHTO Guide Specification for LRFD Seismic Bridge Design. According to AASHTO guidelines, sites characterized by peats or highly organic clays with thickness greater than 10 feet are classified as Site Class F and would require a site-specific evaluation. However, the Sound Transit Design Criteria state that “for Conceptual and Preliminary Design of structures, local site effects of Site Class E may be used to determine Site Class F design response spectra.” Consistent with the purpose of this report, Site Class E is assumed and used to determine preliminary seismic design parameters. It is noted that a site-specific response analysis may still be required for final design. Table 4-1 summarizes the preliminary seismic design coefficients based on an assumed Site Class E, a 7 percent probability of exceedance in 75 years (approximately 1,000-year return period), and a 5 percent critical damping. Other structures not covered in this geotechnical report (such as the planned parking garage building) will need to follow different seismic design criteria that are not included in this report. Table 4-1 Preliminary Seismic Design Coefficients Site Class Mapped Peak Horizontal Ground Accel. PGA, (g) Mapped Spectral Accel. At 0.2 sec. Sa (g) Mapped Spectral Accel. At 1.0 sec. Sa (g) Site Coefficients Design Spectral Accel. At 0.2 sec. Sds (g) Design Spectral Accel. At 0.2 sec. Sd1 (g) Design Peak Horizontal Ground Accel. As (g) Fa Fv Fpga E 0.3433 0.988 0.282 1.015 2.889 1.335 1.002 0.815 0.577 NOTES: 1. g = Gravity 2. Fa = Short period sit coefficient 3. Fv = Long period site coefficient (1.0 second) 4. Fpga = peak ground acceleration site coefficient Stride program: I-405 corridor Page 7 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 4.2 Liquefaction and Seismic Settlement Liquefaction is a phenomenon in which saturated granular soils lose their inherent shear strength due to build-up of excess pore water pressure induced by cyclic loading such as that caused by an earthquake. Liquefaction potential is based on several factors, primarily: 1) relative density and type of soil; 2) depth to groundwater, and 3) duration and intensity of seismic shaking. Loose saturated granular materials (sands and low to non-plastic silts) are most susceptible to liquefaction. Liquefaction susceptibility mapping provided by King County identifies the site as moderate to high susceptibility to liquefaction. Investigations at the site encountered shallow groundwater depths and very loose to medium dense sands and silts. A preliminary liquefaction susceptibility analysis indicates liquefiable soils are present at the site. Based off the preliminary analysis, there is approximately 20 to 40 feet thickness of liquefiable material underlaying the site. The estimated liquefaction-induced settlement varies depending on the boring data used, but it is overall estimated to vary between 1 to 2 feet across the site. 4.3 Foundation Recommendations for Bus Shelters When this report was prepared limited information was available regarding the location and dimensions of potential bus shelter canopies. Therefore, it was assumed for purposes of this report that the bus shelter canopies would be designed similar to those in King County Metro Transit Passenger Facilities Improvements Standard Details (2020). Discrete shallow spread and continuous foundations are not recommended for support of the proposed bus shelter due to the presence of liquefiable soils that could cause severe damage to the planned structure. A slab-on-grade foundation (structural mat) is recommended to support the proposed bus shelter and mitigate the potential adverse impact of liquefaction-induced settlements. An allowable bearing pressure of 1,000 psf may be utilized for design. Anticipated immediate settlement is estimated to be on the order of ½ inch. Isolated areas where thicker deposits of very loose alluvium are present may experience up to 1 inch of immediate settlement. Long-term settlement due to consolidation of the organic material is also estimated to be within ½ inch. Since the foundation is relatively small, differential settlement is anticipated to be relatively small and on the order of ½ inch over the length of the foundation. These preliminary settlement estimates assume a maximum applied pressure of 1,000 psf over the bus shelter and that no fill will be placed to raise the existing grades. If new fills are placed over large areas (such as in the case of a raise in grade elevations), large settlements may be anticipated both short and long term. In this case, additional remediation measures will need to be considered before placing any structure. The slab-on-grade thickness should be determined by the project structural engineer and designed to accommodate the anticipated liquefaction-induced seismic settlements. These recommendations assume that the remedial site preparation recommendations (Section 4.6) are incorporated into the design. Multiple interconnected slabs-on-grade are not recommended due to the potential for liquefaction-induced settlements. The slab-on-grade should be underlain by at least 4 inches of clean coarse sand or fine gravel to provide a capillary moisture break and uniform support to the slab. A polyolefin vapor barrier membrane may be utilized between the prepared subgrade and the bottom of the floor slab. The project architect should design the vapor barrier membrane, including the polyolefin sheeting Stride program: I-405 corridor Page 8 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 selection, water vapor permeance (ASTM F 1249), puncture resistance (ASTM D 1709), and tensile strength (ASTM D 882). A base friction coefficient of 0.35 may be used for footings poured directly on structural fill and 0.30 for footings poured on dense granular native soil. Assuming a relatively level ground surface is present, the passive resistance of the soil can be estimated based on a fully mobilized passive coefficient of 3.3. Full mobilization may be conservatively assumed to occur when horizontal strains exceed 5% of the depth of the base of the shallow foundation element. For intermediate strain values at which full mobilization is not realized, linear interpolation between at-rest and ultimate passive resistance consistent with a simplified, bilinear spring envelope or more advanced hyperbolic models may be used. The passive resistance should not be considered for sliding resistance if there is any possibility of removal of the soil in front of the foundation or if the loading considered is long term and creep effects may reduce the available resistance. 4.4 Recommendations for Earth Retaining Structures It is our understanding that the proposed grading at the site does not require any earth retaining structures. In the event earth retaining structures are required, a flexible wall type such as a mechanically stabilized earth (MSE) wall is recommended. The soft and loose soils present at the subsurface would cause unacceptable differential settlement of rigid wall types. 4.5 Pavement Design and Recommendations Design analyses were performed to develop recommendations for flexible and rigid pavement sections at the SRTC site. Flexible pavement will be used in the parking garage access areas, interim parking lot, and Lake Avenue. Rigid pavement will be used for the bus lanes and layover area. The general approach to design, key assumptions, and recommended pavement sections are discussed below. Detailed design inputs, assumptions, and calculations are presented in Appendix F. Logs of previous and recent borings completed at the site indicate that subgrade soils within about 5 feet of the proposed pavement grade consist of predominantly loose sands and soft, wet silts. These soils are expected to offer poor subgrade support of the proposed pavements. Therefore, a relatively low subgrade resilient modulus of 3,300 psi was assumed for the site soils. This value correlates to a modulus of subgrade reaction of approximately 100 pci for rigid pavement design. It is recommended that laboratory CBR or R-value testing be conducted to validate the subgrade strength value assumed for design. Site grading will consist of up to about 1.5 feet of fill and up to about 3 feet of cut. Depth to groundwater is estimated to be 5 feet. Groundwater fluctuations can occur. Pavement design for the parking garage access area and bus lanes was performed in general accordance with Sound Transit’s Design Criteria Manual (2018) and WSDOT’s Pavement Design Policy (2018). Lake Avenue is located within the City of Renton jurisdiction. The City of Renton (1998) code indicates that the Asphalt Institute’s (AI) Thickness Design Manual may be used for flexible pavement design. The AI manual was not available at the time these analyses Stride program: I-405 corridor Page 9 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 were performed. However, based on information presented on the AI website, the AASHTO (1993) method is an acceptable approach to design. Site-specific traffic data, including average daily traffic, percent trucks, growth rate, initial service year, etc., were provided by the Traffic Engineer. Traffic loading in terms of 18-kip equivalent single-axle loads (ESALs) was estimated for the project roadways using these site-specific traffic data, assumed ESAL factors, and a design life of 20 years. Table 4-2 summarizes the pavement types, design code, and estimated 18-kip ESAL values used for design. Table 4-2 Design ESALs (20-year Design Life) Section Roadway Pavement Type Design Code Design ESALs 1 Bus Lane Rigid Sound Transit (2018) 59,101,400 2 Parking Lot/Garage Access Flexible Sound Transit (2018) 236,700 3 Lake Avenue S Flexible City of Renton (1998) 16,351,600 Flexible pavement design was performed using WinPAS (2012) software based on the AASHTO (1993) design procedure. Rigid pavement design was conducted using the Hall and Smith design workbook based on the AASHTO 1998 procedure. The recommended pavement sections are summarized in Table 4-3 and Table 4-4. Table 4-3 Recommended Flexible Pavement Sections Roadway HMA (WSDOT Item 5-04), inches CSBC (WSDOT Item 4-04), inches Total Thickness*, inches Parking Lot/Garage Access 5.0 8.0 13.0 Lake Avenue S 10.0 9.0 19.0 NOTE: *Pavement section shall be placed over properly prepared subgrade with geosynthetics as described in this report. Table 4-4 Recommended Rigid Pavement Section Roadway PCCP (WSDOT Item 5-05), inches CSBC (WSDOT Item 4-04), inches Total Thickness*, inches Bus Lane 10.5 6 16.5 NOTE: *Pavement section shall be placed over properly prepared subgrade with geosynthetics as described in this report. For rigid pavements, dowel bars for transverse joints and tie bars for longitudinal joints shall meet WSDOT Standard Specifications. The recommended maximum transverse and longitudinal joint spacings are 15 feet and 12 feet, respectively. Stride program: I-405 corridor Page 10 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 Site soils are frost-susceptible. For frost-susceptible soils, the WSDOT Pavement Policy (2018) recommends that pavement sections be equal to at least 50 percent of the frost depth. Based on WSDOT (2018), the frost depth at the site is 15 inches. The recommended pavement structures meet the frost depth requirement. Considering the potential for groundwater fluctuations, it may be assumed that wet subgrade soil conditions will be encountered during construction. These soils will require stabilization for construction of a working platform, separation of the subgrade from the CSBC layer, and reinforcement of the overall pavement section. It is recommended to place geosynthetics over properly prepared subgrade prior to placing pavement materials. Geosynthetics shall meet the requirements in Section 9-33 of the WSDOT Standard Specifications. To allow for both separation and stabilization of soft soils, it is recommended to use a geotextile topped with a geogrid layer. The geotextile shall meet the requirements for separation or stabilization specified in Table 3 of Section 9-33 of the Standard Specifications. Approved geotextiles are listed in the WSDOT Qualified Products List (QPL). The QPL does not include approved geogrids. It is recommended that geogrids such as Tencate’s Mirafi BXG, Tensar’s TriAx, or Carthage Mills GBX be used. Geotextile and geogrid must be placed in accordance with the manufacturer’s recommendations. Precautions should be made during placement and compaction of the first lift of base course to avoid damaging the geogrid. 4.6 Site Preparation and Grading The existing building structures, pavements, buried pipes, hardscape, and landscaping not to remain should be removed prior to the start of construction. All surficial vegetation and deleterious material should be stripped and completely removed from the project site. Removal of walkways, pavements, and various other light features (if required) would likely disrupt the soils to a limited depth. Any remaining voids should be backfilled with approved and properly compacted fill soils. The in-situ soils are considered suitable for direct support of structural elements supporting the planned lightly loaded structure if they are reworked and properly recompacted. However, the shallowest zone of these deposits might have been disturbed by other construction activities, wet/dry cycles, and burrowing animals. It is recommended that after ground clearing/grubbing and existing features demolition that the top 12 inches of existing surficial soils be excavated, moisture conditioned, and recompacted in place to a minimum relative compaction of 90 percent (ASTM D1557). Before recompacting the excavated material, the exposed subgrade should also be scarified to an additional depth of 12 inches (without removal) and recompacted in place to at least 90 percent relative compaction (per ASTM D1557). Therefore, a total depth of 24 inches of recompacted soil shall be provided at the site underneath any structural element. The lateral extent of the building footprint preparations should extend to at least 36 inches beyond the lateral extent of the proposed foundation in all directions. The material should be moisture conditioned to be placed between -2 to +2 percent of the optimum content. In paved areas, it is recommended to place a geotextile topped with a geogrid layer upon properly prepared subgrade, as discussed in Section 4.5. The near surface materials consist of silty sands (SM) that are considered to be moisture sensitive and can pose challenges during wet weather earthwork. General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. Under wet conditions, earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the Stride program: I-405 corridor Page 11 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 placement and compaction of clean structural fill. The size and type of construction equipment used might have to be limited to prevent soil disturbance. Material used as structural fill should consist of clean granular soil with less than 5 percent passing the No. 200 sieve based on wet sieving of the material fraction passing the ¾-inch sieve. The fine-grained portion of the structural fill soils should be non-plastic. The ground surface within the construction area should be graded to promote runoff of surface water and to prevent the ponding of water. All exposed surfaces should be compacted on completion or at the end of a shift to limit infiltration and softening. No material should be left in a loose uncompacted state that would allow infiltration. Materials that have become wet and softened must be either dried and recompacted or removed from the working area and replaced with suitable fill. 4.7 Temporary Excavations Temporary excavations are anticipated for construction of slab-on-grade footings and retaining walls construction (if required). Temporary excavations should be laid back or shored in accordance with U.S. Occupational Safety and Health Administration (OSHA) and any other applicable regulations. Temporary excavations should be sloped no steeper than 1.5H:1V if deeper than 4 feet corresponding to a soil type classification of OSHA Type C soil. If site constraints prevent sloping of the excavations, shoring or worker protection measures such as trench boxes should be used. 4.8 Structural Fill and Compaction Fill placed beneath structures, pavements, or behind walls and reinforced zones should consist of Select Borrow specified in Section 9-03.14(2) of the WSDOT Standard Specifications (WSDOT, 2018). Before any fill is placed, the subgrade should be free of ponded water. Fill should generally be placed and compacted in 10-inch lifts if heavy equipment is used for compaction. If handheld compaction equipment is used, lifts should generally be placed and compacted in 4-inch lifts. Ultimately, the appropriate lift thickness and compaction methods will be determined in the field by the contractor. The fill placement and compaction should be observed and tested by a qualified geotechnical engineer or technician. 4.9 Groundwater Control Dewatering is not anticipated for the construction of slab-on-grade footings and retaining walls. If excavations or grading exceed 5 feet below ground surface, groundwater should be expected. While groundwater monitoring at the site indicates groundwater 5 feet below existing ground surface, seasonal variation should be anticipated, and it is possible that groundwater may be encountered at higher elevations than historical monitoring has indicated. Lundquist, Elizabeth (Lundquist) Digitally signed by Lundquist, Elizabeth (Lundquist)DN: E=Elizabeth.Lundquist@wsp.com, CN="Lundquist, Elizabeth (Lundquist)", OU=Active, OU=Users, OU=US, OU=WSPObjects, DC=corp, DC=pbwan, DC=netDate: 2023.02.01 12:53:46-08'00' Stride program: I-405 corridor Page 12 | AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report March 2022 5 REFERENCES Maps Yount, James C. 1993. Geologic map of surficial deposits in the Seattle 30’ x 60’ quadrangle, Washington. Regulatory Guidance American Association of State Highway and Transportation Officials (AASHTO). 1993. AASHTO Guide for the Design of Pavement Structures. American Association of State Highway and Transportation Officials (AASHTO). 2020. LRFD Bridge Design Specifications. 9th Edition, 2020. 978-1-56051-738-2, LRFDBDS-9. American Association of State Highway and Transportation Officials (AASHTO). 1998. Supplement to the AASHTO Guide for the Design of Pavement Structures. City of Renton (1998). Title IV Development Regulations, Revised and Compiled Ordinances, Section 4-6-060. Sound Transit. 2018. Design Criteria Manual. June 2018. Washington State Department of Transportation (WSDOT). 2021. BEToolbox, Spectra, Version 6.1.0. Built on May 12, 2021.Washington State Department of Transportation (WSDOT). 2019. Geotechnical Design Manual. M 46-03.12. July 2019. Washington State Department of Transportation (WSDOT). 2018. Pavement Policy. September 2018. Washington State Department of Transportation (WSDOT). 2018. Standard Specifications for Road, Bridge, and Municipal Construction. M 41-10. Reports HWA Geosciences, Inc. (HWA). 2020a. I-405 Bus Rapid Transit (BRT) Project – Parking Garages Geotechnical Data Report. HWA Geosciences, Inc. (HWA). 2020b. I-405 Bus Rapid Transit (BRT) Project – Conceptual Geotechnical Recommendations Report – Parking Garages. AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Detailed Figures: A-1 | Site Location Map A-2 | Regional Hazard Map A-3 | Regional Geologic Map A-4 | Geotechnical Exploration Plan File Path: SITE LOCATION MAPSouth Renton Transit CenterI-405 Bus Rapid Transit (BRT) ProjectBurien TC to Lynnwood TCBy: C. BalesProj. No.: 160363P3Date: Aug 2021A-1SCALE IN FEET01000200030004000KEYSee Figure A-4 File Path: REGIONAL HAZARD MAPSouth Renton Transit CenterI-405 Bus Rapid Transit (BRT) ProjectBurien TC to Lynnwood TCBy: C. BalesProj. No.: 160363P3Date: Aug 2021A-2SCALE IN FEET01000200030004000KEY= Very LowLiquefactionHazard= Low to Moderate= Moderate to HighMisc.= Water BodyLandslideHazard= Scarps= Scarps and Flanks= Fans= Lanslide DepositsSee Figure A-4= High See Figure A-4File Path: REGIONAL GEOLOGIC MAPSouth Renton Transit CenterI-405 Bus Rapid Transit (BRT) ProjectBurien TC to Lynnwood TCBy: C. BalesProj. No.: 160363P3Date: Aug 2021A-3SCALE IN FEET0500100015002000KEY= Glaciolacustrine deposits = Renton Formation (bedrock)Qis Trȝ1tpAtWNLLpWStQsr= Alluvium (Cedar River)QacȝptWJWA``` (general)afȝptWJWA``` (urban/industrial)afmQacQawTtaTrTtuTtuTiQawTtuTtaTtaTtaTtlTtlTtlTrafafmQacQitQgtQuQpaQgtQlpQmcQgtQpaQacQasQuQasQasQsrQpaafQacQmcQuQlpQlpQlmQuQasQasQgQacQlmQacafTsTrTsTrQmcafTrQitQikafafTrQsrQisQgtQikTtQpaQgQuQlpTsQuQivQlmMap Source"u``WcNAu|ǇǍ0ǍţūŨŧǍNe`eUWJ"AmeStVN0Nctec/uALpAcU`NǇWcU euct}Ǉ:AqVWcUtecǍNe`eUWJ/uALpAcU`N"Am/ǪŦŢŧǍUnited States Geological Society. File Path: GEOTECHNICAL EXPLORATION PLANSouth Renton Transit CenterI-405 Bus Rapid Transit (BRT) ProjectBurien TC to Lynnwood TCBy: C. BalesProj. No.: 160363P3Date: Aug 2021A-4SCALE IN FEET050100150200KEY= Previously Completed Boring (HWA Geosciences, 2019)= Geotechnical Boring Completed for This PhaseBH-8 [HWA]RW-12 [WSP]RW-11 [WSP]RW-10 [WSP]SB-1 [WSP]SB-2 [WSP]SH-4 [WSP]SH-5 [WSP]BH-7 [HWA]BH-10 [HWA]BH-9 [HWA] AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Existing Geotechnical Information by Others FF#3& /" !"') "$%!& $()"& /" !""./0!& /"#!'"!"+,!&2!1') & 8'((!!&()"& /" '" !"#$%!!!&,6 & /"!##'""'(+,!&2!1 &6#'(& !##'""+,!&(!!'( &2!!'!(! 1)& !#!&(!!'(6 & ! '(!1)- !& !##'""+,!!!&(!! 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Soil Group Symbol:SM Soil Specific Gravity: 2.75 (assumed) Normal Stress (psf)1250.00 2500.00 5000.00 Average Peak Stress (psf)1007.93 1808.48 4035.96 Residual Stress (psf)1021.50 2204.60 3772.60 Cohesion phi Angle Initial Moisture Content (%):29.0 29.0 29.0 29.0 psf (degrees) Wet Unit Weight (pcf):125.3 123.0 124.2 124.2 Peak 0.0 39.3 Dry Unit Weight (pcf):97.1 95.4 96.3 96.3 Calculated Void Ratio 0.767 0.799 0.782 0.783 Calculated Porosity 0.434 0.444 0.439 0.439 Calculated Saturation (%)104.1 99.8 102.0 102.0 Final Moisture Content (%)26.8 27.3 27.5 27.2 Figure % Indicated Strength Parameters HWA GEOSCIENCES INC. Materials Testing Laboratory Direct Shear Test of Soils Under Consolidated Drained Conditions (ASTM D 3080) 2017-135-21 Sample Point: Project Name:Project Number: Sample Depth: 0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00 0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00Shear Stress (psf)Normal Stress (psf) Peak Peak Trend 0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00Shear Stress (psf)% Strain Normal Stress: 1250.00 Normal Stress: 2500.0 Normal Stress: 5000.0 -0.010-0.0050.0000.0050.0100.0150.020 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 Dilation/Contraction(inches)Checked By: S. Greene CONSOLIDATION TEST REPORT Cv(ft.2/day)0.3 0.8 1.3 1.8 2.3 2.8 Applied Pressure - ksf 0.1 1 10Percent Strain20 18 16 14 12 10 8 6 4 2 0 Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf)Ratio 92.3 % 36.7 % 82.8 2.65 ML 1.055 Dark gray, SILT with sand 2017-135 I-405 BRT Project B-13 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: BH-10 Depth: 40.5 Sample Number: S-11b Figure AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Boring Logs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sphalt Very loose to loose, yellowish brown Silty Sandwith Gravel (SM); moist; angular gravel. Very soft to soft, dark brown, Elastic Silt (MH);moist; fine grained sand; medium to high plasticity fines; organics throughout. 40 936 74.5 BORING DIA.: START TIME:START DATE: C. Bales Truck Rig Rotary Wash Austin Vertical Holt 7/19/2021 HAMMER CALIBRATION-ENERGY TRANSFER RATIO:Sample TypeSampleLab Tests VISUAL CLASSIFICATION 4.5"Plasticity IndexLOGGER:Drill Rate Min/ft.ORIENTATION: BORING TYPE: RIG TYPE: I-405 Bus Rapid Transit and Bus Base North unknown 0820 Elevation in FeetDepth in FeetDRILLER FIRM: DRILLER: PROJECT NAME:Graphical LogCOMPLETION DATE: STATION/OFFSET: REFERENCE: COORDINATES: COORDINATE SYS: SURFACE ELEV. (FT): VERTICAL DATUM: PROJECT #: REMARKS Unified SoilClassificationPercent passing#200 SieveMoisture Content (%)of Dry WeightDry Density (pcf)Liquid Limit (%)SEGMENT: COMPLETION TIME: Renton Transit Center N/A 47.47213434 -122.2162898 1230 160363P3.003 7/20/2021 NAVD88 27 NAD83 Not Surveyed Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 0 5 10 15 20 1 of 25.0 20.0 15.0 10.0 5Page BORING LOG I.D.:SB-1 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery ML Soft, brownish gray Silt with Sand (ML); moist; fine sand; low to medium plasticity fines; traceorganics. MH S S S ST S SP-SM OH SM 4-3-3(6) 0-1-3(4) 1-2-2(4) 37-30-29(59) Loose, gray Poorly graded Sand with Silt(SP-SM); wet; mostly fine grained sand; traceorganics; faint hydrocarbon odor. Soft, olive brown Sandy Organic Silt (OH); moist; medium to high plasticity fines. Loose, Gray, Silty Sand (SM). No Recovery. 134.4 25.795.8 2992 62.3Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 20 25 30 35 40 45 2 of 5.0 0.0 -5.0 -10.0 -15.0 5Page BORING LOG I.D.:SB-1 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S S S S MC SP SP GW-GM 9-5-4(9) 10-10-10(20) 6-6-3(9) 20-17-13(30) 55-53-63(108) Loose to medium dense, gray, Poorly GradedSand (SP); moist; medium grained sand. Loose to dense, gray, Poorly Graded Sand withGravel (SP); wet; fine, subrounded gravel; medium to coarse grained sand. Very Dense, olive gray, Well Graded Gravel withSand and Silt (GW-GM); wet; fine to coarse, subrounded gravel; coarse grained sand. 6.1Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 45 50 55 60 65 70 3 of -20.0 -25.0 -30.0 -35.0 -40.0 5Page BORING LOG I.D.:SB-1 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S S S S S GW-GM SP GP ML 23-7-5(12) 14-17-18(35) 19-18-18(36) 50 50/3" Dense to very dense, gray, Poorly Graded Sandwith Gravel (SP); wet; fine to coarse gravel; coarse grained sand. Very dense, dark gray, Poorly Graded Gravelwith Sand (GP); moist; fine to coarse, subangular gravel.Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 70 75 80 85 90 95 4 of -45.0 -50.0 -55.0 -60.0 -65.0 5Page BORING LOG I.D.:SB-1 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S S GP32-21-39(60) 48-33-24(57) Very dense, dark gray, Poorly Graded Gravelwith Sand (GP); moist; fine to coarse,subangular gravel. End of drilling at 105 ft.Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE TIMEDEPTH(ft) GROUNDWATER 95 100 105 110 115 120 5 of -70.0 -75.0 -80.0 -85.0 -90.0 5Page BORING LOG I.D.:SB-1 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S S S ST S S ASPHALT SM SP ML MH 1-3-1 (4) 1-2-1(3) 0-0-0(0) 0-0-0(0) 0-2-3(5) Asphalt Very loose, dark bluish gray, Silty Sand withGravel (SM); moist; fine, angular gravel Very loose, dark bluish gray, Poorly GradedSand; moist; medium grained sand; abundant organics Very soft, brownish gray Silt with Sand (ML);moist; fine grained sand; medium plasticity fines; trace organics. Very soft to medium stiff, dark brown, ElasticSilt (MH); moist; fine grained sand; highplasticity fines; organics throughout. 52.1 1746 97.1 BORING DIA.: START TIME:START DATE: C. Bales Truck Rig Rotary Wash Austin Vertical Holt 7/20/2021 HAMMER CALIBRATION-ENERGY TRANSFER RATIO:Sample TypeSampleLab Tests VISUAL CLASSIFICATION 4.5"Plasticity IndexLOGGER:Drill Rate Min/ft.ORIENTATION: BORING TYPE: RIG TYPE: I-405 Bus Rapid Transit and Bus Base North unknown 1405 Elevation in FeetDepth in FeetDRILLER FIRM: DRILLER: PROJECT NAME:Graphical LogCOMPLETION DATE: STATION/OFFSET: REFERENCE: COORDINATES: COORDINATE SYS: SURFACE ELEV. (FT): VERTICAL DATUM: PROJECT #: REMARKS Unified SoilClassificationPercent passing#200 SieveMoisture Content (%)of Dry WeightDry Density (pcf)Liquid Limit (%)SEGMENT: COMPLETION TIME: Renton Transit Center N/A 47.47181785 -122.2171586 1315 160363P3.003 7/21/2021 NAVD88 27 NAD83 Not Surveyed Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 0 5 10 15 20 1 of 25.0 20.0 15.0 10.0 4Page BORING LOG I.D.:SB-2 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S S S MC S MH GP GW-GM GP 0-1-3(4) 20-9-18(27) 8-20-35(55) 27-25-17(52) 7-21-23(44) Very soft to medium stiff, dark brown, ElasticSilt (MH); moist; fine grained sand; highplasticity fines; organics throughout. Dense to very dense, bluish gray, Poorly Graded Gravel with Sand (GP) to Poorly Gradedsand with Gravel (SP); moist to wet; mediumgrained sand. Dense, gray, Poorly Graded Sand with Gravel (SP) to Poorly Graded Gravel with Sand (GP);wet; subrounded gravel; coarse grained sand. Dense to very dense, bluish gray, PoorlyGraded Gravel (GP); wet; coarse, angular to rounded gravel; little sand. 57.3 8.7 1451 6.2Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 20 25 30 35 40 45 2 of 5.0 0.0 -5.0 -10.0 -15.0 4Page BORING LOG I.D.:SB-2 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery MC S S S S GP SM Sandstone 65-61-47(126) 3-3-7(10) 6-4-4(8) 4-2-2(4) 50/2" Loose, bluish gray, Silty Sand (SM); moist;mostly fine sand; nonplastic to low plasticity fines; some organics. Sandstone [Renton Formation] Severely weathered; light yellowish brown;moist. 28.4 44.4Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE (Continued Next Page) TIMEDEPTH(ft) GROUNDWATER 45 50 55 60 65 70 3 of -20.0 -25.0 -30.0 -35.0 -40.0 4Page BORING LOG I.D.:SB-2 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery S 50/1"Moderately to slightly weathered; dark bluishgray End of drilling at 70 ft.Depth in FeetDrill Rate Min/ft.Elevation in FeetPROJECT:GraphicalLogSampleSample TypeLab Tests Liquid Limit (%)Plasticity IndexI-405 Bus Rapid Transit and Bus Base North Unified SoilClassificationVISUAL CLASSIFICATION PROJECT LOCATION: REMARKS Dry Density (pcf)Moisture Content(%) of Dry WeightPercent passing#200 SieveRenton Transit Center Blow CountDATE METHOD unknown unknown~5 unknown SAMPLE TYPE TIMEDEPTH(ft) GROUNDWATER 70 75 80 85 90 95 4 of -45.0 -50.0 -55.0 -60.0 -65.0 4Page BORING LOG I.D.:SB-2 B - Bulk SampleS - 2" O.D. 1.38" I.D. Split Spoon SampleST - Shelby Tube Sample (Thin Wall Tube) NQ - 2.98" O.D. Core SampleMC - Modified California Sample NR - No Recovery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| South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Geophysical Survey Report DOWNHOLE SHEAR WAVE SEISMIC SURVEY REPORT BORINGS SB-1 AND SB-2 I-405 BUS RAPID TRANSIT and BUS OPERATIONS & MAINTENANCE FACILITY RENTON, WASHINGTON FOR WSP USA, INC. SEATTLE, WASHINGTON WSP Project Number: 160363P3 September 13, 2021 PHILIP H. DUOOS GEOPHYSICAL CONSULTANT 1 1 Philip H. Duoos Geophysical Consultant September 13, 2021 Our Ref: 1363-21 Mr. Cole Bales WSP USA Inc. 999 Third Avenue, Suite 3200 Seattle, WA 98104 REPORT: Downhole Seismic Shear Wave Survey Borings SB-1 and SB-2 I-405 Bus Rabid Transit and Bus Operations & Maintenance Facility Renton, Washington WSP Project No.: 160363P3 Dear Mr. Bales: This letter report summarizes the results of the downhole seismic survey in Borings SB-1 and SB-2 at the subject site located in Renton, Washington. Field work was performed on Monday July 26. The approximate locations of the borings are shown on Figure 1. At both locations, shear wave data were measured in the boring at 2.5-foot intervals, and compressional wave data were measured at 5-foot intervals. The field measurements were referenced to the top of the rim of the protective flush-mount cover housing which is at the ground surface. The depths are to the sensor location in the borehole tool. The bottom of the tool is about 1.3 feet below the sensor location. Boring SB-1 near the northeast corner of the existing building was completed at a depth of 105 feet and the deepest data point is at 103.75 feet. Boring SB-2 is located near the southeast corner, completed at a depth of 70 feet with the deepest data point at 68.75 feet. Boring SB-2 encountered Renton Formation sandstone at a depth of approximately 63 feet. INTERPRETATION RESULTS Table 1 shows the shear wave velocities and the compressional wave velocities for both borings. The tables show the interpreted depth range for each velocity layer and the interpreted seismic wave velocity. For Boring SB-1, the shear wave data and compressional wave data with interpreted velocity layers are provided in Figures 2 and 3, respectively. For Boring SB-1 the results are shown on Figures 4 and 5. The charts show the first arrival times corrected for the wave source offset. For both borings, the sledge hammer seismic wave source for the shear wave data is offset about 8.5 feet from the boring, and the compressional wave source is offset about 4 feet. The times shown are vertical travel times, and are what the travel times would be if the source was directly on the boring. Shear Wave Data Results The shear wave data were recorded using two orientations of the impulse wave created by hitting a wooden beam at both ends with a sledge hammer. The two shear wave arrival times recorded at each depth location were usually very similar and most were within 0.5 milliseconds (ms) of each other. The beam was oriented parallel to one of the sets of vertical grooves in the Slope Indicator casing. This allows the geophone package to be oriented parallel to the signal orientation which allows for optimum data quality. The beam was almost perfectly level (horizontal) and in good contact with the asphalt surface. The quality of the data was generally very good in both holes. Philip H. Duoos 13503 NE 78th Place, Redmond, Washington, 98052 PH/FAX: (425) 882-2634, CELL: (425) 765-6316 Email: geopyg@aol.com 2 2 Figure 2 shows the shear wave first arrival data and interpreted layers for Boring SB-1. Figure 4 shows the shear wave results for Boring SB-2. The interpreted layers and velocities are indicated by the best-fit lines. The lines alternate color (blue and green) to help differentiate between the layers. The shear wave data in both borings are fairly linear and were straightforward in their interpretation. These results were based primarily on the data and the geologic logs were reviewed afterward and correlate well with the original interpretation. On Boring SB-2 I did revise my initial interpretation of the deepest layer in an attempt to get the top of the last layer closer to the approximate top of rock (Renton Formation Sandstone). The results also correlate well between the two borings with the various sequence of layers and their velocities. Compressional Wave Data Results Figure 3 shows the compressional wave data for Boring SB-1, and the results for Boring SB-2 are provided on Figure 5. The compressional wave data is less detailed than the shear wave data, both due to the geologic factors and the larger sampling interval of 5 feet. The velocity layer interpretation is indicated by the alternating red and orange lines. The presence of ground water (at about 5 feet deep at the site) greatly affects the compressional wave data, but has no impact on the shear wave data. In Boring SB-2 I have interpreted a thin low velocity layer above the last velocity layer (Renton Formation). This thin layer (velocity of 3,050 fps) is questionable due to the lack of data (Figure 5) within this layer, and is based more on the geologic log than the seismic data. Inserting the thin layer puts the higher velocity layer of 4,400 fps near the top of rock observed in the boring. However, this thin layer does seem to correlate with the lower blow counts from about 50 to 63 feet deep, with some organics observed at 55 feet deep. The interpreted compressional wave velocity (4,400 fps) of the rock is on the low end of seismic velocities for competent Renton Formation sandstone. I have observed velocities as low as 4,350 fps for competent Renton Formation sandstone, but more often it is in the range of 8,000 to 11,000 fps. I suspect that the wide range of velocities is related to the degree of fracturing and/or cementation of the rock. The velocity of 4,400 fps may also indicate a degree of weathering near the rock surface as we were only able to measure velocities in the upper 10 feet of the rock layer in Boring SB-2. Both shear wave and compressional wave data were obtained at 2-foot intervals in the rock layer in an attempt to get accurate velocity measurements within the unit. The 6,780 fps velocity layer is reasonable for the water-saturated sand and gravel unit observed in Boring SB-2. In Boring SB-1 this layer has a slightly lower velocity of 6,175 fps which may be due to more sand than gravel in Boring SB-1. FIELD METHODOLOGY The first-arrival travel times were measured using a triaxial geophone located at 2.5-foot (shear wave) and 5-foot (compressional wave) increments in the boring; and are referenced to the ground surface. The shear wave energy was generated by hitting both ends of a wood beam (with steel end caps) placed on the ground surface a distance of about 8.5 feet from each boring. Hitting the beam on both ends, and recording both of the orientations of the impulse wave, helps to identify the shear wave and also provides an idea on the quality of the data. The borehole casing was standard Slope Indicator casing (2.75-inch inside diameter) with vertical grooves which allowed us to maintain a constant orientation with the downhole geophone tool. The boring was bailed dry to about 40 feet which allowed for easier data acquisition and minimized the possibility of seismic surface waves traveling down the borehole. The beam was placed parallel to one set of the grooves of the casing. The front wheels of a vehicle were then driven up onto the beam and parked so that the beam would maintain firm contact with the ground. The asphalt surface was smooth, and good contact between the beam and the asphalt was obtained with minimal movement of the beam as it was hit with the sledge hammer. 3 3 After the shear wave data were obtained, the beam was removed and compressional data were recorded. The compressional wave was generated by hitting a steel plate that was placed on asphalt surface about 4 feet from each boring. The triaxial geophone was then placed in the boring again, and compressional wave data were recorded at 5-foot intervals, with the metal plate struck vertically with the sledge hammer. The seismic data were recorded using a Geostuff Instruments BHG-2 triaxial geophone and a Geometrics Strataview seismograph. The seismograph allows the stacking of multiple hits with the sledge hammer where the signal will increase with each blow, while the random noise tends to reduce. The BHG-2 downhole geophone obtains firm coupling with the borehole using a mechanical clamping spring arm. I am confident that the recorded data and interpreted velocities and layer depths are representative of the subsurface materials at the boring location within the constraints of this geophysical method. The interpreted velocities are within the typical ranges for the types of materials described in the geologic logs, and which I have observed at other sites in the Pacific Northwest region. As with any geophysical method, bulk properties are measured and may not discern small variations in geology. Review of these results by a geologist familiar with the site conditions is also recommended. Please feel free to contact me if you have any questions or comments regarding this information. Sincerely, Philip H. Duoos Geophysical Consultant Washington State Licensed Geologist No. 561 Attachments: Table 1: Layer Velocity Summary Table Figure 1: Borehole Location Map Figure 2: Boring SB-1 Shear Wave Results Graph Figure 3: Boring SB-1 Compressional Wave Results Graph Figure 4: Boring SB-2 Shear Wave Results Graph Figure 5: Boring SB-2 Compressional Wave Results Graph Table 1 SHEAR AND COMPRESSIONAL WAVE VELOCITIES Borings SB-1 and SB-2 I-405 Bus Rapid Transit Facility Renton, Washington For WSP USA Inc. WSP # 16036P3 Shear Wave Velocities (ft/sec) Depth Range (ft) Velocity (ft/sec) 0 - 7.5 650 7.5 - 37.0 390 37.0 - 56.0 725 56.0 - 72.0 1,605 72.0 - 77.0 525 77.0 - 104.0 1,505 Shear Wave Velocities (ft/sec) Depth Range (ft) Velocity (ft/sec) 0 - 4.5 1,010 4.5 - 24.0 380 24.0 - 39.0 765 39.0 - 49.0 1,055 49.0 - 61.5 640 61.5 - 69.0 1,910 Compressional Wave Velocities (ft/sec) Depth Range (ft) Velocity (ft/sec) 0 - 8.0 1,350 8.0 - 41.5 2,310 41.5 - 104.0 6,175 Compressional Wave Velocities (ft/sec) Depth Range (ft) Velocity (ft/sec) 0 - 11.0 1,395 11.0 - 27.0 2,685 27.0 - 58.5 6,780 57.0 - 62.0 3,050 ?* 62.0 - 69.0 4,400 *Thin layer with velocity of 3,050 is questionable due to lack of data within the thin layer. While it fits the seismic data, it is based more on the geologic log. Boring SB-1 Boring SB-2 Philip H. Duoos, Geophysical Consultant for WSP USA Inc., WSP #160363P PHD # 1363-21, Sept. 13, 2021 TABLE 1 Shear and Compressional Wave Velocities Borings SB-1 and SB-2 I-405 Bus Rapid Transit Facility 200' N SITE LOCATION MAP Downhole Shear Wave Study I-405 BRT and Bus Operations & Maintenance Facility Renton, Washington WSP Project # 160363P3 P. Duoos, Geophysical Consultant PHD # 1363-21, Sept 13, 2021 Fig. 1 -110 -105 -100 -95 -90 -85 -80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Depth Below Surface ( feet )Travel Time ( ms ) Shear Wave Vertical Travel Time, Boring SB-1 Philip H. Duoos, Geophysical Consultantfor WSP USA Inc. WSP Project #160363P3 PHD #1363-21, Aug. 19, 2021 BORING SB-1 SHEAR WAVE FIRST ARRIVAL TIMES Interpreted Layer Velocity Intervals I-405 Bus Rapid Transit Facility Renton, Washington 650 fps 1,605 fps 725 fps 525 fps 7.5' 37' 72' 56' 77' 1,505 fps 390 fps Boring SB-1 is located near the NE corner of the existing building and completed to a depth of 105'. Fig. 2 Sept. 13, 2021 -105 -100 -95 -90 -85 -80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 010203040Depth Below Surface (feet)Travel Time (ms) Compressional Wave Vertical Travel Time, Boring SB-1 2,310 fps 8' 6400 SE 101st Industrial Portland, Oregon for Terra Associates, Inc., PN T-8251 FIGURE 1 41.5' ? June 7, 2020 1,350 fps 6,175 fps Philip H. Duoos, Geophysical Consultant for WSP USA Inc. WSP Project #160363P3 PHD #1363-21, Aug. 19, 2021 BORING SB-1 COMPRESSIONAL WAVE FIRST ARRIVAL TIMES Interpreted Layer Velocity Intervals I-405 Bus Rapid Transit Facility Renton, Washington Boring SB-1 is located near the NE corner of the existing building and completed to a depth of 105'. Fig. 3 Sept. 13, 2021 -80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 0 102030405060708090100110120Depth Below Surface ( feet )Travel Time ( ms ) Shear Wave Vertical Travel Time, Boring SB-2 1,010 fps 380 fps 1,055 fps 4.5' 24' 49' 39' 61.5' 1,910 fps Philip H. Duoos, Geophysical Consultant for WSP USA Inc. WSP Project #160363P3 PHD #1363-21, Aug. 19, 2021 BORING SB-2 SHEAR WAVE FIRST ARRIVAL TIMES Interpreted Layer Velocity Intervals I-405 Bus Rapid Transit Facility Renton, Washington Boring SB-2 is located near the SW corner of the existing building and completed to a depth of 70'. 765 fps 640 fps Fig. 4 Sept. 13, 2021 -80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 0 10203040Depth Below Surface ( feet )Travel Time ( ms ) Compressional Wave Vertical Travel Time, Boring SB-2 1,395 fps 2,685 fps 4,400 fps 11' 62' 6,780 fps 27' Philip H. Duoos, Geophysical Consultant for WSP USA Inc. WSP Project #160363P3 PHD #1363-21, Aug. 19, 2021 BORING SB-2 COMPRESSIONAL WAVE FIRST ARRIVAL TIMES Interpreted Layer Velocity Intervals I-405 Bus Rapid Transit Facility Renton, Washington Boring SB-2 is located near the SW corner of the existing building and completed to a depth of 70'. 57' 3,050 fps ?? Questionable thin velocity layer to correlate 4,400 fps layer closer to top of rock observed in geologic log (at approximately 63 feet deep) Fig. 5 Sept. 13, 2021 AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Laboratory Test Results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hase 3 Lab Ttesting SB-1 Sample No.:S-11 35.0-36.5 Soil Description:SILT with sand Soil Color:Gray Average Strain Rate: 0.5 % per min. Soil Group Symbol:ML Soil Specific Gravity: 2.65 (assumed) Normal Stress (psf)1750.00 3500.00 7000.00 Average Peak Stress (psf)1106.65 2249.79 4335.24 Initial Moisture Content (%):42.6 42.6 42.6 42.6 Cohesion phi Angle Wet Unit Weight (pcf):104.9 109.3 109.4 107.9 psf (degrees) Dry Unit Weight (pcf):73.6 76.6 76.8 75.6 Peak 63.9 31.5 Calculated Void Ratio 1.248 1.158 1.154 1.187 Calculated Porosity 0.555 0.537 0.536 0.543 Calculated Saturation (%)90.4 97.5 97.8 95.2 Final Moisture Content (%)48.9 41.1 39.2 43.1 Checked By: S. Greene Figure 10 Indicated Strength Parameters HWA GEOSCIENCES INC. Materials Testing Laboratory Direct Shear Test of Soils Under Consolidated Drained Conditions (ASTM D 3080) 2017-135 Phase 3 Sample Point: Project Name:Project Number: Sample Depth: 0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00 5000.00 0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00 7000.00 8000.00Shear Stress (psf)Normal Stress (psf) Peak Peak Trend 0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00 5000.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00Shear Stress (psf)% Strain Normal Stress: 1750.00 Normal Stress: 3500.0 Normal Stress: 7000.0 -0.100 -0.080 -0.060 -0.040 -0.020 0.000 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 Dilation/Contraction(inches) Tested By: GB Checked By: SEG CONSOLIDATION TEST REPORT Cv(ft.2/day)0 0.4 0.8 1.2 1.6 2 Applied Pressure - ksf 0.1 1 10Percent Strain70 60 50 40 30 20 10 0 -10 -20 -30 Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf)Ratio 110.7 % 191.4 % 25.6 1.905 PT 3.294 Very dark brown, PEAT 2017-135 T3 WSP I-405 BRT Project - Phase 3 Client Project No.: 160363P3.003 Task 3.04.2 Specific gravity by ASTM D 854 11 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: RW-11 Depth: 15.0 - 17.0 Sample Number: S-6 Figure 7HVWHG%\*%&KHFNHG%\6(* &2162/,'$7,217(675(3257 &YIWGD\ $SSOLHG3UHVVXUHNVI 3HUFHQW6WUDLQ 1DWXUDO 'U\'HQV// 3, 6S*U 86&6 $$6+72 ,QLWLDO9RLG 6DWXUDWLRQ 0RLVWXUH SFI5DWLR 0/ *UD\LVKEURZQ6,/7 7 :63 ,%573URMHFW3KDVH &OLHQW3URMHFW1R37DVN 6SHFLILFJUDYLW\DVVXPHG 0$7(5,$/'(6&5,37,21 3URMHFW1R &OLHQW5HPDUNV 3URMHFW 6RXUFHRI6DPSOH6%'HSWK 6DPSOH1XPEHU6 )LJXUH Tested By: GB Checked By: SEG CONSOLIDATION TEST REPORT Cv(ft.2/day)0 0.4 0.8 1.2 1.6 2 Applied Pressure - ksf 0.1 1 10Percent Strain80 70 60 50 40 30 20 10 0 -10 -20 Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf)Ratio 76.8 % 223.5 % 20.6 1.822 PT 5.301 Very dark brown, PEAT 2017-135 T3 WSP I-405 BRT Project - Phase 3 Client Project No.: 160363P3.003 Task 3.04.2 Specific gravity by ASTM D 854 13 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: SH-4 Depth: 15.0 - 17.0'Sample Number: S-6 Figure AE 0054-17 | South Renton Transit Center Geotechnical Recommendation Report I-405 corridor Pavement Design Data and Calculations I-405 BRT - SRTC Site - Recommended Pavement SectionsM Cline 2/7/2022SECTION NO.ROADWAYDESIGN LIFE (YEARS)PAVEMENT TYPEREQUIRED STRUCTURAL NUMBERPROVIDED STRUCTURAL NUMBERPCCP THICKNESS1 (IN)HMA THICKNESS2 (IN)CSCB THICKNESS3 (IN)TOTAL THICKNESS (IN)ASSUMED SUBSURFACE CONDITIONS IN UPPER 5-10 FT4MEASURED APPROX. DEPTH TO GROUND-WATER (FT)SUBGRADE PREPARATION NOTES1 Bus Lane 20Rigid N/A N/A11.0 0.0 6.017.0Loose sands and soft, wet silts </=5 Prior to construction of the pavement section, place geosynthetics per Note 5.Recommendation is based on design analysis.2 Parking Lot/Garage Access 20Flexible 3.43 3.540.0 5.0 8.013.0Loose sands and soft, wet silts </=5 Prior to construction of the pavement section, place geosynthetics per Note 5.Recommendation is based on design analysis.3 Lake Ave S 20Flexible 6.14 6.170.0 10.0 9.019.0Loose sands and soft, wet silts </=5 Prior to construction of the pavement section, place geosynthetics per Note 5.Recommendation is based on design analysis.NOTES:1) WSDOT Item 5-052) WSDOT Item 5-043) WSDOT Item 4-044) Assumed subgrade conditions must be verified prior to construction.5) Place geogrid (Tencate’s Mirafi BXG, Tensar’s TriAx, or Carthage Mills GBX) over geotextile (WSDOT Item 9-33, Table 3) on existing subgrade in accordance with manufacturer's specifications.- Analysis and results assume up to 3' cut and 1.5' fill. I-405 BRT - SRTC Site - ESAL ComputationsM Cline 1/12/2022Initial Service Year (ISY): 2026 Rigid ESAL Factor, Car: 0.0002 Rigid ESAL Factor, Truck: 1.7 Rigid ESAL Factor, 40-ft Single Unit (SU) Bus: 4.42 Rigid ESAL Factor, 60-ft Articulated Bus: 6.4SECTION NO.ROADWAYDESIGN CODE (FOR DESIGN LIFE)DESIGN LIFE (YEARS)PAVEMENT TYPE, R OR F1NO. OF LANESGROWTH RATE, BUS TRAFFIC2GROWTH RATE, GEN. PURPOSE TRAFFIC2ADT3% TRUCKS% 40-ft SU BUSSES% 60-ft ARTIC. BUSSESTOTAL % BUSSES%SU/ %TOTAL BUSSES% Artic./ %TOTAL BUSSES% CARSTOTAL % VEHICLES# BUSSES PER DAY# TRUCKS PER DAY# CARS PER DAYGROWTH FACTOR, BUS TRAFFICGROWTH FACTOR, GEN. PURPOSE TRAFFICTOTAL RIGID18K ESALS (NO LDF OR DDF)LDF4DDF5FACTORED RIGID18K ESALSDESIGNLANE18K ESALS (R OR F)1Bus LaneSound Transit (2021)20 R 1 0.0 0.0 1,265 0.0 0.0 100.0100.0 0.0 100 0.0 100.0 1,265 0 0 20.00 20.00 59,101,400 1.01.059,101,40059,101,4002Parking Lot/Garage AccessSound Transit (2021)20 F 1 0.0 0.0 950 3.0 0.0 0.00.0 N/A N/A 97.0 100.0 0 28.5 922 20.00 20.00 355,000 1.01.0355,000236,7003Lake Ave SCity of Renton (1998)20 F 1 0.0 1.0 2,550 2.0 0.0 20.020.0 0.0 100.0 78.0 100.0 510 51 1,989 20.00 22.02 24,527,400 1.01.024,527,40016,351,600NOTES:1) R = Rigid, F = Flexible2) Minimum value must be 0.0001. Do not enter 0.3) ADT = Average Daily Traffic4) LDF = Lane Distribution Factor, from AASHTO (1993) to estimate design lane traffic load based on number of lanes 5) DDF = Directional Distribution Factor, from AASHTO (1993) to estimate design lane traffic load based on directional distribution of trafficCOMPUTATIONS (per AASHTO, 1993):When applicable, used iterative process varying values of % 40-ft busses and % 60-ft busses to obtain the # busses per day (which was provided by the Traffic Engineer)% Cars = 100.0 - % trucks - % bussesGrowth Factor = ((1+Growth Rate/100)^Design Life-1)/(Growth Rate/100)Total Rigid 18K ESALs = (# SU Busses Per Day * SU Bus ESAL Factor + # Artic. Busses Per Day * Artic. Bus Factor + # Trucks Per Day * Truck ESAL Factor + # Cars Per Day * Car ESAL Factor) * 365 * Growth FactorFactored Rigid 18K ESALs = Total Rigid 18K ESALs * LDF * DDFDesign Lane 18K ESALs = For rigid pavement, Design Lane 18K ESALs is Factored Rigid 18K ESALs. For flexible pavement, Design Lane 18K ESALs is Factored Rigid 18K ESALs divided by 1.5 (per AASHTO, 1993). ASSUMPTIONS:Values of one directional ADT for ISY, % trucks, # busses, distribution of busses, and growth rates were provided by the Traffic Engineer.ESAL factors were assumed based on discussions with Seattle Dept of Transportation for Alaskan Way Viaduct Project (2017).Used Design Life of 20 years for Lake Ave to be consistent with other two sections. City of Renton code does not specify design life.Enter values for cells with blue I-405 BRT - SRTC Site - Structural Design Inputs/Assumptions for Flexible Pavement DesignM Cline 1/12/2022SECTION NO.ROADWAY DESIGN CODEANALYSIS METHOD1a,bDESIGN LIFE (YEARS)2PAVEMENT TYPERELIABILITYINITIAL SERVICE-ABILITYINDEXFINAL SERVICE-ABILITYINDEXSTANDARD DEVIATIONSUBSURFACE CONDITIONS IN UPPER 5-10 FTMEASURED APPROX. DEPTH TO GROUND-WATER (FT)FROST GROUP3FROST SUSCEPTIBILITY3FROST DEPTH4 (IN.)ASSUMED SUBGRADE RESILIENT MODULUS5 ELASTIC MODULUS, CSBC(PSI)LAYER COEFFICIENT, HMALAYER COEFFICIENT, CSBC1 Parking Lot/Garage AccessSound Transit (2021)AASHTO (1993)20 Flexible 85 4.2 2.0 0.45 Loose sands and soft, wet silts </=5 F3/F4 High to Very High 15 3,300 30,000 0.50 0.132 Lake Ave SCity of Renton (1998)AASHTO (1993)20 Flexible 85 4.2 2.0 0.45 Loose sands and soft, wet silts </=5 F3/F4 High to Very High 15 3,300 30,000 0.50 0.13NOTES:1a) Used AASHTO (1993) design procedures. City of Renton design code (1998) specifies that the Asphalt Institute's Thickness Design Manual (MS-1) is to be used for pavement design. Based on AI's website, the method is based on the AASHTO 1993, 1998 methods. Must be confirmed.1b) Except where noted below, AASHTO (1993) input parameters were used in the analyses. 2) For Section 1, Design Life based on Sound Transit (2021). Used same for Section 2 since design life is not specified in City of Renton (1998).3) Frost Group/Susceptibility determined based on FHWA's Geotechnical Aspects of Pavements (2006).4) Frost Depth obtained from WSDOT (2018), Figure A2.3.5) Based on correlation with assumed CBR for subgrade soils. Must be confirmed after review of lab test results.Additional note: Drainage coefficient = 1.0. I-405 BRT - SRTC - Structural Design Inputs/Assumptions for Rigid Pavement Design Michelle Cline 1/12/2022 INPUT VALUE REFERENCE Analysis Method -- AASHTO Guide for Design of Pavement Structures (1993, 1998) per WSDOT Pavement Policy (2018) Initial Service Year 2026 Provided by Traffic Engineer Design Life 20 years Sound Transit (2021) ESALs, Bus Lane 59,101,400 Computed in ESALs worksheet Reliability 85% AASHTO(1993)/WSDOT Pavement Policy (2018) for <10 million ESALs Initial Serviceability Index 4.5 AASHTO Guide for Design of Pavement Structures (1993) Terminal Serviceability Index 2.0 AASHTO Guide for Design of Pavement Structures (1993) Standard Deviation 0.35 AASHTO Guide for Design of Pavement Structures (1993) Joint Load Transfer Coefficient 3.2 WSDOT Pavement Policy (2018) Modulus of Rupture 700 psi WSDOT Pavement Policy (2018) Modulus of Elasticity 4.0E06 psi WSDOT Pavement Policy (2018) Subgrade Soil/GW Conditions in Assumed Soil Profile -- Loose sands and soft, wet silts; GW </= 5' References for Subgrade Soil/GW Conditions -- Borings S-1, SB-2, SH-4, SH-5, BH-7 through 10, BH-15 k-value 100 psi per in.Correlations based on soil classification and assumed CBR (Hall, 2001; FHWA, 1997) Frost Depth 15 in. WSDOT Pavement Policy (2018) Frost Group/Susceptibility F3/F4 - High to Very High FHWA Geotechnical Aspects of Pavements (2006) Base Thickness 6.0 Assigned Slab/Base Friction Coefficient 2.0 Estimated based on ranges in 1988 AASHTO Supplement Procedure Worksheet (for slab on aggregate) Joint Spacing 15 ft WSDOT Pavement Policy (2018) Edge Support Adjustment Factor 0.94 1988 AASHTO Supplement Procedure Worksheet for 12' lane and concrete tied shoulder Concrete Poisson's Ratio 0.2 Typical value (FHWA) Layer Modulus, CSBC 30K psi WSDOT Pavement Policy (2018) Mean Annual Temperature 52 deg F LTPP InfoPave online module Mean Annual Precipitation 35 in.LTPP InfoPave online module Mean Annual Wind Speed 2 mph LTPP InfoPave online module Dowel Diameter 1.5 in.WSDOT Pavement Policy (2018) Drainage Coefficient 1.00 WSDOT Pavement Policy (2018) Friction Adjustment Factor 0.8 For aggregate base (per Joint Faulting Check Worksheet) Base Type 0 For unstabilized base (per Joint Faulting Check Worksheet) Widened Slab 0 For slab that is not widened (per Joint Faulting Check Worksheet) Annual Temperature Range 69 deg F LTPP InfoPave online module (Avg Max - Avg Min) Freezing Index 25 F deg-days LTPP InfoPave online module Days above 90 deg F 0.5 LTPP InfoPave online module 1998 AASHTO Supplement Procedure Worksheet General Inputs/Material Properties Joint Faulting Check Worksheet LTPP INFOPAVE - CLIMATE DATA FOR BELLEVUE, WASHINGTON https://infopave.fhwa.dot.gov/Data/ClimateTool 1/7/2022 MERRA_ID YEAR PRECIPITATION 152733 2010 39.06 152733 2011 33.18 152733 2013 30.01 152733 2012 39.86 152733 2014 37.24 152733 2015 38.29 152733 2016 38.57 152733 2017 38.07 152733 2018 31.08 152733 2020 35.64 152733 2019 28.12 AVERAGE: 35.37 MERRA_ID YEAR TEMP_AVG TEMP_MAX TEMP_MIN TEMP_MEAN_AVG TEMP_MEAN_STDEV DAYS_ABOVE_32_C FREEZE_INDEX 152733 2010 50.54 88.7 15.98 50.9 32.3384 0 32 152733 2011 48.92 80.42 19.04 49.1 32.2898 0 27 152733 2012 50 91.04 24.8 50.36 32.4716 1 13 152733 2014 51.98 92.84 14.36 52.52 32.3744 1 49 152733 2013 50.54 90.32 13.64 51.08 32.378 1 40 152733 2016 52.16 90.5 22.82 52.7 32.4122 1 23 152733 2017 50.54 93.02 20.48 50.9 32.3294 1 48 152733 2019 51.08 89.78 19.58 51.62 32.3132 0 31 152733 2020 51.44 91.58 25.52 51.98 32.3618 1 2 152733 2015 53.06 89.6 24.62 53.6 32.234 0 0 152733 2018 51.62 88.16 21.74 51.98 32.3654 0 13 AVERAGE: 51.08 89.63 20.23 51.52 32.35 0.55 25.27 avg temp range: 69.40 MERRA_ID YEAR WIND_VELOCITY_AVG 152733 2011 2 152733 2010 2 152733 2012 2 152733 2013 2 152733 2015 2 152733 2016 2 152733 2019 2 152733 2014 2 152733 2017 2 152733 2018 2 152733 2020 2 soundtransit.org brt@soundtransit.org 206-398-5470