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Home My WebLink AboutEX_04_RS_21_GE Levee Modificattion Report USACE attachI_220202Levee Modification Analysis Cedar River 205 Levee Certification Renton, Washington for Tetra Tech, Inc. February 2, 2022 Levee Modification Analysis Cedar River 205 Levee Certification Renton, Washington for Tetra Tech, Inc. February 2, 2022 1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98402 253.383.4940 February 2, 2022 | Page i File No. 0693-078-01 Table of Contents 1.0 INTRODUCTION ................................................................................................................................. 1 2.0 DESIGN CONDITIONS ........................................................................................................................ 1 3.0 EXISTING FLOOD PROTECTION SYSTEM ......................................................................................... 1 3.1. Proposed Modifications and Repairs ........................................................................................... 3 4.0 LEVEE AND FOUNDATION SEEPAGE AND STABILITY ANALYSIS .................................................... 5 4.1. General .......................................................................................................................................... 5 4.2. Geologic Setting ............................................................................................................................ 5 4.2.1. Subsurface Explorations ................................................................................................... 5 4.2.2. Previous Subsurface Explorations .................................................................................... 5 4.2.3. Groundwater ...................................................................................................................... 6 4.2.4. Design Soil Properties ....................................................................................................... 6 4.3. Levee Seepage Analysis ............................................................................................................... 8 4.3.1. General ............................................................................................................................... 8 4.3.2. Analysis Method ................................................................................................................ 9 4.3.3. Analysis Results ................................................................................................................. 9 4.4. Levee Stability ............................................................................................................................... 9 4.4.1. Analysis Method ................................................................................................................ 9 4.4.2. Stability Analysis Results ................................................................................................. 10 5.0 CONCLUSIONS ............................................................................................................................... 11 6.0 LIMITATIONS .................................................................................................................................. 12 7.0 REFERENCES ................................................................................................................................. 12 LIST OF FIGURES Figure 1. Vicinity Map Figures 2 and 3. Site Plan Figures LB1-I through LB1-S-I2. SlopeW Output – Left Bank Figures LB2-I through LB2-S-12(R). SlopeW Output – Left Bank Figures LB3-I-1-I through LB3-S-12(R). SlopeW Output – Left Bank Figures RB4-I through RB4-S-12(R). SlopeW Output – Right Bank Figures LB1-1 through RB4-3. SeepW Output APPENDICES Appendix A. Subsurface Explorations and Laboratory Testing Figure A-1. Key to Exploration Logs Figures A-2 through A-5. Logs of Borings Figures A-6 through A-14. CPT Logs Figures A-15 and A-16. Sieve Analysis Results Figures A-17 and A-18. Atterberg Limits Test Results February 2, 2022 | Page ii File No. 0693-078-01 Appendix B. Prior Exploration Logs S&EE 2008 S&EE 2012 Boeing 1966 Associated Earth Sciences, Inc. 2001 USACE 2001 Appendix C. Report Limitations and Guidelines for Use February 2, 2022 | Page 1 File No. 0693-078-01 1.0 INTRODUCTION This report presents GeoEngineers, Inc.’s (GeoEngineers’) geotechnical analysis of the proposed modifications to the Cedar River 205 Levee in Renton, Washington. The City of Renton is working to recertify the existing flood protection system along 1.25 miles of the Cedar River. Both banks are protected for a total of 2.5 miles of levees. The existing flood protection system is located on the east (right) and west (left) bank of the Cedar River between Lake Washington and the Williams Avenue South Bridge as shown in the attached Vicinity Map (Figure 1). Tetra Tech and GeoEngineers collaborated on analysis for the recertification of the levee system as part of a Conditional Letter of Map Revision (CLOMR) application. The analysis is summarized in “Cedar River Section 205 Levee System FEMA CLOMR Submittal” prepared by Tetra Tech and dated April 2018. As part of the CLOMR study, some areas of the levee were identified as requiring modifications prior to certification. Plans for these repairs have been developed by Tetra Tech with input from GeoEngineers. Plans are currently at the 75-percent design level and are expected to be refined further following comments from the City of Renton, U.S. Army Corps of Engineers (USACE), and other stakeholders including Boeing. Our services are being provided in accordance with the geotechnical tasks contained within our agreement with Tetra Tech signed on February 16, 2016 and amended on October 24, 2016 and July 30, 2019. 2.0 DESIGN CONDITIONS There are two hydraulic and river conditions considered in our analyses. The river is periodically dredged as part of the 205 project cooperation agreement between the City of Renton and the USACE. The two hydraulic and river conditions capture the variation that occurs just before dredging and just after dredging. The last dredging project occurred the summer of 2016 and the previous dredging effort occurred in 1998. Prior to dredging, the riverbed is high, resulting in a higher water surface elevation for the same flow conditions. This condition is referred to as the “allowable average bed elevation.” When the river is recently dredged, it results in a lower water surface elevation that does not fully engage the flood protection system. This condition is referred to as the “design dredge bed elevation.” For our analyses, we conservatively used the water surface elevation for the allowable average bed elevation condition combined with the river profile from the design dredge condition. This results in higher water surface elevations combined with taller and steeper slopes than would be expected to occur naturally or through a typical dredge cycle. Hydraulic conditions are analyzed and will be described in more detail in Cedar River Section 205 Levee Recertification: Riverine Hydraulics and Freeboard (Tetra Tech 2017). 3.0 EXISTING FLOOD PROTECTION SYSTEM The current flood protection system consists of levees and floodwalls on the left and right banks of the Cedar River, as shown on the Site Plan (Figures 2 and 3). The flood protection system is located on the last 1.25 miles of the Cedar River as it flows into Lake Washington. It protects parts of downtown Renton, the Renton Municipal Airport on the left bank, and the Boeing manufacturing plant on the right bank. February 2, 2022 | Page 2 File No. 0693-078-01 Over the life of the flood protection system, numerous alignments and stationing systems have been used along the river and the banks of the river to reference location. The stationing used within this report is based upon “Lower Cedar River Flood Control: Levees and Floodwalls” as-built plans prepared by USACE in 2003. Tables 1 and 2 summarize the existing flood protection system elements. TABLE 1. STATION FLOOD PROTECTION SYSTEM ELEMENTS – LEFT BANK Floodwall (FW) or Levee (LE) Station Start Station End Notes LE 0+00 18+95 “Type 3” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001. FW 18+95 29+60 USACE Plans and Drawings modified for As-Built conditions dated July 2001, indicate the floodwall is embedded a minimum of 21 feet below ground surface (bgs) (2.5 feet of concrete bgs and 17.5 feet of steel sheet pile). LE 29+60 35+20 “Type 2” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001. FW 35+20 55+68 USACE Plans and Drawings modified for As-Built conditions dated July 2001, indicate the floodwall is embedded a minimum of 21 feet bgs (2.5 feet of concrete bgs and 17.5 feet of steel sheet pile) includes a “pocket” floodgate used to close the opening in the floodwall at the South Boeing Bridge. LE 55+68 59+10 56+75 63+76 “Type 1” and “Landscape Berm” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001. February 2, 2022 | Page 3 File No. 0693-078-01 TABLE 2. STATION FLOOD PROTECTION SYSTEM ELEMENTS – RIGHT BANK Floodwall (FW) or Levee (LE) Station Start Station End Notes LE 10+00 38+20 “Right Bank Trail Section in Park” as well as “Right Bank Levee Section in Park” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001. FW 38+20 42+75 USACE Plans and Drawings modified for As-Built conditions dated July 2001, indicate the floodwall is embedded a minimum of 21 feet bgs (2.5 feet of concrete bgs and 17.5 feet of steel sheet pile). LE 42+75 48+16 “Right Bank Trail Section in Park” as well as “Right Bank Levee Section in Park” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001. FW 48+16 49+62 Includes a “pocket” floodgate used to close the opening in the floodwall at the South Boeing Bridge. LE 49+62 66+85 66+85 67+30 “Right Bank Trail Section in Park” as well as “Landscape Berm” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001; “Landscape Berm” is located south of the Logan Avenue Bridge and reaches high ground tie-in. FW 67+30 68+85 Approximately/ Undetermined Exact high ground tie-in location is currently undetermined. “Landscape Berm” levee design according to USACE Plans and Drawings modified for As-Built conditions dated July 2001 leads to edge of existing senior activity center and terminates at a small concrete floodwall embedded 1-foot bgs. 3.1. Proposed Modifications and Repairs During the certification evaluation, the team identified seven areas that required modifications or repairs to meet minimum Federal Emergency Management Agency (FEMA) requirements for levee certification. In four of these areas, we considered the modification sufficient enough to require slope stability and seepage analyses. These are presented in this report. In three of these areas, the modifications were, in our opinion, minor and consistent with maintenance and returning the levee to the as-built condition. February 2, 2022 | Page 4 File No. 0693-078-01 TABLE 3. PROPOSED MODIFICATIONS AND EVALUATED REGIONS Approximate Location Identified Deficiency Proposed Modification Notes on Stability Analysis Section 1 Left Bank Alignment -- 18+50 to 19+50 Poor connection (insufficient overlap) between soil embankment levee and floodwall. Extend floodwall approximately 26 feet down stream and incorporate into soil embankment levee. This is a new levee/ floodwall configuration. Analysis comparing the current condition to the proposed condition is provided. Left Bank Alignment -- 26+50 to 33+25 Insufficient freeboard. Raise floodwall 0.5 feet from approximately Station 25+50 to 29+50. Construct concrete curb adjacent roadway on top of levee from approximately Station 29+50 to 33+30. The proposed improvements are above the design water level. By inspection, no appreciable change to the overall stability of the levee is expected. No further analysis required. Analysis Section 2 Left Bank Alignment -- 55+40 to 56+90 (Downstream of Logan Avenue Bridge) Insufficient levee crest width. Place fill to widen levee crest. Use structural earth wall (SEW) to limit levee slope encroachment toward E Perimeter Road. This is a new levee/ floodwall configuration. Analysis comparing the current condition to the proposed condition is provided. Analysis Section 3 Left Bank Alignment -- 58+00 to 60+00 (Upstream of Logan Avenue Bridge) Insufficient freeboard and damage from repeated vehicle strike. Replace existing floodwall with floodwall designed as traffic barrier. This is a new levee/ floodwall configuration. Analysis comparing the current condition to the proposed condition is provided. Right Bank Alignment -- 49+30 to 50+30 (Upstream of South Boeing Bridge) Insufficient freeboard. Place fill to reestablish levee crest. This modification returns the levee to an “as-designed” condition and can therefore be considered maintenance. No further analysis required. Right Bank Alignment -- 63+30 to 64+30 (Downstream of Logan Avenue Bridge) Insufficient freeboard. Place fill to reestablish levee crest. This modification returns the levee to an “as- designed” condition and can therefore be considered maintenance. No further analysis required. Analysis Section 4 Right Bank Alignment -- 66+55 to 67+85 (USACE Right Bank Alignment ends at 68+85; stationing projected to end of proposed modifications.) Insufficient freeboard. Construct floodwall. This is a new levee/ floodwall configuration. Analysis comparing the current condition to the proposed condition is provided. February 2, 2022 | Page 5 File No. 0693-078-01 4.0 LEVEE AND FOUNDATION SEEPAGE AND STABILITY ANALYSIS 4.1. General We performed seepage and stability analyses on four of the seven areas where work is proposed. As noted in Table 3, three of the areas are returning the levee to as-designed condition or the modifications are not expected to adversely affect stability. The analysis sections are shown on Figures 2 and 3. The purpose of the analysis is to show that the proposed modifications will increase the stability of the levee. 4.2. Geologic Setting The site is located at the southern extent of Lake Washington in an alluvial valley adjacent to the Cedar River. Within the project area, the Cedar River flows in a channel created in 1912 to divert the Cedar River away from its previous confluence with the Black River to the north into Lake Washington. The Black River later dried up in 1916 when the water level in Lake Washington was controlled as part of the Ship Canal project that connected Lake Washington to Lake Union. As a result, observed geologic conditions within the alluvium might not be consistent with those expected in a natural river system. The “Geologic Map of the Renton Quadrangle, King County, Washington” (D.R. Mullineaux 1965) maps the project area as land of industrial or urban setting extensively or sporadically altered by placement of artificial fill (afm). Shoreline deposits from Lake Washington and alluvium from the Cedar River, and the now extinct Black River underlie the artificial fill. 4.2.1. Subsurface Explorations Subsurface conditions along the alignment of the existing left and right bank flood protection system were explored with four geotechnical borings using mud-rotary techniques and advancing nine cone penetrometer tests (CPTs). The explorations occurred between January 16 and 27, 2017. The locations of these explorations are shown on Figures 2 and 3. Additional details regarding our explorations and laboratory program are provided in Appendix A. 4.2.2. Previous Subsurface Explorations Subsurface conditions in the Cedar River Levee System were initially evaluated within the Needs Assessment Report by reviewing 23 subsurface explorations. The preliminary analysis included review of documents provided by Tetra Tech, as well as the City of Renton, in addition to internal documents from GeoEngineers. Some of the documents include subsurface information near the levee alignment and are directly relevant to the project. These include the explorations at bridge crossings and the explorations completed by the USACE for the initial construction of the levee system. These explorations are included as Appendix B. Other documents include subsurface information in the vicinity of the levee, but not directly relevant to the project, were also reviewed to develop an understanding of the general geologic characteristics of the project area but are not included in this report. There are 14 explorations near the levee alignment we considered directly relevant to levee analysis. The locations of these existing explorations are shown in Figures 2 and 3. Six of these explorations were completed to evaluate structures near the levee. These include two explorations completed for the North Boeing Bridge, two explorations completed for the South Boeing Bridge, and two explorations were for a building at the airport. Only eight explorations completed by the USACE were performed for the purpose of levee evaluation. The USACE explorations appear to be focused on areas that have floodwalls. February 2, 2022 | Page 6 File No. 0693-078-01 All the soils reported in the reviewed explorations are described as alluvium. We categorized the alluvium into upper and lower alluvium layers. The upper alluvium consists of layers of sand and gravel, fine-grained layers of silt/clay, and organic layers of organic silt and peat. The lower alluvium generally consists of layers of sand and gravel. The upper sand-and-gravel alluvium layer is approximately 15 to 30 feet thick and is characterized as primarily very loose to loose with occasional zones of medium dense soil. The silt and clay layers of the upper alluvium are typically 5 to 20 feet thick and are characterized as very soft to very stiff. The lower alluvium layer extends from 30 to 40 feet bgs to the full depth of the explorations, usually about 50 feet deep. Some deeper explorations in the area (greater than 100 feet deep) indicate the presence of very dense glacially consolidated soils underlying the alluvium. This zone of glacial soils was determined to be too deep to affect the stability of the levees and floodwalls and, therefore, was not included in our analysis. 4.2.3. Groundwater CPT data is interpreted to indicate a groundwater level at a depth of approximately 5 to 10 feet bgs. Water levels in the borings could not be measured directly due to the drilling method used. Groundwater is expected to vary in response to precipitation and river stage. For this assessment we have based groundwater levels on the extreme river levels assumed for the levee analysis. 4.2.4. Design Soil Properties 4.2.4.1. General Explorations performed within the project area indicate a soil profile of interbedded alluvial sands, silts, clays, and gravels. As expected in an alluvial soil profile, the layers of soils vary in thickness and composition along the length of the project area. Aside from the generalized trend of upper and lower alluvium, there was no discernable trend in the data, with regard to discrete layering of sands, silts, clays, and gravels within the alluvium. We developed design soil parameters based on the explorations closest to each analysis cross section. These soil parameters are based on correlations from the boring logs and CPT data collected during the subsurface investigation for this report as well as information from the explorations reviewed for this project. Fill was not directly observed in our borings, which were performed on the landside of the levee alignment. If fill is present on the landside of the levee, it is likely similar in composition to the underlying alluvium and, therefore, was not differentiated in the explorations. Fill is expected within the upper 5 feet of the soil profile. In our CPT explorations, soil near the ground surface was consistently observed to be stronger than the underlying alluvium. Due to the variability and uncertainty in the location and compaction of fill, we conservatively assumed that either no fill is present in our seepage and stability analyses or that the material properties for the fill are the same as the underlying alluvium. Fill used to construct levee embankments is described in more detail below. 4.2.4.2. Alluvium The alluvium contains both fine-grained (organic and inorganic silts, clays, and sandy silts) and coarse-grained (sands, gravels and silty sands) soils. The silts, clays, and sandy silts in the alluvium consist February 2, 2022 | Page 7 File No. 0693-078-01 of a mixture of silt, clay, organics, and fine sands with a fines content generally between 50 and 85 percent. Both elastic and non-plastic silts were observed within the project area. The non-plastic silts often appear and behave similar to a very fine sand. The elastic silts were observed to be both organic and inorganic and are more cohesive than the non-plastic silts. The soil strength of the non-plastic silts was evaluated from the boring and CPT data gathered during the site investigation performed for this study. Corrected blowcounts (N60) for the non-plastic silts are generally between 0 and 9 with an average of about 4. Based on published correlations (Meyerhof 1956; Peck et al. 1974) for non-cohesive materials, this corresponds to a friction angle of about 26 to 35 degrees. Data from the CPT explorations were also used to evaluate the soil strength properties and soil unit weight using correlations presented by National Cooperative Highway Research Program (NCHRP) Project 20-05 report. Based on published CPT correlations for non-cohesive materials, the CPT data is consistent with friction angles between 28 and 34 degrees for the upper alluvium silts. For our analysis we used frictions angles between 28 and 30 to model the non-plastic silts in the upper alluvium. Average unit weights were estimated to be between 100 and 115 pounds per cubic foot (pcf). The shear strength of the clays as well as the organic and inorganic elastic silts were evaluated using CPT data gathered during the site investigation performed for this study. Data from the CPT explorations were used to evaluate the soil strength properties and soil unit weight using correlations presented by NCHRP Project 20-05 report. Correlations from the CPT data resulted in estimated undrained shear strengths between 800 and 1,300 pounds per square foot (psf). The effective friction angle for fine-grained sols was produced from CPT data for mixed soil types (Mayne and Campanella 2005, as referenced by NCHRP 20-05 report) and ranged from 28 to 35 degrees. Average unit weights of soil layers were estimated to be between 105 and 110 pcf and are used to model the silts. A peat layer was observed in boring EB-2. It is classified as “medium stiff” and contains interbedded silt and fine sand. It is located between an elastic silt above the layer and a sandy silt below the layer. No peat was observed in explorations near the proposed modification areas. The sands in the upper alluvium are generally classified as very loose to medium dense silty sand to sand with silt. The upper alluvium sands contained variable amounts of gravels and silt and in localized areas was classified as sand. Corrected blowcounts for the upper alluvium material is generally between 0 and 27 with an average of about 16. Relative density as determined by blowcount tends to be variable, but generally increases with depth. Based on published blowcount correlations (Meyerhof 1956; Peck, et al. 1974) for non-cohesive materials, this corresponds to a friction angle of about 28 to 40 degrees. Data from the CPT explorations were also used to evaluate the soil strength properties and soil unit weight using correlations presented by NCHRP Project 20-05 report. Based on published CPT correlations for non-cohesive materials, the CPT data resulted in friction angles between 30 and 40 degrees for the upper alluvium sands. We used friction angles of between 28 to 36 degrees to model the sands within the alluvium. Average unit weights of soil layers from the CPT data were estimated to be between 110 and 120 pcf and are used to model the upper alluvium sands. The gravels in the upper alluvium are generally classified as loose to very dense silty gravel to gravel with sand. The upper alluvium gravels contained variable amounts of silt and sand. Within explorations for the Williams Avenue Apartments, located south of the Logan Avenue Bridge and performed by Associated Earth Sciences, Inc. gravels comprise the majority of the soil profile. Gravels were observed within the majority of the soil borings. They were typically observed as isolated layers between other cohesive and non-cohesive February 2, 2022 | Page 8 File No. 0693-078-01 layers. Corrected blowcounts for the alluvium gravels ranged between 6 and 82 with an average of about 34. Relative density as determined by blowcount tends to be variable, and similar to the alluvial sands, generally increases with depth. Based on published blowcount correlations (Meyerhof 1956; Peck et al. 1974) for non-cohesive materials, this corresponds to a friction angle of about 28 to 40 degrees. Data from the CPT explorations were also used to evaluate the soil strength properties and soil unit weight using correlations presented by NCHRP Project 20-05 report. Based on published CPT correlations for non-cohesive materials, the CPT data resulted in friction angles between 30 and 40 degrees for the upper alluvium gravels. We selected the friction angle based on the relative density and layering reported in the explorations. We used friction angles of between 29 to 40 degrees to model the sands within the upper alluvium. We used a unit weight between 110 and 120 pcf to model the upper alluvium gravels. Hydraulic conductivity values used in seepage analyses were selected based on soil classification and field observations and using guidance from literature (Powers et al. 2007). We used hydraulic conductivity values of 3.28x10-6 feet per second (ft/sec) for silts, 3.28x10-7 ft/sec for clays or elastic silts, 1.64x10-4 ft/sec for sands, and 3.28x10-3 ft/sec for gravel. We estimated the anisotropy, or hydraulic conductivity ratio (horizontal hydraulic conductivity divided by vertical hydraulic conductivity, Kv/Kh), in the alluvium to be between 0.5 to 0.75. This is based on observations of soil layering observed in the explorations and our understanding of the alluvial soils in and around the project area. 4.2.4.3. Fill The USACE plans for the project only indicate that embankment levees are constructed of “Levee Embankment Material.” The Final Detailed Project Report (Seattle District, USACE 1997) states in Section 4.03b that “The levee embankment will be compacted to meet geotechnical seepage and levee embankment integrity criteria”. No other specifications or information regarding fill materials was provided. Levee embankment material is modeled with properties similar to common borrow defined by Washington State Department of Transportation (WSDOT) Standard Specification 9-03.14(3). Common borrow is a specification that encompasses a wide range of naturally occurring soils in the State of Washington. It is our experience that most structural fill placed in western Washington meets these minimum requirements. We did not observe hummocky ground or surface sloughs on the levee prism that would indicate significant amounts of poor-quality material or poorly compacted fill. The WSDOT Geotechnical Design Manual (GDM) (WSDOT 2015) presumes that common borrow has a friction angle between 30 and 34 degrees and a unit weight between 115 and 130 pcf. We used a friction angle of 34 degrees and a unit weight of 125 pcf to model the levee embankment material. 4.3. Levee Seepage Analysis 4.3.1. General The ground elevation on the land side of the levee is typically less than 5 feet below the 100-year flood elevation for a pre-dredged condition. Our analysis also assumes that the groundwater on the landside of the levee is located at the ground surface. The duration of the base flood is limited, but the model is based on full steady state seepage conditions developing. Based on these assumptions, we consider our analysis to be conservative. February 2, 2022 | Page 9 File No. 0693-078-01 4.3.2. Analysis Method Groundwater flow through the design sections was analyzed using the computer program SEEP/W (GEO-SLOPE International, Ltd. 2007). SEEP/W is used to create a numerical groundwater flow model using groundwater flow equations and the finite-element method. We used the program to model the levee as a 2-dimensional cross section. The design sections were analyzed under steady-state conditions for seepage and uplift analyses. The boundary conditions of the flow models were set to model the predicted hydraulic conditions. A constant head boundary condition was used on the riverside of the levee to model the pre-dredged design flood. On the landside, the boundary condition was set to a constant head at the ground surface. On the landside toe of the levee the boundary condition was set to reduce the pressure head to zero if there is a net outflow of water. In some locations it would be possible for water to pond at the ground surface on the landside. We neglected this effect in the model, which allows for more flow and greater head differentials and, accordingly, is conservative. 4.3.3. Analysis Results The simulated head equipotentials for the design sections are shown in Figures LBS-1 through LBS-5 for the left bank and in Figures RBS-1 through RBS-3 for the right bank. The uplift gradient and exit velocity reported in the table below are the maximum calculated values at the landside toe. These were measured at the surface over a single analysis node. TABLE 4. SEEPAGE SUMMARY Approximate Location 100-year Flood Uplift Gradient at Landside Toe (ft/ft) Full Capacity Flood Uplift Gradient at Landside Toe (ft/ft) Section 1 Left Bank 0.06 0.2 Section 2 Left Bank 0.0002 0.0003 Section 3 Left Bank 0.02 0.1 Section 4 Right Bank 0.01 0.1 The maximum vertical exit gradient is estimated to be 0.2, well below a critical gradient of about 0.75, which assumes a conservative total soil unit weight of 110 pcf, and below the USACE’s recommended limit of 0.5. Accordingly, there is little risk of piping, boiling, or soil transport due to seepage forces. 4.4. Levee Stability 4.4.1. Analysis Method Slope stability analyses were performed using the computer program SLOPE/W (GEO-SLOPE International, Ltd. 2007). SLOPE/W evaluates the stability of numerous trial shear surfaces using a vertical slice limit-equilibrium method. This method compares the ratio of forces and moments driving slope movement versus forces and moments resisting slope movement for each trial shear surface and presents the result as the factor of safety. The program then sorts the trial shear surfaces and identifies the surface with the lowest factor of safety, or the “critical” shear surface. In general, we assumed a circular arc slip surfaces and used the Morgenstern-Price method to calculate the forces. In all cases checked, the critical February 2, 2022 | Page 10 File No. 0693-078-01 factor of safety was calculated to be similar or greater to the factor of safety calculated for the circular arc slip surface. Only the circular arc slip surface is reported. We considered four general cases for the analysis areas per USACE EM 1110-2-1913 (USACE 2000) and EM 1110-2-2502 (USACE 1989). 1. End of Construction. The end of construction case is based on the current condition of existing levees or the post-construction condition of improved levees. The water level in the river is assumed to be at mean annual flow with dredged bathymetry for this analysis. 2. Drawdown. The levee stability under drawdown conditions was evaluated in three phases following Duncan et. al. 1990, using the elevation of the river’s water surface captured in the Survey Data. Guidance from USACE “Slope Stability” manual suggests that a drawdown analysis is only required if the soil permeability is less than 0.0001 centimeter per second (cm/second) (0.012 ft/hour) soils above this limit are assumed to drain during drawdown. The alluvial foundation soils contain different interbedded soil units both above and below this limit. 3. Steady State Seepage from Full Flood Stage. The levee stability was evaluated under 100-year flood conditions for failures along the river side and land side of the levee and assuming that seepage through the levee has reached a steady state. 4. Steady State Global Wall Stability. Global stability of the flood walls under a flood to the top of wall analyzed for riverside and landside and assuming that seepage around the structure through the levee has reached a steady state. For the purposes of levee analysis and comparison of the proposed modifications to the existing condition, we only considered the shear surfaces that would impact the crest of the levee. Shallow shear surfaces that would not encroach on the crest are assumed to not affect the function of the levee and were, therefore, considered a riverbank maintenance issue rather than a levee stability issue. In all cases considered the proposed modifications increase the width of the crest. 4.4.2. Stability Analysis Results The results of the slope stability analyses are provided in the tables below. Results are shown to the thousands place; this is to show relatively small differences in the analysis, it is not intended as an indication of precision. TABLE 5. SECTION 1 LEFT BANK Analysis USACE Minimum FOS Existing Conditions Proposed Modification Case I 1.3 1.642 1.811 Case II 1 1.184 1.128 Case III (Landside/Riverside) 1.4 1.645/1.982 1.840/2.773 CASE I21 (Landside/Riverside) 1.33 N/A 1.745/2.201 Note: 1 From USACE EM 1110-2-2502 (USACE 1989). February 2, 2022 | Page 11 File No. 0693-078-01 TABLE 6. SECTION 2 LEFT BANK Analysis USACE Minimum FOS Existing Conditions Proposed Modification Case I 1.3 1.388 1.496 Case II 1 1.017 1.105 Case III (Landside/Riverside) 1.4 1.586/1.477 2.136/1.798 CASE I21 (Landside/Riverside) 1.33 N/A 1.791/2.118 Note: 1 From USACE EM 1110-2-2502 (USACE 1989). TABLE 7. SECTION 3 LEFT BANK Analysis USACE Minimum FOS Existing Conditions Proposed Modification Case I 1.3 3.702 3.693 Case II 1 2.759 2.762 Case III (Landside/Riverside) 1.4 5.5472 5.2032 CASE I21 (Landside/Riverside) 1.33 N/A 5.1392 Notes: 1 From USACE EM 1110-2-2502 (USACE 1989). 2 Levee geometry does not allow for slope failure. TABLE 8. SECTION 4 RIGHT BANK Analysis USACE Minimum FOS Existing Conditions Proposed Modification Case I 1.3 2.09 2.01 Case II 1 1.61 1.549 Case III (Landside/Riverside) 1.4 1.572 1.5192 CASE I21 (Landside/Riverside) 1.33 N/A 1.5322 Notes: 1 From USACE EM 1110-2-2502 (USACE 1989). 2 Levee geometry does not allow for slope failure. The proposed levee cross sections we analyzed meet or exceed USACE recommended minimum factors of safety in all cases. 5.0 CONCLUSIONS It is our opinion based on the analysis provided that the proposed modifications meet or exceed minimum standards for levee design and do not appreciably reduce the stability or function of the Cedar River Section 205 flood protection system. It is also our opinion that with these improvements in place the Cedar River Section 205 flood protection system will meet the geotechnical requirements of 44 CFR 65.10 and USACE Engineering Circular EC 1110- 2-6067 “USACE Process for the National Flood Insurance Program (NFIP) Levee System Evaluation” for the 100-year (1-percent annual-chance) design flood and will provide protection over a certification period of 10 years provided that maintenance is performed, as recommended, on a regular and timely basis (USACE 2010a). February 2, 2022 | Page 12 File No. 0693-078-01 6.0 LIMITATIONS We have prepared this report for the exclusive use of Tetra Tech. Tetra Tech may distribute copies of this report to the City of Renton, their authorized agents, and regulatory agencies including FEMA, USACE, and USACE or FEMA’s designated reviewers, as may be required for the project. Qualified engineering and construction practices can help mitigate flooding risks, but they cannot completely eliminate those risks. Favorable performance of structures in the recent past provides useful information for anticipating likely near-term future performance, but it cannot predict or imply a certainty of similar long-term performance. Levee systems require periodic inspection to confirm that all critical components continue functioning as intended. Confirmation that design flood flows and/or elevations have not significantly changed also requires the periodic review of design criteria and other potential contributing factors including, but not limited to, changes in surrounding development, weather patterns, system operational policies, or sedimentation. The conclusions and recommendations presented in this report are based on an assumed subsurface profile developed through interpolation between widely spaced subsurface investigations. Prior geotechnical borings and other subsurface data by others, if any, presented in our report are for the sake of completeness only; they should not be relied upon without confirmation from the originator of such data. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment and experience. No warranty or other conditions, express or implied, should be understood. Please refer to Appendix C titled “Report Limitations and Guidelines for Use” for additional information pertaining to use of this report. 7.0 REFERENCES Kulhawy, F.H. and P.W. Mayne. 1990. Electric Power Research Institute, “Manual on Estimating Soil Properties for Foundation Design.” Lowe, J., Ill, P.F. Zaccheo, and H.S. Feldman. 1964. Consolidation testing with back pressure: J. Soil Mech. Found., Div. Am. Soc. Civil Engrs., v. 90, p. 69. Mullineaux, D.R. 1965. Geologic Map of the Renton Quadrangle, King County, Washington. Powers, Patrick J., A.B. Corwin, P.C. Schmall, and W.E. Kaeck. 2007. “Construction Dewatering and Groundwater Control” New Methods and Applications, Third Edition. Rockscience, Inc. 2009-2014. Settle3D Settlement and Consolidation Analysis Theory Manual. Tetra Tech. 2017. Cedar River Section 205 Levee Recertification: Riverine Hydraulics and Freeboard. Prepared for the City of Renton, Department of Public Works. February 2, 2022 | Page 13 File No. 0693-078-01 Tokimatsu, K. and H.B. Seed. 1987. “Evaluation of settlements in sands due to earthquake shaking” J. Geotechnical Eng., ASCE 113(GT8), 861–78. United States Army Corps of Engineers (USACE). 1994. “Design of Sheet Pile Walls” EM 1110-2-2504. United States Army Corps of Engineers (USACE), Seattle District. 1997. “Cedar River Section 205 Study, Renton, WA.” United States Army Corps of Engineers (USACE). 2000. “Design and Construction of Levees” ER 1110-2- 1913. United States Army Corps of Engineers (USACE). 2010a. “USACE Process for The National Flood Insurance Program (NFIP) Levee System Evaluation” EC 1110-2-6067. United States Army Corps of Engineers (USACE). 2010b. “Earthquake Design and Evaluation for Civil Works Projects” ER 1110-2-1806. United States Army Corps of Engineers (USACE). 2011. “Design of I-Walls” EC 1110-2-6066. United States Army Corps of Engineers (USACE). 1989. “Retaining and Flood Walls” EM 1110-2-2502. Washington State Department of Transportation (WSDOT). 2015. Geotechnical Design Manual. FIGURES µ Site Vicinity Map Figure 1 Cedar River 205 Levee Certification ProjectRenton, Washington 2,000 2,0000 Feet Data Source: Mapbox Open Street Map, 2016 Notes:1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Projection: NAD 1983 UTM Zone 10N P:\0\0693078\GIS\MXD\069307801_F01_VicinityMap.mxd Date Exported: 02/01/22 by glohrmeyer ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! #0r @Ñ< #0r #0r @Ñ< #0r @Ñ< #0r #0r Ñ&¡Ñ&¡Ñ&¡Ñ&¡Ñ&¡Lake Washington Cedar RiverMaintenance Section Section 1 0+00 5+00 10+00 15+00 20+00 25+00 30+00 10+00 15+00 20+00 25+00 30+00 35+00 40+00 45+00 WC-1 WB-2 WC-2 WC-3 WB-3 EC-1 EB-1 EC-2 EC-3 BH-3 BH-2 BH-1 B-1 B-2 Site Plan North Cedar River 205 Levee Certification Renton, Washington Figure 2 µ 300 0 300 Feet Legend Major Stationing (USACE, Dec 1998) Minor Stationing (USACE, Dec 1998) Proposed Construction Earthen Levee Embankment Flood Wall Landscape Berm Approximate Location of Boring #0r GeoEngineers, 2017 @Ñ<GeoEngineers, 2017 Ñ&¡S&EE, 2012 Ñ&¡USACE, 1999 Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Projection: NAD 1983 StatePlane Washington North FIPS 4601 Feet P:\0\0693078\GIS\0693078_Project\0693078_Project.aprx\0693078_Project Date Exported: 02/01/22 by glohrmeyer Data Source: Stationing and alignments from TetraTech. ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! @Ñ< #0r @Ñ< #0r #0r Ñ&¡Ñ&¡Ñ&¡Ñ&¡Ñ&¡Ñ&¡@Ñ¡@Ñ¡ Ñ&¡Ñ&¡@Ñ¡@Ñ¡ @Ñ¡@Ñ¡@Ñ¡ @Ñ¡ Maintenance Section Section 2 Section 3 Section 4 Maintenance Section 30+00 35+00 40+00 45+00 50+00 55+00 60+00 40+00 45+00 50+00 55+00 60+00 65+00 WB-3 EC-5 EB-2 EC-3 EC-4 BH-1 PA-104 PA-103 PA-102 PA-101 PA-100 PA-1 PA-2 B-1 B-2 EB-2 EB-3 EB-1 EB-5 EB-6 EB-4 Site Plan South Cedar River 205 Levee Certification Renton, Washington Figure 3 µ 300 0 300 Feet Legend Major Stationing (USACE, Dec 1998) Minor Stationing (USACE, Dec 1998) Proposed Construction Earthen Levee Embankment Flood Wall Landscape Berm Approximate Location of Boring #0r GeoEngineers, 2017 @Ñ<GeoEngineers, 2017 Ñ&¡S&EE, 2008 @Ñ¡Associated Earth Sciences, Inc, 2001 Ñ&¡USACE, 1999 @Ñ¡Boeing, 1966 Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Projection: NAD 1983 StatePlane Washington North FIPS 4601 Feet P:\0\0693078\GIS\0693078_Project\0693078_Project.aprx\0693078_Project Date Exported: 02/01/22 by glohrmeyer Data Source: Stationing and alignments from TetraTech. 1.642Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Embankment 125 0 34Lower Clay 110 0 28Lower Silty Sands 110 0 31Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Existing Conditions End of Construction Mean WaterFigure LB1- ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.184Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownLevee Embankment 125 0 34 0 0 12Lower Clay 110 0 28 1,300 0 12Lower Silty Sands 110 0 31 0 0 12Middle Sand 115 038 0 0 12Upper Elastic Silt 105 0 28 800 0 12Upper Sand 110 034 0 0 12 SlopeW - Left Bank STA 18+00 Existing Conditions Sudden Drawdown 100 year FloodFigure LB1- IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.645Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Embankment 125 0 34Lower Clay 110 0 28Lower Silty Sands 110 0 31Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Improved conditionSteady State 100 Year Flood - Landside FailureFigure LB1-S-III(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.982Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Embankment 125 0 34Lower Clay 110 0 28Lower Silty Sands 110 0 31Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Improved ConditionSteady State 100 Year Flood - Riverside FailureFigure LB1-S-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.811Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)PiezometricLineConcrete1501Levee Embankment 125 0 34 1Lower Clay 110 028 1Lower Silty Sands 110 031 1Middle Sand 115 0 38 1Upper Elastic Silt 105 0 28 1Upper Sand 110 0 34 1 SlopeW - Left Bank STA 18+00 Improved ConditionEnd of Construction Mean WaterFigure LB1-S-ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.128Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownConcrete15012Levee Embankment 125 0 34 0 0 12Lower Clay 110 0 28 1,300 0 12Lower Silty Sands 110 031 0 0 12Middle Sand 115 0 38 0 0 12Upper Elastic Silt 105 0 28 800 0 12Upper Sand 110 0 34 0 0 12 SlopeW - Left Bank STA 18+00 Improved ConditionSudden Drawdown 100 Year FloodFigure LB1-S-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.773Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Concrete150Levee Embankment 125 0 34Lower Clay 110 028Lower Silty Sands 110 031Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Improved ConditionSteady State 100 Year Flood - Landside FailureFigure LB1-S-III(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.840Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Concrete150Levee Embankment 125 0 34Lower Clay 110 028Lower Silty Sands 110 031Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Improved ConditionSteady State 100 Year Flood - Riverside FailureFigure LB1-S-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.745Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Concrete150Levee Embankment 125 0 34Lower Clay 110 0 28Lower Silty Sands 110 0 31Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00Improved ConditionSteady State Top of Wall - Landside FailureFigure LB1-S-I2(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.201Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Concrete150Levee Embankment 125 0 34Lower Clay 110 0 28Lower Silty Sands 110 0 31Middle Sand 115 0 38Upper Elastic Silt 105 0 28Upper Sand 110 0 34 SlopeW - Left Bank STA 18+00 Improved ConditionSteady State Top of Wall - Riverside FailureFigure LB1-S-I2(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.388Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)PiezometricLineLevee Material 125 0 34 1Lower Sand and Gravel 120 0 34 1Middle Clay110 028 1Rip Rap/Wall Facing 130 0 45 1Upper Silty Gravel 110 0 30 1Upper Silty Sand 110 0 29 1SlopeW - Left Bank STA 55+00 Existing Conditions End of Construction Mean Water LevelFigure LB2- ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.017Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownLevee Material 125 0 34 0 0 12Lower Sand and Gravel 120 0 34 0 0 12Middle Clay110 028 1,300 0 12Rip Rap/Wall Facing 130 0 45 0 0 12Upper Silty Gravel 110 0 30 0 0 12Upper Silty Sand 110 0 29 0 0 12SlopeW - Left Bank STA 55+00 Existing Conditions Sudden Drawdown 100 year FloodFigure LB2- IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.586Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 028Rip Rap/Wall Facing 130 0 45Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00 Existing Conditions Steady State 100 year Flood - Landside FailureFigure LB2- III(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.477Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 028Rip Rap/Wall Facing 130 0 45Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00 Existing Conditions Steady State 100 year Flood - Riverside FailureFigure LB2- III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.496Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)PiezometricLineLevee Material 125 0 34 1Lower Sand and Gravel 120 0 34 1Middle Clay110 028 1Rip Rap/Wall Facing 130 0 45 1Structural Fill135 0 38 1Upper Silty Gravel 110 0 30 1Upper Silty Sand 110 0 29 1 SlopeW - Left Bank STA 55+00 Improved ConditionsEnd of Construction Mean WaterFigure LB2-S-ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.105Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownLevee Material 125 0 34 0 0 12Lower Sand and Gravel 120 0 34 0 0 12Middle Clay110 028 1,300 0 12Rip Rap/Wall Facing 130 0 45 0 0 12Structural Fill135 0 38 0 0 12Upper Silty Gravel 110 0 30 0 0 12Upper Silty Sand 110 0 29 0 0 12 SlopeW - Left Bank STA 55+00 Improved ConditionRapid Drawdown 100 year FloodFigure LB2-S-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.136Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 028Rip Rap/Wall Facing 130 0 45Structural Fill135 0 38Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00Improved ConditionSteady State 100 year Flood - Landside FailureFigure LB2-S-III(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.798Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 028Rip Rap/Wall Facing 130 0 45Structural Fill135 0 38Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00 Improved Condition Steady State 100 year Flood - Riverside FailureFigure LB2-S-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.791Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 0 28Rip Rap/Wall Facing 130 0 45Structural Fill135 0 38Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00 Improved Condition Steady State Top of Wall - Landside FailureFigure LB2-S-I2(L)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.118Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Levee Material 125 0 34Lower Sand and Gravel 120 0 34Middle Clay110 0 28Rip Rap/Wall Facing 130 0 45Structural Fill135 0 38Upper Silty Gravel 110 0 30Upper Silty Sand 110 0 29SlopeW - Left Bank STA 55+00 Improved Condition Steady State Top of Wall - Riverside FailureFigure LB2-S-I2(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 3.702Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)PiezometricLineLower Sand 115 0 34 1Middle Clay 110 0 28 1Upper Sand 110 0 29 1Upper Silty Gravel 110 030 1 SlopeW - Left Bank STA 58+50 Existing ConditionsEnd of Construction Mean WaterFigure LB3-ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.759Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownLower Sand 115 0 34 0 0 12Middle Clay 110 0 28 1,300 0 12Upper Sand 110 0 29 0 0 12Upper Silty Gravel 110 030 0 0 12 SlopeW - Left Bank STA 58+50 Existing ConditionsSudden Drawdown 100 Year FloodFigure LB3-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 5.547Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 030 SlopeW - Left Bank STA 58+50 Existing ConditionsSteady State 100 Year Flood - Riverside FailureFigure LB3-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 3.693Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)PiezometricLineConcrete 1501Lower Sand 115 0 34 1Middle Clay 110 0 28 1Upper Sand 110 0 29 1Upper Silty Gravel 110 0 30 1 SlopeW - Left Bank STA 58+50 Improved ConditionEnd of Construction Mean WaterFigure LB3-S-ICedar River 205 CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.762Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownConcrete 15012Lower Sand 115 0 34 0 0 12Middle Clay 110 0 28 1,300 0 12Upper Sand 110 0 29 0 0 12Upper Silty Gravel 110 0 30 0 0 12 SlopeW - Left Bank STA 58+50 Improved ConditionSudden Drawdown 100 Year FloodFigure LB3-S-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 5.203Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Concrete 150Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 0 30 SlopeW - Left Bank STA 58+50 Improved ConditionSteady State 100 Year Flood - Riverside FailureFigure LB3-S-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 6.198Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameUnit Weight(pcf)Cohesion'(psf)Phi' (°)Concrete 150Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 0 30 SlopeW - Left Bank STA 58+50 Improved ConditionSteady State Top of Wall - Riverside FailureFigure LB3-S-I2(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.09Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)PiezometricLineLower Sand 115 034 1Middle Clay 110 028 1Upper Sand 110 029 1Upper Silty Gravel 110 030 1 SlopeW - Right Bank STA 67+25 Existing ConditionsEnd of Construction Mean WaterFigure RB4-ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.61Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLinePiezometricLine After DrawdownLower Sand 115 034 0 0 12Middle Clay 110 028 1,300 0 12Upper Sand 110 029 0 0 12Upper Silty Gravel 110 030 0 0 12 SlopeW - Right Bank STA 67+25 Existing ConditionsSudden Drawdown 100 Year FloodFigure RB4-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.57Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Lower Sand 115 034Middle Clay 110 028Upper Sand 110 029Upper Silty Gravel 110 030SlopeW - Right Bank STA 67+25 Existing ConditionsSteady State 100 Year Flood - Riverside FailureFigure RB4-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 2.010Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Concrete 150Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 030 SlopeW - Right Bank STA 67+25 Improved ConditionEnd of Construction Mean WaterFigure RB4-S-ICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.549Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)CohesionR (psf)Phi R (°)PiezometricLine After DrawdownConcrete 1502Lower Sand 115 0 34 0 0 2Middle Clay 110 0 28 1,300 0 2Upper Sand 110 0 29 0 0 2Upper Silty Gravel 110 030 0 0 2 SlopeW - Right Bank STA 67+25 Improved ConditionSudden Drawdown 100 Year FloodFigure RB4-S-IICedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.519Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Concrete 150Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 030SlopeW - Right Bank STA 67+25Improved ConditionSteady State 100 Year Flood - Riverside FailureFigure RB4-S-III(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 1.532Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameUnit Weight (pcf)Cohesion'(psf)Phi' (°)Concrete 150Lower Sand 115 0 34Middle Clay 110 0 28Upper Sand 110 0 29Upper Silty Gravel 110 0 30SlopeW - Right Bank STA 67+25 Improved ConditionSteady State Top of Wall - Riverside FailureFigure RB4-S-I2(R)Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameModelKy'/Kx'RatioLevee Embankment Saturated / Unsaturated 0.75Lower Clay Saturated / Unsaturated 0.5Lower Silty Sands Saturated / Unsaturated 0.75Middle Sand Saturated / Unsaturated 0.75Upper Elastic Silt Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.75SeepW - Left Bank STA 18+00 Existing Conditions 100 Year FloodFigure LB1-1Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameModelKy'/Kx'RatioConcrete(none)Levee Embankment Saturated / Unsaturated 0.75Lower Clay Saturated / Unsaturated 0.5Lower Silty Sands Saturated / Unsaturated 0.75Middle Sand Saturated / Unsaturated 0.75Upper Elastic Silt Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.75SeepW - Left Bank STA 18+00 Improved Condition 100 Year FloodFigure LB1-2Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120Elevation (ft)-20-100102030405060-20-100102030405060Color NameModelKy'/Kx'RatioConcrete(none)Levee Embankment Saturated / Unsaturated 0.75Lower Clay Saturated / Unsaturated 0.5Lower Silty Sands Saturated / Unsaturated 0.75Middle Sand Saturated / Unsaturated 0.75Upper Elastic Silt Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.75SeepW - Left Bank STA 18+00 Existing Conditions Top of WallFigure LB1-3Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameModelKy'/Kx'RatioLevee Material Saturated / Unsaturated 0.5Lower Sand and Gravel Saturated / Unsaturated 0.75Middle ClaySaturated / Unsaturated 0.5Rip Rap/Wall Facing Saturated / Unsaturated 1Upper Silty Gravel Saturated / Unsaturated 0.75Upper Silty Sand Saturated / Unsaturated 0.75SeepW - Left Bank STA 55+00 Existing Conditions 100 Year FloodFigure LB2-1Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameKy'/Kx'RatioLevee Material 0.5Lower Sand and Gravel 0.75Middle Clay0.5Rip Rap/Wall Facing 1Structural Fill1Upper Silty Gravel 0.75Upper Silty Sand 0.75SeepW - Left Bank STA 55+00 Improved Condition 100 Year FloodFigure LB2-1Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10-30-20-100102030405060Elevation (ft)-30-20-100102030405060Color NameModelKy'/Kx'RatioLevee Material Saturated / Unsaturated 0.5Lower Sand and Gravel Saturated / Unsaturated 0.75Middle ClaySaturated / Unsaturated 0.5Rip Rap/Wall Facing Saturated / Unsaturated 1Structural FillSaturated / Unsaturated 1Upper Silty Gravel Saturated / Unsaturated 0.75Upper Silty Sand Saturated / Unsaturated 0.75SeepW - Left Bank STA 55+00 Improved Condition Top of WallFigure LB1-3Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameModelKy'/Kx'RatioLower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Left Bank STA 58+50 Existing Conditions 100 Year FloodFigure LB3-1Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameModelKy'/Kx'RatioConcrete (none)Lower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Left Bank STA 58+50 Improved Condition 100 Year FloodFigure LB3-2Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160Elevation (ft)-30-20-100102030405060-30-20-100102030405060Color NameModelKy'/Kx'RatioConcrete (none)Lower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Left Bank STA 58+50 Improved Condition Top of WallFigure LB3-3Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameModelKy'/Kx'RatioLower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Right Bank STA 67+25 Existing Conditions 100 Year FloodFigure RB4-1Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameModelKy'/Kx'RatioConcrete (none)Lower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Right Bank STA 67+25 Improved Condition 100 Year FloodFigure RB4-2Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 Distance (ft)-280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160 -150-140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40Elevation (ft)-30-20-100102030405060-30-20-100102030405060Existing BuildingColor NameModelKy'/Kx'RatioConcrete (none)Lower Sand Saturated / Unsaturated 0.5Middle Clay Saturated / Unsaturated 0.5Upper Sand Saturated / Unsaturated 0.5Upper Silty Gravel Saturated / Unsaturated 0.5SeepW - Right Bank STA 67+25 Improved Condition Top of WallFigure RB4-3Cedar River 205 Levee CertificationNotes:1. The locations of all features shown areapproximate.Renton, Washington2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. 3. GeoEngineers, Inc. cannot guarantee the accuracy and context of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.0693-078-01 Date Exported: 07/22/2021 APPENDICES APPENDIX A Subsurface Explorations and Laboratory Testing February 2, 2022 | Page A-2 File No. 0693-078-01 APPENDIX A SUBSURFACE EXPLORATIONS AND LABORATORY TESTING General Subsurface conditions were explored by advancing four mud-rotary borings and nine Cone Penetration Tests (CPTs). Subsurface exploratory services were completed by Holocene Drilling, Inc. and In-Situ Engineering under subcontract to GeoEngineers, Inc. Borings The borings were completed between January 16 and 18, 2017. The locations of the borings were determined by measuring from existing site features such as roadways and structures. The elevations presented on the boring logs are based on the topographic survey data provided by Tetra Tech, Inc. The location and elevation of the explorations should be considered approximate. The exploration location and other site features are included on the Site Plans, Figures 2 and 3. Our field representative obtained samples, classified soils, maintained a detailed log of the exploration and observed groundwater conditions where applicable. The samples were taken with a standard split spoon sampler as well as a Shelby tube sampler in general accordance with ASTM International (ASTM) D 1586 and D 1587, respectively. The samples collected with the split spoon sampler were retained in sealed plastic bags. The soils were classified visually in general accordance with the system described in Figure A-1, which includes a Key to Exploration Logs. Summary logs of the exploration are included as Figures A-2 through A-5. Cone Penetration Tests The CPTs were completed on January 19 and 27, 2017. CPT soundings were completed using truck- mounted hydraulically driven cone penetrometers. Soil friction, tip resistance and dynamic pore pressure were recorded using electronic methods. The CPT soundings were advanced to depths ranging from approximately 28 to 100 feet below ground surface (bgs). The CPTs data are presented as Figures A-6 through A-14. No soil samples are obtained during CPT soundings. Soil types are interpreted based on empirical relationships between measured CPTs data and the parameters described above. Laboratory Testing Soil samples obtained from the borings were returned to our laboratory for further examination and testing. Representative soil samples were selected for testing to assist in our evaluation of pertinent geotechnical engineering properties and to confirm our field classifications. Laboratory test descriptions are provided below. Moisture Content The moisture content of selected samples was determined in general accordance with ASTM Test Method D 2216. The test results are used to aid in soil classification and correlation with other pertinent engineering soil properties. The results of these tests are presented on the exploration logs at the respective sample depths. February 2, 2022 | Page A-3 File No. 0693-078-01 Sieve Analyses Particle-size analyses were completed on selected samples in general accordance with ASTM Test Method D 422. This test method covers the quantitative determination of the distribution of particle sizes in soils. Typically, the distribution of particle sizes larger than 75 micrometers (μm) is determined by sieving. The results of the tests were used to verify field soil classifications and determine pertinent engineering characteristics. Figures A-15 and A-16 presents the results of our sieve analyses. Atterberg Limits Atterberg Limit tests were performed on selected samples in general accordance with ASTM Test Method D 4318. This test method determines the liquid limit, plastic limit and plasticity index of soil particles passing the No. 40 sieve. The results of the tests are used to assist in soil classification and determine pertinent engineering characteristics. Results for plastic soils are presented in Figures A-17 and A-18. Liquid limits and plasticity index are also presented on the exploration logs at the respective sample depths. Percent Fines Determination Selected samples were “washed” through the U.S. No. 200-mesh sieve to estimate the relative percentages of coarse- and fine-grained particles in the soil. The tests were conducted in general accordance with ASTM 1140. The percent passing value represents the percentage by weight of the sample finer than the U.S. No. 200 sieve. These tests were conducted to verify field descriptions and to estimate the fines content for analysis purposes. The test results are shown on the exploration logs at the respective sample depths. AC Cement ConcreteCC Asphalt Concrete No Visible Sheen Slight Sheen Moderate Sheen Heavy Sheen Not Tested NS SS MS HS NT ADDITIONAL MATERIAL SYMBOLS Measured groundwater level in exploration, well, or piezometer Measured free product in well or piezometer Graphic Log Contact Groundwater Contact Material Description Contact Laboratory / Field Tests Sheen Classification Sampler Symbol Descriptions NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions. Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or times. GRAPH Topsoil/ Forest Duff/Sod Crushed Rock/ Quarry Spalls FIGURE A-1 2.4-inch I.D. split barrel SYMBOLS TYPICAL KEY TO EXPLORATION LOGS CR DESCRIPTIONSLETTER TS GC PT OH CH MH OL GM GP GW DESCRIPTIONS TYPICAL LETTER (APPRECIABLE AMOUNT OF FINES) MAJOR DIVISIONS POORLY-GRADED SANDS, GRAVELLY SAND PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS CLEAN SANDS GRAVELS WITH FINES CLEAN GRAVELS HIGHLY ORGANIC SOILS SILTS AND CLAYS SILTS AND CLAYS SAND AND SANDY SOILS GRAVEL AND GRAVELLY SOILS (LITTLE OR NO FINES) FINE GRAINED SOILS COARSE GRAINED SOILS SW MORE THAN 50% OF COARSE FRACTION RETAINED ON NO. 4 SIEVE CL WELL-GRADED SANDS, GRAVELLY SANDS SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES LIQUID LIMIT GREATER THAN 50 SILTY SANDS, SAND - SILTMIXTURES (APPRECIABLE AMOUNT OF FINES) SOIL CLASSIFICATION CHART LIQUID LIMIT LESS THAN 50 SANDS WITH FINES SP (LITTLE OR NO FINES) ML SC SM NOTE: Multiple symbols are used to indicate borderline or dual soil classifications MORE THAN 50% OF COARSE FRACTION PASSING NO. 4 SIEVE CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS, ROCK FLOUR, CLAYEY SILTS WITH SLIGHT PLASTICITY ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS SILTY SOILS ORGANIC CLAYS AND SILTS OF MEDIUM TO HIGH PLASTICITY INORGANIC CLAYS OF HIGH PLASTICITY MORE THAN 50% PASSING NO. 200 SIEVE MORE THAN 50% RETAINED ON NO. 200 SIEVE WELL-GRADED GRAVELS, GRAVEL - SAND MIXTURES POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS GRAPH SYMBOLS Standard Penetration Test (SPT) Shelby tube Piston Direct-Push Bulk or grab Continuous Coring Distinct contact between soil strata Approximate contact between soil strata Contact between geologic units Contact between soil of the same geologic unit %F %G AL CA CP CS DS HA MC MD OC PM PI PP PPM SA TX UC VS Percent fines Percent gravel Atterberg limits Chemical analysis Laboratory compaction test Consolidation test Direct shear Hydrometer analysis Moisture content Moisture content and dry density Organic content Permeability or hydraulic conductivity Plasticity index Pocket penetrometer Parts per million Sieve analysis Triaxial compression Unconfined compression Vane shear Blowcount is recorded for driven samplers as the number of blows required to advance sampler 12 inches (or distance noted). See exploration log for hammer weight and drop. A "P" indicates sampler pushed using the weight of the drill rig. A "WOH" indicates sampler pushed using the weight of the hammer. Rev. 02/16 No recovery AL(LL=82; PI=29) 5 16 7 8 14 22 75 18 26 1 SA 2 3 SA 4 AL 5 %F 6 %F 2.5 0 12 18 12 12 9 10 7 2 20 17 AC SP-SM GM MH SP-SM SP-SM Approximately 6 inches of asphalt concrete pavement Dark gray fine to coarse sand with silt and occasional gravel (loose, moist) (alluvium) Grades to medium dense Dark gray silty fine to coarse gravel with sand (loose, moist) (alluvium) Dark gray elastic silt with fine sand and trace organic matter (soft, moist) (alluvium) Dark gray fine to coarse sand with silt and gravel (medium dense, moist) (alluvium) Dark gray fine to medium sand with silt (medium dense, moist) (alluvium) Total Depth (ft) Hammer Data System Datum Start End Checked By Logged By LJSDrilled Notes: CH Surface Elevation (ft) Vertical Datum Driller Groundwater Depth to Water (ft)Date Measured Elevation (ft) Latitude Longitude Mobile B61 Truck-mounted Drill Rig Holocene Drilling, Inc.Drilling Method Mud-Rotary51.5 Autohammer 140 (lbs) / 30 (in) Drop Drilling Equipment 1/16/20171/16/2017 24 NAVD88 47.4964 -122.2136 Geographic WGS84 None Observed Note: See Figure A-1 for explanation of symbols. Log of Boring EB-1 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-2 Sheet 1 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS FinesContent (%)MoistureContent (%)FIELD DATA Depth (feet)0 5 10 15 20 25 30 35 IntervalElevation (feet)20151050-5-10Sample NameTestingRecovered (in)Collected SampleBlows/footGraphic LogGroupClassificationMATERIAL DESCRIPTION 13 52 12 7 39 42 26 23 7 %F 8 %F 9 %F 10 %F 12 18 16 10 9 4 21 20 SM ML SP-SM Dark gray silty fine to medium sand with trace organic matter (loose, wet) (alluvium) Dark gray sandy silt with trace organic matter (medium stiff, moist) (alluvium) Dark gray fine to coarse sand with silt and occasional gravel (medium dense, moist) (alluvium) Note: See Figure A-1 for explanation of symbols. Log of Boring EB-1 (continued) Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-2 Sheet 2 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS FinesContent (%)MoistureContent (%)FIELD DATA Depth (feet)35 40 45 50 IntervalElevation (feet)-15-20-25Sample NameTestingRecovered (in)Collected SampleBlows/footGraphic LogGroupClassificationMATERIAL DESCRIPTION 1 AL 2 SA 3 AL 4 SA 5 %F 6 MC 7 9.5 18 14 0 16 Approximately 6 inches of asphalt concrete pavement Tan sandy silt with oxidation staining (medium stiff, moist) (alluvium) Dark gray silt with sand (medium stiff, wet) (alluvium) Dark gray silt with interbedded fine sand (very soft, moist) (alluvium) Dark gray silty fine to medium sand with trace organic matter (loose, moist) (alluvium) Dark gray elastic silt with sand and trace organic matter (soft, moist) (alluvium) Dark gray peat with interbedded silt and fine sand (medium stiff, moist) (alluvium) Dark gray sandy silt (medium stiff, wet) AC ML ML ML SM MH PT ML 4 5 WOH 7 2 4 AL(LL=36; PI=9) AL(LL=39; PI=11) Drill chatter at 24 feet 77 40 60 33 35 47 38 40 82 Total Depth (ft) Hammer Data System Datum Start End Checked By Logged By LJSDrilled Notes: CH Surface Elevation (ft) Vertical Datum Driller Groundwater Depth to Water (ft)Date Measured Elevation (ft) Latitude Longitude Mobile B61 Truck-mounted Drill Rig Holocene Drilling, Inc.Drilling Method Mud-Rotary51.5 Autohammer 140 (lbs) / 30 (in) Drop Drilling Equipment 1/16/20171/16/2017 30 NAVD88 47.4882 -122.2108 Geographic WGS84 None Observed Note: See Figure A-1 for explanation of symbols. FIELD DATA Depth (feet)0 5 10 15 20 25 30 35 IntervalElevation (feet)2520151050-5Sample NameTestingRecovered (in)Graphic LogMATERIAL DESCRIPTION GroupClassificationWater LevelBlows/foot(N60)Collected SampleLog of Boring EB-2 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-3 Sheet 1 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GT_STANDARD_NVALUEREMARKS FinesContent (%)MoistureContent (%) 7 %F 8 %F/AL 9 %F 10 %F 12 18 18 6 (alluvium) 4-inch silt layer at 36 feet Dark gray silt with sand (soft, moist) (alluvium) Dark gray silty fine to coarse gravel with sand (very dense, moist) (alluvium) Dark gray fine to coarse gravel with silt and sand (dense, wet) (alluvium) ML GM GP-GM 6 2 54 44 AL(LL=39; PI=12) 54 83 16 7 33 36 12 14 Note: See Figure A-1 for explanation of symbols. FIELD DATA Depth (feet)35 40 45 50 IntervalElevation (feet)-10-15-20Sample NameTestingRecovered (in)Graphic LogMATERIAL DESCRIPTION GroupClassificationWater LevelBlows/foot(N60)Collected SampleLog of Boring EB-2 (continued) Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-3 Sheet 2 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GT_STANDARD_NVALUEREMARKS FinesContent (%)MoistureContent (%) 1 AL 2 SA 3 SA 4 %F 5 %F 6 %F 9 18 7 3 10.5 12 Dark gray fine to coarse sand with silt and occasional gravel (medium dense, moist) (alluvium) Dark gray and brown elastic silt with sand, gravel and organic matter (very soft, moist) (alluvium) Dark gray and brown silty fine sand with trace organic matter (wood fragments) (very loose, moist) (alluvium) Dark gray fine to coarse sand with silt and gravel (loose, wet) (alluvium) Dark gray silty fine sand with occasional gravel (loose, moist) (alluvium) Dark gray fine to coarse sand with silt, gravel and trace organic matter (very loose, moist) (alluvium) Dark gray fine to coarse sand with silt and occasional gravel (medium dense, moist) (alluvium) SM MH SM SP-SM SM SP-SM SP-SM 0 2 4 9 2 26 Gravel in returns; drill chatter 3 to 4 feet Drilling smooths out from 4 to 5 feet AL(LL=96; PI=38) Slight wobble to drill pipe at 13 feet 49 7 18 12 7 61 84 25 31 40 17 Total Depth (ft) Hammer Data System Datum Start End Checked By Logged By LJSDrilled Notes: CH Surface Elevation (ft) Vertical Datum Driller Groundwater Depth to Water (ft)Date Measured Elevation (ft) Latitude Longitude Mobile B61 Truck-mounted Drill Rig Holocene Drilling, Inc.Drilling Method Mud-Rotary51.5 Autohammer 140 (lbs) / 30 (in) Drop Drilling Equipment 1/17/20171/17/2017 23 NAVD88 47.4965 -122.215 Geographic WGS84 None Observed Note: See Figure A-1 for explanation of symbols. FIELD DATA Depth (feet)0 5 10 15 20 25 30 35 IntervalElevation (feet)20151050-5-10Sample NameTestingRecovered (in)Graphic LogMATERIAL DESCRIPTION GroupClassificationWater LevelBlows/foot(N60)Collected SampleLog of Boring WB-2 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-4 Sheet 1 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GT_STANDARD_NVALUEREMARKS FinesContent (%)MoistureContent (%) 7 %F 8 %F 9 %F 10 %F 12 13 14 13 Dark gray silty fine to medium sand (medium dense, moist) (alluvium) SM 17 18 15 12 7 6 6 14 22 19 19 30 Note: See Figure A-1 for explanation of symbols. FIELD DATA Depth (feet)35 40 45 50 IntervalElevation (feet)-15-20-25Sample NameTestingRecovered (in)Graphic LogMATERIAL DESCRIPTION GroupClassificationWater LevelBlows/foot(N60)Collected SampleLog of Boring WB-2 (continued) Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-4 Sheet 2 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GT_STANDARD_NVALUEREMARKS FinesContent (%)MoistureContent (%) AL (LL = 195; PI = 66) AL (LL = 113; PI = 38) 34 45 51 208 40 78 61 150 1 MC 2 AL 3 SA 4 AL 5 SA 6 MC 18 18 14 18 18 18 2 0 6 0 5 2 SM OH SM OH SM OH ML Dark gray and tan silty fine to coarse sand with occasional gravel (very loose, moist) (alluvium) Grades to without gravel Brown and dark gray organic silt with sand and organic matter (roots) (very soft, moist) Dark gray silty fine to coarse sand (loose, moist) Dark gray and tan organic silt with sand (very soft, moist) Brown and tan silty fine sand with organic matter (rotted wood) and occasional interbedded silt with sand (loose, moist) Brown and dark gray organic silt with sand and organic matter (soft, moist) Dark gray sandy silt with trace organic matter (wood) (soft, moist) Total Depth (ft) Hammer Data System Datum Start End Checked By Logged By LJSDrilled Notes: CH Surface Elevation (ft) Vertical Datum Driller Groundwater Depth to Water (ft)Date Measured Elevation (ft) Latitude Longitude Mobile B61 Truck-mounted Drill Rig Holocene Drilling, Inc.Drilling Method Mud-Rotary51.5 Autohammer 140 (lbs) / 30 (in) Drop Drilling Equipment 1/18/20171/18/2017 23 NAVD88 47.4921 -122.2135 Geographic WGS84 None Observed Note: See Figure A-1 for explanation of symbols. Log of Boring WB-3 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-5 Sheet 1 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS FinesContent (%)MoistureContent (%)FIELD DATA Depth (feet)0 5 10 15 20 25 30 35 IntervalElevation (feet)20151050-5-10Sample NameTestingRecovered (in)Collected SampleBlows/footGraphic LogGroupClassificationMATERIAL DESCRIPTION AL (non-plastic) AL (non-plastic) AL (non-plastic) 49 66 163 41 7 AL 8 AL 9 MC 10 AL 18 14 18 18 3 0 1 2 ML Dark gray silt with sand (very soft, moist) Grades to with organic matter (wood) Grades to soft without organic matter Note: See Figure A-1 for explanation of symbols. Log of Boring WB-3 (continued) Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Project: Project Location: Project Number:Figure A-5 Sheet 2 of 2Date:7/6/17 Path:P:\0\0693078\GINT\069307800.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS FinesContent (%)MoistureContent (%)FIELD DATA Depth (feet)35 40 45 50 IntervalElevation (feet)-15-20-25Sample NameTestingRecovered (in)Collected SampleBlows/footGraphic LogGroupClassificationMATERIAL DESCRIPTION Figure A-6 CPT EC-01 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-7 CPT EC-02a Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-8 CPT EC-03 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-9 CPT EC-05 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-10 CPT EC-06 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-11 CPT WC-01 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-12 CPT WC-02 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A-13 CPT WC-03 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure A -14 CPT WC-04 Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 070717Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000PERCENT PASSING BY WEIGHT GRAIN SIZE IN MILLIMETERS U.S. STANDARD SIEVE SIZE SAND SILT OR CLAYCOBBLES GRAVEL COARSE MEDIUM FINECOARSEFINE Boring Number Depth (feet)Soil Description EB-1 EB-1 EB-2 EB-2 5 15 10 20 Poorly-graded sand with silt and gravel (SP-SM) Silty gravel with sand (GM) Silt with sand (ML) Silty sand (SM) Symbol Moisture (%) 14.4 21.5 34.9 38 3/8”3”1.5”#4 #10 #20 #40 #60 #1003/4”Figure A-15Sieve Analysis ResultsCedar River 205 Levee CertificationRenton, Washington0693-078-00 Date Exported: 07/07/17 Note:This report may not be reproduced,except in full,without written approval of GeoEngineers,Inc.Test results are applicable only to the specific sample on which they were performed,and should not be interpreted as representative of any other samples obtained at other times,depths or locations,or generated by separate operations or processes. The grain size analysis results were obtained in general accordance with ASTM D 6913. #200 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000PERCENT PASSING BY WEIGHT GRAIN SIZE IN MILLIMETERS U.S. STANDARD SIEVE SIZE SAND SILT OR CLAYCOBBLES GRAVEL COARSE MEDIUM FINECOARSEFINE Boring Number Depth (feet)Soil Description WB-2 WB-2 WB-3 WB-3 10 15 15 25 Silty sand (SM) Well-graded sand with silt (SW-SM) Silty sand (SM) Silty sand (SM) Symbol Moisture (%) 83.5 24.6 40.3 61.3 3/8”3”1.5”#4 #10 #20 #40 #60 #1003/4”Figure A-16Sieve Analysis ResultsCedar River 205 Levee CertificationRenton, Washington0693-078-00 Date Exported: 07/07/17 Note:This report may not be reproduced,except in full,without written approval of GeoEngineers,Inc.Test results are applicable only to the specific sample on which they were performed,and should not be interpreted as representative of any other samples obtained at other times,depths or locations,or generated by separate operations or processes. The grain size analysis results were obtained in general accordance with ASTM D 6913. #200 Notes: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as representative of any other samples obtained at other times, depths or locations, or generated by separate operations or processes. The liquid limit and plasticity index were obtained in general accordance with ASTM D 4318. Figure A-17 Atterberg Limits Test Results Cedar River 205 Levee Certification Renton, Washington 0693-078-00 Date Exported: 07/07/17Symbol Boring Number Depth (feet) Moisture Content (%) Liquid Limit (%) Plasticity Index (%)Soil Description EB-1 EB-2 EB-2 EB-2 20 5 15 40 75 33 47 36 82 36 39 39 29 9 11 12 Elastic silt with occasional sand (MH) Sandy silt with occasional o.m. (ML) Silt with sand and gravel (ML) Silt with sand (ML) 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100PLASTICITY INDEX LIQUID LIMIT PLASTICITY CHART CL-ML ML or OL CL or OL OH or MH CH or OH Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as representative of any other samples obtained at other times, depths or locations, or generated by separate operations or processes. The liquid limit and plasticity index were obtained in general accordance with ASTM D 4318. Figure A -18 Atterberg Limits Test Results Cedar River 205 Levee Certification Renton, Washington Symbol Boring Number Depth (feet) Moisture Content (%) Liquid Limit (%) Plasticity Index (%)Soil Description WB-2 WB-3 WB-3 5 10 20 61 208 78 96 195 113 38 66 38 Elastic silt with sand and o.m. (MH) Organic silt (OH) Organic silt (OH) 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200PLASTICITY INDEX LIQUID LIMIT PLASTICITY CHART CL-ML ML or OL CL or OL OH or MH CH or OH 0693-078-00 Date Exported: 07/07/17 APPENDIX B Prior Exploration Logs S&EE 2008 S&EE 2012 Boeing 1966 Associated Earth Sciences, Inc. 2001 USACE 2001 APPENDIX C Report Limitations and Guidelines for Use February 2, 2022 | Page C-1 File No. 0693-078-01 APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE1 This appendix provides information to help you manage your risks with respect to the use of this report. Geotechnical Services are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of the Tetra Tech, Inc. under contract with the City of Renton and their authorized agents. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of our Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with the Client and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Geotechnical Engineering or Geologic Report is Based on a Unique Set of Project-Specific Factors This report has been prepared for the Cedar River 205 Levee Certification project in Renton, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: ■ not prepared for you, ■ not prepared for your project, ■ not prepared for the specific site explored, or ■ completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: ■ the function of the proposed structure; ■ elevation, configuration, location, orientation or weight of the proposed structure; ■ composition of the design team; or ■ project ownership. 1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. February 2, 2022 | Page C-2 File No. 0693-078-01 If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. Topsoil For the purposes of this report, we consider topsoil to consist of generally fine-grained soil with an appreciable amount of organic matter based on visual examination, and to be unsuitable for direct support of the proposed improvements. However, the organic content and other mineralogical and gradational characteristics used to evaluate the suitability of soil for use in landscaping and agricultural purposes was not determined, nor considered in our analyses. Therefore, the information and recommendations in this report, and our logs and descriptions should not be used as a basis for estimating the volume of topsoil available for such purposes. Most Geotechnical and Geologic Findings Are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Geotechnical Engineering Report Recommendations Are Not Final Do not over-rely on the preliminary construction recommendations included in this report. These recommendations are not final, because they were developed principally from GeoEngineers’ professional judgment and opinion. GeoEngineers’ recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for this report's recommendations if we do not perform construction observation. Sufficient monitoring, testing and consultation by GeoEngineers should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. February 2, 2022 | Page C-3 File No. 0693-078-01 A Geotechnical Engineering or Geologic Report Could be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. You could lower that risk by having GeoEngineers confer with appropriate members of the design team after submitting the report. Also retain GeoEngineers to review pertinent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or geologic report. Reduce that risk by having GeoEngineers participate in pre-bid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Exploration Logs Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might an owner be in a position to give contractors the best information available, while requiring them to at least share the financial responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be included in your project budget and schedule. Contractors are Responsible for Site Safety on their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractor’s procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and to adjacent properties. Read These Provisions Closely Some clients, design professionals and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory “limitations” provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these “Report Limitations and Guidelines for Use” apply to your project or site. February 2, 2022 | Page C-4 File No. 0693-078-01 Geotechnical, Geologic and Environmental Reports Should not be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations, e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. Biological Pollutants GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention, or assessment of the presence of Biological Pollutants in or around any structure. Accordingly, this report includes no interpretations, recommendations, findings, or conclusions for the purpose of detecting, preventing, assessing, or abating Biological Pollutants. The term “Biological Pollutants” includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts.