Geotechnical Report Alteration of Geologic Hazard Areas City of Redmond

Attachment 13

Sound Transit | Downtown Redmond Link Extension Design-Build Contract No. RTA/CN 0148-18

April 7, 2020

Prepared for: Prepared by: Attachment 13 Geotechnical Report – Alteration of Geologic Hazard Areas

Revision History/Signature Page

Version Description/Comment Geotechnical Report – Geologic Hazard Areas, City 0 January 6, 2020 of Redmond Geotechnical Report – Geologic Hazard Areas, City 1 January 16, 2020 of Redmond Geotechnical Report – Geologic Hazard Areas, City 2 March 19, 2020 of Redmond Geotechnical Report – Geologic Hazard Areas, City 3 April 7, 2020 of Redmond

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EXECUTIVE SUMMARY

The Downtown Redmond Link Extension (DRLE) project extends East Link light rail from Redmond Technology Center Station to downtown Redmond and will consist of two parallel lines of track running side by side. The project alignment runs along eastbound State Route 520 (SR 520) through critical landslide hazard areas (geologic hazard areas) between NE 60th Street and the SR 520/West Lake Sammamish Parkway NE interchange. The existing steep slopes in this area of the project are considered a potential landslide hazard by the City of Redmond. The project alignment cannot avoid these potential landslide hazard areas (steep slopes) due to the limited space between SR 520 and the adjacent private properties above the slopes. As a result, landslide hazards along the project are either reduced or not adversely affected through use of earth retaining systems (e.g. retaining walls) in areas of slope cut or by placing fill retention systems at the base of existing steep slopes, i.e. providing new buttressing. Earth retaining systems for the project are designed to meet or exceed the slope stability requirements for the State of Washington, and typically improve the stability compared to the existing slopes. Construction of the project will reduce potential hazard impacts by minimizing grading and slope cuts to the extent practical and adhering to recommended erosion and sediment control practices. Monitoring will take place throughout construction along the steep slopes to actively measure for potential slope movement. If excessive slope movements were to occur during construction, corrective action would be taken to prevent potential damage to nearby properties and structures. Introduction

The DRLE project extends East Link light rail 3.4 miles from the Redmond Technology Center Station to downtown Redmond and includes two new stations. Most of the light rail alignment, including both stations, will be within the Redmond city limits. The purpose of this report is to demonstrate project compliance with the City of Redmond’s (City) critical areas regulations (Redmond Zoning Code [RZC] Chapter 21.64) in support of the permit application to the City related to Alteration of Geologic Hazard Areas. This report addresses the geotechnical aspects of critical areas regulated under RZC Chapter 21.64.060 regarding geologic hazard areas (GHA). Overall Project Background The DRLE project is a component of the larger East Link Light Rail Transit Project. Sound Transit, Washington State Department of Transportation (WSDOT), and the Federal Transit Administration (FTA) issued the East Link Project Final Environmental Impact Statement (EIS) pursuant to the National Environmental Policy Act (NEPA) and the State Environmental Policy Act (SEPA) in July 2011. The EIS evaluated approximately 18 miles of light rail, and the study area was divided into five segments. Segment E included the City of Redmond portion of the study area from Redmond Technology Station (formerly called the Overlake Transit Center Station) to downtown Redmond. Three build alternatives, in addition to the No Build Alternative, were considered in Segment E.

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The Final EIS and Record of Decision (ROD) identified Marymoor Alternative E2 as the Preferred Alternative in Segment E (FTA et al. 2011; FTA 2011; Federal Highway Administration [FHWA] 2011). This alignment was selected by the Sound Transit Board in 2011 as part of the East Link Project, although Segment E was not funded at the time for construction and operation. Both the Final EIS and the ROD noted that the Sound Transit 2 (ST2) Plan does not provide sufficient funding for Segment E; therefore, the Redmond Technology Station was selected as the interim terminus. In 2011, Sound Transit deferred further work on an extension to the downtown Redmond terminus until funding became available. Preliminary engineering to extend light rail from the Redmond Technology Station to downtown Redmond resumed in 2016, and funding for constructing this extension was approved by voters in the Sound Transit 3 (ST3) Plan. As part of ST3, the Sound Transit Board identified 2024 as the start of operation—one year after East Link begins operating to the interim terminus at the Redmond Technology Station. The portion of the full-length East Link corridor, referred to as Segment E in the Final EIS, was subsequently renamed the Downtown Redmond Link Extension (DRLE) Project. Overall Project Description The current design for the DRLE segment consists of a mix of at-grade and elevated track. The DRLE project alignment begins at the Redmond Technology Center and extends north and east along the eastside of the SR 520 freeway using at-grade track generally supported on retained- cut sections to cut into the hillside and pass under existing overpasses. The alignment then turns east with the freeway and transitions to an elevated structure, crossing the Sammamish River and descending into Marymoor Park. The alignment transitions to retained fill and at-grade sections as it reaches the Southeast (SE) Redmond Station. After the station, the light rail alignment turns to the northwest at grade, crosses under SR 520, transitions to an elevated structure over Bear Creek, and then continues as an elevated structure following the Redmond Central Connector (RCC) alignment into downtown Redmond, terminating at the Downtown Redmond Station located at the north side of Redmond Town Center. Report Preparation and Technical Experience This report has been prepared by Mr. Garry Horvitz, a licensed geotechnical engineer and engineering geologist in the State of Washington, meeting the requirements specified in RZC Appendix 1.E. Garry has 44 years of geotechnical engineering experience including landslide stabilization, slope stability evaluations, and geotechnical engineering design of slopes, embankments, roadways, tunnels, elevated structures, and retaining walls. Additional relevant technical expertise and professional registrations for Garry are shown in the geotechnical engineering resume attached to this report. Designated Geologic Hazard Areas of the Project

The remainder of this report focuses on the DRLE alignment along the east side of SR 520 between NE 60th Street and the SR 520/West Lake Sammamish Parkway NE (WLSP) Sound Transit | Downtown Redmond Link Extension Page | 2 April 7, 2020 Attachment 13 Geotechnical Report – Alteration of Geologic Hazard Areas

interchange, hereafter referred to as the Geologic Hazard Areas (GHA) of the project. The project site area, designated by Redmond Zoning Code (RZC) Chapter 21.64.060, as the GHA comprises approximately 2.7 acres and generally consists of currently undeveloped areas of Washington State Department of Transportation (WSDOT) right-of-way along eastbound SR 520. The GHA is bordered by NE 60th Street to the south, SR 520 to the west, private residences and a community center to the east, and the SR 520/WLSP interchange to the north. Historical site grading consisting of cut and fill were completed in the vicinity of the GHA as part of the initial SR 520 construction and subsequent widening. In general, the existing steep slopes in this area appear to be either cuts made during SR 520 construction or existed prior to construction of SR 520. A soldier pile retaining wall was also constructed along the SR 520 roadway just west of the SR 520/WLSP interchange, to retain an apparent cut in this area. Fills were completed for the NE 60th Street abutment just south of the critical areas, and fills were also likely completed in the flatter areas adjacent to the shoulder of SR 520. Guideway Stationing in the project area designated as the GHA runs from approximately East Bound Station 5050+00 to 5072+00. Proposed Construction in the Critical Areas The width of the proposed DRLE project alignment is approximately 35 feet from wall to wall and consists of an eastbound and westbound track running approximately parallel to SR 520. The tracks are planned at-grade through the GHA from approximately Station 5050+00 to 5071+50, and as the track alignment continues northeast past approximately Station 5071+50, it transitions to an elevated segment over the SR 520/WLSP interchange. Along portions of the alignment, the GHA slopes make up nearly all of the area between SR 520 and the private properties above the GHA slopes. Note that the project alignment is already established and cannot avoid the GHA due to the site constraints and will have to be constructed with suitable use of earth retaining system and other measures to not adversely affect the GHA. For two portions of the alignment, between approximately Station 5050+00 to 5052+00 and 5064+00 to 5067+00, the track will be supported on retained structural fill along the base of existing slopes. The remaining portions of the alignment within the GHA, from approximately Station 5052+00 to 5064+00 and 5067+00 to 5071+50, the site grading for the proposed track alignment will generally consist of retained cuts on the east (uphill) side of the track alignment. Site Reconnaissance

We conducted a surface reconnaissance at the project site GHA on November 18 ‒ 19, 2019. During our reconnaissance, we observed the site along the east of SR 520, between NE 60th Street and the SR 520/WLSP interchange. We noted existing chain-link fencing along the top of the slopes separating WSDOT right-of-way along SR 520 and the private properties above the slopes. We did not note any sections of the fence that appeared to be sagging, leaning, or otherwise indicating previous movement of the existing steep slopes in this area. We did not observe any existing slope failures during our reconnaissance of the steep slopes.

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We also did not note any seeps or springs on the slopes during our reconnaissance. We did not observe any rill erosion channels or other surficial erosion indicators during our site reconnaissance. Geology and Groundwater

We reviewed the relevant publicly available geologic and hydrogeologic maps and studies of the region (Liesch et. al. 1963; Richardson 1968; Minard 1982; WDNR 2019) to determine geologic conditions around the project site GHA. Project-specific explorations completed along the DRLE track alignment were completed by Golder (2018a, b) and historic borings completed by WSDOT in the vicinity are included in the Golder data report (2018a). Borings DRLE-G012 to DRLE-G015 were completed by Golder along the GHA of the project. Logs of these borings are attached. As the Sammamish River Valley formed over geological epochs, it is believed to have been filled with fluvial and glacial sediments transported by streams associated with glacial activity. As such, the geological units in the vicinity are identified as alluvium and glacial deposits. Major Geologic Units Golder (2018a, b) identified four geologic units during the subsurface investigations along the project alignment between NE 60th Street and the SR 520/WLSP interchange (from approximately. Station 5050+00 to 5072+00). The geologic units fall into three general groups, based on age: Holocene Units, Quaternary Vashon Units, and Quaternary Pre-Vashon Units. The symbols in parenthesis following the sediment type (e.g. Qvt, Qva, etc.) are the map symbols used on the subsurface cross sections on Figures 3C and 3D. Holocene units consist of sediments deposited since the last glaciation, within the last 12,000 years. These units include engineered and non-engineered human placed fill and soil deposits resulting from natural processes. These units have not been overridden by glacial ice. Quaternary glacial units consist of soils deposited during the last glaciation. These units include soil deposits resulting from glacial processes ranging in composition from a mix of till-like diamicton, granular outwash deposits and glaciolacustrine deposits. We interpret the steep slopes at the site to consist of the Quaternary glacial soil units. It is considered unlikely that WSDOT placed fill on the steep slopes as a part of SR 520 construction. 4.1.1 Fill/Modified Land (af) Fill soils are a result of human activity and, in this area, include fill associated with the construction of SR 520 as the route descends in the Sammamish River Valley. The fill varies in composition. Along SR 520 in this area, the fill includes medium dense to very dense, silty fine to coarse sand, some gravel with a trace of wood fragments, fine to medium sand with some fines, and trace gravel.

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4.1.2 Vashon Till (Qvt) Till soils are typically dense to very dense and were deposited directly beneath glacial ice. These soils generally consist of a mix of silty sand and sandy silt with varying amounts of gravel and occasional cobbles and boulders. 4.1.3 Vashon Advance Outwash Deposits (Qva) Advance outwash soils are typically dense to very dense since they have been glacially overridden. These soils are generally composed of sand and silty sand with varying amounts of gravel and cobbles. Outwash soils may contain thin interbeds of lenses of fine-grained soils. 4.1.4 Vashon Glaciolacustrine Deposits (Qvgl) Glaciolacustrine soils are generally fine-grained deposits with a trace of dropstones and are glacially consolidated. These soils typically consist of hard clay, silty clay, and very dense silt. The fine-grained soils are lower-permeability and will typically perch groundwater in overlying granular soils. 4.1.5 Pre-Vashon Till/Till-Like Deposits (Qvd) The till-like glacial drift deposits at the site are generally composed of silty sand to sandy silt, clayey gravel, and clay with gravel. These soils are typically very dense to hard and may be transitional regarding the overlying fine-grained Qvgl soils. Groundwater Golder (2018a, b) identified groundwater zones with the Holocene and Quaternary glacial units. Within the glacial units, groundwater occurs as isolated, perched, and regional groundwater. Groundwater was noted in three of the borings along the GHA portion of the project, at depths varying from about 24 to 32 feet below ground surface (bgs). Groundwater elevations range from approximately +190 feet (NAVD88) at Station 5050+00 to approximately +140 feet at Station 5071+00. Proposed track elevations in this area range from approximately +234 feet at Station 5050+00 to approximately +152 feet at Station 5071+00. Section 6.2.4.1 of the Geotechnical Baseline Report (Golder 2018b) states that “a layer of gravelly soil, up to 5 feet thick [from Station 5066+00 to 5070+00], should be anticipated within the fine-grained soils (Qvgl/Qvd). The top of the gravelly layer should be anticipated at an elevation of approximately 140 feet (+/- 5 feet). The gravelly layer should be anticipated to produce water”. Based on current plans the track elevations through this section are at an elevation of approximately +158 to +175 feet, and the regional groundwater is at elevation of approximately +140 feet. Therefore, the gravelly layer within the fine-grained soils where groundwater is anticipated will likely not be encountered during construction. It is possible that seasonal surface water and perched groundwater may be encountered. This water can be managed with sump-and-pump systems as needed during construction. There is a low

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probability that horizontal drains may be required to capture perched groundwater to reduce the risk of soil loss and instability. Geologic Hazard Areas

Geologic Hazard Areas (GHA) are defined as areas susceptible to erosion, sliding, earthquake, or other geologic events (RZC 21.78). The following sections of this report present information on the GHA, our evaluation and analysis of potential hazards, and mitigation measures to reduce, or not adversely affect, the geologic hazards. Geologic Hazard Areas in the Project Area City critical areas mapping (2016) identifies the presence of landslide hazard areas in the project area. City mapping (2016) identifies landslide hazard areas along the east side of SR 520 between NE 60th Street and the SR 520/WLSP interchange (Exhibit GH-01 to GH-03). King County (2016) mapped landslide hazards along river corridors for several types of landslides, and the mapping study area for the Sammamish River corridor includes a portion of the project area near the SR 520/WLSP interchange. The King County (2016) mapped area overlaps a portion of the landslide hazard areas mapped by the City (2016). The King County (2016) mapping does not indicate the presence of landslide hazards in the project area. WDNR (2019) does not indicate the presence of any recent or historic landslide activity in the vicinity of the project. Similarly, USGS (2019) mapping does not indicate the presence of landslide hazards or previous landslides in the area. Landslide Hazard Areas Section 21.64.060.A.1.b. of the RZC defines landslide hazard areas as those “potentially subject to significant or severe risk of landslides based on a combination of geologic, topographic, and hydrogeologic factors. They include areas susceptible because of any combination of bedrock, soil, slope, slope aspect, structure, hydrology, or other factors. They are areas of the landscape that are at a high risk of failure or that presently exhibit downslope movement of soil and/or rocks and that are separated from the underlying stationary part of the slope by a definite plane of separation.” A landslide is a mass of rock, earth, or debris moving down a slope. Landslides may be minor or very large and can move at slow to very high speeds. Landslides can cause damage by the slide mass colliding with or burying structures below the slope, and movement of the slope can cause damage to structures on or adjacent to the slide mass that moves. RZC Section 21.64.060.A.1.b. lists seven criteria for determining whether an area is a landslide hazard.

• Criteria 1 includes areas of historic slope failures or landslides designated or identified by the United States Geologic Survey (USGS) or the United States Department of Agriculture (USDA).

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• Criteria 2 includes areas containing a combination of slopes steeper than 15 percent, springs or groundwater seepage, and hillsides intersecting geologic contacts with a relatively permeable sediment overlying a relatively impermeable sediment or bedrock.

• Criteria 3 includes areas that have shown movement during the Holocene epoch (from 10,000 years ago to the present) or which are underlain or covered by mass wastage debris of that epoch.

• Criteria 4 includes slopes that are parallel or subparallel to planes of weakness in subsurface materials.

• Criteria 5 includes having gradients steeper than 80 percent subject to rockfall during seismic shaking. • Criteria 6 includes areas potentially unstable as a result of rapid stream incision, stream bank erosion, and undercutting by wave action.

• Criteria 7 includes any areas with a slope 40 percent or steeper with a vertical relief of 10 feet or more. Topography in this area does indicate a large portion of the project area with slopes 40 percent or steeper and vertical relief up to approximately 40 feet (Exhibit GH-01 to GH-03). We note that the potentially water-producing gravelly layer indicated between Station 5066+00 and 5070+00 occurs in an area already identified as a GHA based on the 40 percent or steeper slope criteria. Based on historical mapping, available subsurface information, and our site reconnaissance, we did not identify any slopes or features that meet the other criteria at this project site. Slope Stability Assessment

We have evaluated the overall slope stability of the proposed track alignment and related grading, retaining walls, and other improvements. Slope stability analyses consisting of two- dimensional slope cross sections using Spencer and Morgenstern-Price methods of limit equilibrium analysis were performed on two cross sections, Station 5063+50 (Figures 1A through 1D) and Station 5069+00 (Figures 1E through 1H). We selected cross sections in the GHA of the project to represent the critical slope areas, based on the geometry of the slope, proposed grade changes to the slope, and proposed retaining wall heights. We analyzed slope stability of the selected sections in their existing configuration and final configuration based on preliminary design expectations. We analyzed the existing and final configurations for both the static and 2,500-year pseudo-static (seismic) conditions. The slope stability, under the various conditions, was analyzed using effective stress analysis method. Based on existing information for the site, the following drained shear strength parameters were used in our slope stability analyses.

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Table 1. Generalized / Assumed Design Soil Parameters

Soil Type Unit Drained Drained Weight Friction Angle Cohesion (pcfa) (degrees) (psfb) Artificial Fill (af) 125 34 0 Till (Qvt) 140 40 0 Advance Outwash (Qva) 135 40 0

Glacial Drift (Qvd) 130 37 0 Glaciolacustrine (Qvgl) 130 35 50

Notes: a. pcf = pounds per cubic foot b. psf = pounds per square foot

We used the preliminary ultimate soil nail adhesion values below in Table 2 for our slope stability analyses.

Table 2. Preliminary Nail Bond Adhesion

Soil Type Ultimate Bond Adhesion (ksf) Artificial Fill (af) 1.5 Till (Qvt) 5.0 Advance Outwash (Qva) 5.0 Glacial Drift (Qvd) 4.0 Glaciolacustrine (Qvgl) 2.5 Notes: a. ksf = pounds per cubic foot

We evaluated the slopes for the Maximum Design Earthquake (MDE) (2,500-year return period) earthquake hazard level because it is assumed to govern over the Operating Design Earthquake (ODE) (150-year return period) earthquake hazard level. For this project area, the MDE Peak Ground Acceleration (PGA) is consistently about 0.55g (site class B), and the site coefficient is 1.0 for either site class D or C. AS is calculated using the 2014 USGS uniform hazard model for Vs=760 meters/second and the site coefficients in AASHTO load resistance factored design (LRFD). AASHTO LRFD C3.10.2.1 notes that AASHTO uses the uniform hazard for the 975-year

return period. As is therefore assumed to be 0.55g for the GHA of the project. Kh is calculated

using a minimum of 0.5*AS, which assumes some permanent wall deformation after the MDE is acceptable (AASHTO LRFD 11.6.5.2.2). Live load from rails is taken as a 390 psf uniform vertical surcharge, per RFP documents.

The SLIDE 2018 computer program was used in our slope stability analyses. The Morgenstern- Price and Spencer methods of limit equilibrium were used to evaluate the balance of both forces

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and moments acting within the slope to determine the Factor of Safety (FS) for the slope. The methods assume a circular slip surface, and divides it into slices, each with finite mass. The results of our slope stability analyses are summarized in Table 3. In addition, graphic presentations of our slope stability analyses are presented in Figures 1 to 8.

Table 3. Slope Stability Analysis Results

Calculated Factor of Condition Minimum Requirement Safety Station 5063+50 Existing (Static) [Fig 1A] 1.3 NA Existing (Pseudostatic) [Fig 1B] 0.7 NA Final (Static) [Fig 1C] 1.8 1.5 Final (Pseudostatic) [Fig 1D] 1.2 1.1 Station 5069+00 Existing (Static) [Fig 1E] 1.6 NA Existing (Pseudostatic) [Fig 1F] 0.9 NA Final (Static) [Fig 1G] 1.8 1.5 Final (Pseudostatic) [Fig 1H] 1.3 1.1

Conclusion: The results of the slope stability analyses indicate that the potential for instability at the site includes BOTH the onsite areas (i.e., within the Sound Transit project right-of-way) and offsite areas. Slope stability analyses indicate that the onsite and offsite slopes are stable under static conditions but that slopes within both areas may be unstable during a design level seismic event. Results of the slope stability analysis indicate the proposed retaining wall systems at both selected locations can be designed to provide an appropriate factor of safety against instability in both the onsite areas and offsite areas after the completion of the project in both static and pseudo-static (i.e., seismic) conditions. Our analysis indicates the final overall slope stability at both locations would be improved over the existing condition of the slopes for static and pseudo-static (seismic) conditions.

Temporary Conditions

The temporary, during construction, case for the slopes was not analyzed at this time as the construction sequencing is not yet available. We will work with the construction team during planning and construction to limit temporary slope cuts such that they do not degrade overall global stability of the GHAs during construction of the proposed retaining walls and guideway. Potential temporary construction risks include, but are not limited to, the following: temporary slope cuts being too deep, grading over too large an area, and wet weather during construction could cause local (minor) slope instability.

We understand temporary conditions will likely include installing a haul road roughly parallel to SR-520 and some grading to accommodate the temporary haul road. The exact grading required to accommodate the temporary haul road is not yet known. It is not clear at this time what, if Sound Transit | Downtown Redmond Link Extension Page | 9 April 7, 2020 Attachment 13 Geotechnical Report – Alteration of Geologic Hazard Areas

any, temporary earth retaining systems will be needed in the geologic hazard areas. Temporary slope conditions and any temporary retaining systems will be designed for a minimum static factory of safety (FS) of 1.3 in accordance with the WSDOT Geotechnical Design Manual (GDM) 15-7.3.2. Monitoring

Section 3.4.2 of the Project Requirements, Geotechnical Instrumentation and Monitoring, includes specifications for the Instrumentation Installation and Monitoring Plan; “The Contractor shall develop an Instrumentation Installation and Monitoring Plan (IIMP) for all existing buildings, structures, utilities, and infrastructure along the Project alignment, as deemed necessary by the Contractor and required by permits, to verify successful completion of the Project without causing damage to existing facilities. The IIMP shall be prepared in accordance with Volume 3-02, 31 09 00 Geotechnical Instrumentation and Monitoring of Earthwork.”

In accordance with the Project Requirements, the IIMP will be completed and submitted at least 60 days prior to the start of construction activities. Based on the Project Specifications, Section 31 09 00, we anticipate the IIMP will address the following monitoring in the GHA. Prior to construction baseline readings will be taken of all the monitoring points to establish the existing conditions and provide a basis for comparison.

Optical Survey

We expect optical survey points will be installed at the top of new soil nail retaining walls at the start of construction at intervals of 25 feet or less along the length of the walls. Optical survey points will be used to measure relative horizontal and vertical movement of the walls during and after construction. Optical survey points on new soil nail walls will be monitored at least once daily during construction/excavation of the wall, and at least once per week after completion of the wall and movements have stabilized. The monitoring will continue for four weeks after completion of each wall. Additional reading intervals may be necessary if sudden changes are measured.

Inclinometer

We anticipate inclinometers will be installed above the proposed soil nail walls or at the top of the GHA steep slopes to monitor horizontal movement of the slopes. Inclinometers are typically installed in a vertical plastic casing and can indicate relative movement at specific depths in the slope. Inclinometers will be monitored daily during wall excavation on or below the GHA slopes and at least once per week after wall excavation is completed and movements have stabilized. Additional readings may be necessary if sudden changes are measured.

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Vibration Monitoring

Vibration monitoring will occur during all construction activity within 100 feet of existing structures and buried utilities. Vibration monitoring consists of geophones placed between the construction work and the nearby structure or utility, to measure vibrations in the ground. Vibration monitoring will be continuous during construction work within 100 feet of existing structures or utilities, and work will be stopped immediately if the vibration measurements exceed the specified limits. Geologic Hazard Mitigation Potential Geologic Hazard Impacts

Some temporary construction impacts are discussed in Section 6.1 of this report. This section includes these temporary construction impacts as well as longer-term potential geologic hazard impacts for the project. The onsite and offsite impacts (including adjacent residential parcels) have been identified as having the same potential impacts. In other words, the areas within the Geologic Hazard Areas (i.e., steep slopes) that have the greatest potential for instability straddle both the project right-of-way and adjacent properties, concurrently. Potential geologic hazard impacts are listed below.

Potential Onsite and Offsite Impacts include:

• Temporary slope cuts being too deep could cause local (minor) slope instability.

• Temporary slope cuts or grading over a large area could cause local (minor) slope instability or erosion.

• Temporary open cuts/clearing during construction could cause (minor) sloughing and erosion of the slopes, especially during wet weather.

• Seepage from slope faces during construction could cause local (minor) sloughing and erosion.

• Steepened slopes or large cuts could cause slope instability if not supported with earth retention systems in final configuration.

• Seismic (earthquake) event could cause slope instability if not supported by earth retention systems after construction.

Recommended Mitigation Measures

As the onsite and offsite (including adjacent affected residential parcels) share the same potential impacts, we recommend the following mitigation measures within the GHAs to reduce

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or not adversely affect the existing geologic hazards and address the potential impacts listed above:

• Project design will minimize alterations or reduce steepness of the natural contour of the slopes to the extent practical. • Clearing of existing vegetation on the GHA slopes will be minimized to the extent practical.

• Design will provide retaining wall systems to support slopes where abrupt grade changes are unavoidable due to the track alignment. Retaining walls and other structures will be designed to maintain or enhance the overall stability of the slopes, in both static and seismic (earthquake) conditions. • Design and construction methods should minimize the length and steepness of slopes with exposed soils as much as practical.

• Construction sequencing and methods should be selected to improve or not adversely affect overall slope stability during construction.

• Provide temporary erosion and sedimentation controls during construction to prevent sloughing and erosion of the slopes. (Additional erosion control information provided in Section 8.3 below).

• Permanent erosion protection will be provided by reestablishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. • As mentioned above, a potential seepage layer was noted by Golder (2018b) at an elevation of approximately +140 feet (+/- 5 feet) from Station 5066+00 to 5070+00 [Exhibit GH-03]. Track elevations in this area range from approximately +158 to +175 feet, and construction is not expected to extend to this layer. However, dewatering may be required during construction and possibly permanent horizontal drains, to reduce the risk of soil loss and instability. • RFP drawings V3-01.05 "SR520 148th Ave to SR901_as-builts_July 1978" indicates horizontal drains and piezometers were installed into the hillside during SR 520 construction from about Station 5055+80 to 5071+80 [Exhibit GH-02 to GH-03]. The as-built plans do not include as-built elevations of these drains. If retaining wall or other construction in the GHA impact the existing drainage system, then the construction team should assume that the drainage system will need to be repaired or replaced in-kind. Coordination with WSDOT will likely be required if existing drains are encountered. Erosion and Sedimentation Control

The DRLE project is required to meet all applicable local, State, and Federal regulations to avoid environmental impacts. Potential sources and causes of erosion depend on construction

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methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing, and weather. The impacts on erosion-prone areas, such as steep slopes, will be reduced by implementing an approved erosion and sedimentation control plan.

DRLE project Temporary Erosion and Sedimentation Control (TESC) plans include, but are not limited to, the following items related to GHA on the project:

• Install siltation control fencing around project work areas to protect all adjacent properties from sediment deposition and runoff. • All exposed soils will be stabilized with an approved TESC method (e.g. seeding, mulching, plastic covering, crushed rock) within two days during wet weather months or seven days during dry months.

• Where straw mulch is required for temporary erosion control, it will be applied at a minimum 2-inch thickness. • Provide temporary curb or drainage bypass to direct runoff away from exposed soils and slopes.

• Inspect and maintain erosion and sediment control measures frequently. Repair and/or replacement of dysfunctional erosion control elements should be completed as quickly as possible.

• Decreasing runoff velocities with check dams, straw bales, or wattles. Conclusions

In summary, our findings and recommendations are as follows:

• The project alignment runs through critical landslide hazard areas which are GHAs along eastbound SR 520 between NE 60th Street and the SR 520/WLSP interchange. • Landslide hazards along the project are either reduced or not adversely affected through use of earth retaining systems in areas of slope cut (approximate station 5052+00 to 5064+00 [Exhibit GH-01 to GH-02] and 5067+00 to 5071+50 [Exhibit GH-03]) or by placing fill retention systems at the base of existing slopes, providing new buttressing.

• Temporary construction slope cuts will be further analyzed during the final design process to limit cuts so as not to degrade overall stability of the GHA slopes.

• Proposed site activities must follow best management practices (BMPs) and the proposed mitigation measures in Section 8.0 to ensure construction activities will not adversely affect slope stability.

• The proposed work will be designed, constructed, operated, and maintained in conformance with the contract requirements and appropriate construction practices. As such, landslide

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hazard areas are unlikely to be degraded by the project, and City requirements for GHA will be satisfied. Decision Criteria Analysis and Response

Three decision criteria are identified by the City of Redmond Permitting Framework Attachment H, “DRLE Alteration of Geologic Hazard Areas Checklist” of V2-02.04 of the Contract Requirements. The criteria (A, B, and C) are listed below along with responses to each. A) There must be no reasonable alternative to locating in a Landslide Hazard Area. Alternative locations which would avoid impact to the Landslide Hazard Area must be shown to be economically or functionally infeasible. Response: Sound Transit conducted a lengthy evaluation of potential alternate locations and determined this alignment was the most economically and functionally feasible location. Sound Transit’s analysis and evaluation are shown in the City of Redmond Alteration of Geologic Hazard Area Permit: Alternative Alignment Location Assessment document included with the Alteration of Geologic Hazard Permit Application for this project. B) A geotechnical evaluation must be conducted to identify the risks of damage from the proposal, both on-site and off-site, and to identify measures to eliminate or reduce risks. The proposal must not increase the risk of occurrence of the potential geologic hazard. Response: This report constitutes our geotechnical evaluation of the risks of the proposed construction and identifies measures to eliminate or reduce the risks. Section 6.0 of this report contains our slope stability evaluations and Section 8.0 contains recommended measures to not adversely affect stability of the slopes. In general, the steep slopes altered by this project will be reinforced with earth retaining systems in areas of slope cut, or by placing fill retention systems at the base of existing slopes, providing new buttressing. As indicated in Section 6.0 and elsewhere in this report, the proposed construction is unlikely to increase the risk of occurrence of the geologic hazard. C) Impacts shall be minimized by limiting the magnitude of the proposed construction to the extent possible, any impacts must be eliminated or mitigated by repairing, rehabilitating, restoring, replacing, or providing substitute resources consistent with the mitigation and performance standards set forth in RZC 21.64.010.L and 21.64.010.M. Response: Impacts to the affected geologic hazards will be minimized or mitigated to the extent practical in accordance with the recommendations in Section 8.0 of this report. As mentioned previously the proposed construction should not adversely affect the stability of the slopes, and the contractor will provide monitoring during construction to verify. The construction team is obligated by contract to repair potential damage caused by the project to the geologic hazard areas.

Sound Transit | Downtown Redmond Link Extension Page | 14 April 7, 2020 Attachment 13 Geotechnical Report – Alteration of Geologic Hazard Areas

Report Limitations

The conclusions and recommendations provided in this report are based on the conditions encountered by Golder (2018a, b) in their explorations completed for the DRLE project and our review of available geologic information. Extrapolation of subsurface conditions beyond the field explorations is necessary due to the spacing between explorations and infeasibility of exploring the entire site. Variations may exist between or outside the explorations due to the nature of geologic deposition or alterations such as grading and/or filling. The nature and extent of any variations between the field explorations may not be evident until construction. If variations are observed during construction, it may be necessary to revise specific recommendations in this report. References

American Association of State Highway and Transportation Officials (AASHTO). 2017. AASHTO LRFD Bridge Design Specifications. Customary U.S. units, 8th Ed. Publication no. LRFD-8.

City of Redmond. 2005a. Critical Areas Map for Seismic Hazard Areas. https://www.redmond.gov/DocumentCenter/View/60/Seismic-Hazard-Areas-PDF.

City of Redmond. 2005b. Critical Areas Map for Erosion Hazard Areas. https://www.redmond.gov/DocumentCenter/View/72/Erosion-Hazard-Areas-PDF.

City of Redmond. 2016. Critical Areas Map for Landslide Hazard Areas. https://www.redmond.gov/DocumentCenter/View/71/Landslide-Hazard-Areas-PDF.

King County. 2016. Mapping of Potential Landslide Hazards along the River Corridors of King County, Washington. Seattle, WA. https://gismaps.kingcounty.gov/iMap/. Accessed December 10, 2019.

Golder Associates Inc (Golder). 2018a. Downtown Redmond Link Extension Geotechnical Data Report. Dated July 23, 2018.

Golder Associates Inc (Golder). 2018b. Downtown Redmond Link Extension Geotechnical Baseline Report. Dated October 4, 2018.

Liesch, B.A., Price, C.E., and Walters, K.L. 1963. Geology and ground-water resources of northwestern King County, Washington. Washington Division of Water Resources. Water-Supply Bulletin No. 20. 241 p.

Minard, J.P., and Booth, D.B. 1988. Geologic map of the Redmond quadrangle, King County, Washington U.S. Geological Survey Miscellaneous Field Studies Map MF-2016.

Parametrix, Inc. 2019. City of Redmond Critical Areas Report. Prepared for Sound Transit. February 2019. Sound Transit | Downtown Redmond Link Extension Page | 15 April 7, 2020 Attachment 13 Geotechnical Report – Alteration of Geologic Hazard Areas

United States Department of Agriculture. Web Soil Survey. https://websoilsurvey.sc.egov.usda.gov/. Accessed December 12, 2019.

United States Geologic Survey (USGS). 2019. US Landslide Inventory Map. September 16, 2019. https://www.usgs.gov/natural-hazards/landslide-hazards/maps.

Washington State Department of Natural Resources (WDNR). 2019. Washington State Geologic Information Portal. https://geologyportal.dnr.wa.gov/. Accessed December 9, 2019.

Washington State Department of Transportation (WSDOT). 2015. Geotechnical Design Manual. Publication no. M46-03.12.

Washington State Department of Transportation (WSDOT) and CH2M Hill. 2008. “S R 520 W Lake Sammamish Pkwy to SR 202 HOV and SR 202 Interchange” As-Built Plans. Retaining Wall RW-F1 Plans.

Attachments

Geologic Hazard Area Exhibit – GH-01 to GH-03 Boring Location Plan and Subsurface Profile (Golder) – Figures 3C and 3D Logs for Borings DRLE-G012 to DRLE-G015 Slope Stability Results – Figures 1A to 1H Geotechnical Engineering Resume related to Geologic Hazards – Garry Horvitz, PE

\\seafs\Projects\Notebooks\1942703_DRLE_R200_Heavy_Civil\Deliverables\Reports\Geologic Hazard Critical Area Report rev0\Geotechnical Report - Alteration of Geologic Hazard Area.docx

Sound Transit | Downtown Redmond Link Extension Page | 16 April 7, 2020 Attachment 13

LEGEND:

AREA OF SLOPE (40% OR STEEPER) TOTAL = 119,269 SF, OR 2.74 ACRES

WSDOT JURISDICTIONAL EXISTING STREAM, WETLAND, POND, DITCH OR SURFACE WATER FEATURE 8' OR GREATER NE 60TH ST RETAINING WALLS UNDERCROSSING X GUIDEWAY FENCING SR 520 WSDOT ROW TEMPORARY CONSTRUCTION ESMT SR 520 NO PIN

> >

> NE 60TH ST 60TH NE > > 226

EQNBK = WB E 5046+44.68 EQAHD = WB F 5046+43.16 230 228

15' UTILITY ESMT ARE FROM AFN 7905301039 EQNBK = WB F 5051+84.67 F WB = EQNBK

EQAHD = WB G 5051+86.29 G WB = EQAHD 222

224 0.00' 5052+75.00, WB ST = WB F 5051+84.40 F WB = ST

END BALLAST MAT BALLAST END

252 232 CS = WB E 5044+94.14 E WB = CS

238 236 SC = WB E 5044+31.13 E WB = SC 256 ST = WB E 5046+44.68 246 X

WB 5044+75.86, 0.00' 5044+75.86, WB 248 TS = WB F 5048+08.50 BEGIN BALLAST MAT BALLAST BEGIN 234 254 5050+34.93 F WB = CS X

TS = WB E 5042+80.59 E WB = TS CL WB TRACK 250 5049+57.97 F WB = SC > 256 X

> 258 X

X X X X X X

> 0.4' ^

X X X X X ^ 222

X X X WB E 5045+00 X X X X ^ X ^ ^

X X ^ X 228 X X X X 224 > X X X X X X X 230 224 X X 226 X 256 WB F 5050+00

258 226

228 X

248 244 X

^ X 240 X X

230 ^ 246

232 ^ X 242

238 234 ^ X 264

X l 236 ^

EB 5045+00 ^ 262 260 ^ X X X ^ X X X X ^ X X X X X X X 260 X X^ ^ X X 256 ^ ^X EB 5050+00X

X 258 10' WATER ESMT ARE5' FROM MAINT AFN UTILITY 7905301039 ESMT AFN 7910050386 8.4' 260 256 CL EB TRACK 256 GH-02 DWG SEE

252 R/W NO. RL129 248 244

20' WIDE CITY OF REDMOND UTILITY

258 258 244 254 AFN8405041123-10' POWER ESMT AS CONSTRUCTED IN WHOLE OF

254 242 NO PIN

254 236 LOT 1 ESMT PER SHORT PLAT 250 246 226

AFN8107140077- SEPTIC TANK AND DRAINFIELD ESMT AS

262 252 260 234 220 246 230 CONSTRUCTED IF ENCROACHMENT EXISTS

240 228 224

242 F 236 232 262

248 224 230 238

226 228 234 5053+50 EB STA MATCHLINE: 252 92.8' 232 R/W NO. RL133AFN9811201272-AS CONSTRUCTED NATURAL GAS PIPELINE 10' 252 2.5' MAINT UTILITY ESMT AFN 67.5' WIDE 7904100752 238 AFN19991006900016 MUNICIPAL ACCESS AND UTILITY BLANKET

250 943530TR-BEASEMENT ON TRACT B & UTILITY ESMT 2.5' ON ALL INTERIOR 2507' PUGET POWER ESMT AFN NUMBERED LOT LINES, AND 5' ON ALL EXTERIOR NUMBERED LOT 7904100752 LINES AS WELL AS WEST AND SOUTH LINE OF TRACT B

154TH AVE NE R/W NO. RL132

EB 5052+75.00, 0.00' 5052+75.00, EB END BALLAST MAT BALLAST END

2.5' & 7' PUGET POWER OFFSET EASEMENTS 943530005910' SEWER ESMT AFN 7111050445

AFN 7904100752 5051+86.29 EB = ST

EB 5044+75.00, 0.00' 5044+75.00, EB BEGIN BALLAST MAT BALLAST BEGIN

CS = EB 5044+92.89 EB = CS SC = EB 5044+30.86 EB = SC

ST = EB 5046+42.89

TS = EB 5048+08.24

CS = EB 5050+36.29 EB = CS TS = EB 5042+80.86 EB = TS

LIGHT RAIL TRANSIT WAY (TYP) WAY 59TH NE 248 5049+58.24 EB = SC 15' UTILITY ESMT AFN 7905301039 INGRESS, EGRESS & UTILITIES ESMT AFN 8105070859 R/W NO. NONE 246 9435300055 N

40 20 0 40 80 (1" = 40')

SCALE IN FEET BALLAST B D E D B 290 290 L90-KYX102 L90-KYX104 L90-KYX104 L90-KYX104 L90-KYX102

LVC 170.00' 280 280

HORSE 270 NE 60TH ST 270 TRAIL

EXISTING G/L -4.29% 260 260 BEGIN BALLAST MAT EB 5044+75.00, EL 255.36'

250 250 17.0' MIN PGL (T/LR) PVC EB 5047+54.69 EL 243.34 PVI EB 5048+39.69 EL 239.69

240 PVT EB 5049+24.69 EL 236.91 240

230 -3.28% 230 END BALLAST MAT EB 5052+75.00, EL 225.42' 268.2 265.02 266.9 262.87 265.2 260.72 263.8 258.58 260.1 256.43 258.2 254.28 260.9 252.13 259.4 249.99 253.1 247.84 248.9 245.69 244.9 243.55 245.1 241.46 259.3 239.52 264.3 237.73 250.9 236.08 235.6 234.44 231.8 232.80 224.6 231.16 209.6 229.52 226.2 227.88 230.7 226.24 229.0 224.61 223.3 222.97 5042+50 5044+00 5046+00 5048+00 5050+00 5052+00 5053+50

DESIGNED BY: SCALE: DESIGN DRAWING No.: PACKAGE: GEOLOGIC HAZARD AREA EXHIBIT H: 1" = 40'; V: 1" = 10' GH-01 DRAWN BY: FILENAME: PERMIT INFORMATION: GH-01 FACILITY ID: CHECKED BY: CONTRACT No.: SHEET No.: REV: PLAN & EASTBOUND (EB) PROFILE APPROVED BY: REVIEWED BY: SUBMITTED BY: LINE IS 1" AT FULL SCALE DATE: EB 5042+50 TO EB 5053+50 No. DATE DSN CHK APP REVISION J. SCHETTLER A. TISCAREÑO 12/20/2019 01/08/20 | 3:32 PM | TORREYD C:\PWWORKING\JACOBS_B&I\JEG_TORREYD\D0214667\GH-01.DWG Attachment 13

LEGEND:

AREA OF SLOPE (40% OR STEEPER) TOTAL = 119,269 SF, OR 2.74 ACRES

EXISTING STREAM, WETLAND, POND, OR SURFACE WATER FEATURE WSDOT ROW 8' OR GREATER NO PIN RETAINING WALLS WSDOT JURISDICTIONAL X GUIDEWAY FENCING DITCH SR 520 TEMPORARY CONSTRUCTION ESMT

l l l l l l l l l MATCHLINE: STA EB 5053+50 l l l l l l l l l l l l l l l l l l 194 l 206 200 198 196 192 190 188 186 208 204 202 5059+17.22 G WB = SC 184 182 210 180 212 5057+36.44 G WB = TS SEE DWG GH-01 214 X X X LIGHT RAIL TRANSIT WAY (TYP) X 0.4' X X 216 CL WB TRACK X WB G 5060+00 X FIG 1A - FIG 1D X ^ X 214 218 X ^ ^ 224 X 202 200 198 ^ ^ X 220 X 204 196 ^ X 220 X 206 X 194 ^ 218 216 216 X ^ X

X 192 l X 208

X WB G 5055+00 190 X 210 ^ ^ ^ EB 5060+00 X ^ ^ ^ X ^ X X ^ X ^ ^ X ^ X ^ X ^ X l

212 ^ X ^ ^ X ^ 188 214 ^

216 ^ X 224 ^X ^ ^ X ^ ^ 204X ^ X

^ X ^ 222 208 206 ^

218 ^ 226 X ^ ^ ^ X 210 ^ 186

220 ^ 214 204 ^ l 222 X 216 X ^ 228 224 ^ ^ EB 5055+00X CL EB TRACK 29.5' 206 X ^ X 208 ^ 184 ^ X X 228 57.3' 216 X ^ X 226 218 210 ^ X 218 226 ^ ^ 222 230 54.4' 230 230 228 212214 X ^ 182 X ^ ^ SEE DWG GH-03 54.6' 10' WIDE SANITARY SEWER ESMT 216 X WB^ G 5065+00 234 FOR CITY OF REDMOND AFN 7109230314 218 214 ^ X 232 X ^ ^ FOR CITY OF REDMOND AFN 7109230315 X R/W NO. RL141XX X 10' WIDE SANITARY SEWER ESMT 232 EMERGENCY ACCESS, 212 202 ^ 20' WIDE CITY OF REDMOND UTILITY 9435300076 ESMT PER SHORT PLAT 10' PRIVATE SEWER ESMT 20071204900004 210 200 X AFN20060504900003- 5' WIDE UTILITY ESMT ON ALL EXTERIOR BOUNDARY LINES SEE L90-CRP314 MATCHLINE: STA EB 5064+50 20' WIDE CITY OF REDMOND UTILITY 10' WIDE SANITARY SEWER ESMT UTILITY ESMTS OFFSET FROM LOT BOUNDARIES PER 198 FOR KING COUNTY AFN99.3' 7109230313 AFN19991006900017 208

ESMT PER SHORT PLAT 98.0' AFN1991006900017- UTILITY ESMT2.5' WIDE ON ALL INTERIOR LOT R/W NO. RL142 196 XEB 5065+00

LINES & 5' AFN20060426001230- 10' WIDE PSE ESMT AS CONSTRUCTED OVER WHOLE OF SHORTPLAT 20' WIDE CITY OF REDMOND UTILITY ESMT FOR KING COUNTY AFNAFN9811201272-AS 19991006900017 CONSTRUCTED NATURAL GAS PIPELINE 10' 206 ^ WIDE R/W NO. RL138 XX 194 15' PRIVATE ESMT AFN20020809002593- AGREEMENT TO MAINTAIN ROAD NO PIN 192 SC = EB 5059+16.83 EB = SC R/W NO. RL140 204 FOR STORM DRAINAGE AFN 19991006900017 R/W NO. RL136 9435300065 R/W NO. RL133 5057+36.83 EB = TS 9435300077 AFN9811201272-AS CONSTRUCTED NATURAL943530TR-B GAS PIPELINE 10' R/W NO. RL134 9435300066 AFN19991006900016 MUNICIPAL ACCESS AND UTILITY BLANKET R/W NO. RL135 EASEMENT ON TRACT B & UTILITY ESMT 2.5' ON ALL INTERIOR 20' ACCESS ESMT AFN 19991006900016 R/W NO. RL139 156TH AVE NE NUMBERED LOT LINES, AND 5' ON ALL EXTERIOR NUMBERED LOT 9435300063 5' PRIVATE DRAINAGE ESMT 20060504900003 LINES AS WELL AS WEST AND SOUTH LINE OF TRACT B R/W NO. RL143 9435300062 - 2.5' WIDE UTILITY ESMT ON ALL INTERIOR LOT LINES - BLANKET EMERGENCY VEHICLE ACCESS ESMT 4' UTILITY ESMT 20040513002520 9435300067 N 10' PRIVATE UTILITY ESMT 20071204900004 542256TRCT 10' SEWER ESMT 20060504900003

AFN1991006900017- UTILITY ESMT2.5' WIDE ON ALL INTERIOR LOT LINES & 5' TPSS #E28 AFN9811201272-AS CONSTRUCTED NATURAL GAS PIPELINE 10' WIDE ON ALL EXTERIOR LINES WIDE AFN20020809002593- AGREEMENT TO MAINTAIN ROAD 40 20 0 40 80 (1" = 40')

SCALE IN FEET BALLAST 250 250 B CS = EB 5065+59.83 LVC 170.00' L90-KYX102

240 240

230 230

EXISTING G/L PVC EB 5054+15.03 -3.28% EL 220.83 PVI EB 5055+00.03 220 EL 218.05 220 PVT EB 5055+85.03 EL 214.73

210 210

200 PGL (T/LR) 200

-3.90%

190 190

180 180

170 170 223.3 222.97 215.5 221.33 222.5 219.67 228.5 217.92 227.9 216.08 225.0 214.15 223.9 212.20 224.3 210.25 223.6 208.30 222.0 206.35 221.0 204.40 219.6 202.45 213.7 200.50 208.9 205.0 202.1 208.5 212.1 198.55 196.60 194.65 197.6 192.70 199.6 190.75 188.80 186.85 197.7 184.90 181.7 182.95 170.3 181.00 5053+50 5054+00 5056+00 5058+00 5060+00 5062+00 5064+00 5064+50

DESIGNED BY: SCALE: DESIGN DRAWING No.: PACKAGE: GEOLOGIC HAZARD AREA EXHIBIT H: 1" = 40'; V: 1" = 10' GH-02 DRAWN BY: FILENAME: PERMIT INFORMATION: GH-02 FACILITY ID: CHECKED BY: CONTRACT No.: SHEET No.: REV: PLAN & EASTBOUND (EB) PROFILE APPROVED BY: REVIEWED BY: SUBMITTED BY: LINE IS 1" AT FULL SCALE DATE: EB 5053+50 TO EB 5064+50 No. DATE DSN CHK APP REVISION J. SCHETTLER A. TISCAREÑO 12/20/2019 01/08/20 | 3:32 PM | TORREYD C:\PWWORKING\JACOBS_B&I\JEG_TORREYD\D0214667\GH-02.DWG Attachment 13

LEGEND: 5' NOISE WALL MAINT. ESMT WSDOT ROW PLAN: 520_NORTHRUP_INTERCHANGE_TO_JCT_SR_202.PDF AREA OF SLOPE (40% OR STEEPER) WSDOT JURISDICTIONAL DITCH TOTAL = 119,269 SF, OR 2.74 ACRES WSDOT ROW SR 520 NO PIN SR 520 EXISTING STREAM, WETLAND, POND, OR SURFACE WATER FEATURE APPROACH SLAB WSDOT SLOPE DRAINAGE & 8' OR GREATER FIG 1E - FIG 1H TRANSITIONNOISE WALL SLAB MAINT. ESMT. RETAINING WALLS LIGHT RAIL TRANSIT WAY (TYP) WSDOT ROW PLAN: 520_NORTHRUP_INTERCHANGE_TO_JCT_SR_202.PDF X GUIDEWAY FENCING > > 116 MATCHLINE: STA EB 5064+50 > 144 > 142 COLUMN (TYP) 146 > 110 152 148 142 140136 128 122 l 156 154 150 132 126 114 0.39' > 158 X X TEMPORARY CONSTRUCTION ESMT l l 160 X X ^ ^ ^ ^ X X 162 X ^ ^ ^ SD ^ WB G 5070+00SD ^ SD^ ^ ^ X > SR 520 l > X ^ ^ ^ ^ ^ 112 X ^ SD 156 l OFF RAMP SD 106

l CL WB TRACK ^ SD^ 162 160 158 154 152 SD SC = WB G 5066+26.75 G WB = SC ^ l > X ^ 166 164 SD SEE DWG GH-02 X ^ l l ^ 168 l

> 152 SD > 102 CS = WB G 5065+66.27 G WB = CS ^ 108 X ^ 170 EB 5070+00 l 154 ^ SD ^ ^ X X X X X X X ^ ^ X 150 ^ 172 ^ ^ X 136 100 SD > 156 ^ ^ X 16.6' 20' VEGITATION ESMT 7607090632 X ^ X ^ 148146 l l 158 ^ ^ 134

^ 174 ^ X 182 144 WB G 5075+00SD X SD ^ 184 20' VEGITATION ESMT 7607090632 142 132 120 104 > 160 ^ ^ X 42.9' 124 104> ^ BWA 190 188 186 140 130 162 X ^ X 138 128 122 114 108 SD 62.5' 118 102 98 SD ^ 178 126 112 106

WB G 5065+00 176 116 110 l

X ^ X 168 CL EB TRACK SD 96

^ 170 R/W NO. RL144 180 R/W NO. RL147 ^ 182 180 ^ 172 89.7' EB 5075+00 X ^ E79 174 192 X 178 5422560680 5422560650 OSD 176 180 R/W NO. RL145 94 ^SD 182 98.6' 192 184 194 R/W NO. RL146 XEB 5065+00196 5422560670 BWA 190 186 188 5422560660 92 198 194 184 92

X 200 FOR PARTS OF THE MEADOWS PLAT 202 196 ^ E80 180 178 ^ X HOA COMMON USE AREA R/W NO. RL149 204 5422560630 CCRR/W AND NO. RL143 ENCUMBERANCES LISTED IN 176 206 542256TRCT AFN7701110259,7805150590,7905110776,8108110413174 172 R/W NO. RL150

208 5066+19.83 EB = SC R/W NO. RL148

5422560640 5422560620 CS = EB 5065+59.83 EB = CS ALSO NEED TO REFERENCE ALL 520 DEDICATIONS FROM ALL TITLE N

REPORTS FOR P3 40 20 0 40 80 (1" = 40')

SCALE IN FEET EB 5071+39.90 BALLAST DIRECT FIXATION B G 190 190 L90-KYX102 L90-KYX105 LVC 420.00' F L90-KYX105

180 180

-3.90% PVC EB 5067+35.95 EL 169.85 170 170 PVI EB 5069+45.95 EL 161.66

160 160 PVT EB 5071+55.95 EL 149.05 150 150 PGL (T/LR)

140 140 TRANSITION SLAB -6.00% APPROACH SLAB

130 130 EXISTING G/L

120 120

COLUMN (TYP) AERIAL GUIDEWAY SR 520 110 OFF-RAMP 110 96.0 98.5 170.3 181.00 179.4 179.05 168.5 177.10 155.7 175.15 163.8 173.20 172.5 171.25 176.0 169.29 171.8 167.25 176.3 165.07 171.6 162.78 160.35 157.80 155.13 149.5 152.33 136.6 149.40 124.1 146.40 114.9 143.40 106.4 140.40 105.1 137.40 102.5 134.39 131.39 128.39 106.5 125.39 5064+50 5066+00 5068+00 5070+00 5072+00 5074+00 5075+50

DESIGNED BY: SCALE: DESIGN DRAWING No.: PACKAGE: GEOLOGIC HAZARD AREA EXHIBIT H: 1" = 40'; V: 1" = 10' GH-03 DRAWN BY: FILENAME: PERMIT INFORMATION: GH-03 FACILITY ID: CHECKED BY: CONTRACT No.: SHEET No.: REV: PLAN & EASTBOUND (EB) PROFILE APPROVED BY: REVIEWED BY: SUBMITTED BY: LINE IS 1" AT FULL SCALE DATE: EB 5064+50 TO EB 5075+50 No. DATE DSN CHK APP REVISION J. SCHETTLER A. TISCAREÑO 12/20/2019 01/08/20 | 3:35 PM | TORREYD C:\PWWORKING\JACOBS_B&I\JEG_TORREYD\D0214667\GH-03.DWG Attachment 13

H-A-2 WB 5065+00 WB 5070+00 DRLE-G014 H-A-3 EB 5065+00 EB 5070+00 WB 5060+00

DRLE-G013EB 5060+00

DRLE-G012WB 5055+00 EB 5055+00 DRLE-G011

WB 5050+00 EB 5050+00

WB 5045+00 DRLE-G010 EB 5045+00

WB 5040+00 EB 5040+00 DRLE-G008

WB 5035+00 EB 5035+00 DRLE-G008 320 39.2 320 DRLE-G010 NE 60TH ST 300 25.6 300 DRLE-G011 DRLE-G012 280 af 83.7 79.9 280 260 Qva 260 TD 26.5 af 240 DRLE-G013 240 Qvd/Qvgl 69.9 Qvt 220 DRLE-G014 220 59.3 H-A-2 TD 41.5 Qvt 60.9 200 200 ATD af H-A-3 TD 41.5 12.0 180 180 TD 50.4 Qva Qvt 160 160 TD 51.5 Qva 140 140 Qva 120 TD 51.3 120 TD 48.5 100 100

80 TD 58.5 80 Qvd/Qvgl 60 60

40 40

20 20

0 0

5035+00 5040+00 5045+00 5050+00 5055+00 5060+00 5065+00 5070+005071+00

LEGEND NOTE(S) REFERENCE(S) · SEE RECORDS OF BOREHOLES IN GEOTECHNICAL DATA REPORT FOR SUBSURFACE BASE DRAWINGS, PROVIDED BY SOUND TRANSIT, IN DWG FORMAT. GOLDER BOREHOLE LOCATION AND ID INFORMATION AND DATA AT INDIVIDUAL LOCATIONS. · CONTACTS BETWEEN SOIL UNITS ARE BASED ON BOREHOLE INFORMATION AND PROPOSED EASTBOUND TRACK ALIGNMENT REPRESENT THE INTERPRETATION OF SUBSURFACE CONDITIONS. THE BASELINE 0 50 100 ELEVATION OF SOIL UNIT CONTACTS IS PLUS OR MINUS 5 FEET OF THE ELEVATION SHOWN 1'' = 50' VERT. FEET BORING LOCATION AND ID (BY OTHERS) ON THE SOIL PROFILES. · COMPLETE SOIL UNIT DESCRIPTIONS ARE PROVIDED IN SECTION 5.0 OF THE 0 200 400 GEOTECHNICAL BASELINE REPORT (GBR). 1'' = 200' HORIZ. FEET · FOR THE PURPOSE OF THIS GBR IN ESTABLISHING SOIL CONDITIONS, THE CONTRACTOR IS RESPONSIBLE FOR SOIL CONDITIONS BEYOND THE DEPTH SHOWN ON THE SOIL PROFILES. DESIGNED BY: SCALE: PROJECT: DRAWING No.: SOUND TRANSIT DOWNTOWN REDMOND DF 1" = 200' 1657705_200_GDR_003 DRAWN BY: FILENAME: LINK EXTENSION THR 1657705_200_GDR_003 KING COUNTY, WASHINGTON LOCATION ID: REDMOND CHECKED BY: ENGINEERING . PLANNING . ENVIRONMENTAL SCIENCES FULL SCALE CONTRACT No.: TITLE: LINE IS 1" AT PLAN AND PROFILE - STA 5035+00 - 5071+00 BB 1657705/200 FIGURE: REV: APPROVED BY: SUBMITTED BY: DATE: REVIEWED BY: DATE: DATE: 0 2018-09-05 DF BB RAM FINAL 3C 0 No. DATE DSN CHK APP REVISION RAM GOLDER 2018-09-07 2018-09-07 09/05/18 | 2:01 PM | NCHRISTENSEN | 2:01 PM09/05/18 | G:\SOUNDTRANSIT\REDMONDLINK\99_PROJECTS\1657705_REDMONDLINK\200\02_PRODUCTION\DWG\1657705_200_GDR_003.DWG Attachment 13

WB 5125+00 DRLE-G018 WB 5090+00 WB 5095+00 DRLE-G027EB 5125+00 WB 5085+00 WB 5100+00 WB 5105+00 DRLE-G020 DRLE-G021 WB 5110+00 DRLE-G016 EB 5090+00 EB 5095+00 DRLE-G022 DRLE-G023 WB 5080+00 EB 5085+00 EB 5100+00 EB 5105+00 WB 5115+00 APPROXIMATE DRLE-G045 EB 5110+00DRLE-G024 EB 5120+00 SE REDMOND EB 5080+00 DRLE-G023b EBDRLE-G025 5115+00 DRLE-G017 DRLE-G044 STATION AREA WB 5075+00 DRLE-G017a DRLE-G019 EB 5075+00 DRLE-G015

H-A-3

H-A-2WB 5070+00 EB 5070+00

160 DRLE-G015 160 14.9 WEST LAKE SAMMAMISH PARKWAY NE 140 SAMMAMISH RIVER 140 DRLE-G016 DRLE-G017 DRLE-G018(PMT) (SW) DRLE-G023b 120 34.9 77.3 29.5 0.2 120 DRLE-G017a DRLE-G044 100 143.5 30.5 100 af DRLE-G019DRLE-G045 DRLE-G020 DRLE-G021 DRLE-G022 DRLE-G023 DRLE-G024 DRLE-G025 DRLE-G027 80 25.8 37.7 11.6 2.4 1.1 0.3 19.7 15.4 12.6 80 60 af/Hp 60 af af/Hp 40 ATD 40 ATD ATD ATD Ha ATD ATD ATD 20 20 TD 101 Qvd/Qvgl Ha Ha Ha Ha 0 Ha Ha 0 TD 60 TD 51.5 TD 51.5 -20 TD 51.5 TD 51.5 TD 51.5 TD 51.5 -20 TD 101.5 -40 -40

-60 -60 Hl Hl -80 Qvd/Qvgl -80 -100 Hl -100

-120 -120 Qvgl TD 160 -140 -140 Qvgl -160 -160 TD 201 -180 -180 TD 220 Qvd Qvd -200 TD 240.1 Qvd TD 225 TD 225 -200

5071+00 5075+00 5080+00 5085+00 5090+00 5095+00 5100+00 5105+00 5110+00 5115+00 5120+00 5125+00

DESIGNED BY: SCALE: PROJECT: DRAWING No.: SOUND TRANSIT DOWNTOWN REDMOND DF 1" = 200' 1657705_200_GDR_004 DRAWN BY: FILENAME: LINK EXTENSION THR 1657705_200_GDR_004 KING COUNTY, WASHINGTON LOCATION ID: REDMOND CHECKED BY: ENGINEERING . PLANNING . ENVIRONMENTAL SCIENCES FULL SCALE CONTRACT No.: TITLE: LINE IS 1" AT PLAN AND PROFILE - STA 5071+00 - 5125+00 BB 1657705/200 FIGURE: REV: APPROVED BY: SUBMITTED BY: DATE: REVIEWED BY: DATE: DATE: 0 2018-09-05 DF BB RAM FINAL 3D 0 No. DATE DSN CHK APP REVISION RAM GOLDER 2018-09-07 2018-09-07 09/05/18 | 2:09 PM | NCHRISTENSEN | 2:09 PM09/05/18 | G:\SOUNDTRANSIT\REDMONDLINK\99_PROJECTS\1657705_REDMONDLINK\200\02_PRODUCTION\DWG\1657705_200_GDR_004.DWG Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G012 SHEET: 1 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 2, 2017 09:43 GS ELEV.: 223.2 feet PROJECT NO.: 1657705 DRILLING END: November 2, 2017 12:14 TOC ELEV.: na LOCATION: NB SR520 Shoulder COORDINATES: N: 344,115 E: 1,419,864 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 0 0.0 223.2 20 40 60 80 (PT), SANDY PEAT, some fine sand, very dark brown-brown; moist PT 1.8 221.4 (SM), SILTY SAND, fine to coarse sand, some nonplastic fines, trace fine to coarse 32 subangular gravel, pale gray-blue; medium 15-14-18 13 SS dense to very dense, moist, iron staining S-1 (32) 18

5 5: S-2: % Fines = 37 3-5-12 12 17 SS

S-2 (17) 18

Color change to pale tan gray 44-14-27 11 41 SS

S-3 (41) 18

10 11-30-50/4" 12

SS >>

S-4 (80/10") 16

Trace wood fragments SM 6-16-16 13 32 SS

S-5 (32) 18

15 Color change to pale brown 27-30-26 14

SS >>

S-6 (56) 18

SS 50/4" 2 >> S-7 (50/4") 4 Hollow Stem Auger Stem Hollow

24.0 199.2 (SP), POORLY GRADED SAND WITH 25 GRAVEL, fine to coarse sand, little fine to coarse subrounded gravel, trace 26-50/5" 11

SS >> nonplastic fines, pale gray to dark gray; S-8 (50/5") 11 very dense, moist SP

30 30.5 192.7 13-25-35 18 (SP-SM), POORLY GRADED SAND WITH

SS >>

S-9 (60) 18 SILT, fine sand, few nonplastic fines, pale tan-brown; very dense, moist to wet 32.7 ft, ADT

35 6-inch thick lense of Sandy Silt SP-SM 26-28-27 18

SS (55) 18 >> S-10 S-10

40 Log continued on next page

DRILLING CO.: Holt Services Inc LOGGED: Daniel Bida DRILLER: Todd Knipscheld CHECKED: Margaret Pryor DRILL RIG: Mobile B58 REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G012 1 of 2 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G012 SHEET: 2 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 2, 2017 09:43 GS ELEV.: 223.2 feet PROJECT NO.: 1657705 DRILLING END: November 2, 2017 12:14 TOC ELEV.: na LOCATION: NB SR520 Shoulder COORDINATES: N: 344,115 E: 1,419,864 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 40 40.0 183.2 20 40 60 80 (SP-SM), POORLY GRADED SAND WITH 12-18-50/5" 17

SILT, fine sand, few nonplastic fines, pale SS (68/11") 17 >> tan-brown; very dense, moist to wet S-11 (continued) SP-SM

44.0 179.2 (SP), POORLY GRADED SAND WITH 45 GRAVEL, fine to coarse sand, little fine to

coarse subrounded to subangular gravel, SS 50/5" 5 >> pale brown-tan; very dense, wet S-12 (50/5") 5

Hollow Stem Auger Stem Hollow SP

50 50.4 172.8

SS 50/5" 5 >> Bottom of borehole at 50.4 ft. S-13 (50/5") 5 Backfilled with bentonite chips.

DRILLING CO.: Holt Services Inc LOGGED: Daniel Bida DRILLER: Todd Knipscheld CHECKED: Margaret Pryor DRILL RIG: Mobile B58 REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G012 2 of 2 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G013 SHEET: 1 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 3, 2017 09:45 GS ELEV.: 205.6 feet PROJECT NO.: 1657705 DRILLING END: November 3, 2017 12:14 TOC ELEV.: na LOCATION: EB SR520 Shoulder COORDINATES: N: 344,452 E: 1,419,988 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 0 0.0 205.6 20 40 60 80 (ML), SANDY SILT, nonplastic fines, some fine to medium sand, very dark brown; moist ML

2.5 203.1 (SM), SILTY SAND WITH GRAVEL, fine to 5-12-18 18 30

coarse sand, some nonplastic fines, little SS

S-1 (30) 18 fine to coarse subrounded to subangular gravel, pale gray; medium dense, moist, 5 trace wood fragments SM 5: S-2: % Fines = 28 4-5-6 2 11 SS

S-2 (11) 18

7.5 198.1 (SP), POORLY GRADED SAND WITH 5-7-12 0 19

GRAVEL, fine to medium sand, few fine to SS

S-3 (19) 18 coarse subrounded to subangular gravel, trace nonplastic fines, light tan-brown; 10 medium dense to very dense, moist to wet 18-16-18 18 34 SS

S-4 (34) 18

SP 15-20-16 11 36 SS

S-5 (36) 18 Brown, Lean Clay (CL) observed in tip of 15 sampler shoe (S-5) 16-21-30 12 15.4 ft, 03/04/2018 VWP reading

SS >>

S-6 (51) 18 15.5 ft, 06/02/2018 VWP reading 17.5 188.1 (SP), POORLY GRADED SAND, fine to coarse sand, trace nonplastic fines, pale tan-gray; dense to very dense, wet 20 8-12-19 18 31 SS

S-7 (31) 18 Hollow Stem Auger Stem Hollow

25 24.7 ft, ADT 6 inch thick lense of Sandy Silt; color 22-34-40 18

change to pale tan SS (74) 18 >> S--8

30 30: 6 inches of heave Increased coarse sand content 20-50/5" 11 in S-9

SS >> S-9 (50/5") 11

35 35: 6 inches of heave Color change to pale gray brown 19-28-50/4" 16 in S-10

SS (78/10") 16 >> S-10 S-10

40 Log continued on next page

DRILLING CO.: Holt Services Inc. LOGGED: Daniel Bida DRILLER: Todd CHECKED: Margaret Pryor DRILL RIG: Mobile B58 Truck REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G013 1 of 2 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G013 SHEET: 2 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 3, 2017 09:45 GS ELEV.: 205.6 feet PROJECT NO.: 1657705 DRILLING END: November 3, 2017 12:14 TOC ELEV.: na LOCATION: EB SR520 Shoulder COORDINATES: N: 344,452 E: 1,419,988 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 40 40.0 165.6 20 40 60 80 (SP), POORLY GRADED SAND, fine to 5-18-50 18

coarse sand, trace nonplastic fines, pale SS (68) 18 >> tan-gray; dense to very dense, wet S-11 (continued)

45 45: VWP installed Color change to dark gray 10-50/5" 11 SP SS >>

S-12 S-12 (50/5") 11 Hollow Stem Auger Stem Hollow

50 Color change to pale gray 10-20-50 18

SS (70) 18 >> 51.5 154.1 S-13 Bottom of borehole at 51.5 ft. Installed vibrating wire piezometer

DRILLING CO.: Holt Services Inc. LOGGED: Daniel Bida DRILLER: Todd CHECKED: Margaret Pryor DRILL RIG: Mobile B58 Truck REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G013 2 of 2 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G014 SHEET: 1 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 6, 2017 09:30 GS ELEV.: 179.6 feet PROJECT NO.: 1657705 DRILLING END: November 6, 2017 12:12 TOC ELEV.: na LOCATION: EB SR520 shoulder COORDINATES: N: 344,876 E: 1,420,171 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 0 0.0 179.6 20 40 60 80 (ML), SILT, nonplastic fines, trace fine 0 - 28: Difficult drilling sand, trace coarse rounded gravel, pale gray; hard, moist to wet

9-18-30 18 48 SS

S-1 (48) 18

5 6-18-29 18 47 SS

S-2 (47) 18

16-30-50 18

SS >>

S-3 (80) 18

10 20-40-50/5" 17

SS >>

S-4 (90/11") 17

18-30-39 18

SS >>

S-5 (69) 18 ML 15 22-30-50 18

SS >>

S-6 (80) 18

20 10-30-50 18

SS >>

S-7 (80) 18 Hollow Stem Auger Stem Hollow

24.2 ft, ADT 25 22-36-50 18

SS >>

S-8 (86) 18

28.0 151.6 (SP), POORLY GRADED SAND, fine sand, trace nonplastic fines, pale gray; dense to very dense, wet 30 30: S-9: % Fines = 4 8-8-26 18 34 SS

S-9 (34) 18

35 22-28-34 18

SS (62) 18 >> S-10 S-10

39.0 140.6 SM 40 40: S-11: % Fines = 16 Log continued on next page

DRILLING CO.: Holt Services Inc. LOGGED: Daniel Bida DRILLER: Todd CHECKED: Margaret Pryor DRILL RIG: Mobile B58 Truck REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G014 1 of 2 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G014 SHEET: 2 of 2 PROJECT: Downtown Redmond Link Extension DRILLING START: November 6, 2017 09:30 GS ELEV.: 179.6 feet PROJECT NO.: 1657705 DRILLING END: November 6, 2017 12:12 TOC ELEV.: na LOCATION: EB SR520 shoulder COORDINATES: N: 344,876 E: 1,420,171 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES

(ft) per 6 in REC WATER LEVELS DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 40 40.0 139.6 20 40 60 80 (SM), SILTY SAND, fine sand, little 6-10-22 18 32

nonplastic fines, pale gray; dense to very SS (32) 18 dense, wet (continued) S-11

45 SM 22-34-50/5" 17 SS (84/11") 17 >> S-12 S-12 Hollow Stem Auger Stem Hollow

50 28-40-50/4" 16

SS (90/10") 16 >> 51.3 128.3 S-13 Bottom of borehole at 51.3 ft. Backfilled with bentonite chips.

(ft) LOCATION: PROJECT: DRILL RIG:

DRILLER: BORING Addendum 05, Item05 Addendum Mud rotary METHOD 0.0 Depth fragments, glass, and plastic dense to very dense, trace moist, wood nonplastic fines, pale gray-brown; medium subangular to angular gravel, little fine to coarse sand, some fine to coarse (SM), FILL: SILTY SAND GRAVEL, WITH EB SR520 shoulder 1657705 Downtown Redmond Link Extension Mobile B58 Truck Todd Holt Services Inc. Log continued on next page Log continued DESCRIPTION SOIL PROFILE RECORD OF BOREHOLE DRLE-G015 110.0 Elev SM USCS DRILLING START: COORDINATES: DRILLING END: REVIEWED:

CHECKED: GRAPHIC LOGGED: LOG

SAMPLE Reports andStudies-V3-05.02 Volume 3-Item05,Geotechnical SS SS SS SS SS SS SS SS SS SS TYPE & S-10 S-9 S-8 S-7 S-6 S-5 S-4 S-3 S-2 S-1 NUMBER SAMPLES Dave Findley Margaret Pryor Daniel Bida 40-46-50/4" Hammer,30 inch Automatic140 lb 4-30-50/5" N: 34 13:36 2017 8, November November 7, 2017 10:10 11-12-14 22-26-30 23-22-27 12-40-22 12-50/5" BLOWS per 6 in (80/11") (96/10") (50/4") (50/5") 7-7-7 7-5-6 50/4" (14) (11) (26) (56) (49) (62) drop 5, 657 E:1,42 REC ATT 18 14 17 13 18 13 18 12 18 18 14 18 11 16 12 (in) 9 7 8 4 4 W 1, PENETRATION RESISTANCE p 021 WATER CONTENT (%) 04 080 60 40 40 20 30 20 10 11 14

BLOWS /ft BLOWS 26 W Attachment >> >> >> >> >> >> W 49 l TOC ELEV.:TOC GS ELEV.: DATUM: HE:1 of 3 SHEET: 2.5: Possible cobbles 35: S-10: % Fines = 24 32: chatter Drilling 25: S-8: % Fines = 23 22: chatter Drilling 20: S-7: % Fines = 28 NOTES 13 110.0 NAVD88/Project Datum na DRLE-G015 feet 1 of 3 ADDITIONAL LAB TESTING Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G015 SHEET: 2 of 3 PROJECT: Downtown Redmond Link Extension DRILLING START: November 7, 2017 10:10 GS ELEV.: 110.0 feet PROJECT NO.: 1657705 DRILLING END: November 8, 2017 13:36 TOC ELEV.: na LOCATION: EB SR520 shoulder COORDINATES: N: 345,657 E: 1,421,021 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES (ft) per 6 in REC DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 40 40.0 70.0 20 40 60 80 7-18-30 10 48

SS (48) 18 SM S-11

42.5 67.5 (CH), FAT CLAY WITH SAND, high plasticity fines, trace fine to coarse sand, trace fine to coarse subrounded to rounded gravel, pale gray; hard, moist 45 Thin seams < 1/4 inch thick of preserved 9-20-30 18 50

wood fibers observed throughout SS (50) 18 S-12 S-12

50 50: S-13: PI = 37 19-30-50/5" 17

SS (80/11") 17 >> S-13 S-13

55 55: S-14: % Fines = 91 12-23-50 18

SS (73) 18 >> S-14 S-14

60 16-21-30 18

SS >> Mud rotary Mud

S15 S15 (51) 18

65 17-28-37 18

SS (65) 18 >> S-16 S-16

70 70: S-17: PI = 46 21-17-28 18 45

SS (45) 18 S-17 S-17

74.0 36.0 (CH), SANDY FAT CLAY, high plasticity 75 fines, some fine to coarse sand, trace fine 75: S-18: % Fines = 55 to coarse subrounded to rounded gravel, 19-28-36 18

pale gray; hard, moist SS (64) 18 >> S-18 S-18 CH

80 Log continued on next page

DRILLING CO.: Holt Services Inc. LOGGED: Daniel Bida DRILLER: Todd CHECKED: Margaret Pryor DRILL RIG: Mobile B58 Truck REVIEWED: Dave Findley 01 - GOLDER - BOREHOLE STD US LAB RECORD DF 6/28/18 E-M.GDT - - 08:40 C:\USERS\CSCHAEFFER\DESKTOP\DRLE LOGS.GPJ DRLE-G015 2 of 3 Addendum 05, Item 05 Volume 3 - Item 05, Geotechnical ReportsAttachment and Studies - V3-05.02 13 RECORD OF BOREHOLE DRLE-G015 SHEET: 3 of 3 PROJECT: Downtown Redmond Link Extension DRILLING START: November 7, 2017 10:10 GS ELEV.: 110.0 feet PROJECT NO.: 1657705 DRILLING END: November 8, 2017 13:36 TOC ELEV.: na LOCATION: EB SR520 shoulder COORDINATES: N: 345,657 E: 1,421,021 DATUM: NAVD88/Project Datum

SOIL PROFILE SAMPLES PENETRATION RESISTANCE BLOWS / ft BLOWS 10 20 30 40 NOTES (ft) per 6 in REC DESCRIPTION WATER CONTENT (%) BORING DEPTH

METHOD Automatic 140 lb Depth Elev

LOG ATT

USCS Hammer, 30 inch W ADDITIONAL

TYPE & W W p l LAB TESTING SAMPLE NUMBER GRAPHIC drop (in) 80 80.0 30.0 20 40 60 80 (CH), SANDY FAT CLAY, high plasticity 36-50/5" 11 >> fines, some fine to coarse sand, trace fine SS (50/5") 11 to coarse subrounded to rounded gravel, S-19 pale gray; hard, moist (continued)

85 50/5" 5

SS >>

S-20 S-20 (50/5") 5

90 CH 40-50/5" 11

SS >> (50/5") 11 S-21 S-21 Mud rotary Mud

95 30-29-26 18

SS (55) 18 >> S-22 S-22

100 40-50/5" 11

SS >> 101.0 9.0 (50/5") 11 S-23 S-23 Bottom of borehole at 101.0 ft. Backfilled with bentonite grout. Groundwater not observed during drilling

105

110

115

120

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg)

Glacial Dri (Qvd) 130 Mohr-Coulomb 0 37

Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35 220

Method Name Min FS

Spencer 1.302

GLE / Morgenstern-Price 1.300 200 180 160 140

0 20 40 60 80 100 120 140 160 180 200 Downtown Redmond Link Extension Redmond, Washington

Station 5063+50 Existing

19427-03 Scale 1:247 12/19/2019 Figure 1A Attachment 13

0.28 240

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg)

Glacial Dri (Qvd) 130 Mohr-Coulomb 0 37

Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35 220 Method Name Min FS

Spencer 0.788

GLE / Morgenstern-Price 0.786 200 180 160 140

0 20 40 60 80 100 120 140 160 180 200 Downtown Redmond Link Extension Redmond, Washington

Station 5063+50 Existing

19427-03 Scale 1:247 12/19/2019 Figure 1BB Attachment 13

Out-Of-Plane Tensile Capacity Plate Capacity Shear Capacity Compression Bond Strength Material Support Name Color Type Force Applicaon Force Orientaon Spacing () (lbs) (lbs) (lbs) Capacity (lbs) (lbs/) Dependent 240 Soil Parallel to #11 soil nail (Grade 75) Passive (Method B) 6 105000 100 0 0 50 Yes Nail Reinforcement

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg)

Glacial Dri (Qvd) 130 Mohr-Coulomb 0 37

Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35

220 Shotcrete Wall 150 Mohr-Coulomb 4000 42 1.823

Method Name Min FS

Spencer 1.823

GLE / Morgenstern-Price 1.805 200 Track Live Load = 390 psf

390.00 lbs/ft2 180 160 140 0 20 40 60 80 100 120 140 160 180 Downtown Redmond Link Extension Redmond, Washington

Station 5063+50 Final

19427-03 Scale 1:215 12/19/2019 Figure 1CC Attachment 13 240 0.28

Soil Parallel to #11 soil nail (Grade 75) Passive (Method B) 6 105000 100 0 0 50 Yes Nail Reinforcement 220 Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg)

Glacial Dri (Qvd) 130 Mohr-Coulomb 0 37

Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35

Shotcrete Wall 150 Mohr-Coulomb 4000 42 200 Method Name Min FS Track Live Load = 390 psf Spencer 1.205

GLE / Morgenstern-Price 1.207

390.00 lbs/ft2 180 160 140

0 20 40 60 80 100 120 140 160 180 200 Downtown Redmond Link Extension Redmond, Washington

Station 5063+50 Final

19427-03 Scale 1:236 12/19/2019 Figure 1DD Attachment 13

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg) 200 Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35

Method Name Min FS

180 Spencer 1.611

GLE / Morgenstern-Price 1.611 160 140

40 60 80 100 120 140 160 Downtown Redmond Link Extension Redmond, Washington

Station 5069+00 Existing

19427-03 Scale 1:172 12/19/2019 Figure 1EE Attachment 13

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg) 200 Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35 0.28

Method Name Min FS

180 Spencer 0.938

GLE / Morgenstern-Price 0.941 160 140

40 60 80 100 120 140 160 Downtown Redmond Link Extension Redmond, Washington

Station 5069+00 Existing

19427-03 Scale 1:161 12/19/2019 Figure 1FF Attachment 13

Unit Weight Cohesion Phi Material Name Color Strength Type (lbs/3) (psf) (deg) 200 Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35

Shotcrete Wall 150 Mohr-Coulomb 4000 42

Soil Parallel to #10 soil nail (grade 75) Passive (Method B) 6 86000 100 0 0 50 Yes Nail Reinforcement

Method Name Min FS

180 Spencer 1.893 1.893

GLE / Morgenstern-Price 1.897

Track Live Load = 390 psf

390.00 lbs/ft2 160 140

40 60 80 100 120 140 160 Downtown Redmond Link Extension Redmond, Washington

Station 5069+00 Final

19427-03 Scale 1:171 12/19/2019 Figure 1GG Attachment 13

Unit Weight Cohesion Phi Water Material Name Color Strength Type Ru (lbs/3) (psf) (deg) Surface

200 0.28 Glaciolacustrine (Qvgl) 130 Mohr-Coulomb 50 35 None 0

Shotcrete Wall 150 Mohr-Coulomb 4000 42 None 0

Soil Parallel to #10 soil nail (grade 75) Passive (Method B) 6 86000 100 0 0 50 Yes Nail Reinforcement

Method Name Min FS

180 Spencer 1.391

GLE / Morgenstern-Price 1.394

Track Live Load = 390 psf

390.00 lbs/ft2 160 140

40 60 80 100 120 140 160 Downtown Redmond Link Extension Redmond, Washington

Station 5069+00 Final

19427-03 Scale 1:170 12/19/2019 Figure 1HH Attachment 13

GARRY E. HORVITZ, PE, LEG Senior Principal Geotechnical Engineer

EDUCATION Garry has 44 years of geotechnical engineering experience including project management and senior-level review for soil and foundation studies and MS, Civil (Geotechnical) Engineering, Massachusetts engineering design for hundreds of developments and redevelopments in the Institute of Technology, Puget Sound area. His expertise includes engineering for landslide stabilization; 1975 slope stability evaluations in Environmentally Critical Areas; slope and BS, Civil Engineering, State embankment design; trails, pavement, and roads; and geotechnical engineering University of New York at design of roadways, utilities, tunnels and elevated structures. Buffalo, 1973 REGISTRATIONS REPRESENTATIVE PROJECT EXPERIENCE

Professional Engineer, Landslide Evaluation and Mitigation, Issaquah, WA WA, 1981, #19478 HI, 1992, #7705 Garry is Principal in Charge of geotechnical engineering services for evaluation AK, #AELC-5255 and mitigation/remediation of a 150-foot-high landslide that occurred during Licensed Engineering interim grading activities. Original pre-landslide design work was performed by Geologist, WA other firms; the site owner called on Hart Crowser to evaluate the 2002, #2201 appropriateness of the proposed solutions and advance the remedial Transportation Worker alternatives. Garry’s team reviewed the available information, technical analysis, Identification Credential and remedial design plans; conducted a site reconnaissance; discussed likely AFFILIATIONS causes of the failure based on the information developed to date; provided a preliminary evaluation of additional alternatives to be considered; and prepared American Society of Civil recommendations for follow on explorations as necessary. Landslide repair Engineers (ASCE); Coasts, Ocean, Ports, and Rivers alternatives considered subsurface soil and groundwater conditions, loading Institute (COPRI) mechanisms, resistance mechanisms, constructability, and administrative Society of American Military constraints. Garry and his team worked closely with specialty contractors and Engineers (SAME) evaluated a number of landslide repair alternatives. These concepts were considered before selecting the three-tiered slope stabilization system including tie-back anchors, anchor blocks, and drilled shafts analyzed. We discussed these repair concepts with the owner and other design consultants, and the three- tiered system was selected based on our analysis and the discussion.

Helsell Residence Landslide Repair, Greater Seattle (Shoreline), WA Garry was geotechnical Project Manager for geologic/hydrogeologic assessments and design for repair of a major landslide in the Highlands area of Greater Seattle. The Helsell landslide involved a significant volume of slide debris which ultimately covered a 100-foot span of the BN railroad tracks at an elevation of about 200 feet below the residence. An estimated 10,000 to 15,000 cubic yards of material were involved in the event which involved three separate properties. The escarpment was up to 90 feet high and more than 200 feet long. Garry worked with the design team and owner to assess a wide variety of slope stabilization alternatives, considering not only the technical feasibility, but also constructability issues, relative cost, aesthetics, and logistics. An enhanced

Attachment 13

drainage/geosynthetic-reinforced soil slope was selected as the most cost-effective and constructible repair solution to provide stability long-term stability for the residence. Drainage design and surface erosion control were important elements of the repair.

Beach Drive Residence Landslide Repair, Shoreline, WA Garry was Project Manager for multiple solutions at this residence based on the different site development needs. The work included designing stabilization methods for retention of a high bluff along Puget Sound. In areas where the top of steep slope was close to the new house, Garry designed a structural wall that could be retrofitted with permanent tieback anchors in the event of loss of ground in front of the wall. Based on a thorough review of past slide activity in the area, including aerial photos dating back to 1940, he assessed the rate of loss of the top of bank over time and then developed design parameters for the wall system that were not overly conservative in the assumptions of how much material might be lost in front of the wall over the life of the project. In other areas that were not close to planned structures, he identified the geologic hazard so the owner could plan for future development. In these areas, installation of enhanced subsurface drainage provided the greatest cost benefit to maintain the edge of bluff in its position. The use of structural alternatives was not considered appropriate due to the high cost and low potential for increasing the stability of the bluff.

Bonair Drive SW Slide Stabilization, West Seattle, WA Garry provided senior-level technical review for fast-track work to stabilize portions of Bonair Drive SW which was experiencing accelerated movement, slipping approximately 1 to 3.5 feet downward, leaving an exposed scarp along 125 feet of Bonair Drive. At the same time, near-surface landsliding or mud flows occurred farther down the slope, causing damage to homes along Alki Avenue. The project included a site reconnaissance and deep borings in the slide area to assess soil and groundwater conditions. A key element was the identification of groundwater seepage zones about half-way down the slope face and saturated sands above hard silts. The project team worked with the contractor to design a trench drainage system to extend through the sand and into the underlying silt, thereby intercepting groundwater that was tending to flow along the top of the hard silt and daylighting about halfway down the slope face, causing the instability. In order to improve the stability for a longer segment of Bonair Drive, the trench drain was extended several hundred feet, toward the northeast. Even during construction, a significant amount of water was being picked up by the drainage system. To handle discharge of the water (another significant challenge), the design used an existing manhole, a new tightline on the face of a steep slope, and a new manhole installed at a critical location on the slope that was connected to the system using directional drilling.

Diablo Lake Barge Facility, North Cascades National Park, WA A rock slope failed, sending 16,000 cubic yards of rock and soil debris onto barge landing facilities and a road. As Project Manager for geotechnical services, Garry helped Seattle City Light evaluate options for constructing a new barge landing facility and road. Tasks include seismic design, evaluation of slope stability, evaluation of constraints on earth moving operations, assessment of alternatives for foundation design and construction including shallow foundations, structural slabs use of micropiles and/or driven piles, gravity systems, and tieback anchors.

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WPYR Cruise Ship Dock Rockfall Hazard Evaluation, White Pass-Yukon Route Railroad, Skagway, AK, Principal-in-charge providing engineering geology review and analysis related to a rockslide and rockfall hazard evaluation for a busy cruise ship terminal in Skagway, Alaska. Work included developing a remote site safety plan and use of a rock slope climbing crew and rope rappelling geologists to assess rock/site conditions. Geologic site reconnaissance data was collected along distinct traverse lines and analyzed to evaluate rockslide/rockfall stability and risk management options. A complete photographic record and LIDAR evaluation of site conditions was used, along with computer software analysis, to evaluate rockslide stability and historical rockfall occurrence, magnitude, and delivery mechanism. A rockslide/rockfall hazard evaluation report was provided, including a comprehensive slope risk assessment and recommended mitigation/monitoring options. Garry helped develop and implement a long-term instrumentation monitoring program to provide instantaneous rockslide movement data and trigger level alerts if significant movement should occur. Extensometers and inclinometer live internet data is provided via a remote site cellular transmission network. Site evaluation methods also include developing digital elevation model (DEM) for the site using unmanned aerial vehicle (UAV) photogrammetric and LiDAR based methods, and review of potential past site movement using historical InSAR satellite data.

Garry E. Horvitz, PE, LEG Page 3