20262033_A1_Attachment B_Goodpasture Island Bridge Geotechnical Report.pdf

Preliminary Geotechnical Report

Seismic Bridges (Eugene)

Eugene, Oregon

Prepared for:

DOWL, LLC

Eugene, Oregon

March 18, 2020

Foundation Engineering, Inc.

Professional Geotechnical Services jhuffman Text Box Digitally Signed

Seismic Bridges (Eugene) March 18, 2020 Preliminary Geotechnical Report Project 2191118 Eugene, Oregon 1 DOWL LLC

PRELIMINARY GEOTECHNICAL REPORT

SEISMIC BRIDGES (EUGENE)

EUGENE, OREGON

INTRODUCTION

Project Description

The City of Eugene plans to seismically strengthen ten (10) bridges at the following locations:

Goodpasture Road over Delta Highway (009359)

Valley River Drive over Delta Highway (009360)

Patterson Slough, Martin Luther King Jr. Boulevard (039C09)

Debrick Slough, Goodpasture Loop (039C11)

Chambers Street over UPRR Mainline (39C184)

Amazon Creek, Amazon Parkway (40020)

Amazon Creek, Bailey Hill Road (40039)

Amazon Creek, West 11th Avenue (40040)

Amazon Creek, Bertelsen Road (40041)

Amazon Creek, Danebo Avenue (40042)

The bridge locations are shown on the Vicinity Map (Figure 1, attached). The selected bridges were identified in a seismic vulnerability assessment of 56 City of Eugene bridges and documented in a report prepared by OBEC Consulting Engineers (now DOWL) titled: Final Vulnerability Assessment and Recommendations Report, dated January 29, 2016. Foundation Engineering, Inc. provided consultation for geotechnical seismic parameters as part of the development of the report.

DOWL was selected by the City of Eugene for the current project, which includes seismic analysis and preliminary design for retrofitting vulnerable bridge elements based on a full (Phase 1 and Phase 2) seismic retrofit approach. Foundation Engineering was retained by DOWL as the geotechnical consultant. Our scope for geotechnical services was included as Task 2 of the Statement of Work (Exhibit A, Contract No.: 2020-00204) between the City and DOWL.

Scope of Work

The purpose of this investigation is to evaluate geotechnical conditions at each bridge site to develop soil parameters for seismic and foundation analysis. The scope of work included reconnaissance, a review of available documents, interpretation of subsurface and/or geologic conditions, engineering analysis, evaluation of potential geologic hazards, consultation with the structural designers, and preparation of this report.

Eugene, Oregon 2 DOWL LLC

Two bridge sites (No. 039C09 and 40042) were identified as needing additional subsurface information. Therefore, in addition to the items noted above, the scope of work for these locations also included exploratory drilling and laboratory testing on selected samples. Details of the explorations are provided in the respective sections for each bridge.

Our work was completed in accordance with the following standards and specifications:

AASHTO LRFD Bridge Design Specifications – Eighth Edition, September 2017

(AASHTO, 2017)

ODOT Bridge Design Manual (BDM) (ODOT, 2019)

ODOT Geotechnical Design Manual (GDM) Version 2.0 (ODOT, 2018)

Seismic Retrofitting Manual for Highway Structures: Part 1 – Bridges, Publication FHWA-HRT-06-032 (FHWA, 2006)

The following sections provide a discussion of the regional geology and seismic setting for Eugene. A general discussion of our approach for the seismic and foundation analyses is also included. More detailed evaluations of the individual bridge sites are presented in the appended reports. The reports include supporting figures and tables, and pertinent documents such as boring logs and “as-constructed” plans that were used to inform our analysis and develop recommendations. The appendices are organized as follows:

Appendix A: Goodpasture Road over Delta Highway (009359)

Appendix B: Valley River Drive over Delta Highway (009360)

Appendix C: Patterson Slough, Martin Luther King Jr. Boulevard (039C09)

Appendix D: Debrick Slough, Goodpasture Loop (039C11)

Appendix E: Chambers Street over UPRR Mainline (39C184)

Appendix F: Amazon Creek, Amazon Parkway (40020)

Appendix G: Amazon Creek, Bailey Hill Road (40039)

Appendix H: Amazon Creek, West 11th Avenue (40040)

Appendix I: Amazon Creek, Bertelsen Road (40041)

Appendix J: Amazon Creek, Danebo Avenue (40042)

Eugene, Oregon 3 DOWL LLC

REGIONAL GEOLOGY AND SEISMIC SETTING

Regional Geology

Eugene is located within the southern extent of the Willamette Valley, which is a broad, north-south-trending basin separating the Coast Range to the west from the Cascade Range to the east.

In the early Eocene (±55 million years ago), the present location of the Willamette Valley was part of a broad continental shelf extending west from the Western Cascades beyond the present coastline (Orr and Orr, 1999). Basement rock underlying most of the north-central portion of the Valley includes the Siletz River Volcanics (early to middle Eocene, ±50 to 58 million years old), which erupted as part of a submarine oceanic island-arc (Bela, 1979; Yeats et al., 1996). The thickness of the basement volcanic rock is unknown; however, it is estimated to be ±3 to 4 miles thick (Yeats et al., 1996). Siletz River Volcanics and Spencer Formation represent the basement rocks in the Eugene area (Yeats et al., 1996;

Madin and Murray, 2006).

The island-arc collided with, and was accreted to, the western margin of the converging North American plate near the end of the early Eocene. Throughout the late Eocene and Oligocene, volcanism subsided and a forearc basin was created and infilled to the south with marine sediments of the marine Eugene Formation and terrestrial sedimentary and volcanic deposits of the Fisher Formation and Little Butte Volcanics (Orr and Orr, 1999; Wiley, 2008). These sediments typically overlie, but are also interbedded with, basalt and volcanics of the Siletz River Volcanics and younger Tertiary volcanics in the Eugene area.

After emerging from a gradually shallowing ocean, the marine sediments and volcanic formations to the north were covered by terrestrial Columbia River Basalt (CRB).

About 17 to 10 million years ago (middle to late Miocene) CRB poured through the Columbia Gorge from northeastern Oregon and southeastern Washington and spread as far south as Salem, Oregon (Tolan et al., 2000). Uplift and folding of the Coast Range and the Western Cascades during the late Miocene formed the trough-like configuration of the Willamette Valley. (Orr and Orr, 1999; O'Connor et al., 2001;

Wiley, 2008; McClaughry et al., 2010)

Following the formation of the Willamette Valley, thick layers of Pliocene gravel filled the Southern Valley (McClaughry et al., 2010). The deposits were then incised by the Willamette River, forming alluvial terraces. In the Pleistocene (±1.6 million to 10,000 years ago), the Central and Southern Valley was refilled with fan-delta gravel originating from the melting glaciers in the Cascade Range (Yeats et al., 1996; Madin and Murray, 2006). The Willamette and McKenzie Rivers in the Eugene area incised deeply into the fan-delta deposits during the Quaternary and deposited recent alluvium adjacent to the river banks and major tributaries (Madin and Murray, 2006).

Also during the Pleistocene (over 15,000 years ago), catastrophic flood deposits mantled the Willamette Valley floor as far south as Eugene (Hampton, 1972; Yeats et al., 1996; O'Connor et al., 2001; McClaughry et al., 2010). These deposits

Eugene, Oregon 4 DOWL LLC originated from a series of glacial-outburst floods that periodically drained Glacial Lake Missoula in western Montana (Allen et al., 2009a). The floods repeatedly scoured southeastern Washington, and the resulting sediment-laden water flowed along the Columbia River to the Willamette River (Wilson, 1998; Allen et al., 2009b).

The flood water and deposits extended as far south as Eugene (Schlicker and Finlayson, 1979; Yeats et al., 1996; Madin, 2004; Ma et al., 2012). In the southern Willamette Valley, turbid floodwater eventually settled, depositing up to 100 feet of silt and clay (Willamette Silt) (Orr and Orr, 1999).

Seismicity and Faulting

Available information indicates the seismic hazard in Eugene is affected by the Cascadia Subduction Zone (CSZ) and crustal fault sources. A discussion of these earthquake sources is provided below.

Cascadia Subduction Zone. The City of Eugene lies ±110 miles inland from the surface expression of the CSZ (Goldfinger et al., 1992). The CSZ is a converging, oblique plate boundary where the oceanic Juan de Fuca, Explorer, and Gorda plates are being subducted beneath the western edge of the continental North American plate (Geomatrix Consultants, 1995; Personius and Nelson, 2006). The CSZ extends from central Vancouver Island in British Columbia, Canada, west of Washington and Oregon to Northern California (Atwater, 1970).

Available information indicates the CSZ is capable of generating earthquakes along the inclined interface between the two plates (interface or subduction zone) and within the descending Juan de Fuca plate (intraslab or intraplate) (Weaver and Shedlock, 1996).

The fault rupture for a CSZ interface earthquake may occur along a portion (locked zone) or along the entire length of the CSZ (Weaver and Shedlock, 1996). The estimated maximum magnitude of a CSZ interface earthquake is a moment magnitude (Mw) 9.3 (Petersen et al., 2014).

A 2012 study of turbidites from the last ±10,000 years suggests the return period for CSZ interface earthquakes varies with location and rupture length (Goldfinger et al., 2012). That study estimated an average recurrence interval of ±220 to 380 years for a CSZ interface earthquake on the southern portion of the CSZ and an average recurrence interval of ±500 to 530 years for an interface earthquake extending the entire length of the CSZ. More recent research for the northern portion of the subduction zone suggests a recurrence interval of ±340 years for the northern Oregon Coast (Goldfinger et al., 2016). The most recent CSZ interface earthquake occurred ±320 years ago on January 26, 1700 (Nelson et al., 1995; Satake et al., 1996).

CSZ intraslab (Intraplate or Wadati-Benioff Zone) earthquakes occur within the Juan de Fuca plate at depths of ±28 to 37 miles (Weaver and Shedlock, 1996). The maximum estimated magnitude of an intraslab earthquake is about Mw 7.5 (Petersen et al., 2014).

Eugene, Oregon 5 DOWL LLC

The record for intraslab earthquakes in Oregon is limited. The available data indicates a body wave magnitude (Mb) 4.6 event occurred in 1963 ±23 miles east of Salem at a depth of ±29 miles (Barnett et al., 2009). Based on its depth, this earthquake may be an intraslab event. No other intraslab earthquake records are available in Oregon. However, the Puget Sound region of Washington State has experienced three intraplate events in the last ±70 years, including a surface wave magnitude (Ms) 7.1 event in 1949 (Olympia), a Ms 6.5 event in 1965 (Seattle/Tacoma) (Wong and Silva, 1998), and a Mw 6.8 event in 2001 (Nisqually) (Dewey et al., 2002).

Crustal Faults. Crustal earthquakes dominate Oregon's seismic history. Crustal earthquakes occur within the North American Plate, typically at depths of ±6 to 12 miles. The estimated maximum magnitude of a crustal earthquake in the Willamette Valley and adjacent physiographic regions is about Mw 7.0 (Petersen et al., 2014).

Only two major crustal events in Oregon have reached Richter local magnitude (ML) 6 (the 1936 Milton-Freewater ML 6.1 earthquake and the 1993 Klamath Falls ML 6.0 earthquake). The majority of Oregon’s larger crustal earthquakes are in the ML 4 to 5 range (Wong and Bott, 1995).

The US Geological Survey (USGS) has defined four fault classifications based on evidence for Quaternary displacement (<1.6 million years) in their US fault database (Palmer, 1983; Personius et al., 2003). The fault classes are defined as follows:

Class A faults have geologic evidence supporting tectonic movement in the Quaternary known or presumed to be associated with large-magnitude earthquakes.

Class B faults are of non-tectonic origin (e.g. volcanic activity) or demonstrate less evidence of tectonic displacement.

Class C faults are crustal features that lack evidence of a tectonic fault, Quaternary slip, or deformation of a known fault.

Class D faults are features that are not tectonic faults and include joints, joint zones, landslides, erosional or scarp surfaces, and lacustrine shorelines.

Class A and B crustal faults are included in the USGS fault database and interactive fault map. USGS considers 17 features in Oregon to be Class C faults (USGS, 2006), including the Harrisburg anticline located ±15 miles north of Eugene. The USGS does not consider any features in Oregon as Class D faults (USGS, 2006).

Much of the Quaternary crustal faulting is located in the southwestern hills of Eugene. However, none of these faults show any evidence of movement in the last ±1.6 million years (Palmer, 1983; Geomatrix Consultants, 1995; Personius et al., 2003; USGS, 2006).

Eugene, Oregon 6 DOWL LLC

USGS has mapped three potentially active Quaternary Class A and B crustal fault zones within ±40 miles of Eugene (Palmer, 1983; Geomatrix Consultants, 1995;

Personius et al., 2003; USGS, 2006). These faults are listed in Table 1. Site-specific faulting information for each bridge site is provided in the appendices.

Table 1. USGS Class A and Class B Crustal Faults within a ±40-mile Radius of Eugene (1)

Fault Name and Class

Fault Number

Approximate Length (miles)

Approximate Distance and Direction from Site (miles)(2)

Last Known Deformation

(years)(3)

Slip Rate (mm/yr)

Owl Creek (A) 870 ±9 ±30 N-NW <750,000 <0.20

Upper Willamette River (B)

863 ±27 ±26 SE <1.6 million <0.20

Corvallis (B) 869 ±25 ±35 NW <1.6 million <0.20

Notes:

(1) Fault data based on Personius et al., 2003 and USGS, 2006.

(2) Distance and direction from Latitude = 44.052190 and Longitude= -123.101073 (approximate center of

Eugene) to nearest surface projection of the fault.

(3) Quaternary time period defined at <1.6 million years based on the 1983 Geologic Time Scale (Palmer, 1983).

The USGS website includes an interactive deaggregation tool, which allows evaluation of the contribution of the various seismic sources to the overall seismic hazard (USGS, 2014). The USGS interactive deaggregation indicates the CSZ is the primary source for the seismic hazard in Eugene.

DISCUSSION OF SEISMIC ANALYSIS AND HAZARD EVALUATION

Bedrock Acceleration and Site Response

Response spectra for each bridge site were developed based on the 2018 ODOT GDM “life-safety” and “operational” criteria. The “life-safety” (i.e., no collapse) seismic performance criteria assumes earthquake ground motions having a 1,000-year average return period. The “operational” (i.e., remain in service) criteria assumes a full-rupture Cascadia Subduction Zone Earthquake (CSZE) event.

Response spectra and design parameters for each bridge site are provided in the appendices.

The ground motions for the 1,000-year return period life-safety response spectrum were developed using the General Procedure in the 2017 AASHTO LRFD Bridge Design Specifications, with modifications recommended in the 2018 ODOT GDM.

The ground motion parameters, including peak ground accelerations (PGA), short period (0.2 second) spectral accelerations (Ss), and long period (1.0 second) spectral accelerations (S1) on bedrock were calculated using the ODOT ARS V 2014.16

Eugene, Oregon 7 DOWL LLC spreadsheet, which is based on the 2014 USGS seismic hazard maps (Peterson et al., 2014). Following the AASHTO General Procedure, the spectral accelerations on bedrock were scaled to the ground surface using Fpga, Fa, and Fv values appropriate for the Site Class. The Site Class accounts for the average subsurface conditions within 100 feet of the ground surface. The scaling factors were selected based on ODOT GDM Tables 6.2-A, 6.2-B, and 6.2-C.

The ground motions for the CSZE operational response spectrum were obtained using the Portland State University (PSU) Acceleration Response Spectra website (PSU, 2017). The website requires inputting latitude and longitude coordinates for the project site and an assumed average shear wave velocity to a depth of ±30 meters (VS30). We assumed a VS30 values for each bridge site based on the selected site class and corresponding default VS30 values refenced in the PSU website.

Seismic Hazards

Earthquake-induced geologic hazards typically include liquefaction and its associated effects (e.g., settlement, lateral spread, and/or flow failure), slope instability or similar ground deformations, settlement of unsaturated soils (e.g., densification), fault rupture, and flooding due to tsunami run-up or seiche.

Liquefaction is typically observed in saturated deposits of loose sand and non-plastic or low plasticity silt subject to intense ground shaking. Potentially liquefiable soils are present in some areas of Eugene. However, the available subsurface data (described in the appendices) does not indicate evidence of liquefiable soils at the bridge sites. Therefore, we believe the risk of liquefaction at bridge sites included in this study is low or negligible.

Seismic loads could trigger minor slope instability or embankment settlement at some of the bridge sites. But, overall, we believe the risk of damage to the bridges is relatively low. More discussion of this potential hazard is provided in the appendices.

Fault rupture is not considered a significant seismic hazard at any of the bridge sites because most of the bridges are located a significant distance from any mapped faults. The bridge crossing Amazon Creek at Danebo Avenue (40042) may cross a concealed fault. However, USGS does not consider that fault or any other nearby fault to be potentially active in the Quaternary (USGS, 2006). That is, the fault is not Class A or B and the risk of fault rupture at the site is assumed to be very low.

Tsunami and seiche hazards are not considered a risk at any of the bridge sites because of the absence of large nearby water bodies at those locations.

Eugene, Oregon 8 DOWL LLC

DISCUSSION OF FOUNDATION ANALYSIS

The ten bridges included in this study are supported on shallow footings, driven piles, or a combination of footings and piles. The bridge foundation systems for each bridge are described in detail in the appendices.

The appended bridge reports provide recommended design parameters for developing and/or evaluating equivalent bridge foundation springs under seismic loading conditions. Shallow foundation spring parameters were analyzed based on 2019 ODOT BDM Section 1.10.4 (Foundation Modeling), with nominal bearing resistances calculated based on AASHTO 2017. For pile and drilled shaft foundations, parameters are provided for evaluating lateral resistance using P-Y methods (e.g., LPILE or GROUP software) and depth-to-fixity methods based on AASHTO 2017 Section C10.7.3.13.4. Pile axial resistance versus depth calculations were also completed to evaluate axial resistance for individual piles and help inform our estimate of existing pile depths. In most cases the actual pile depths are not known. The results of our analyses are summarized in the appended sections for each bridge.

DISCUSSION OF ABUTMENT WALL ANALYSIS

Existing Walls

Analysis for the earthquake resisting system of the bridges includes the translational resistance provided by the abutment walls. DOWL is estimating the translational stiffness of the existing walls based on recommendations in Section 1.10.4.2(1) of the 2019 ODOT BDM. The passive resistance is modeled as a bilinear curve with a wall stiffness, Kabut, acting up to a capacity limit, Pabut. ODOT recommends assuming an initial stiffness, Ki, of 20 kips/in/ft for backwalls and pile caps. The wall stiffness, Kabut, is then calculated as:

Kabut = Ki x Wbw x (Hbw/5.5) where Wbw and Hbw are the wall width and height (in feet). The passive capacity limit, Pabut, is calculated (in kips) as:

Pabut = Hbw x Wbw x 5.0 ksf x (Hbw/5.5)

Wing walls are calculated in the same manner as the abutment walls, but are assumed to provide 2/3 of the stiffness and total resistance for the leading wall and no resistance for the trailing wall. A reduction factor is applied to the passive capacity based on recommendations by ODOT and others. We understand DOWL has adopted a reduction factor of 0.7 for the “life safety” (1,000-year) design scenario and a reduction factor of 0.5 for the “operational” (CSZE) design scenario.

Based on new research being implemented by some transportation agencies (e.g., Rollins and Snow, 2019), we recommend reducing the passive resistance for skewed bridge abutments. The research has shown a skew reduction factor, Rskew, applied to the translational resistance more accurately reflects the average passive resistance that develops in skewed abutments. The skew reduction factor is calculated as:

Eugene, Oregon 9 DOWL LLC

Rskew = e(-/45°) where is the abutment skew (in degrees).

The passive pressure mobilized across the width of skewed abutments is not uniform due to rotational effects that cause binding in the abutment wall backfill adjacent to the obtuse corner of the bridge deck. The binding leads to the development of higher passive forces at the obtuse corner of the bridge deck and reduced passive forces at the acute corner. There are no current guidelines for selecting a pressure distribution.

However, recent studies by BYU researchers (Curtis, 2018 and Rollins and Snow, 2019) provide pressure distribution data for full scale load tests with abutments having skew angles of 30 and 45 degrees. Based on our review of available data, we recommend analyzing the skewed bridges assuming the passive pressure distribution varies linearly along the width of the abutment with the maximum passive pressure at the acute corner of the bridge deck corresponding to 60% of the maximum passive pressure at the obtuse corner. For estimating the passive pressure, we recommend the following:

1. Calculate the average passive pressure (or force = Pabut*Rskew).

2. Calculate the minimum passive pressure at the acute corner of the bridge deck as 0.75 x average pressure (or force).

3. Calculate the maximum passive pressure at the obtuse corner of the bridge deck as 1.25 x average pressure (or force).

4. Linearly interpolate for passive pressure values between the minimum and maximum values.

Abutment Wall Retrofit

DOWL is evaluating a retrofit option for some of the bridge sites that will include constructing deeper, cast-in-place reinforced concrete backwalls and fin walls. The intent is for the deeper backwalls to improve longitudinal stiffness and the fin walls to improve transverse stiffness under seismic loading conditions. DOWL indicated the fin walls will extend ±5 to 7 feet behind the abutments and will be spaced at a minimum distance of 2H (where H is the wall height). The preliminary fin spacing was selected to help develop full passive resistance and limit the potential of shadowing effects between walls. We discussed this approach with DOWL and agreed on the following design parameters:

Excavation behind the backwalls should extend a minimum distance Hbw at the base of the wall (where Hbw is the backwall height). The base of the excavation should then extend back at an approximate 1H:1V slope. This distance is intended to encompass the passive zone behind the walls. The excavated zone should be backfilled with compacted Granular Structure Backfill (ODOT Section 00510.13), Granular Wall Backfill (ODOT Section 00510.12), or similar material.

Eugene, Oregon 10 DOWL LLC

Passive resistance is assumed to develop in the same manner as described above for the existing abutment walls and wing walls. However, it is assumed the fin walls will not have a skew reduction for loading in the transverse direction. Furthermore, abutment walls retrofit with fins will have narrower effective abutment widths and less reduction in passive resistance due to skew effects.

Research summarized in Rollins and Snow (2019) indicates narrow abutments do not experience as great of a reduction in passive resistance compared wider abutments with similar skew. This is because the rotation and binding effects described above are lessened as the wall narrows. For the purpose of mobilizing skewed passive resistance, abutment walls retrofit with fins will have an effective abutment width equal to the distance between the fins. In the case of the proposed abutment retrofits, we understand the distance between fins will be on the order of 10 to 14 feet. In consultation with DOWL and using data provided in Rollins and Snow (2019), a revised skew reduction factor was selected equal to:

Rskew = e(-/90°)

This equation provides a best-fit solution to the data in Rollins and Snow (2019) for the narrower abutment widths.

VARIATION OF SUBSURFACE CONDITIONS, USE OF THIS REPORT, AND WARRANTY

The analysis, conclusions, and recommendations contained herein are based on a compilation of subsurface data from recent borings (at two bridge locations), from historical boring data shown on available bridge plans, and from previous projects completed by Foundation Engineering or others in close proximity to the bridge sites.

In some cases, our analysis relied on limited data. Therefore, we used professional judgement and attempted to incorporate conservatism in the geotechnical parameters provided. Any persons relying on this study should understand the associated limitations with the work.

This report was prepared for the exclusive use of the City of Eugene, DOWL, and their design consultants for the Seismic Bridges (Eugene) project in Eugene, Oregon.

Information contained herein should not be used for other sites not addressed in this report, or for unanticipated construction without our written consent.

This report is intended for planning and design purposes to support preliminary design and development of retrofit options for the selected bridges. Additional subsurface explorations and foundation analyses may be warranted to support final design. No changes in the enclosed recommendations should be made without our approval. We will assume no responsibility or liability for any engineering judgment, inspection or testing performed by others.

Contractors using this information to estimate construction quantities, production rates, or costs do so at their own risk. Our services do not include any survey or assessment of potential surface contamination or contamination of the soil or ground water by hazardous or toxic materials. We assume those services, if needed, have been completed by others.

Eugene, Oregon 11 DOWL LLC

Our work was done in accordance with generally accepted soil and foundation engineering practices. No other warranty, expressed or implied, is made.

REFERENCES

The references provided below are cited in the above text and in the appendices.

AASHTO, 2017, AASHTO LRFD Bridge Design Specifications – Eighth Edition:

American Association of State Highway and Transportation Officials

(AASHTO).

Adams, J., 1990, Paleoseismicity of the Cascadia Subduction Zone: Evidence from Turbidites Off the Oregon-Washington Margin: Tectonics, vol. 9, no. 4, p.

569-583.

Allen, J. E., Burns, M., and Burns, S., 2009b, Cataclysms on the Columbia, The Great Missoula Floods: Ooligan Press, Portland State University, Portland, Oregon, Revised Edition, 2004 p.

Atwater, B. F., Carson, B., Griggs, G. B., Johnson, H. P., and Salmi, M. S., 2014, Rethinking Turbidite Paleoseismology Along the Cascadia Subduction Zone:

Geology, published online 29 July 2014, doi: 10.1130/G35902.1.

Atwater, B. F., Nelson, A. R., Clague, J. J., Carver, G. A., Yamaguchi, D. K., Bobrowsky, P. T., Bourgeois, J., Darienzo, M. E., Grant, W. C., Hemphill- Haley, E., Kelsey, H. M., Jacoby, G. C., Nishenko, S. P., Palmer, S. P., Peterson, C. D., and Reinhart, M. A., 1995, Summary of Coastal Geologic Evidence for Past Great Earthquakes at the Cascadia Subduction Zone:

Earthquake Spectra, vol. 11, no. 1, p. 1-18.

Atwater, T., 1970, Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America: Geological Society of America (GSA), Bulletin 81, p. 3513-3536.

Barnett, E. A., Weaver, C. S., Meagher, K. L., Haugerud, R. A., Wang, Z., Madin, I.

P., Yang, Y., Wells, R. E., Blakely, R. J., Ballantyne, D. B., and Darienzo, M., 2009, Earthquake Hazards and Lifelines in the Interstate 5 Urban Corridor:

Cottage Grove to Woodburn, Oregon: US Geologic Survey (USGS), Scientific Investigations Map 3028, 1 Plate.

Bela, J. L., 1979, Geologic Hazards of Eastern Benton County, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), Bulletin 98, 122 p.

Curtis, J.R., 2018, Effect of Inclined Loading on Passive Force Deflection Curves and Skew Adjustment Factors, Master’s Thesis Department of Civil and Environmental Engineering, Brigham Young University.

Eugene, Oregon 12 DOWL LLC

DeMets, C., Gordon, R. G., and Argus, D. F., 2010, Geologically Current Plate Motions: Geophysical Journal International, vol. 181, no. 1, 1-80 p.

Dewey, J. W., Hopper, M. G., Wald, D. J., Quitoriano, V., and Adams, E. R., 2002, Intensity Distribution and Isoseismal Maps for the Nisqually, Washington, Earthquake of 28 February 2001: U.S. Geological Survey (USGS), Open-File Report 02-346, 57 p.

Geomatrix Consultants, 1995, Final Report: Seismic Design Mapping, State of Oregon: Prepared for Oregon Department of Transportation, Salem, Oregon, Personal Services Contract 11688, January 1995, Project No. 2442.

Goldfinger, C., Galer, S., Beeson, J., Hamilton, T., Black, B., Romsos, C., Patton, J., Nelson, C. H., Hausmann, R., and Morey, A., 2016, The Importance of Site Selection, Sediment Supply, and Hydrodynamics: A Case Study of Submarine Paleoseismology on the Northern Cascadia Margin, Washington, USA: Marine Geology, In Press, http://dx.doi.org/10.1016/j.margeo.2016.06.008.

Goldfinger, C., Kulm, L. D., Yeats, R. S., Mitchell, C., Weldon, R., II, Peterson, C., Darienzo, M., Grant, W., and Priest, G. R., 1992, Neotectonic Map of the Oregon Continental Margin and Adjacent Abyssal Plain: Oregon Department of Geology and Mineral Industries (DOGAMI), Open File Report O-92-4.

Goldfinger, C., Nelson, C. H., Morey, A. E., Johnson, J. R., Patton, J., Karabanov, E., Gutierrez-Pastor, J., Eriksson, A. T., Gracia, E., Dunhill, G., Enkin, R. J., Dallimore, A., and Vallier, T., 2012, Turbidite Event History - Methods and Implications for Holocene Paleoseismicity of the Cascade Subduction Zone:

U.S. Geologic Survey (USGS), Professional Paper 1661-F, 170 p., 64 figures, http://pubs.usgs.gov/pp/pp1661/f.

Hampton, E. R., 1972, Geology and Ground Water of the Molalla-Salem Slope Area, Northern Willamette Valley, Oregon: U. S. Geological Survey (USGS), Water- Supply Paper 1997, 83 p.

Kavazanjian, E., Jr., Wang, J-N., Martin, G.R., Shamsabadi, A., Lam, I.P., Dickenson, S.E., and Hung, C.J., 2011; Geotechnical Engineering Circular No. 3, LRFD Seismic Analysis and Design of Transportation Geotechnical Features and Structural Foundations: Report No. FHWA-NHI-11-032, National Highway Institute, Washington, D.C.

Ma, L., Madin, I. P., Duplantis, S., and Williams, K. J., 2012, Lidar-Based Surficial Geologic Map and Database of the Greater Portland Area, Clackamas, Columbia, Marion, Multnomah, Washington, and Yamhill Counties, Oregon, and Clark County, Washington: Oregon Department of Geology and Mineral Industries (DOGAMI), Open-File Report O-12-02, Map Scale 1 : 63,360, p. 30.

Madin, I. P., 2004, Geologic Mapping and Database for Portland Area Fault Studies:

Final Technical Report: Oregon Department of Geology and Mineral Industries (DOGAMI), Open-File Report, OFR O-04-02, p. 6, CD-ROM.

Eugene, Oregon 13 DOWL LLC

Madin, I. P., and Murray, R. B., 2006, Preliminary Geologic Map of the Eugene East and Eugene West 7.5' Quadrangles, Lane County, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), OFR O-03-11, p. 20.

McClaughry, J. D., Wiley, T. J., Ferns, M. L., and Madin, I. P., 2010, Digital Geologic Map of the Southern Willamette Valley, Benton, Lane, Linn, Marion, and Polk Counties, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), O-10-03, Scale: 1:63,360, p. 116.

Nelson, A. R., Atwater, B. F., Bobrowsky, P. T., Bradley, L.-A., Claque, J. J., Carver, G. A., Darienzo, M. E., Grant, W. C., Drueger, H. W., Sparks, R., Stafford, T.

W., Jr., and Stulver, M., 1995, Radiocarbon Evidence for Extensive Plate-boundary Rupture About 300 Years Ago at the Cascadia Subduction Zone:

Letters to Nature, vol. 378, no. 23, p. 372-374.

O'Connor, J., Sarna-Wojcicki, A., Wozniak, K. C., Polette, D. J., and Fleck, R. J., 2001, Origin, Extent, and Thickness of Quaternary Geologic Units in the Willamette Valley, Oregon: U.S. Geological Survey (USGS), Professional Paper 1620, p. 52.

ODOT, 2019; Bridge Design Manual: Oregon Department of Transportation (ODOT), Bridge Engineering Section.

ODOT, 2018; Geotechnical Design Manual, Version 2.0: Oregon Department of Transportation (ODOT), Geo-Environmental Section.

ODOT, 2018; Oregon Standard Specifications for Construction, Oregon Department of Transportation (ODOT), Highway Division.

Orr, E. L., and Orr, W. N., 1999, Geology of Oregon: Kendall/Hunt Publishing Company, Fifth Edition, 254 p.

Palmer, A. R., 1983, The Decade of North American Geology - 1983 Geologic Time Scale: Geology, vol. 11, p. 503-504, September 1983.

Personius, S. F., Dart, R. L., Bradley, L.-A., and Haller, K. M., 2003, Map and Data for Quaternary Faults and Folds in Oregon: U.S. Geological Survey (USGS), Open-File Report 03-095, v.1.1, Scale: 1:750,000, 507 p.

Personius, S. F., and Nelson, A. R., 2006, Fault Number 781, Cascadia Megathrust, in Quaternary Fault and Fold Database of the United States: U.S. Geological Survey (USGS) website, https://earthquakes.usgs.gov/hazards/qfaults, accessed April 2019.

Petersen, M. D., Moschetti, M. P., Powers, P. M., Muller, C. S., Haller, K. M., Frankel, A. D., Zeng, Y., Rezaeian, S., Harmsen, S. C., Boyd, O. S., Field, N., Chen, R., Rukstales, K. S., Luco, N., Wheeler, R. L., Williams, R. A., and Olsen, A.

H., 2014, Documentation for the 2014 Update of the United States National Seismic Hazard Maps: U.S. Geological Survey (USGS), Open-File Report 2014- 1091, 243 p, https://pubs.usgs.gov/of/2014/1091/.

Eugene, Oregon 14 DOWL LLC

Peterson, C. D., Darienzo, M. E., Burns, S. F., and Burris, W. K., 1993, Field Trip Guide to Cascadia Paleoseismic Evidence Along the Northern Oregon Coast:

Evidence of Subduction Zone Seismicity in the Central Cascadia Margin:

Oregon Geology, vol. 55, no. 5, p. 99-114.

PSU, 2017; Acceleration Response Spectra for Full Rupture CSZ Earthquake, Portland State University (PSU) website http://csz.cee.pdx.edu/.

Rollins, K.M. and Snow, S.K., 2019, Numerical Analysis of Passive Force on Skewed Bridge Abutments with Reinforced Concrete Wingwalls, Draft Final Report UT- 1X.19 prepared by Brigham Young University for the Utah Department of Transportation Research Division, April 2019.

Satake, K., Shimazaki, K., Tsuji, Y., and Ueda, K., 1996, Time and Size of a Giant Earthquake in Cascadia Inferred from Japanese Tsunami Records of January 1700: Nature, vol. 379, no. 6562, p. 246-249.

Schlicker, H. G., and Finlayson, C. T., 1979, Geology and Geologic Hazards of Northwestern Clackamas County, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), Bulletin 99, 79 p.

Tolan, T. L., Beeson, M. H., and DuRoss, C. B., 2000, Geologic map and database of the Salem East and Turner 7.5 minute quadrangles, Marion County, Oregon:

A digital database: U.S. Geological Survey, Open-File Report 00-351, p. 13.

USGS, 2006, Quaternary Fault and Fold Database for the United States - Oregon:

U.S. Geological Survey (USGS), accessed November 2019, website:

http://earthquake.usgs.gov/hazards/qfaults.

USGS, 2014, Unified Hazard Tool, Dynamic: Conterminous U.S. 2014 (v4.1.1): U.S.

Geological Survey (USGS), Earthquake Hazards Program, 5% in 50 years (975-year) return period, 760 m/s (B/C Boundary), PGA spectral acceleration, latitude/longitude search, accessed November 2019, https://earthquake.usgs.gov/hazards/interactive/.

Weaver, C. S., and Shedlock, K. M., 1996, Estimates of Seismic Source Regions from the Earthquake Distribution and Regional Tectonics in the Pacific Northwest: in Roger, A. M., Walsh, T. J., Kockelman, W. J., and Priest, G. R., eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest: vol. 1, U.S. Geological Survey (USGS), Professional Paper 1560,

p. 285-306.

Wiley, T. J., 2008, Preliminary Geologic Maps of the Corvallis, Wren, and Marys Peak 7.5' Quadrangles, Benton, Lincoln and Linn Counties, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), Open-File Report O- 08-14, Scale: 1:24,000, 11 p.

Wilson, D. C., 1998, Post-middle Miocene Geologic Evolution of the Tualatin Basin, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), Oregon Geology, vol. 60, no. 5, p. 99-116.

Eugene, Oregon 15 DOWL LLC

Wong, I. G., and Bott, J. D. J., 1995, A Look Back at Oregon's Earthquake History, 1841-1994: Oregon Geology, vol. 57, no. 6, p. 125-139.

Wong, I. G., and Silva, W. J., 1998, Earthquake Ground Shaking Hazards in the Portland and Seattle Metropolitan Areas: in Dakoulas, P., Yegian, M., and Holtz, R. D., eds., Geotechnical Earthquake Engineering and Soil Dynamics III, American Society of Civil Engineers (ASCE), Geotechnical Special Publication No. 75, vol. 1, p. 66-78.

Yeats, R. S., Graven, E. P., Werner, K. S., Goldfinger, C., and Popowski, T. A., 1996, Tectonics of the Willamette Valley, Oregon: in Roger, A. M., Walsh, T. J., Kockelman, W. J., and Priest, G. R., eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest: U.S. Geological Survey (USGS), Professional Paper 1560, p. 183-222.

Youd, T. L., and Idriss, I. M., 1996; Proceedings of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils: Professional Paper, 40 p.

Youd, T.L.; Idriss, I.M.; Andrus, R.D.; Arango, I.; Castro, G.; Christian, J.T.; Dobry, R.; Finn, W.D.; Harder, L.; Hynes, M.E.; Ishihara, K.; Koester, J.P.; Liao, S.S.C.; Marcuson, W.F.; Martin, G.R.; Mitchell, J.K.; Moriwaki, Y.; Power, M.S.; Robertson, P.K.; Seed, R.B. and Stokoe, K.H., 2001, Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils:

ASCE Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, pp. 817-833.

2191118

Source: ODOT City Maps; Eugene (2019 ed.)

M c

K

E

N

Z

I

E

BR 009359

EUGENE

0 1/4 1/2 1 mile

SCALE

BR 039C11

BR 039C09

BR 009360

BR 39C184

BR 40040

BR 40042

BR 40041

BR 40039

BR 40020

AutoCAD SHX Text

FIGURE NO.

AutoCAD SHX Text

PROJECT NO.

AutoCAD SHX Text

REVIS.

AutoCAD SHX Text

DWN.

AutoCAD SHX Text

APPR.

AutoCAD SHX Text

DATE

AutoCAD SHX Text

FILE NAME:

AutoCAD SHX Text

820 NW CORNELL AVENUE

AutoCAD SHX Text

BUS. (541) 757-7645 FAX (541) 757-7650

AutoCAD SHX Text

CORVALLIS, OR 97330-4517

AutoCAD SHX Text

FOUNDATION ENGINEERING INC.

AutoCAD SHX Text

PROFESSIONAL GEOTECHNICAL SERVICES

AutoCAD SHX Text

VICINITY MAP

AutoCAD SHX Text Seismic Bridges (Eugene)

AutoCAD SHX Text Eugene, Oregon

AutoCAD SHX Text

AutoCAD SHX Text Dec. 2019

AutoCAD SHX Text

JCH

Appendix A Goodpasture Island Road over Delta Highway (009359)

Professional Geotechnical Services

Seismic Bridges (Eugene) – Goodpasture Road over Delta Hwy (009359) March 18, 2020 Preliminary Geotechnical Report – Appendix A Project 2191118 Eugene, Oregon 1A DOWL LLC

APPENDIX A

GOODPASTURE ROAD OVER DELTA HIGHWAY (BRIDGE No. 009359)

BRIDGE DESCRIPTION AND SITE LAYOUT

The Goodpasture Road bridge crossing Delta Highway (Bridge No. 009359) is a ±228-foot long by ±39.7-foot wide (out-to-out), 4-span, prestressed concrete structure. The original structure was built in 1965. A second bridge was built in 2015 immediately north of the older bridge to widen the crossing. An aerial photo showing the current site layout is presented in Figure 1A (attached). Current analysis focuses on the original structure only.

Approach embankments were constructed on the west and east sides of Delta Highway to accommodate the bridge crossing. The west and east bridge abutments (Bents 1 and 5) are supported on continuous spread footings underlain by the approach fill. The interior bents (Bents 2 through 4) are each supported on two, ±9.5-foot square spread footings. Each of the spread footings for the interior bents are assumed to extend to native alluvial soil.

REVIEW OF EXISTING DATA

Bridge Records

We reviewed available information provided in the as-constructed plans for the bridge. Those plans provide bridge and foundation dimensions, foundation elevations, embankment slope configurations, and other details. The as-constructed plans for original bridge are included in this appendix.

One exploratory boring (Test hole #1) is identified on the sheet titled Foundation Data & Bent 1 Details. The sheet indicates Test hole #1 was drilled June 5, 1964. The boring was ±30 feet deep, extending from ±El. 392 to ±El. 362. An updated note indicates the foundation material encountered during excavation for footings is the same as indicated in the foundation data (i.e., same as the boring log). Subsurface data is discussed in a subsequent section of this report.

Based on the age of the bridge, we anticipate the elevations indicated in the plans, including the boring and bottom of footing elevations described above, are based on the National Geodetic Vertical Datum of 1929 (NGVD 29). At the bridge site, NGVD 29 is ±3.59 feet lower than the current North American Vertical Datum of 1988 (NAVD 88). Therefore, these elevations should be adjusted if they are to be compared to current survey elevations using NAVD 88.

Other Subsurface Information

A geotechnical investigation was completed by K & A Engineering, Inc. (K & A) as part of the design for the newer bridge crossing Delta Highway. The results of that investigation are summarized in a report dated June 23, 2010. The report was made available to us for review via DOWL and the City for Eugene.

Eugene, Oregon 2A DOWL LLC

The investigation by K & A included eight exploratory borings (BH1 through BH8) drilled adjacent to the older (circa 1965) bridge. The explorations extended through fill, native soil, and decomposed bedrock. Two of the borings (BH1 and BH5) were drilled through the approach fill near the bridge abutments. The site plan and logs from the K & A report are included in this appendix.

LOCAL GEOLOGY

The project site is located within the southern Willamette Valley, ±¾ miles east of the Willamette River. The project area is situated on a relatively flat alluvial plain.

Local geologic mapping suggests the project site is underlain by meander-belt alluvium incised into fan-delta alluvium (Madin and Murray, 2006). The meander alluvial deposits within the active channel consist primarily of silt, sand, and gravel.

The underlying fan-delta alluvial deposits consist of silt to boulder-sized material that was primarily deposited by the Willamette River (Yeats et al., 1996; Orr and Orr, 1999; O'Connor et al., 2001; Madin and Murray, 2006).

The alluvium is underlain by the Eugene Formation. The Eugene Formation (early Oligocene to late Eocene, ±30 to 40 million years old) is comprised of marine tuffaceous sandstone and siltstone (Yeats et al., 1996; Madin and Murray, 2006).

Eugene Formation with an interior of Tertiary intrusions compose the buttes near the site, including Gillespie Butte ±1 mile to the southeast of the site (Madin and Murray, 2006). Local geologic mapping does not indicate any mapped faults at or in the near vicinity of the bridge site (Madin and Murray, 2006).

The subsurface conditions documented in the information we reviewed is consistent with the mapped local geology.

DISCUSSION OF SUBSURFACE CONDITIONS

The available subsurface data suggests the soils underlying the bridge site are comprised of predominantly alluvial gravel containing varying amounts of silt, sand, and cobbles. The 1964 boring (Test Hole #1) shown on the bridge plans does not indicate soil stiffness or density. However, SPT N-values and soil descriptions in the K & A borings indicate the gravel stratum extending below the footing elevations is typically dense to very dense.

Decomposed sandstone of the Eugene Formation was encountered in several of the K & A borings at depths corresponding to ±10 to 15 feet below the bottom of the interior footings.

Borings completed by K & A through the approach embankments suggests the embankment fill is comprised of gravel or gravel with sand that is typically dense to very dense below the abutment foundation elevations.

Ground water was reported in some borings completed by K & A, typically at a depth of ±10 feet below surface grades near the location of the interior bents.

Eugene, Oregon 3A DOWL LLC

SEISMIC ANALYSIS AND HAZARD EVALUATION

Bedrock Acceleration and Site Response

Response spectra for the site were developed based on the 2018 ODOT GDM “life-safety” and “operational” criteria, as described in the front section of this report.

The subsurface conditions at the bridge site correspond to a Site Class C based on the subsurface profile and depth-averaged SPT N-values documented in the borings provided in the K & A report. A VS30 equal to 560 meters/second (based on a Site Class C) was assumed for calculating the operational response spectrum. The resulting response spectra and seismic parameters are presented in Figure 2A (attached).

Seismic Hazards

The site is generally underlain by dense to very dense gravel, followed by weathered bedrock. The approach embankments are also comprised of predominantly dense to very dense gravel and were constructed with ±2(H):1(V) side slopes. Based on the conditions, we believe the risk of seismic-induced geologic and/or geotechnical hazards (e.g., liquefaction, lateral spread, slope instability, fault rupture, or flooding) at this site is very low to negligible.

FOUNDATION ANALYSIS AND DESIGN RECOMMENDATIONS

Discussion of Existing Bridge Foundations

Design documents indicate the abutments are supported on ±5.5-foot wide continuous footings. The interior bents are each supported on two, ±9.5-foot square spread footings. A bottom of footing elevation of ±El. 406 is indicated for both abutments. Bottom of footing elevations ranging from ±El. 386.2 to El. 387.2 are indicated for the interior foundations. As noted previously, we anticipate these elevations are based on the NGVD 29 datum.

The foundations are completely embedded below grade. The exact embedment depths are not known because there is no current survey data and the bottom of footing elevations have not been confirmed based on current datum. For the analysis discussed herein, we neglected any footing embedment for the abutment footings when calculating bearing resistance. For the interior bents, we assumed an embedment depth of ±5 feet. We believe these assumptions are conservative based on information provided in the “as-constructed” Plan & Elevation sheet.

The abutment footings are located near the top of the approach embankments, with an estimated setback of ±10 feet from the embankment slope based on measurements taken from the plans. The interior footings are buried below relatively flat ground.

Eugene, Oregon 4A DOWL LLC

Soil Strength Parameters

The alluvial soils underlying the interior footings and the embankment fill underlying the abutment footings appears to be similar in composition, consisting of predominantly dense to very dense gravel with varying silt, sand, and cobbles. Backfill adjacent to the footings is likely similar to the foundation soils. However, there may be some variability in the relative compaction (and/or density) of the backfill. Therefore, we assumed slightly lower strength parameters for the backfill material. The assumed soil strength parameters are summarized in Table 1A. The internal friction angle () selected for these materials is conservative for dense soil conditions.

Table 1A. Assumed Soil Strength Parameters

Material

Moist Unit Weight m (pcf)

Friction Angle

(degrees)

Cohesion c

(psf)

Abutment Foundation Soil 120 35 0

Interior Bent Foundation Soil 120 35 0

Footing Backfill 120 34 0

Based on the anticipated ground water depth, we assumed saturated (i.e., buoyant) conditions below the interior footings for bearing capacity analysis.

Foundation Analysis

Spread footings for the existing bridge are being evaluated based on guidelines in the 2019 ODOT BDM Section 1.10.4 for uncoupled translation and rotational springs.

The initial spring stiffness, k, is estimated based on the foundation shape and depth and soil deformation parameters that include the elastic (Young’s) modulus (E), shear modulus (G), and Poisson’s ratio (). The vertical translation capacity and rotational (i.e., rocking) capacities are based on the nominal bearing resistance of the foundation soil. The horizontal translation capacity is based on passive resistance developed along the leading edge of the footing and sliding resistance along the base.

2019 ODOT BDM Tables A and C provide recommended soil deformation and strength parameters based on the relative density or stiffness of the foundation soils.

The recommended soil parameters for evaluating the foundation springs based on ODOT BDM guidelines are summarized in Table 2A (attached). The soil density and/or stiffness was assumed based on the soil descriptions and SPT data, where available.

Eugene, Oregon 5A DOWL LLC

The nominal bearing resistances provided in Table 2A were calculated based on bearing capacity equations in AASHTO 2017 and the foundation soil parameters summarized in Table 1A. The bearing resistance for the abutment footings included a reduction based on the footing locations adjacent to the embankment slopes. We calculated a nominal bearing resistance of 11.0 ksf for the abutment footings and

35.2 ksf for the interior bent footings. Relevant parameters for bearing capacity calculations are included in the attached calculation sheets for the abutment and interior footings.

Abutment Retrofit

DOWL indicated concrete-fill PP20x0.5 driven pipe piles may be used to strength the abutments (Bents 1 and 5).