Geotechnical Investigation and Seismic Hazard Study

SUB Glenwood Substation

4001 E 22nd Avenue Glenwood, Oregon

Prepared for:

Springfield Utility Board Springfield, Oregon

September 19, 2018

Foundation Engineering, Inc. Professional Geotechnical Services

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 1. Project 2181086 Glenwood, Oregon Springfield Utility Board

GEOTECHNICAL INVESTIGATION SUB GLENWOOD SUBSTATION

GLENWOOD, OREGON

BACKGROUND

The Springfield Utility Board (SUB) plans to construct a new substation on an undeveloped parcel located at approximately 4001 E 22nd Avenue (Tax Lot 18-03-03-13-00101). The site location is shown on Figure 1A (Appendix A). A layout of the site is included on Figure 2A (Appendix A).

Preliminary drawings provided by SUB indicate the project will include an access driveway that extends south from E 22nd Avenue and encircles the new facility. A small control house will be located at the north end of the facility and the electrical equipment will be located to the south. The new structures will be supported on shallow, spread or continuous footings, concrete mats, or on short pier foundations.

SUB is the project owner and Triaxis is the design lead. SUB retained Foundation Engineering, Inc. as the geotechnical consultant. Our scope of work was outlined in a proposal dated August 1, 2018, and authorized by SUB Purchase Order PO 0100008683 dated August 23, 2018.

LOCAL GEOLOGY

Detailed discussions of the local and regional geology, tectonic setting, local faulting, and historical seismicity are presented as part of the Seismic Hazard Study (Appendix D). References cited in this section are also in Appendix D. An abbreviated discussion of local geology is provided below.

The project site is located within the southern Willamette Valley, south of the Willamette River in Glenwood. Local geologic mapping and previous explorations indicate the project site is underlain by the Eugene Formation (Yeats et al., 1996; Madin and Murray, 2006; McClaughry et al., 2010), which consists of tuffaceous sandstone and siltstone deposited in a shallow marine environment (Yeats et al., 1996; Orr and Orr, 1999; O'Connor et al., 2001; Madin and Murray, 2006). The subsurface conditions encountered in our explorations are consistent with the mapped local geology and the previous explorations on site.

PRIOR GEOTECHNICAL WORK

A previous geotechnical investigation was completed by Professional Services, Inc. (PSI) and encompassed the project site. The results of that investigation are documented in PSI Report Number 722-85043-1 dated November 4, 2008. The PSI investigation was completed for the prior property owners for facilities that were not built. SUB provided the report as part of the Request for Proposals (RFP 06.18) for the current project. For completeness, that report is included in Appendix E.

We reviewed the information in PSI’s report. Their subsurface investigation included a series of test pits identified as TP-1 through TP-11. Test pits TP-2 and TP-3 were excavated nearest to the proposed substation site and extended to depths of ±5 to

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 2. Project 2181086 Glenwood, Oregon Springfield Utility Board

6 feet below the existing grade. Both test pits identified sandstone extending from the ground surface to the bottom of the test pit. The sandstone is characterized as being moderately strong, with weak or partial cementation. Actual or estimated compressive rock strengths were not indicated. Both test pits encountered practical digging refusal with the excavation equipment (John Deere 135C excavator).

Based on the limited description of the bedrock in the PSI report and limited excavation depths relative to the planned foundations, we recommended additional explorations, which are documented below.

FIELD EXPLORATION

We drilled two exploratory boreholes (BH-1 and BH-2) within the proposed substation site on September 4, 2018. The approximate locations are identified on Figure 2A. The borehole locations were not surveyed. However, we estimated elevations (to the nearest ±1 foot) based on their approximate locations and topographic data from a survey completed by Branch Engineering, Inc and provided by SUB.

The borings were drilled using a CME-850 track-mounted drill rig with mud-rotary and HQ-size wire-line coring techniques and extended to maximum depths of ±19.8 feet and 17.5 feet, respectively. Sampling was completed at 2½-foot intervals in the upper soil stratum until reaching relatively competent (i.e., coreable) bedrock. Disturbed soil samples were obtained by driving a split-spoon sampler in conjunction with the Standard Penetration Test (SPT), which provides an indication of the relative stiffness or density of the soil. Continuous rock coring was completed below a depth of ±10 feet in BH-1 and ±15 feet in BH-2.

The borings were continually logged during drilling. The final logs (Appendix B) were prepared based on a review of the field logs, the laboratory test results, and an examination of the soil and rock samples in our office.

DISCUSSION OF SITE CONDITIONS

Surface Conditions and Site Topography

The substation will be located on an undeveloped lot bordered to the north by E 22nd Avenue and to the south by I-5. Most of the southern portion of the parcel where the facilities are planned is covered with grass and scattered weeds. The northern portion of the parcel includes low ground cover, short brambles and scattered deciduous trees. Taller conifer trees and thicker brambles grow along the eastern property border.

The property generally slopes gently to moderately down from south to north. The survey provided by SUB indicates ground surface elevations ranging from ±El. 512 near the northwest property corner (near E 22nd Avenue) to ±El. 549 near the southeast property corner (adjacent to I-5). The substation area is relatively flat. The survey indicates ground surface elevations ranging from ±El. 538 to El. 541 where the new equipment is planned. The ground surface where the control house is planned ranges from ±El. 534 to El. 537.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 3. Project 2181086 Glenwood, Oregon Springfield Utility Board

The ground surface along the eastern property boarder is significantly steeper and likely represents a rock ledge. The surface of the east slope is covered with thick brambles.

Subsurface Conditions

The subsurface profiles were relatively consistent between BH-1 and BH-2. A general discussion of the soil and bedrock units is provided below. Details of the conditions encountered in each boring are summarized on the boring logs (Appendix B). Photos of the retained rock core are also included in Appendix B.

Both borings encountered residual soil followed by sandstone of the Eugene Formation. The residual soil represents bedrock that has decomposed to a soil-like consistency. In BH-1, the residual soil consists of very dense silty sand with some clay and rock fragments. In BH-2, the residual soil consists of stiff grading to hard sandy clay with some rock fragments. Based on the relative depths and descriptions, we anticipate the residual soil encountered in the borings is consistent with the moderately strong, weakly or partially-cemented sandstone described in TP-2 and TP-3 of PSI’s report (Appendix E).

The residual soil transitions to sandstone at a depth of ±7.5 feet in BH-1 and ±10.6 feet in BH-2. In BH-1, the sandstone is extremely weak to very weak (R0 to R1) and slightly weathered from ±7.5 to 15.5 feet, then grades to weak (R2) and slightly weathered to fresh below ±15.5 feet. In BH-2, the sandstone is very weak (R1) and moderately weathered from ±10.6 to 16.3 feet, then grades to weak (R2) and slightly weathered to fresh below ±16.3 feet.

A description of relative rock strengths and their corresponding range of estimated unconfined compressive strengths is included with the attached information sheets in Appendix B.

Ground Water

The use of mud-rotary drilling methods precluded the measurement of ground water levels in the borings. The PSI report indicated ground water at a depth of 10 feet in TP-10, located west and downhill of the proposed substation facility. Ground water was not reported in the other test pits.

Based on the terrain and depth to bedrock, we anticipate static ground water is relatively deep. However, seasonal perched ground water may accumulate during periods of wet weather on the bedrock surface or at shallow depths within the low permeable residual soils.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 4. Project 2181086 Glenwood, Oregon Springfield Utility Board

LABORATORY TESTING

The laboratory work included moisture contents, percent fines, and Atterberg limits testing to help classify the soils according to the Unified Soil Classification System (USCS) and estimate their overall engineering properties. The results are summarized in Table 1. The moisture contents are also shown on the boring logs. Non-tested samples were visually classified in accordance with ASTM D2488-09a and ASTM D2487-11.

Table 1. Natural Moisture Contents, Atterberg Limits and Percent Fines

Sample Designation

Sample Depth

(ft)

Natural Moisture Content

(%)

LL PL PI Fines

Content (%)

USCS Classification

SS-1-1 2.5 – 4.0 22.2 38.2 SM

SS-2-2 5.0 – 6.5 19.9 31 20 11 60.4 CL

An unconfined compression test was complete on core sample CS-1-2 obtained from BH-1 at a depth of ±16 feet to estimate the unconfined compressive strength (qu) of the deeper sandstone. The test results and loading versus strain curve are summarized in Figure 1C (Appendix C). The results indicate a compressive strength of 1,823 lb/in2 (psi), which is in the range of weak (R2) rock.

DISCUSSION OF GEOTECHNICAL CONSIDERATIONS

The subsurface profile includes residual soil over shallow bedrock. The consistency of the residual soil varies to some extent. At BH-1 the residual soil is primarily granular, comprised of silty sand with some clay and rock fragments. At BH-2 the residual soil is primarily fine-grained, comprised of sandy clay with rock fragments.

As indicated by the laboratory testing, the fines content of the residual soil is relatively high across the site. Therefore, even though the residual soil is typically stiff to hard or very dense, it could become disturbed and soften or otherwise degrade if exposed to construction traffic during wet weather. Therefore, we recommend the earthwork occur during dry weather (typically mid-June through September) when the moisture content of the soil can be more carefully controlled. If earthwork occurs during wet weather, steps will be required to help reduce the risk of subgrade disturbance, including thickened sections of granular fill beneath foundations and slabs or along access roads.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 5. Project 2181086 Glenwood, Oregon Springfield Utility Board

SEISMIC DESIGN

A detailed discussion of the local seismic hazards is provided in the Seismic Hazard Study (Appendix D). The recommendations provided in this section are limited to the design response spectrum based on OSSC (2014) seismic parameters. A brief discussion of the liquefaction hazard is also provided.

Seismic Response Spectrum

A site response spectrum was developed for the site in accordance with the Oregon Structural Specialty Code (OSSC 2014), which is based on Section 1613 of the International Building Code (IBC 2012). The design maximum considered earthquake ground motion maps in the IBC (2012) are based on modified USGS (2008) maps with a 1% probability of exceedance in 50 years (i.e., a ±4,975-year return period). The modifications include factors to adjust the spectral accelerations to account for directivity and risk.

The subsurface profile consists of a thin mantle of residual soil over shallow sandstone (bedrock). Based on these conditions, a Site Class C is appropriate. The seismic design parameters and OSSC response spectrum are shown on Figure 3A (Appendix A).

Liquefaction

Liquefiable soils typically consist of saturated, loose sands and non-plastic or low plasticity silt (i.e., a PI of less than 8). The site is underlain by stiff to hard or very dense residual soil followed by shallow bedrock. Therefore, liquefaction is not a hazard at this site.

ENGINEERING ANALYSIS

Project Information and Foundation Assumptions

Preliminary plans provided by SUB (Appendix E) indicate the electrical equipment within the facility will be supported by a combination of spread footings, mat foundations, or short pier foundations. We understand the pier foundations will be 2 to 3 feet in diameter. For preliminary sizing, pier depths of 6.5 to 7.5 feet were assumed. The foundations will be design based on 2014 OSSC parameters. Therefore, we anticipate spread footings and mats will be design per Section 1808 and 1809, and pier foundations will be design per Section 1807.3.

Bearing Capacity

The foundations for the new structures will be supported on stiff to hard or very dense residual soil. Spread or mat foundations should be underlain by a minimum of 6 inches of compacted Select Fill, as defined in the recommendations section of this report. Pier foundations may be poured neat into the excavations. However, prior to constructing the pier foundation, all loose or disturbed soils must be removed from the excavation and concrete placement must be completed in a manner that does not disturb the foundation soils.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 6. Project 2181086 Glenwood, Oregon Springfield Utility Board

Provided the foundations are designed and constructed as recommended herein, we recommend using an allowable bearing pressure of 3,000 psf for design. This includes a nominal factor of safety of 3. The allowable bearing pressure may be increased by one-third to evaluate short-term (e.g., seismic or wind) loads.

Settlement

For foundations designed using the allowable bearing pressure, foundation settlement should be limited to ±½ inch or less. This assumes any soft or disturbed soils are excavated and replaced, as required, with compacted Select Fill.

Concrete Slab or Mat Foundations

If mat design requires a modulus of subgrade reaction, ks, we recommend a design ks value of 200 pci. This value assumes the mat will be supported on at least 6 inches of compacted Select Fill over stiff to hard or very dense, undisturbed subgrade. All slabs and mat foundations should be reinforced to reduce the risk of cracking and warping.

Sliding Coefficient and Passive Resistance

A coefficient of friction of 0.5 is recommended for evaluating the sliding resistance between the base of the concrete footings or mats and the underlying Select Fill.

Passive resistance will develop on the sides of the footings or piers in response to lateral loading. Based on the foundation soils, we recommend assuming an allowable lateral resistance of 150 psf/ft. This value accounts for the variability in the shallow residual soil.

For spread footings and mats, the passive resistance should only be considered if the foundation embedment depth can be confirmed for the entire life of the footing. For pier foundations design per OSSC Section 1807.3, if the foundation is considered non-constrained at the ground surface and no lateral constraint is provided for the structure above the ground surface, the allowable lateral soil resistance should only be applied over a depth of one-third the pier embedment depth.

Access Road

If the access driveway will be paved, we anticipate recommendations from PSI’s report can be used based on the expected traffic.

If the driveway remains unpaved, we recommend providing a minimum of 12 inches of compacted base rock meeting the specifications for Select Fill. Furthermore, we recommend providing a Separation Geotextile between the base rock and the subgrade. Material definitions are provided below. This section is intended to provide support for pick-up trucks or similar-sized SUB service vehicles and is suitable for dry weather construction.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 7. Project 2181086 Glenwood, Oregon Springfield Utility Board

RECOMMENDATIONS

The construction recommendations provided below assume earthwork will occur during dry weather. Depending on the actual time of year construction begins, modifications to the respective recommendations may be required.

General Earthwork and Material Recommendations

1. Select Fill as defined in this report should consist of 1 or ¾-inch minus, clean (i.e., less than 5% passing the #200 U.S. Sieve), well-graded, crushed gravel or rock.

2. Separation Geotextile as defined in this report should be a woven geotextile with Mean Average Roll Value (MARV) strength properties meeting the requirements of an AASHTO M 288-17 Class 2 geotextile. The geotextile should have MARV hydraulic properties meeting the requirements of AASHTO M 288-17 with a permittivity greater than 0.05 sec.-1 and an Apparent Opening Size (AOS) less than 0.6 mm (max average roll value).

3. Compact the Select Fill in loose lifts not exceeding 12 inches. Thinner lifts (8 inches or less) will be required where light or hand-operated equipment is used. Compact the Select Fill to a minimum of 95% relative compaction. The maximum dry density of ASTM D 698 should be used as the standard for estimating relative compaction. Field density tests should be run frequently to confirm adequate compaction of the fill.

During wet weather, it may be necessary to increase the thickness of the initial lift of fill to ±18 to 24 inches to reduce the risk of subgrade pumping. The need for a thickened initial lift will need to be verified by a Foundation Engineering representative at the time of construction.

4. If trenches are required for below-grade construction, provide shoring to protect workers from sloughing or caving soils. Because the residual soil includes significant sand content, an OR-OSHA Type C soil should be assumed for planning utility trenching and/or shoring (OR-OSHA, 2011). Shoring and safety is the exclusive responsibility of the contactor.

Site Preparation for Structures

We recommend the foundation areas under the structures be prepared during dry weather as follows:

5. Strip the existing ground ±6 inches, or as required to remove roots, sod, or other deleterious material. Deeper grubbing may be needed where trees or thick brambles are present. Dispose of all strippings outside of construction areas, including pavements.

6. Grade the finished ground surface surrounding all structures to promote runoff away from the foundations.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 8. Project 2181086 Glenwood, Oregon Springfield Utility Board

7. Finished excavations for footings, slabs and mat foundations should be completed using a hoe equipped with a smooth bucket to minimize subgrade disturbance. The excavations should terminate in stiff to very hard or very dense, undisturbed residual soil (or weathered bedrock). The required excavation depths will need to be confirmed at the time of construction. All footing excavations should be evaluated by a Foundation Engineering representative prior to backfilling.

8. Do not allow the subgrade to dry out excessively following compaction. Immediately construct the foundation pads using compacted Select Fill.

9. Backfill the excavations to the planned foundation grade with compacted Select Fill. At least 6 inches of Select Fill should be provided beneath the foundations and slabs to help protect the underlying soil from disturbance. The fill thickness may need to be increased if construction occurs during wet weather.

Design Spread Footings and Mats

We recommend new footings and mat foundations be designed in accordance with the following recommendations.

10. Design footings and structural mats using an allowable bearing pressure of 3,000 psf. A one-third increase in the allowable bearing pressure may be assumed for transient (i.e., wind and seismic) loading. This value assumes footings or mats will be constructed on a minimum of 6 inches of Select Fill underlain by stiff to hard or very dense soil. The foundation soil should be confirmed by a representative of Foundation Engineering at the time of construction.

11. Assume new footings could settle up to ½ inch. This also represents the potential differential settlement between the foundations.

12. Use a coefficient of friction of 0.5 for footings bearing on compacted Select Fill for sliding analysis.

13. Use an allowable passive resistance of 150 psf/ft if the footings are backfilled with compacted Select Fill. The passive resistance should only be considered if the foundation embedment depth can be confirmed for the entire life of the footing.

Design and Construction of Pier Foundations

We recommend new pier foundations be designed and constructed in accordance with the following recommendations.

14. Design pier foundations using an allowable bearing resistance of 3,000 psf and allowable passive resistance of 150 psf/ft.

15. The bottom of the pier footings should terminate in very stiff to hard or very dense residual soil, or in sandstone bedrock. The required

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 9. Project 2181086 Glenwood, Oregon Springfield Utility Board

excavation depths and conditions should be confirmed by a representative of Foundation Engineering at the time of construction.

16. Drilling equipment used to advance the pier excavations should be capable of meeting the required design diameter and depth and maintain vertical alignment while drilling. While the pier excavations are expected to terminate in residual soil, site conditions may vary, and bedrock may be encountered in the excavations. The drilling equipment should be able to advance the excavation through rock with an unconfined compressive strength (qu) up to at least 2,000 psi.

17. The excavation should remove loose or disturbed materials at the base of the excavation prior to installing the rebar cage and pouring concrete.

18. Concrete can be placed by free-fall (i.e., through a chute) only if the pier excavation is relatively dry (i.e., no standing water) and the bottom of the excavation is free of debris. If water is present in the excavation, the excavation should be pumped dry prior to concrete placement or the concrete should be placed with a tremie to place concrete from the bottom of the excavation up and displace water or any deleterious materials. Concrete placement should continue until all water is displaced from the excavation.

19. Concrete for the pier foundations should meet all 2014 OSSC requirements. An 8-inch concrete slump (±1 inch) is recommended to facilitate placement.

Access Road Construction

The following recommendations assume the site grading and subgrade preparation for the access road will occur during dry weather.

20. Strip the existing ground ±6 inches, or as required to remove roots, sod, or other deleterious material. Deeper grubbing may be needed where trees or thick brambles are present. Dispose of all strippings outside of construction areas.

21. Excavate to the planned subgrade elevation for the required pavement section. Moisture-condition and compact the subgrade (during dry weather). Prior to placing base rock, proof-roll the subgrade with a loaded dump truck or other approved vehicle to identify any soft or pumping areas. Moisture-condition and recompact any pumping subgrade or overexcavate and replace the pumping subgrade with Select Fill.

22. Do not allow the subgrade to dry out excessively. Cover the approved subgrade with a Separation Geotextile and the required base rock section. The geotextile should be laid smooth, without wrinkles or folds in the direction of construction traffic. Overlap adjacent rolls a minimum of 2 feet. Pin fabric overlaps or place the base rock in a manner that will

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 10. Project 2181086 Glenwood, Oregon Springfield Utility Board

not separate the overlap during construction. Seams that have separated will require removal of the Base Rock to establish the required overlap.

23. Base rock used for the access road should meet the specifications for Select Fill as defined in Item 1. For an unpaved access road, a minimum base rock thickness of 12 inches is recommended. A thicker base rock section will likely be required to support construction traffic if construction occurs during wet weather.

For a paved access road, it is anticipated the selected pavement section thickness will be based on recommendations provided in the PSI report.

24. Compact the base rock as recommended in Item 3. If paving is planned, the completed base rock should be proof-roll prior to paving to determine if any subgrade softening has occurred. Overexcavate any soft subgrade and replace it with additional Select Fill, as required.

DESIGN REVIEW/CONSTRUCTION OBSERVATION/TESTING

Foundation Engineering should be provided the opportunity to review all drawings and specifications that pertain to site preparation, foundation construction and pavements. Site preparation will require field confirmation of foundation soils and pavement subgrade conditions. Mitigation of any subgrade pumping will also require engineering review and judgment. That judgment should be provided by one of our representatives. Frequent field density tests should be run on all engineered fill. We recommend we be retained to provide the necessary construction observation.

VARIATION OF SUBSURFACE CONDITIONS, USE OF THIS REPORT AND WARRANTY

The analyses, conclusions and recommendations contained herein assume the soil and rock conditions encountered in the borings and previous test pits (by others) are representative of the site conditions. The above recommendations assume we will have the opportunity to review final drawings and be present during construction to confirm the assumed foundation conditions. 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.

This report was prepared for the exclusive use of the Springfield Utility Board and their design consultants for the SUB Glenwood Substation project in Glenwood, Oregon. Information contained herein should not be used for other sites or for unanticipated construction without our written consent. This report is intended for planning and design purposes. Contractors using this information to estimate construction quantities 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.

SUB Glenwood Substation September 19, 2018 Geotechnical Investigation and Seismic Hazard Study 11. Project 2181086 Glenwood, Oregon Springfield Utility Board

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 that those services, if needed, have been completed by others.

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

AASHTO, 2017, Geotextile Specification for Highway Applications: American Association of State Highway and Transportation Officials (AASHTO), AASHTO Designation: M 288-17.

ASTM, 2011, Standard Test Method for Classification of Soils for Engineering Purposes (Unified Soil Classification System, USCS): American Society of Testing and Materials (ASTM) International, ASTM Standard D2487, DOI: 10.1520/D2487-11, 11 p.

ASTM, 2009, Standard Test Method for Description and Identification of Soils (Visual-Manual Procedure): American Society of Testing and Materials (ASTM) International, ASTM Standard D2488, DOI: 10.1520/D2488-09A, 11 p.

IBC, 2012, International Building Code: International Code Council, Inc.,

OR-OSHA, 2011, Oregon Administrative Rules, Chapter 437, Division 3 - Construction, Subdivision P – Excavations: Oregon Occupational Safety and Health Division (OR-OSHA).

OSSC, 2014, Oregon Structural Specialty Code (OSSC): Based on IBC 2012.

USGS, 2008, National Seismic Hazard Mapping Project, US Seismic Design Maps: USGS website: http://earthquake.usgs.gov/designmaps/us/application.php.

See Appendix D for geologic references noted herein.

Appendix A Figures

ProfessionalGeotechnicalServices

Foundation Engineering, Inc.

2181086

SITE

SCALE IN MILES

0 2.0 4.0 8.0

2181086

Notes:1. The Design Response Spectrum is based on IBC 2012 Section 1613.

2. The following parameters are based on the modified USGS 2008 maps provided in IBC 2012/OSSC 2014:

Site Class= C Damping = 5%SS = 0.75 Fa = 1.10 SMS = 0.82 SDS = 0.55

S1 = 0.39 Fv = 1.41 SM1 = 0.55 SD1 = 0.37

3. SS and S1 values indicated in Note 2 are the mapped, risk-targeted maximum considered

earthquake spectral acclerations for 1% probability of exceedence in 50 years.

4. Fa and Fv were established based on IBC 2012, Tables 1613.3.3(1) and 1613.3.3(2) using the selected SS and S1 values. SDS and SD1 values include a 2/3 reduction on SMS and SM1 as discussed in IBC 2012 Section 1613.3.4.

5. Site location is: Latitude 44.0355, Longitude -123.0344.

Glenwood, Oregon

FIGURE 3A

SUB Glenwood SubstationIBC 2012/OSSC 2014 SITE RESPONSE SPECTRUM

Project 2181086

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.5 1 1.5 2 2.5 3

Sp

ectr

al A

ccel

erat

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, S

a(g

)

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IBC 2012/OSSC 2014Response Spectrum

Appendix B Boring Logs and Core Box Photos

ProfessionalGeotechnicalServices

Foundation Engineering, Inc.

Very dense silty SAND, some clay and rock fragments(SM); light brown and iron-stained, damp, lowplasticity silt and clay, fine sand, sand to gravel-sizedangular siltstone rock fragments, relict rock texture,(residual soil).

Extremely to very weak (R0 to R1) SANDSTONE;dark grey, slightly weathered, fine sand, (EugeneFormation).

Weak (R2) SANDSTONE; light grey, fresh to slightlyweathered, close joints are planar to irregular, roughto smooth, and open, fine sand, (Eugene Formation).Calcite veining below ±16.1 feet.

Thin to very thin, dark grey siltstone interbeds from±15.5 to ±17.7 feet and ±18.0 to ±19.5 feet.

BOTTOM OF BORING

7.5

15.5

19.8

SS-1-1

SS-1-2

SS-1-3

SS-1-4

SS-1-5

SS-1-6CS-1-1

CS-1-2

Backfilledwith

bentonitechips

Foundation Engineering, Inc.

Moisture, %

RQD., %

Foundation Engineering, Inc.

Elev.

Depth0 50 100

SPT,Installations/

Backfill/

0 50 100

Depth

Feet

Soil and Rock Descriptionand

CommentsLog

SPT,N-Value

Water TableDepthSamples N-Value

Moisture, %

RQD., %

Elev.Samples

RecoveryRecovery

Depth

Feet

Soil and Rock Descriptionand

CommentsLog

Surface Elevation:

Date of Boring:

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Boring Log: BH-1

September 4, 2018

Surface Elevation: SUB Glenwood Substation

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Boring Log: BH-1

September 4, 2018

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2

3

4

5

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7

8

9

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0.0

78

91

50/4"

50/1st 5"

50/3"

50/1st 5"

78

91

50/4"

50/1st 5"

50/3"

50/1st 5"

78

91

50/4"

50/1st 5"

50/3"

50/1st 5"

78

91

50/4"

50/1st 5"

50/3"

50/1st 5"

541 feet (approx.)

Glenwood,

Stiff sandy CLAY, some rock fragments (CL); lightbrown and iron-stained, damp, low plasticity, finesand, sand to gravel-sized angular siltstone rockfragments, relict rock texture, (residual soil).

Very stiff below ±5.0 feet.

Hard below ±7.5 feet.

Very weak (R1) SANDSTONE; light brown andiron-stained, moderately weathered, very close toclose joints are planar to irregular, rough, open toclosed, fine sand, (Eugene Formation).

Weak (R2) SANDSTONE interbedded with siltstone;light grey, fresh to slightly weathered, very close toclose joints are planar to irregular, rough, and open toclosed, fine sand, thin to very thin, dark grey siltstoneinterbeds, (Eugene Formation).Calcite veining below ±17.1 feet.BOTTOM OF BORING

10.6

16.3

17.5

SS-2-1

SS-2-2

SS-2-3

SS-2-4CS-2-1

CS-2-2

CS-2-3

Backfilledwith

bentonitechips

Foundation Engineering, Inc.

Moisture, %

RQD., %

Foundation Engineering, Inc.

Elev.

Depth0 50 100

SPT,Installations/

Backfill/

0 50 100

Depth

Feet

Soil and Rock Descriptionand

CommentsLog

SPT,N-Value

Water TableDepthSamples N-Value

Moisture, %

RQD., %

Elev.Samples

RecoveryRecovery

Depth

Feet

Soil and Rock Descriptionand

CommentsLog

Surface Elevation:

Date of Boring:

2181086Project No.:

Springfield, Oregon

Boring Log: BH-2

September 4, 2018

Surface Elevation: SUB Glenwood Substation

Springfield, Oregon

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SUB Glenwood Substation

Project No.:

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N/A

Boring Log: BH-2

September 4, 2018

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539 feet (approx.)

Glenwood,

Foundation Engineering, Inc. SUB Glenwood Substation Project 2181086

Photo 1B. BH-1

Photo 2B. BH-2

Appendix C

Laboratory Test Results

Professional Geotechnical Services

Foundation Engineering, Inc.

UNCONFINED COMPRESSION TEST

UNCONFINED COMPRESSION TESTFEI Testing & Inspection, Inc.

Corvallis, OR

Project No.: 2186001-619

Date Sampled:

Remarks:

Figure 1C

Client: Foundation Engineering, Inc.; Project No. 2181086

Project: SUB Glenwood Substation

Source of Sample: 7632 Depth: 16.0' - 17.0'

Sample Number: CS-1-2

Description:

LL = PI = PL = Assumed GS= 2.65 Type:

Sample No.Unconfined strength, psi

Failure strain, %Strain rate, in./min.Water content, % Wet density, pcfDry density, pcfSaturation, %Void ratioSpecimen diameter, in.Specimen height, in.Height/diameter ratio

11823.15

1.4

0.100

13.3

136.0

120.0

92.9

0.3782

2.31

4.67

2.02

Com

pres

sive

Stre

ss, p

si

0

500

1000

1500

2000

Axial Strain, %

0 0.5 1 1.5 2

1

Appendix D

Seismic Hazard Study

Professional Geotechnical Services

Foundation Engineering, Inc.

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 1 Project 2181086 Glenwood, Oregon Springfield Utility Board

SEISMIC HAZARD STUDY SUB GLENWOOD SUBSTATION

GLENWOOD, OREGON

INTRODUCTION

The seismic hazard study was completed to identify potential geologic and seismic hazards and evaluate the effect those hazards may have on the proposed project. The study fulfills the requirements presented in the 2014 Oregon Structural Specialty Code (OSSC), Section 1803 for site-specific seismic hazard reports for essential and hazardous facilities and major and special-occupancy structures (OSSC, 2014).

The following sections provide a discussion of the local and regional geology, seismic and tectonic setting, earthquakes, and seismic hazards. A detailed discussion of the subsurface conditions at the project location, including exploration logs, is provided in the main report.

LITERATURE REVIEW

Available geologic and seismic publications and maps were reviewed to characterize the local and regional geology and evaluate relative seismic hazards at the site, including a local water-well search on the Oregon Water Resources Department (OWRD) website. Information from other geotechnical and seismic investigations previously conducted by others at the site were also reviewed. The literature review included information from several geotechnical and seismic hazard investigations completed by Foundation Engineering, Inc. in the Glenwood area.

Regional Geology

The proposed substation is located within the southern Willamette Valley. The Willamette Valley 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 (±50 to 58 million years ago), the present location of the Willamette Valley was part of a broad continental shelf extending from the Western Cascades west beyond the present coastline (Orr and Orr, 1999). Basement rock underlying most of Willamette Valley includes the Siletz River Volcanics, which erupted as part of a submarine oceanic island-arc. The thickness of the basement volcanic rock is unknown. However, it is estimated to be ±3 to 4 miles thick (Yeats et al., 1996).

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. Volcanism subsided, and a fore arc basin was created and infilled (primarily to the south) with marine sediments of the Flournoy, Yamhill, Spencer and Eugene Formations throughout the late Eocene and Oligocene, and terrestrial sedimentary deposits of the Fisher Formation and Little Butte Volcanics of the Oligocene (Orr and Orr, 1999). These sediments typically overlie, but are also interbedded with, basalt and volcanics of the Siletz River Volcanics and younger Tertiary volcanics. The eastern margin of the Willamette Valley includes deeply weathered foothills of the Western Cascades which are composed primarily of Little Butte Volcanics (Hladky and McCaslin, 2006). Uplift and tilting of the Coast Range and the Western Cascades formed the trough-like

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 2 Project 2181086 Glenwood, Oregon Springfield Utility Board

configuration of the Willamette Valley during the late Miocene. Following the formation of the Willamette Valley, thick layers of Pliocene gravel filled the southern valley (Madin and Murray, 2006; McClaughry et al., 2010). The deposits were then incised by the Willamette River forming alluvial terraces. In the Pleistocene (±1.8 million to 10,000 years ago), the southern valley was refilled with fan-delta gravel, originating from the melting glaciers in the Cascades. The Willamette and McKenzie Rivers 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).

Local Geology

The project site is located within the southern Willamette Valley, south of the Willamette River in Glenwood. Local geologic mapping and previous explorations indicate the project site is underlain by the Eugene Formation (Yeats et al., 1996; Madin and Murray, 2006; McClaughry et al., 2010). The Eugene Formation consists of tuffaceous sandstone and siltstone deposited in a shallow marine environment (Yeats et al., 1996; Orr and Orr, 1999; O'Connor et al., 2001; Madin and Murray, 2006). The formation outcrops in the Coburg Hills, ±5 miles north of the site, where it is estimated to be ±1,800 feet thick (Yeats et al., 1996).

The subsurface conditions encountered in our explorations are consistent with the mapped local geology and the previous explorations on site. Residual soil consisting of stiff sandy clay extending to ±7.5 feet in BH-1 and very dense silty sand extending to ±10 feet in BH-2. Extremely weak to weak (R0 to R2) sandstone extends to the limits of the explorations. Additional subsurface details are provided in the Subsurface Conditions section of the main report and on the boring logs in Appendix B.

Tectonic Setting

The Southern Willamette Valley lies ±120 miles inland from the surface expression of the Cascadia Subduction Zone (CSZ) (Goldfinger et al., 1992). The CSZ is a converging, oblique plate boundary, where the Juan de Fuca plate is being subducted beneath the western edge of the North American continent (Geomatrix Consultants, 1995). The CSZ extends from central Vancouver Island in British Columbia, Canada, through Washington and Oregon to Northern California (Atwater, 1970).

Available information indicates the CSZ is capable of generating earthquakes within the descending Juan de Fuca plate (intraplate), along the inclined interface between the two plates (interface or subduction zone), or within the overriding North American Plate (crustal) (Weaver and Shedlock, 1996). Therefore, Western Oregon is located in an area of potentially high seismic activity due to its proximity to the CSZ.

Local Faulting

A review of nearby faults was completed to establish the seismic setting and the seismic sources. Three potentially active Quaternary (<1.6 million years or less) crustal fault zones have been mapped within ±40 miles of the site (Geomatrix Consultants, 1995; Personius et al., 2003; USGS, 2006) and are listed in Table 1D. The approximate surface projection locations of these faults in the southern Willamette Valley are shown

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 3 Project 2181086 Glenwood, Oregon Springfield Utility Board

on Figure 1D (attached) (Personius et al., 2003). Additional fault information is available in the literature (Personius et al., 2003; USGS, 2006).

Of the listed faults, the Owl Creek fault is the only US Geologic Survey (USGS) Class A fault. Class A faults have geologic evidence supporting tectonic movement in the Quaternary, known or presumed to be associated with large-magnitude earthquakes (Personius et al., 2003). The remaining two fault zones are considered Class B faults by the USGS. Class B faults are of non-tectonic origin (e.g. volcanic activity) or demonstrate less evidence of tectonic displacement (Personius et al., 2003).

Table 1D. Potentially Active Quaternary Crustal Faults within ±40 miles of the SUB Glenwood Substation1

Fault Name Length (miles)

Most Recent Estimated

Deformation

Distance from Site (miles)2

Slip Rate (mm/yr)

Upper Willamette River (#863) ±27 <1.6 million years ±23 to 37 SE <0.20

Owl Creek (#870) ±9 <750,000 years ±32 N-NW <0.20

Corvallis (#869) ±25 <1.6 million years ±38 NW <0.20

Notes: 1. Fault data based on Personius et al., 2003, USGS, 2006 and USGS, 2017. 2. Distance from site to nearest surface projection of the fault.

Numerous concealed and inferred crustal faults have been mapped within ±20 miles of Eugene/Springfield area (Yeats et al., 1996; Hladky and McCaslin, 2006; Madin and Murray, 2006; McClaughry et al., 2010). However, none of these faults show any evidence of movement in the last ±1.6 million years (Geomatrix Consultants, 1995; USGS, 2006).

The USGS (2008) interactive deaggregation indicates the primary seismic sources affecting the site are the CSZ faults. For a more detailed list and discussion of folds and faults associated with the CSZ, one can review the USGS website (http://earthquake.usgs.gov/hazards/qfaults/or/index.php). Additional fault information is available in the literature (Personius et al., 2003; USGS, 2006).

Historic Earthquakes

No significant interface (subduction zone) earthquakes have occurred on the CSZ in historic times. However, several large-magnitude (>M ~8.0, M = unspecified magnitude scale) subduction zone earthquakes are thought to have occurred in the past few thousand years. This is evidenced by tsunami inundation deposits, combined with evidence for episodic subsidence along the Oregon and Washington coasts (Peterson et al., 1993; Atwater et al., 1995).

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 4 Project 2181086 Glenwood, Oregon Springfield Utility Board

The Oregon Department of Geology and Mineral Industries (DOGAMI) estimates the maximum magnitude of an interface subduction zone earthquake ranges from moment magnitude (Mw) 8.5 to Mw 9.0 (Wang and Leonard, 1996; Wang et al., 1998; Wang et al., 2001). The fault rupture may occur along a portion or the entire length of the CSZ (Weaver and Shedlock, 1996). The most recent CSZ interface event occurred ±318 years ago (January 26, 1700) (Nelson et al., 1995; Satake et al., 1996).

Numerous detailed studies of coastal subsidence, tsunamis, and turbidite deposits estimate a wide range of CSZ earthquake recurrence intervals. Turbidite deposits in the Cascadia Basin have been investigated to help develop a paleoseismic record for the CSZ and estimate recurrence intervals for interface earthquakes (Adams, 1990; Goldfinger et al., 2012). A study of turbidites from the last ±10,000 years suggests the return period for interface earthquakes varies with location and rupture length. That study estimated an average recurrence interval of ±220 to 380 years for an 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 (Goldfinger et al., 2012). However, older, deep-sea cores have been re-examined and the findings may indicate greater Holocene stratigraphy variability along the Washington coast (Atwater et al., 2014). Additional research by Goldfinger for the northern portion of the subduction zone suggests a recurrence interval of ±340 years for the northern Oregon Coast (Goldfinger et al., 2016).

Intraplate (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 intraplate earthquake is about Mw 7.5 (Wang et al., 2001). No intraplate earthquakes have been recorded in Oregon in modern times. However, the Puget Sound region of Washington State has experienced three intraplate events in the last ±69 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 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 6.5 (Wang and Leonard, 1996; Wang et al., 1998; Wang et al., 2001). 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) (Wong and Bott, 1995). The majority of Oregon’s larger crustal earthquakes are in the ML 4 to 5 range (Wong and Bott, 1995).

Table 2D summarizes earthquakes with a M of 4.0 or greater or Modified Mercalli Intensity (MM) of V or greater has occurred within a ±50-mile radius of Springfield in the last ±185 years (Johnson et al., 1994; USGS, 2016).

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 5 Project 2181086 Glenwood, Oregon Springfield Utility Board

Table 2D. Historic Earthquakes Within a ±50-mile Radius of Springfield

Year Month Day Hour Minute Latitude Longitude Depth (miles)

Magnitude or Intensity

1921 02 25 20 00 44.4 -122.4 unknown MMI = V

1942 05 13 01 52 44.5 -123.3 unknown MM = V

1961 08 19 04 56 44.7 -122.5 unknown M = 4.5

2015 07 04 15 42 44.09 -122.83 4.9 ML = 4.1

Notes: M = unspecified magnitude, Mb = compressional body wave magnitude, Mc = primary coda magnitude, ML = local Richter magnitude, and MMI = Modified Mercalli Intensity. The site is located at Latitude 44.035521, Longitude -123.034383.

It should be noted that seismic events in Oregon were not comprehensively documented until the 1840's (Wong and Bott, 1995). According to Wong and Bott (1995), seismograph stations sensitive to smaller earthquakes (ML 4 to 5) were not implemented in northwestern Oregon until 1979 when the University of Washington expanded their seismograph network to Oregon. Prior to 1979, few seismograph stations were installed in Oregon. OSU likely had the first station installed in 1946 (Wong and Bott, 1995). The local Richter magnitude (ML) of events occurring prior to the establishment of seismograph stations have been estimated based on correlations between magnitude and MM intensities. Some discrepancy exists in the correlations.

Table 3D summarizes distant, strong earthquakes felt in the Springfield area (Noson et al., 1988; Bott and Wong, 1993; Stover and Coffman, 1993; Wiley et al., 1993; Dewey et al., 1994; Wong and Bott, 1995; Black, 1996; Dewey et al., 2002). None of these events caused significant, reportable damage in the Eugene/Springfield area.

Table 3D. Distant Earthquakes Felt in the Springfield Area

Earthquake Modified Mercalli Intensities (MM)

2001 Nisqually, Washington II to III

1993 Klamath Falls, Oregon IV

1993 Scotts Mills, Oregon IV

1965 Seattle – Tacoma, Washington I to IV

1962 Portland, Oregon I to IV

1961 Lebanon/Albany, Oregon IV

1949 Olympia, Washington IV

1873 Crescent City, California V

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 6 Project 2181086 Glenwood, Oregon Springfield Utility Board

Seismic and Geologic Hazards

Section 1803.7 of the 2014 OSSC requires the evaluation of risks from a range of seismic hazards including: ground motion amplification, ground rupture, earthquake-induced landslides, liquefaction and lateral spread, and tsunami/seiche.

Geologic and seismic hazard studies by DOGAMI have been completed for the Eugene-Springfield Metropolitan area and they also provide on-line hazard information through HazVu (web viewer), which also includes SLIDO and LiDAR viewers (Black et al., 2000; DOGAMI, 2018). However, these studies are only a guide and do not have precedence over site-specific evaluations. We have developed conclusions regarding the seismic hazards based on the subsurface profiles encountered in our exploratory boreholes at the site. The conclusions are also based on our knowledge of the site geology, a review of previous geotechnical and seismic hazard studies performed in the Glenwood area, and available geologic hazard maps (including information available from DOGAMI).

The relative earthquake hazard is based on the combined effects of ground shaking amplification and earthquake-induced landslides with a range in hazard from Zone A (highest hazard) to Zone D (lowest hazard). Based on the DOGAMI mapping, the site is within Zone D (lowest hazard) for the overall, relative earthquake hazard (Black et al., 2000).

Ground Motion Amplification

Ground motion amplification is the influence of a soil deposit on the earthquake motion. As seismic energy propagates up through the soil strata, the ground motion is typically increased (i.e., amplified) or decreased (i.e., attenuated) to some extent.

Based on the site soil profile consisting of residual soil overlying sandstone bedrock, we anticipate the ground motion amplification will be low and consistent with an OSSC (2014) Site Class C profile. Our recommendation is consistent with the DOGAMI findings for Lane County, including a low amplification susceptibility (Burns et al., 2008) and a low hazard amplification (amplifies by a factor of ≤1.0) (Black et al., 2000).

Ground Rupture

The risk of ground rupture is expected to be low due to the lack of known active faulting beneath the site (Yeats et al., 1996; Madin and Murray, 2006). Hidden and/or deep-seated active faults could remain undetected. Additionally, recent crustal seismic activity cannot always be tied to observable faults. The closest potentially active fault is the Owl Creek (#870), ±32 miles north-northwest of the project site. The fault is considered active within <750,000 years (USGS, 2006).

Liquefaction, Settlement, and Lateral Spread

Where liquefaction has been documented, those soils typically consist of saturated, loose, clean sand, and non-plastic to low plasticity silt with a plasticity index (PI) less than 8. These soils were not encountered in our explorations. Therefore, the risk of liquefaction triggering and liquefaction-induced settlement is non-existent. This is consistent with the DOGAMI findings for HazVu and Lane County that concluded no to very low liquefaction susceptibility (Burns et al., 2008; DOGAMI, 2018).

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 7 Project 2181086 Glenwood, Oregon Springfield Utility Board

Lateral spread is a liquefaction-induced hazard which occurs when soil or blocks of soil are displaced down slope or toward a free face (such as a river bank) along a liquefied layer. A lateral spread hazard does not exist at the sites since there is no liquefaction hazard.

Landslides and Earthquake-Induced Landslides

DOGAMI’s HazVu web viewer, which includes SLIDO and LiDAR viewers, and other references indicate no mapped historic landslides or slope instability features at the site with a no hazard to moderate landslide hazard (landsliding possible) (Black et al., 2000; Burns et al., 2008; DOGAMI, 2017b, a, 2018). The HazVu and the Lane County Identified Landslide Hazard map indicate that no historic landslides are mapped at the site (Burns et al., 2008; DOGAMI, 2017b). The earthquake-induced landslide hazard is considered low, since there are no mapped or active landslide hazards at the site and shallow bedrock is present.

The existing site topography is relatively flat in the immediate vicinity of the proposed substation and no landslide features or deposits were observed during the exploration. Therefore, based on the on-site, subsurface and mapped information, there is no risk of landslides or earthquake-induced landslides at the site.

Tsunami / Seiche

Tsunami are waves created by a large-scale displacement of the sea floor due to earthquakes, landslides, or volcanic eruptions (Priest, 1995). Tsunami inundation is not applicable to this site, since the project site is not on the Oregon Coast. Seiche (the back and forth oscillations of a water body during a seismic event) is also not a local hazard due to the absence of large bodies of water near the site.

Radon Potential

DOGAMI has recently added radon potential to their HazVu website list of geologic hazards (DOGAMI, 2018). Radon is a naturally occurring radioactive gas with no odor or color and forms as a byproduct from radium found in soil and rock typically containing uranium (uranium minerals present in rocks or the soil weathering product from these rocks). The gas spreads out from the ground and can accumulate in buildings built above, resulting in high radon concentrations. The high concentrations can pose a health hazard and through long-term inhalation exposure may lead to lung cancer.

Based on the HazVu website, the proposed site is found within the low radon potential zone (DOGAMI, 2018). This is an estimate based on uranium host rock data, Oregon indoor radon test results shared by the Oregon Health Authority (OHA), data from the National Uranium Resource Evaluation project and statewide geologic mapping by DOGAMI.

Foundation Engineering does not perform radon testing or remediation. We assume that those services, if required, will be completed by others. Refer to the OHA website for additional information: http://www.oregon.gov/oha/ph/healthyenvironments/healthyneighborhoods/radongas/pages/index.aspx.

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 8 Project 2181086 Glenwood, Oregon Springfield Utility Board

SEISMIC DESIGN

Design Earthquakes

The 2014 OSSC, Section 1803.3.2.1, requires the design of structures classified as essential or hazardous facilities, and major and special-occupancy structures address, at a minimum, the following earthquakes:

Crustal: A shallow crustal earthquake on a real or assumed fault near the site with a minimum MW 6.0 or the design earthquake ground motion acceleration determined in accordance with the 2014 OSSC Section 1613.

Intraplate: A CSZ intraplate earthquake with MW of at least 7.0.

Interface: A CSZ interface earthquake with a MW of at least 8.5.

The design maximum considered earthquake ground motion maps provided in the 2014 OSSC are based on modified (risk-targeted) 2008 maps prepared by the USGS for an earthquake with a 1% probability of exceedance in 50 years (i.e., a ±4,975-year return period) for design spectral accelerations. The modifications include factors to adjust the spectral accelerations to account for directivity and risk.

The 2008 USGS maps were established based on probabilistic studies and include aggregate hazards from a variety of seismic sources. The interactive deaggregation search tool on the USGS National Earthquake Hazard Mapping website allows the breakdown of earthquake sources to be identified (USGS, 2018). Interactive deaggregation of the 4,975-year return period USGS spectral acceleration maps indicates the seismic hazard at the site is dominated by the CSZ, contributing 99% to the overall aggregate hazard. Crustal earthquakes were included in the studies but were not considered to be a principal seismic hazard at this site. The CSZ scenarios considered ranged from Mw 8.1 to 9.0, located ±40 to 86 miles west of the site.

The earthquake magnitudes and source-to-site distances used to generate the 2008 USGS maps satisfy the requirements of 2014 OSSC. Seismic design parameters and a 2014 OSSC design response spectrum are discussed in the Seismic Design section of the main report and are shown on Figure 3A (Appendix A).

CONCLUSION

Based on the findings presented herein, it is our opinion there are no geologic or seismic hazards that would preclude the design and construction of the proposed project or that require site mitigation. This site-specific hazard investigation was prepared by Brooke Running, R.G., C.E.G.

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 9 Project 2181086 Glenwood, Oregon Springfield Utility Board

REFERENCES

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.

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.

Black, G. L., 1996, Earthquake Intensity Maps for the March 25, 1993, Scotts Mills, Oregon, Earthquake: Oregon Geology, vol. 58, no. 2, p. 35-41.

Black, G. L., Wang, Z., Wiley, T. J., Wang, Y., and Keefer, D. K., 2000, Relative Earthquake Hazard Map of the Eugene-Springfield Metropolitan Area, Lane County, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), IMS-14, p. 16.

Bott, J. D. J., and Wong, I. G., 1993, Historical Earthquakes In and Around Portland, Oregon: Oregon Geology, vol. 55, no. 5, p. 116-122.

Burns, W. J., Hofmeister, R. J., and Wang, Y., 2008, Geologic Hazards, Earthquake and Landslide Hazard Maps, and Future Earthquake Damage Estimates for Six Counties in the Mid/Southern Willamette Valley; Including Yamhill, Marion, Polk, Benton, Linn, and Lane Counties, and the City of Albany, Oregon: Oregon Department of Geology and Mineral Industries (DOGAMI), IMS-24, 50 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.

Dewey, J. W., Reagor, B. G., Johnson, D., Choy, G. L., and Baldwin, F., 1994, The Scotts Mills, Oregon, Earthquake of March 25, 1993: Intensities, Strong-motion Data, and Teleseismic Data: U.S. Geological Survey (USGS), OFR 94-163, 26 p.

DOGAMI, 2017a, LiDAR (Light Detection and Ranging) Viewer Online Map: Oregon Department of Geology and Mineral Industries (DOGAMI), Portland, Oregon, last updated 10-17-17, accessed September 2018, http://www.oregongeology.org/sub/lidardataviewer/index.htm.

SUB Glenwood Substation September 19, 2018 Seismic Hazard Study 10 Project 2181086 Glenwood, Oregon Springfield Utility Board

DOGAMI, 2017b, SLIDO (Statewide Landslide Information Database for Oregon) Viewer Online Map, SLIDO 3.4: Oregon Department of Geology and Mineral Industries (DOGAMI), Portland, Oregon, last updated 12-14-17, accessed September 2018, http://www.oregongeology.com/sub/slido/index.htm.

DOGAMI, 2018, Oregon HazVu: Statewide Geohazards Viewer: Oregon Department of Geology and Mineral Industries (DOGAMI), Portland, Oregon, last updated 03-13-18, accessed September 2018, Online Map Viewer http://www.oregongeology.org/hazvu.

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., Vallier, T., and 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.

Hladky, F. R., and McCaslin, G. R., 2006, Preliminary Geologic Map of the Springfield 7.5' Quadrangle, Lane County, Oregon: Oregon Department of Mineral Industries, Open-File Report O-06-07, p. 31.

Johnson, A. G., Scofield, D. H., and Madin, I. P., 1994, Earthquake Database for Oregon, 1833 Through October 25, 1993: Oregon Department of Geology and Mineral Industries (DOGAMI), Open-File Report O-94-04.

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, 116 p.

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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.

Noson, L. L., Qamar, A., and Thorsen, G. W., 1988, Washington Earthquake Hazards: Washington Department of Natural Resources (WADNR), Division of Geology and Earth Resources, Olympia, Washington, 77 p.

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Appendix E Project Documents

ProfessionalGeotechnicalServices

Foundation Engineering, Inc.