[Supplemental]_Geotechnical_Report.pdf

Foundation Engineering, Inc.

Professional Geotechnical Services

820 NW Cornell Avenue • Corvallis, Oregon 97330 • 541-757-7645

7857 SW Cirrus Drive, Bldg 24 • Beaverton, Oregon 97008 • 503-643-1541

Date: November 6, 2025

To: Amanda Blankenship, P.E.

David Evans and Associates, Inc.

From: Jeffery D. Tucker, P.E., G.E.

Subject: Supplemental Geotechnical Consultation for Final Design

Project: SW 205th Avenue Bridge

Project No.: 2241123

We have completed geotechnical consultation for the above-referenced project. This memorandum provides a summary of the work completed to date and final design information and recommendations. The information provided in this memorandum supersedes information provided in the final geotechnical report prepared by NV5 dated August 29, 2024 (NV5, 2024).

There are numerous values in geotechnical investigations that are approximate, including calculated values, measured lengths and heights, soil and rock layer depths and elevations, and strength measurements. For brevity, the symbol “±” is used throughout this memorandum to represent the words “approximate” or

“approximately” when discussing approximate values.

BACKGROUND

Washington County is planning to replace the existing SW 205th Avenue bridge over

Beaverton Creek in Hillsboro, Oregon. A geotechnical report for the project dated

August 9, 2024, was prepared by NV5 based on the 60 precent design drawings.

Revisions to the 60 precent design require additional geotechnical recommendations to the geotechnical report. Therefore, Foundation Engineering, Inc. (FE) was retained by DEA to perform supplemental geotechnical engineering for final design.

The proposed bridge will be a three-span bridge supported on deep foundations.

Interior Bents 2 and 3 were designed to be supported on drilled shafts in the

60 percent drawings. Since then, the design team has elected to support Bents 2 and 3 on driven, PP24X0.5 pipe piles. Bent loads have also been revised from the

60 percent plans. Recommendations are also required for a temporary work bridge.

We understand the stormwater detention pond proposed southeast of the bridge was eliminated during final design. Therefore, a stormwater detention pond will be constructed on the southwest side of the bridge.

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SW 205th Avenue Bridge Replacement November 6, 2025 Supplemental Geotechnical Investigation 2 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

FOUNDATION ANALYSIS AND DESIGN RECOMMENDATIONS

Based on the soft subsurface conditions, deep foundations will be required to support the replacement bridge. Bents 1 and 4 will be supported on PP16X0.5 pipe piles, and Bents 2 and 3 will be supported on PP24X0.5 pipe piles.

Design Loads

Bents 1 and 4 will be supported on a single row of twelve, PP16X0.5 pipe piles spaced at 6 feet 9 inches on center, and Bents 2 and 3 will be supported on a single row of eight, PP24X0.5 pipe piles spaced at 10 feet on center. DEA provided estimated abutment loads and axial loads per pile for this layout summarized in Table 1.

Table 1. Factored and Unfactored Loads

Bent

Number of Piles per Bent

Strength I Load per Pile (kips)

Strength II Load per Pile (kips)

Service Load per Pile (kips)

Extreme Event I Load per Pile (kips)

Extreme Event II

Load per Pile (kips)

1 12 396 353 274 185 259

2 8 734 760 519 595 483

3 8 734 760 519 613 483

4 12 419 373 290 193 272

Driven Pile Analysis and Design

Pile Type and Material Specifications. PP16x0.5 piles consisting of ASTM A252 Grade 3 steel were selected for Bents 1 and 4 based on the design loads, and PP24x0.5 consisting of ASTM A252 Grade 3 steel were selected for Bents 2 and 3 based on the design loads and because these sections are typically readily available.

The pipe piles should be driven closed-ended.

Driving will extend through predominantly soft to medium stiff soil and the pile tips will be seated in very stiff silt and clay. The recommended pile properties are summarized in Tables 2 and 3.

Supplemental Geotechnical Investigation 3 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Table 2. Recommended Pile Properties for Bents 1 and 4

Property Recommended Value

Pile Type PP16x0.5

Steel Grade ASTM A252 Grade 3

Minimum Yield Stress (Fy) 45 ksi

Area Steel (As) 24.3 in2

Min. Nom. Structural Resistance (Fy x As) 1,094 kips

End Condition Closed-ended

Table 3. Recommended Pile Properties for Bents 2 and 3

Property Recommended Value

Pile Type PP24x0.5

Steel Grade ASTM A252 Grade 3

Minimum Yield Stress (Fy) 45 ksi

Area Steel (As) 36.9 in2

Min. Nom. Structural Resistance (Fy x As) 1,661 kips

End Condition Closed-ended

Downdrag. We understand the schedule and sequencing will provide enough time to allow for the completion of settlement of the approach fills prior to installing the piles. We also understand the piles at Bents 1 and 4 will be driven after the settlement is complete. Therefore, a settlement-induced downdrag load is not anticipated.

Downdrag due to seismically-induced strain softening is anticipated for the design crustal and CSZ earthquakes for the piles driven at Bents 1, 2 and 3. Seismic downdrag loads were calculated using residual undrained shear strengths estimated for the very soft to soft alluvial soils and the static skin resistance in the approach fill above these layers. The residual undrained shear strengths were assumed to be ±80% of the undrained shear strengths used for static loading. Our analyses indicate a seismic downdrag load of ±49 kips/pile for Bent 1, ±48 kips for Bent 2, and ±9 kips for Bent 3. We believe this approach provides a conservatively high estimate of the seismic downdrag load. The seismic downdrag load should also be applied to the Extreme Event I load to estimate the driving resistance.

Supplemental Geotechnical Investigation 4 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Nominal and Factored Axial Resistances. The nominal and factored axial resistances for the driven piles were calculated based on the subsurface profiles encountered in the borings. Axial pile analyses were completed using the AASHTO (2020) Load Resistance Factor Design (LRFD) approach. Strength parameters for the foundation soils were selected based on correlations to SPT N-values and our experience with similar materials. The nominal axial resistances were calculated based on skin friction along the lengths of the driven piles and end-bearing at the pile tips. The end-bearing calculations assume the piles will be driven closed-ended. The calculated nominal and factored axial resistances versus embedment are shown in Figure 1A for Bent 1, Figure 2A for Bent 2, Figure 3A for Bent 3, and Figure 4A for Bent 4. For static loading, the nominal axial pile resistance needed to resist the factored loads is:

Rn = ∑γiQi/φdyn where: ∑γiQi is the Strength I factored load per pile and φdyn is the resistance factor based on the driving criterion. A φdyn of 0.65 was selected because dynamic pile testing will be used to establish the final driving criteria.

For seismic loading, the nominal axial pile resistance needed to resist the foundation loads and downdrag due to cyclic softening is:

Rndr = ∑γiQi/φdyn + γpDD/φseis

Where: ∑γiQi is the Service factored load per pile, DD is the downdrag load due to settlement associated with cyclic softening after a seismic event; φseis is the seismic resistance factor; and γp is the load factor for downdrag. φdyn is equal to 0.65 and γp is equal to 1.0.

Where: ∑γiQi is the Extreme Event I factored load per pile, DD is the downdrag load due to settlement associated with cyclic softening; φseis is the seismic resistance factor; and γp is the load factor for downdrag. φseis and γp are both equal to 1.0 for Extreme Event I limit state design.

The required Rndr for the Extreme Event case must account for the skin friction that has to be overcome during pile driving above and within the downdrag zone, Rsdd.

The required nominal driving resistance is:

Rndr = Rn + Rsdd = ∑γiQi/φseis + γpDD/φseis + Rsdd where: Rsdd is calculated using static design methods.

If the piles are driven prior to the completion of approach settlement, downdrag loads should be used to determine the nominal driving resistance. The seismic downdrag loads were applied to Bents 1, 2 and 3 for the Extreme Event I load case. The calculated required nominal driving resistance including the seismic downdrag load per pile for the maximum Strength and Extreme Event load cases are summarized in Table 4. The nominal driving resistances were rounded up to the nearest 5-kip increment.

Supplemental Geotechnical Investigation 5 Project No.: 2241123

Hillsboro, Oregon David Evans and Associates, Inc.

Table 4. Required Nominal and Factored Axial Resistances Per Pile

Bent

No.

Maximum Loading Condition Qp

(kips)

Seismic DD

(kips)

Rsdd

(kips)

Rndr

(kips)

1 Extreme Event I 185 83 104 375

1 Strength I 409.5 0 0 630

2 Extreme Event I 595 63 78 740

2 Strength II 806 0 0 1240

3 Extreme Event I 613 9 11 635

3 Strength II 806 0 0 1240

4 Strength I 433 0 0 665

The required nominal driving resistance for maximum Strength I/II loading condition exceeds the required nominal driving resistance for Extreme Event I load case for

Bents 1, 2, and 3. Therefore, the required nominal driving resistance and estimated pile lengths are based on Strength I/II loading.

Minimum/Estimated Pile Tip Elevations and Estimated Pile Lengths. Estimated tip elevations were established based on the design loads, axial resistance calculations, and our previous experience driving piles into silts and clays in the area of the project site.

The required nominal driving resistance for Strength I/II loading exceeds the required nominal driving resistance for Extreme Event I loading with the addition of seismicly-induced downdrag. Therefore, the required nominal driving resistance and estimated pile lengths are based on Strength I/II loading.

Table 5 summarizes the bottom of cap, pile cut-off, and minimum and estimated tip elevations, and estimated pile lengths for each bent.

Table 5. Minimum and Estimated Tip Elevations and Estimated Pile Lengths

Bent

Ave. Bottom of

Cap Elevation

(ft)

Ave. Pile Cut-

Off Elevation

(ft)

Minimum

Tip

Elevation

(ft)

Estimated

Tip

Elevation

(ft)

Estimated

Pile Length

(ft)

1 El. 147.00 El. 149.17 El. 78.75 El. 58 92

2 El. 150.66 El. 153.33 El. 61.00 El. 33 121

3 El. 151.16 El. 153.83 El. 64.15 El. 30 124

4 El. 147.25 El. 149.42 El. 93.57 El. 61 89

Supplemental Geotechnical Investigation 7 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Per AASHTO Section 10.5.2.2, the tolerable movements for a prestressed multi-girder bridge structure may be estimated by the following expression:

∆ = 0.13 L/S-0.17

Where, ∆ = tolerable differential settlement in inches

L = the minimum adjacent span length in feet

S = the girder spacing in feet.

Based on a minimum adjacent span length of 100 feet and a girder spacing of

6.75 feet, the tolerable differential settlement between bridge bents is 2.1 inches.

Based on our analysis, the maximum differential settlement of adjacent bridge bents is 0.2 inches.

Lateral Pile Analysis. We developed recommended static and cyclic soil parameters for LPILE analyses. The parameters are summarized in Tables 1A through 4A (Appendix A). The plans indicate the piles at Bents 1 and 4 will be installed in a single row with a center-to-center spacing of 6.75 feet. This spacing corresponds to ±5B for PP16x0.5 piles, where B is the pile diameter. The plans indicate the piles at Bents 2 and 3 will be installed in a single row with a center-to-center spacing of 10 feet. This spacing corresponds to ±5B for PP24x0.5 piles. P-Y reduction factors are required for analyzing the transverse load case with these pile spacings. The reduction factors are provided in Table 8.

Table 8. P-Y Reduction Factors for Transverse Loading

Pile Center to Center Spacing Row 1 Row 2 Row 3 and higher

5B 1.0 0.85 0.7

MSE Wall Approach Settlement

The bridge approaches will be supported by MSE walls. Wall 1 will support the south approach with wall heights ranging from ±5 to 19 feet, and Wall 2 will support the north approach with wall heights ranging from ±2 to 16 feet.

We completed analysis using Settle3 software to calculate the settlement associated with the existing embankments and proposed embankment widening. A moist unit weight (γm) of 125 pcf was assumed for the new embankment fill and MSE wall backfill, presuming imported granular materials will be used. The consolidation test results were used to select unit weight and compressibility parameters for the very soft to stiff alluvial soil. Unit weights and compressibility parameters for the other soil layers were assigned based on our previous experience with similar materials.

Supplemental Geotechnical Investigation 8 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Based on our analysis, the maximum settlement of the south approach is estimated to be ±8 to 9 inches, and the maximum settlement of the north approach is estimated to be ±4 to 5 inches. It is difficult to predict the magnitude and timing of settlement in deep, soft soil deposits due to variability in the material properties (including the compressibility, organics content, and permeability) and because the drainage path required to dissipate pore water pressure during consolidation is very long.

The actual settlement typically varies from our estimates. We anticipate the actual settlement will be on order of 50 to 70 percent of the estimated settlement. We have provided DEA with a point cloud data file of the estimated settlement for the north and south MSE walls. Consolidation models typically over predict settlement adjacent to the fill loads. We anticipate settlement due to the north and south approach walls will be negligible at distances of 30 feet from the proposed MSE walls.

We conducted an analysis to estimate the time required to complete the primary consolidation of the soft soils under the weight of the new approach MSE walls. The analysis, using the consolidation test results, suggests a period of 3 to 4 month for ±90% of the consolidation to occur. Given the site conditions, we recommend constructing the approach MSE walls as early as possible in the construction sequence to allow as much of the settlement to occur as possible prior to paving and bridge construction. Settlement monitoring should be performed after the approach walls have been constructed to confirm that settlement is complete.

Minimum MSE Wall Reinforcement Length

We conducted global stability analyses for proposed MSE Walls 1 and 2 using the computer program SLIDE2. For the abutment walls, we included a vertical deal load to account for the weight of the abutment backfill above the MSE reinforced zone, assuming a moist unit weight of 125 pcf. We also included a vertical live load surcharge to account for traffic loading after the bridge is constructed. The traffic surcharge was calculated using a unit weight of 125 pcf and a surcharge height of 2 feet, as recommended in AASHTO 2020 Table 3.11.6.4-1. An inextensible reinforcement per ODOT QPL was assumed for the geogrid reinforcement. Tables 9 and 10 summarize the recommended minimum reinforced lengths for each wall section and the corresponding reinforcement to wall height ratios, where H is the total wall height.

Supplemental Geotechnical Investigation 9 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Table 9. Wall 1 Summary of Recommended Minimum Reinforcement Lengths

Wall Section Wall Height (feet)

Wall Embedment

(feet)

Minimum Reinforcement

Length (feet)

Reinforcement to Wall Height Ratio

(L = )

Sta. 10+00.00 to Sta.

10+19.37 4.7 to 11.4 2.0 to 4.0 8.0 0.7H

Sta. 10+19.37 to Sta.

10+70.09 8.8 to 11.4 2.0 to 3.5 8.0 0.7H

Sta. 10+70.09 to Sta.

10+82.10 11.0 to 16.4 2.0 to 4.1 8.0 to 11.5 0.7H

Sta. 10+82.10 to Sta.

12+90.97 16.5 to 20.3 2.0 to 4.0 14.9 to 18.3 0.9H

Sta. 12+90.97 to Sta.

13+72.11 16.0 to 17.3 3.3 to 4.9 16.4 to 20.1 1.1H

Sta. 13+72.11 to Sta.

13+93.67 10.8 to 13.0 2.0 to 4.1 8.0 to 9.1 0.7H

Sta. 13+93.67 to Sta.

15+12.11 6.1 to 11.8 2.0 to 3.8 8.0 to 8.3 0.7H

Note: H is the wall height.

Table 10. Wall 2 Summary of Recommended Minimum Reinforcement Lengths

Wall Section Wall Height (feet)

Wall Embedment

(feet)

Minimum Reinforcement

Length (feet)

Reinforcement to Wall Height Ratio

(L = )

Sta. 10+00.00 to Sta.

11+20.52 5.1 to 12.8 2.0 to 6.1 8.0 to 9.0 0.7H

Sta. 11+20.52 to Sta.

11+36.65 15.8 to 18.8 2.0 to 4.9 20.5 to 24.4 1.3H

Sta. 11+36.65 to Sta.

12+04.12 16.9 to 21.0 4.2 to 8.0 23.7 to 29.4 1.4H

Sta. 12+04.12 to Sta.

12+87.99 16.9 to 19.5 4.2 15.2 to 17.6 0.9H

Sta. 12+87.99 to Sta.

13+49.14 15.6 to 17.6 2.2 to 4.3 10.9 to 12.3 0.7H

Sta. 13+49.14 to Sta.

13+76.64 7.5 to 13.6 2.0 to 7.6 8.0 to 9.5 0.7H

Note: H is the wall height.

Supplemental Geotechnical Investigation 10 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

Wall 3 will be located from “205” Sta. 46+93.93, 39.50 feet right to Sta. 47+37.70, 39.50 feet right. The planned wall height ranges from 1.5 to

3.5 feet which is considered a non-structural or landscape wall. The minimum reinforcement length for a non-structural wall is 6 feet.

Pond Berm Slope Stability

We understand a detention pond is being proposed southwest of the bridge. Based on the plan sheets provided by DEA, a berm will be constructed above the existing grade with maximum 3H:1V interior slopes and maximum 2H:1V exterior slopes.

The performance of the pond berm in terms of slope stability and seepage will depend on the type of material selected for berm construction. We recommend the berm be constructed with material that consists of 20 percent silt and clay with a maximum of 60 percent sand and a maximum of 60 precent silt. The berm embankment material should be compacted to a minimum of 95 percent of maximum density per AASHTO T-99 with a placement moisture content within 1 percent dry and 3 percent wet of optimum moisture content.

We have completed slope stability analysis for the detention pond berm using the computer software SLIDE 2.0. Our analysis has assumed typical strength parameters for the berm material selected above. Based on our analysis, the berm will have a minimum factor of safety of 1.3 for the static condition and 1.1 for the seismic condition.

Temporary Construction Bridge

We understand a temporary construction bridge may be required. The temporary structure will consist of a contractor designed work bridge supported on spread footings. Based on the weak and compressible soils encountered in the near surface soils adjacent to the creek, spread footings for a temporary structure should be founded on at least 2 feet of granular fill overlying a geogrid reinforcement.

The granular backfill should comply with Section 00330.14 in ODOT (2024). The geogrid reinforcement should comply with Section 2320.10 in ODOT (2024) for subgrade reinforcement. For subgrade prepared as stated above, we recommend a factored bearing resistance of 2,000 psf for the footings. Based on the compressibility of the near surface soils, temporary footings could experience settlements of ±2 to 3 inches at the factored bearing resistance.

Pond Access Road

We understand an access road will be constructed west of the north end of SW 206th Avenue, southwest of the proposed bridge. The access road was designed to meet the Clean Water Services standard section for maintenance access roads.

The standard section consists of 3 inches of Asphaltic Concrete Pavement (ACP) wearing course over 2 inches of ¾-inch aggregate base followed by 6 inches of

Supplemental Geotechnical Investigation 11 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

1-1/2-inch aggregate base. The section is intended to support a 30-ton maintenance vehicle in all weather conditions.

The recommended pavement section should consist of 3-inch of ACP over 6 inches of ¾-inch aggregate base. A woven subgrade geotextile should also be placed over the subgrade prior to placing the aggregate base. The recommended section is suitable to support a 30-ton maintenance vehicle in all weather conditions.

LIMITATIONS

Variation of Subsurface Conditions, Use of Report, and Warranty

The conclusions contained herein assume the subsurface profile encountered in the boring is representative of the site conditions. No changes to the enclosed recommendations should be made without our approval. We will assume no responsibility or liability for any engineering judgement, inspection, or testing performed by others.

This memorandum was prepared for the exclusive use of Washington County, David Evans and Associates, and their design consultants for the SW 205th Avenue Bridge project in Hillsboro, Oregon. The information contained herein should not be used for other sites or for unanticipated construction without our written consent. This memorandum is intended for planning and design purposes only. 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 groundwater by hazardous or toxic materials. We assume 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.

Supplemental Geotechnical Investigation 12 Project No.: 2241123 Hillsboro, Oregon David Evans and Associates, Inc.

REFERENCES

AASHTO, 2020, AASHTO LRFD Bridge Design Specifications, American Association of State Highway and Transportation Officials (AASHTO), 9th Edition.

ODOT, 2024, Oregon Standard Specifications for Construction, Oregon Department of Transportation (ODOT) Highway Division.

NV5, 2024, Report of Geotechnical Engineering Services, NV5, dated August 9, 2024.

Appendix A Figures and Tables

Professional Geotechnical Services

0 200 400 600 800 1000 1200

E le v a ti o n ft

Axial Resistance (kips)

FIGURE 1A

AXIAL RESISTANCE vs. ELEVATION - BENT 1

PP16x0.5 Closed-ended Driven Pile SW 205th Avenue Bridge

Washington County, Oregon Project No.: 2241123

1,2Factored Axial Resistance

3Factored Uplift Resistance

Ground Surface (±El. 151)

Very Stiff to Hard

SILT

Pile Cutoff (El. 149.17)

Medium stiff

CLAY

Soft SILT

Very Stiff SILT

Very Soft SILT

Stiff SILT

Very stiff SILT

Very stiff SILT

1 Nominal Axial Resistance

Notes:

(1) Nominal and factored axial resistances based on skin friction and end-bearing, and the subsurface profile of BH-4. Analysis assumes the piles are driven closed-ended.

(2) Factored axial resistance based on an AASHTO resistance factor (φ) of 0.65 assuming dynamic pile testing will be used to establish the required final driving resistance.

(3) Factored uplift resistance based on an AASHTO resistance factor (f) of 0.8.

Very Stiff

CLAY

0 200 400 600 800 1000 1200

E le v a ti o n ft

Axial Resistance (kips)

FIGURE 2A

AXIAL RESISTANCE vs. ELEVATION - BENT 2

PP24x0.75 Closed-ended Driven Pile SW 205th Avenue Bridge

Washington County, Oregon Project No.: 2241123

1,2Factored Axial Resistance

2Factored Uplift Resistance

Ground Surface (±El. 145)

Very soft Silt

Pile Cutoff (±El. 153.28)

Medium stiff

CLAY

Very soft

SILT

Medium stiff

SILT

Stiff

SILT

Stiff

SILT

Very stiff

SILT

Stiff to very stiff CLAY

Very stiff to hard

CLAY

1,4Nominal Axial Resistance

Notes:

(1) Nominal and factored axial resistances based on skin friction and end-bearing, and the subsurface profile of BH-3. Analysis assumes the piles are driven closed-ended.

(2) Factored axial resistance based on an AASHTO resistance factor (φ) of 0.65 assuming dynamic pile testing will be used to establish the required final driving resistance.

(3) Factored uplift resistance based on an AASHTO resistance factor (f) of 0.8.

(4) Reduce the nominal resistance by 7 kips to account for scour for Extreme II Loading.

Medium dense

SAND

0 200 400 600 800 1000 1200

E le v a ti o n ft

Axial Resistance (kips)

FIGURE 3A

AXIAL RESISTANCE vs. ELEVATION - BENT 3

PP24x0.75 Closed-ended Driven Pile SW 205th Avenue Bridge

Washington County, Oregon Project No.: 2241123

1,2Factored Axial Resistance

3Factored Uplift Resistance

Ground Surface (±El. 145)

Very soft to Soft Silt

Pile Cutoff (±El. 153.78)

Stiff to Very Stiff

SILT

Stiff to Very Stiff

SILT

Very Stiff

CLAY

Very stiff CLAY

Notes:

(1) Nominal and factored axial resistances based on skin friction and end-bearing, and the subsurface profile of BH-2. Analysis assumes the piles are driven closed-ended.

(2) Factored axial resistance based on an AASHTO resistance factor (φ) of 0.65 assuming dynamic pile testing will be used to establish the required final driving resistance.

(3) Factored uplift resistance based on an AASHTO resistance factor (f) of 0.8.

(4) Reduce the nominal resistance by 7 kips to account for scour for Extreme II Loading.

1,4Nominal Axial Resistance

Medium dense

SAND

0 200 400 600 800 1000 1200

E le v a ti o n ft

Axial Resistance (kips)

FIGURE 4A

AXIAL RESISTANCE vs. ELEVATION - BENT 4

PP16x0.5 Closed-ended Driven Pile SW 205th Avenue Bridge

Washington County, Oregon Project No.: 2241123

1,2Factored Axial Resistance

2Factored Uplift Resistance

Ground Surface (±El. 153)

Soft SILT

Pile Cutoff (±El. 149.42)

Medium stiff

CLAY

Stiff CLAY

Medium Stiff

CLAY

Very Stiff

CLAY

Stiff CLAY

Very stiff

CLAY

Notes:

(1) Nominal and factored axial resistances based on skin friction and end-bearing, and the subsurface profile of BH-1. Analysis assumes the piles are driven closed-ended.

(2) Factored axial resistance based on an AASHTO resistance factor (φ) of 0.65 assuming dynamic pile testing will be used to establish the required final driving resistance.

(3) Factored uplift resistance based on an AASHTO resistance factor (f) of 0.8.

1Nominal Axial Resistance

Very Stiff

SILT

SW 205th Avenue Bridge

Project No.: 2241123

Table 1A. Recommended LPILE Soil Parameters for Bent 1

Depth

(ft)

Elev.

(ft)

Material Description LPile p-y Criteria γ' (pcf)

(o)

K (Static)

(pci)

K (Cyclic)

(pci)

Soil c

(psf) e50

0.0 147.0 Medium Stiff Clay STIFF CLAY w/ free water

110 - 100 100 500 0.01

9.0 138.0 47.6 - 100 100 500 0.01

9.0 138.0 Very Soft to Soft SILT Soft Clay

47.6 - - - 250 0.02

14.0 133.0 47.6 - - - 250 0.02

14.0 133.0 Soft to Medium Stiff

CLAY

STIFF CLAY w/ free water

47.6 - 30 30 500 0.010

28.0 119.0 47.6 - 30 30 500 0.010

28.0 119.0 Soft SILT Soft CLAY

47.6 - - - 250 0.02

47.0 100.0 47.6 - - - 250 0.02

47.0 100.0 Stiff SILT STIFF CLAY w/ free water

47.6 - 500 200 1,000 0.005

58.3 89.0 47.6 - 500 200 1,000 0.005

58.3 89.0 Medium Dense SAND Sand (Reese)

52.6 34 60 - - -

63.0 84.0 52.6 34 60 - - -

63.0 84.0 Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

80.0 67.0 47.6 - 1,000 400 2,000 0.004

80.0 67.0

Very Stiff SILT STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

117.0 30.0 47.6 - 1,000 400 2,000 0.004

Notes:

1. Subsurface profile interpreted based on conditions encountered in BH-4.

2. Top elevation of the soil profile corresponds ± to the bottom of pile cap.

4. Assumes groundwater table (gwt) is at El. 141.5.

Project No.: 2241123

Table 2A. Recommended LPILE Soil Parameters for Bent 2

Depth

(ft)

Elev.

(ft)

Material Description LPile p-y Criteria γ' (pcf)

(o)

K

(Static)

(pci)

K

(Cyclic)

(pci)

Soil c

(psf) e50

0.0 145.0 Soft SILT Soft CLAY

110 - 30 30 250 0.020

5.0 140.0 110 - 30 30 250 0.020

5.0 140.0 Medium Stiff CLAY

STIFF CLAY w/ free water

47.6 - 100 100 500 0.010

15.0 130.0 47.6 - 100 100 500 0.010

15.0 130.0 Stiff SILT

STIFF CLAY w/ free water

47.6 - 500 200 1,000 0.005

25.0 120.0 47.6 - 500 200 1,000 0.005

25.0 120.0 Very Soft to Soft SILT Soft CLAY

47.6 - 30 30 250 0.020

35.0 110.0 47.6 - 30 30 250 0.020

35.0 110.0 Medium Stiff SILT

STIFF CLAY w/ free water

47.6 - 100 100 500 0.010

40.0 105.0 47.6 - 100 100 500 0.010

40.0 105.0 Stiff SILT

STIFF CLAY w/ free water

47.6 - 500 200 1,000 0.005

50.0 95.0 47.6 - 500 200 1,000 0.005

50.0 95.0 Very Stiff SILT

STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

75.0 70.0 47.6 - 1,000 400 2,000 0.004

75.0 70.0 Medium Dense SAND SAND (Reese)

52.6 34 60 60 - -

85.0 60.0 52.6 34 60 60 - -

85.0 60.0

Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

120.0 25.0 47.6 - 1,000 400 2,000 0.004

Notes:

1. Subsurface profile interpreted based on conditions encountered in BH-3.

2. Top elevation of the soil profile corresponds ± to the finished ground surface.

Project No.: 2241123

Table 3A. Recommended LPILE Soil Parameters for Bent 3

Depth

(ft)

Elev.

(ft)

Material Description LPile p-y Criteria γ' (pcf) f'

(o)

K

(Static)

(pci)

K

(Cyclic)

(pci)

Soil c

(psf) e50

0.0 145.0 Soft to Medium Stiff

SILT

STIFF CLAY w/ free water

48 - 100 100 500 0.010

4.0 141.0 48 - 100 100 500 0.010

4.0 141.0 Very Soft SILT Soft CLAY

47.6 - 30 30 250 0.020

13.0 132.0 47.6 - 30 30 250 0.020

13.0 132.0 Stiff SILT STIFF CLAY w/ free water

47.6 - 500 200 1,000 0.005

39.0 106.0 47.6 - 500 200 1,000 0.005

39.0 106.0 Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

65.0 80.0 47.6 - 1,000 400 2,000 0.004

65.0 80.0 Medium Dense SAND SAND (Reese)

47.6 34 60 60 - -

75.0 70.0 47.6 34 60 60 - -

75.0 70.0 Stiff to Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

85.0 60.0 47.6 - 1,000 400 2,000 0.004

85.0 60.0 Stiff SILT STIFF CLAY w/ free water

47.6 - 500 200 1,000 0.005

95.0 50.0 47.6 - 500 200 1,000 0.005

95.0 50.0

Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

115.0 30.0 47.6 - 1,000 400 2,000 0.004

Notes:

1. Subsurface profile interpreted based on conditions encountered in BH-2.

2. Top elevation of the soil profile corresponds ± to the finished ground surface.

Project No.: 2241123

Table 4A. Recommended LPILE Soil Parameters for Bent 4

Depth

(ft)

Elev.

(ft)

Material Description LPile p-y Criteria γ' (pcf) f'

(o)

K

(Static)

(pci)

K

(Cyclic)

(pci)

Soil c

(psf) e50

0.0 147.0 Medium Stiff SILT STIFF CLAY w/o free water

110 - 100 100 500 0.010

7.0 140.0 110 - 100 100 500 0.010

7.0 140.0 Stiff CLAY STIFF CLAY w/o free water

110 - 500 200 1,000 0.005

14.0 133.0 110 - 500 200 1,000 0.005

14.0 133.0 Medium Stiff CLAY STIFF CLAY w/ free water

47.6 - 100 100 500 0.010

27.0 120.0 47.6 - 100 100 500 0.010

27.0 120.0 Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

64.0 83.0 47.6 - 1,000 400 2,000 0.004

64.0 83.0 Very Stiff SILT STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

94.0 53.0 47.6 - 1,000 400 2,000 0.004

94.0 53.0

Very Stiff CLAY STIFF CLAY w/ free water

47.6 - 1,000 400 2,000 0.004

117.0 30.0 47.6 - 1,000 400 2,000 0.004

Notes:

1. Subsurface profile interpreted based on conditions encountered in BH-1.

2. Top elevation of the soil profile corresponds ± to the bottom of pile cap.