Attachment #4 - Allied Engineering Geotech Report.pdf

Civil Engineering ● Geotechnical Engineering ● Land Surveying ● Construction Services

ALLIED ENGINEERING

32 Discovery Dr.

Bozeman, MT 59718

Ph: (406) 582-0221 www.alliedengineering.com

December 1, 2023

Kelly Larkin Schade Fisheries Biologist – Diversions/Fish Passage USFS Salmon-Challis National Forest

(208) 756-5229 Email: kelly.schade@usda.gov

RE: Final Geotechnical Report for Bia Po’i Naokwaide Culvert Replacement North Fork, Idaho

Dear Ms. Schade:

Please find enclosed an electronic PDF copy of our geotechnical report for the above-referenced project.

As per our scope of work, this report presents our geotechnical assessment of the project site and provides recommendations pertaining to site design and construction, earthwork, foundation, walls, fill materials, and surface drainage.

This report was prepared for use by all associated parties during the planning, design, and construction phases of this project. It is important that all Contractors that are involved with the site grading, foundation earthwork, underground utility installation, and construction are provided with copies of the report, so they are informed of the site conditions found at our exploration locations and our construction recommendations.

If you have any questions regarding this report, please give us a call. Thank you!

Sincerely, Allied Engineering Services, Inc.

Doug Chandler, PE Founder

Glen Clements, EI Geological Engineer enc: Final Geotechnical Report

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ATTACHMENT #4

mailto:kelly.schade@usda.gov i

Table of Contents

Table of Contents

INTRODUCTION

SCOPE OF WORK

GEOLOGY OF THE SITE

EXPLORATIONS AND SUBSURFACE CONDITIONS

Subsurface Explorations

Subsurface Conditions

Laboratory Testing

BRIDGE FOUNDATION DESIGN RECOMMENDATIONS

Foundation Recommendations

Scour Protection

Seismic Design Factors

Recommended Foundation Bearing Pressures

Lateral Earth Pressures

Foundation Wall Backfill

FOUNDATION RELATED FILL MATERIAL RECOMMENDATIONS

Excavated Foundation Soils

Structural Fill

FILL PLACEMENT AND COMPACTION

COLD/WINTER WEATHER CONSTRUCTION

LIMITATIONS

REFERENCES

ii

List of Tables

Table 1: Summary of Subsurface Conditions

List of Figures

Figure 1 – Vicinity Map Figure 2 – Quadrangle Map Figure 3 – Geology Map Figure 4 – Borehole Location Map

List of Appendices

Appendix A – Borehole Logs Appendix B – Laboratory Testing Results Appendix C – Limitations of Your Geotechnical Report www.alliedengineering.com

INTRODUCTION

This report presents our geotechnical assessment for the proposed Bia Po’i Naokwaide Culvert Replacement located near North Fork, Idaho. The information contained herein is based on an investigation and analysis of the property’s topographical and subsurface conditions, a review of geologic maps and literature for the project area, and previous experience gained during our involvement with other similar projects.

The site is located west of U.S. Highway 93 approximately 11 miles west of the intersection with Salmon

River Road. The location is in the Northwest One-Quarter of Section 24, Township 24 North, Range 19

East, Lemhi County, Idaho. See Figures 1 and 2 for site location maps.

We understand the project proposes replacing two culverts on Bia Po’i Naokwaide; one culvert where the creek crosses Salmon River Road, and another culvert approximately 300 feet to the northwest where the creek crosses National Forest Road 39 (NF39). Both culverts are slated to be replaced with prefabricated modular bridges with prefabricated modular abutments and spread footings.

Based on our review of preliminary design, the depth of the abutment and spread footing for the Salmon

River Road bridge is proposed to be 19.5 feet below existing ground. Some hard rock excavation should be expected (hard quartz monzonite was found in one of the boreholes at 10.0 feet deep).

SCOPE OF WORK

Our Scope of Services for this project included:

▪ Review of project site information, geologic maps, and nearby well logs.

▪ Completion of four boreholes to a depth of 30 feet below the ground surface or 10 feet into rock to provide coverage of the anticipated bridge sites. The borehole locations are provided in Figure 3.

▪ Perform laboratory testing of select soil samples from the borehole explorations.

▪ Provide foundation recommendations, allowable bearing capacity criteria, lateral earth pressures, foundation earthwork recommendations, as well as associated anticipated settlements.

▪ Minimum foundation depth for frost protection.

▪ Lateral earth pressures for cantilevered and for braced wall conditions and sliding resistance due to friction and passive pressure.

▪ Provide surface and subsurface drainage recommendations.

▪ Provide backfill material and compaction recommendations.

▪ General site earthwork, utilities, and construction recommendations.

Kelly Larkin Schade December 1, 2023

Geotechnical Report for Bia Po’i Naokwaide Culvert Replacement AESI Project: 23-147

32 Discovery Drive. Bozeman, Montana 59718. ● Ph: (406) 582-0221 ● Fax: (406) 582-5770

The results of the above scope of work are summarized in this geotechnical report. The purpose of the report is to inform the Owner, Builder, Engineer, and Architect of the subsurface conditions encountered in our explorations; and to present geotechnical recommendations for consideration and implementation during the planning, design, and construction of the proposed improvements. We can work with the design team to provide more specific recommendations as the construction plans are further developed.

GEOLOGY OF THE SITE

Based on the "Reconnaissance Geologic Map of the Ulysses Mountain Quadrangle, Lemhi County, Idaho,” prepared by the USGS in 1982, several different geological formations are mapped near the site. An excerpt of the geology map is provided in Figure 3 and indicates the site is underlain by porphyritic quartz monzonite (Yqm), described as medium-gray to pinkish-gray, coarse-grained biotite quartz monzonite.

This is consistent with our borehole explorations which encountered silty sand and gravel overlying pink and gray quartz monzonite.

We also reviewed a nearby well log located east of the site (IDWR ID: 286638). The well log lists decomposed granite and fractured granite with sand alternating with solid granite in the upper 75 feet of the well. Below 75 feet, solid granite rock extends to the bottom of the well at 123 feet below the ground surface. The static water level was recorded at 10 feet in November of 1995.

EXPLORATIONS AND SUBSURFACE CONDITIONS

Subsurface Explorations

Subsurface conditions were investigated on October 10th and 11th, 2023, by Glen Clements, EI, a geological engineer with Allied Engineering. Four boreholes were drilled on site using a truck-mounted CME 85 drill rig operated by Aaron Delvalle with Haz-Tech Drilling, Inc. out of Nampa, Idaho. The four boreholes were drilled near the anticipated bridge abutments. The approximate locations of these boreholes are shown in Figure 4. All boreholes were initiated with a hollow stem auger, Standard Penetration Testing (SPT), and split spoon sampling to investigate the soils overlying bedrock. Upon refusal of the auger, the drill tooling was switched to rock coring, which produces an intact sample (core) of the rock minus any portions that are susceptible to washing away during drilling or sampling. The rock cores that were extracted were measured, characterized, and logged.

During drilling with the auger, soil and subsurface moisture conditions were visually characterized, measured, and logged using split spoon samples taken at regular intervals. Blow counts noted on the borehole logs attached consist of the blows required to drive the 2-inch O.D. split spoon sampler in three, 6-inch increments using a 140-pound hammer dropped 30 inches. The final blow counts from the final 12 inches of driving are added together and recorded as the blow count (N). The blow counts are used to evaluate the consistency, density, and shear strength of the soil. Blow counts greater than 50 in any 6-inch increment is deemed as sampler refusal. All blow counts provided on the logs are uncorrected for overburden pressures. Where a blow count of zero is noted, the weight of the hammer was enough to advance the split spoon (an indication of very weak soils).

Copies of our borehole logs are provided in Appendix A. The logs provide assorted field information, such as soil depths and descriptions, groundwater conditions, relative density data, and a sketch of the soil stratigraphy. Please be aware that the detail provided in the logs cannot be summarized in a paragraph;

therefore, it is important to review the logs in conjunction with this report. Following completion of the fieldwork, the borehole locations were backfilled and cleaned up to the extent possible. Each was staked with a wooden lath that identified it accordingly. Select soil samples were brought back to the laboratory for further testing and classification. Laboratory testing results are provided in Appendix B.

Subsurface Conditions

Soil conditions were relatively consistent in all four boreholes with minimal (3 inches or less) topsoil on top of gravelly sand alluvium overlying bedrock. A summary of the soil and rock conditions encountered is provided below. Please refer to Appendix A for detailed borehole and rock core logs.

Near-surface soil conditions for the two boreholes near Salmon River Road generally consisted of 10 to 26 feet of alluvium overlying quartz monzonite bedrock (very similar to granite). The two boreholes along Bia Po’i Naokwaide Road were drilled entirely through the alluvium that extended to depths of drilling between 29 and 34 feet. Groundwater was discovered at depths of 13’ to 15’ in all boreholes. The upper coarse-grained soils were generally slightly moist and became wetter with depth.

Table 1 provides a summary of the subsurface conditions encountered at the site.

Table 1: Summary of Subsurface Conditions

BOREHOLE # ALLUVIUM BEDROCK

BH-1 0.0’ – 26.0’ 26.0’ – 34.0’

BH-2 0.0’ – 10.0’ 10.0’ – 29.0’

BH-3 0.0’ – 30.0’ Not encountered

BH-4 0.0’ – 30.0’ Not encountered

Suitable “target” bearing material for the prefabricated foundations is in the gravelly sand starting just below the thin layer of topsoil or the underlying quartz monzonite. We recommend removal of the overlying layer of topsoil down to target bearing within the footprint of each planned abutment. Please note that a deeper foundation or the use of bank protection (riprap) may be necessary for scour protection.

Laboratory Testing

Select samples were collected from all four boreholes for moisture content testing and soil classification.

Moisture contents at the time of the explorations ranged from approximately 2.3% to 17.8% percent. All laboratory testing results are provided in Appendix B.

BRIDGE FOUNDATION DESIGN RECOMMENDATIONS

In reviewing the proposed bridge foundation design, we noticed that the elevation of the top of the footings for the Salmon River Road bridge is nearly the same elevation as the bottom of the Salmon River and is below the surface water elevation of the river. It may be very difficult to construct the footings in such conditions due to the need to dewater a portion of the riverbank. The designer could consider excavating underneath the footings to below scour depth, and then build back up to a dry footing elevation with immovable riprap. This would allow for more shallow footings that could be constructed above the surface water level of the river. Foundations on riprap rock with suitable gradation and with slope of 1.5H:1V or flatter could be built upon using the same geotechnical parameters as the native gravelly sands. The channel configuration, rock size, and other hydraulic criteria to achieve fish passage and stability against erosion are outside the scope of this report. We would be willing to review such design and provide geotechnical concurrence, if desired.

Provided below are our geotechnical-related recommendations for the two creek crossings for the culvert replacement sites shown in Figure 3.

Foundation Recommendations

The coarse-grain soils (primarily sand and gravel) found at the Bia Po’i Naokwaide site may be prone to scour but are not prone to settlement. For this reason, we recommend excavating to the native gravelly sands to a depth that is below the maximum scour depth or to the quartz monzonite bedrock. Footings should bear on the native gravely sands, the quartz monzonite, riprap, or engineered granular structural fill (3-inch minus pitrun gravel or 1.5-inch minus road mix) that is founded on this material. The native gravelly sands should be compacted to an unyielding condition prior to the placement of either structural fill or the foundation. All structural fill used to bring up the grade to the foundation elevation should be compacted to 98 percent of ASTM D-698. The excavation should extend at least four feet outside the footprint of the foundation to ensure successful load transfer to the target bearing material. Frost depth is 4 feet at the site (measured to the bottom of footing). However, the designer may consider frost protecting the foundations using insulation if they are not founded below frost depth.

Structural fill should consist of select excavated foundation soils or imported materials free of rocks greater than 3 inches in diameter, deleterious debris, or contamination. Select excavated foundation soils or import may be used for structural fill provided they are within 2% of their optimum moisture content, not overly rocky, have less than 50 percent fines, and the fines are non-plastic. Structural fill should be placed in multiple thin horizontal lifts with the thickness dependent upon the size and energy of the compactor but in no case thicker than 10 inches loose. The lifts should be compacted to 98 percent ASTM D-698 under the footings and 95 percent of ASTM D-698 (Standard Proctor) density elsewhere. Achieving adequate compaction is important to provide the design allowable bearing capacity and to avoid undesirable differential settlements in the future.

Scour Protection

Our geotechnical study did not include a scour analysis. Preliminarily, the foundations would likely need to be set 4 to 5 feet below the bottom of the channel to be protected from scour. Alternatively, if the foundations are kept high, the adjacent stream may be riprapped with appropriately sized, angular rock that is “toed in” below the bottom of the channel. We anticipate that riprap rock would need to have a D50 of at least 14 inches to provide adequate protection. We can conduct a scour analysis and provide more details if retained by the Owner.

Seismic Design Factors

Based on our on-site explorations and knowledge of the underlying geology, the project site should be considered Site Class D (as per criteria presented in the ASCE 7-22). Note that this is not the Default Site

Class D. Site Class CD was considered for this site based on the relatively shallow bedrock encountered in two of the four boreholes and the quality of the gravelly sand above the bedrock. However, due to the fact that bedrock was not encountered in two of the boreholes and given the high degree of variability of the geology of mountainous regions (such as this area of Idaho), we decided to use the more conservative Site Class D. Performing additional site investigation could provide enough information to confirm Site Class CD.

Site-specific seismic loading and response spectrum parameters can be obtained from a web-based platform provided by the USGS Earthquake Hazards Programs, located at:

https://earthquake.usgs.gov/hazards/designmaps/.

Recommended Foundation Bearing Pressures

If the above foundation support recommendations are followed, the net allowable bearing pressure for the foundation is 3,000 pounds per square foot (psf). (We estimate that the above referenced bearing pressure will result in total settlement of less than 1 inch, and differential settlements of less than 1/600.)

Allowable bearing pressures from transient loading (due to wind or seismic forces) may be increased by 50 percent.

Lateral Earth Pressures

All foundation or retaining walls that will be fixed at the top prior to the placement of backfill should be designed for an “at rest” equivalent fluid pressure of 60 pounds per cubic foot (pcf). In contrast, cantilevered retaining walls may be designed for a lower, “active” equivalent fluid pressure of 45 pcf, provided either some slight outward rotation of the wall is acceptable upon backfilling, or the wall is constructed in such a way that accommodates the expected rotation. The “at rest” and “active” design values are only applicable for walls that will have backfill slopes of less than 10 percent and will not be externally loaded by surface pressures applied above and/or behind the wall. If slopes will exceed 10 percent within 10 feet of the wall, please consult with our office. These lateral earth pressures assume proper subsurface drainage provisions (footing drains) are installed to prevent the development of hydrostatic pressures.

Lateral forces from wind, earthquakes, and earth pressures on the opposite side of the structure will be resisted by passive earth pressure against the buried portion of the foundation wall and by friction at the bottom of the footings. Passive earth pressures in compacted backfill should be assumed to have an equivalent fluid pressure of 280 pcf, and a coefficient of friction of 0.35 should be used between cast-in-place concrete and granular structural fill. Actual footing loads (not factored or allowable loads) should be used for calculating frictional resistance to sliding along the base of the footing. Please be aware that the friction coefficient has no built-in factor of safety; therefore, an appropriate safety factor should be selected and used in all subsequent calculations for each load case.

The lateral earth pressures summarized above are for static conditions and should be factored for seismic conditions in accordance with structural design standards. We recommend adding at least an additional 15 pcf equivalent fluid pressures for the seismic component to the “at rest” and “active” fluid pressures.

Foundation Wall Backfill https://earthquake.usgs.gov/hazards/designmaps/

Abutment foundation wall backfill can consist of excavated foundation soil, other than topsoil, provided it is not overly moist, organic, highly plastic, or too rocky in composition and compacted to 95% ASTM D-

698. Rocks larger than 3 inches in diameter will need to be removed and drying may be required to re-use the native soils as exterior wall backfill.

All select backfill materials should be placed in multiple thin lifts and properly compacted to 95 percent of its ASTM D-698 (Standard Proctor) density. Foundation walls intended to be braced should not be backfilled until the bracing is in place to prevent unintended rotation/deflection of the wall. To prevent damaging foundation walls during the backfilling process, only hand-operated compaction equipment is recommended within three feet of walls that are not buried on both sides. Note that it is important that adequate compaction is achieved along foundation walls to prevent surface water from infiltrating into the subgrade soils. Additionally, abutment foundation walls should be damp-proofed.

Finally, the use of topsoil as backfill should be limited to the uppermost four to six inches in reclaimed areas.

FOUNDATION RELATED FILL MATERIAL RECOMMENDATIONS

Provided below are recommendations for the foundation-related fill materials that may be used during construction. These include on-site excavated soils and clean crushed rock. Placement and compaction criteria follow the specifications for these materials.

Excavated Foundation Soils

A variety of existing fill soils will be excavated during foundation earthwork including road base and a mixture of sand and gravel in various conditions. All topsoil and any organic materials should be stripped and stockpiled for re-use during site reclamation. We also recommend that on-site soils suitable for re- Use as embankment fill be separated from wet, rocky, or otherwise unsuitable soils during excavation.

The suitability of the non-organic excavated soils will depend on their rocky condition, plasticity, natural moisture content, and ability to be re-compacted. The driest soils containing an even mixture of soil matrix and smaller rock fragments should be selected for use as compacted fill, while the wettest and rockiest soils should either be hauled off-site or used for general site grading in non-critical locations. Depending on the time of year, some of the native soil that is excavated may be wetter than optimum and require drying prior to re-use. This may necessitate the import of easily compacted fill material if work is conducted during the wet or winter season when drying is not an option.

Excavated soils from the site may be used selectively as backfill as long as they do not contain organics, excess moisture, fat clays, or rock larger than 4 inches). Provided these criteria are met, this material may be selectively re-used as backfill of exterior foundation walls. Please refer to the Foundation section earlier in this report for more details.

Structural Fill

Granular structural fill may consist of select excavated foundation soils, 1.5-inch-minus crushed road mix gravel or 3-inch-minus sandy pit run gravel. These materials should be non-plastic, well-graded mixtures

Geotechnical Report for Bia Po’i Naokwaide Culvert Replacement AESI Project: 23-147

32 Discovery Drive. Bozeman, Montana 59718. ● Ph: (406) 582-0221 ● Fax: (406) 582-5770 Page 7 of clean sand and gravel and should meet all other applicable specifications as presented in Section 703 of the Idaho Department of Transportation Standard Specifications for Highway Construction.

FILL PLACEMENT AND COMPACTION

All fill materials should be placed in uniform, horizontal lifts and compacted to an unyielding condition.

This includes clean crushed rock, which can be compacted and/or consolidated by vibratory means. The maximum “loose lift thickness” for all fill materials (prior to compaction) should be limited to 10 inches for large, self-propelled rollers, 6 inches for remote-controlled trench rollers, and 4 inches for walk-behind plate or jumping jack compactors. The moisture content of any fill material to be compacted should be within 2 percent (+/-) of its optimum value for maximum compaction.

Provided in Table 2 are compaction recommendations for general site applications. These recommendations apply to all fill materials and are presented as a percentage of the maximum dry density of the material being placed as defined by ASTM D-698.

Table 2. Compaction Recommendations (Application vs. Percent Compaction)

APPLICATION % COMPACTION

Granular Structural Fill Under Footings: 98

Embankment Fill Under Approach Slabs: 95

Foundation Backfill: 95

Sub-base and Base Course Materials for Asphalt Pavement: 95

COLD/WINTER WEATHER CONSTRUCTION

If foundation construction will occur during the cold/winter weather season, the Contractor shall take all necessary precautions to prevent the earthwork from freezing and/or from being contaminated with snow or ice. Exposed subgrade and fill materials (under footings, slabs, and walls) should be adequately covered with concrete insulation blankets to prevent frost penetration and to protect them from snow.

All soils that are used for fill under or around foundation components should be relatively dry, free of intermixed snow and frozen clods, and must not be placed when it is snowing. Fill materials or foundations should not be placed over frozen soils, which may be in a “frost-heaved condition,” or over layers of snow.

When earthwork will proceed during the non-optimal times of the year, we recommend that it be performed expeditiously to minimize the time that the foundation excavation is open and exposed to the elements.

Groundwater should be carefully controlled during construction (particularly during the spring melt) to avoid impacts to foundations. If high groundwater conditions are encountered during construction, the site should be dewatered to below the bottom of the excavation. An alternative to dewatering the excavation would be to place and compact clean crushed rock beneath the footings.

LIMITATIONS

This report provides our geotechnical-related recommendations for the proposed culvert replacement on the Bia Po’i Naokwaide near North Fork, Idaho. These recommendations are based on our observation

Geotechnical Report for Bia Po’i Naokwaide Culvert Replacement AESI Project: 23-147

32 Discovery Drive. Bozeman, Montana 59718. ● Ph: (406) 582-0221 ● Fax: (406) 582-5770 Page 8 and evaluation of the site’s surface and subsurface conditions, our review and interpretation of available geologic information, and our previous experience in the area. We recommend we be retained both during design and construction to provide input and recommendations as necessary.

Please be aware that there is always inherent risk when building in or adjacent to mountainous areas that are seismically active. The Salmon River region is periodically subject to large earthquakes and annual precipitation/snow melt events that can cause large-scale movements or flooding that can impact developed areas. These risks can be reduced with proper development guidelines as discussed in this report. However, the risk can never be completely removed or assumed by the geotechnical engineer and ultimately lies with the owner. Our duty in the performance of this geotechnical evaluation is to perform our work in accordance with the standard of care and practice that is present at the place and time the report is issued.

All individuals directly associated with this project site should consult this report during the planning, design, and construction involved in the development of the site. It should be made available to other parties for information on factual data only and not as a warranty of actual subsurface conditions such as those interpreted herein.

We appreciate the opportunity to perform our geotechnical services. Please call if you have questions.

Sincerely, Allied Engineering Services, Inc.

Douglas S. Chandler Ph.D., PE Founder

Glen Clements, EI Geological Engineer

12/01/2023

REFERENCES

1. International Code Council, 2024. “International Building Code”.

2. American Society of Civil Engineers, 2022. “Minimum Design Loads and Associated Criteria for

Buildings and Other Structures”.

3. Idaho Transportation Department, 2018. “2018 Standard Specifications for Highway Construction”.

4. Lopez, D.A., 1982. “Reconnaissance Geologic Map of the Ulysses Mountain Quadrangle, Lemhi County, Idaho”. USGS Map MF-1445.

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LIST OF FIGURES

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FFiigguurree 33 –– GGeeoollooggyy MMaapp

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© 2023 Microsoft Corporation © 2023 Maxar ©CNES (2023) Distribution Airbus DS

FIGURECivil Engineering Geotechnical Engineering

Land Surveying

32 DISCOVERY DRIVE . BOZEMAN, MT 59718

PHONE (406) 582-0221 . FAX (406) 582-5770

www.alliedengineering.com

BIA PO'I NAOKWAIDE CULVERTS

GEOLOGY MAP

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SCALE (FEET)

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32 DISCOVERY DRIVE

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FAX (406) 582-5770

PHONE (406) 582-0221

Land Surveying Civil Engineering

Structural Engineering

LOG OF BORING

PROJECT: BPN Culverts JOB #: 23-147 DATE: 10/10/2023 PAGE: 1

LOCATION: North Fork, ID ELEVATION: 3470 DEPTH: 34.0' GW: 13.1'

DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: GHC BORING: BH-1

DRILLER: Aaron with Haztech CASING/HAMMER/SAMPLER: N/A/ 140#/ SSS

{0'-6.0'}: Alluvium Medium; grey; gravelly SAND with silt, sub-rounded pebbles; dry.

{6.0'-13.0'}: Alluvium Loose; brown; gravelly SAND with silt;

slightly moist.

{13.0'-18.0'}: Alluvium Loose; brown ; gravelly SAND with silt, sub-angular pebbles; wet.

{18.0'-26.0'}: Alluvium Dense; brown gravelly SAND with cobbles;

wet.

Auger refusal at 26.0' bgs. Switch tooling to rock coring.

{26.0'-34.0'}: Bedrock See rock coring log for BH-1

S1-A @ 0.0'-1.5'

7/16/6

2.3% General Notes:

1. Easy drilling

2. Gravel in cuttings

SWL at 13.1' bgs

3. Rig is bouncing.

· SSS - 2.0'' O.D. Split Spoon Sample

· The beginning and ending depths of the individual soil layers are approximate.End of Boring

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30.0

35.0

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S1-C @ 5.0'-6.5'

S1-D @ 7.5'-9.0'

S1-E @ 10.0'-11.5'

S1-F @ 15.0'-16.5'

S1-G @ 20.0'-21.5'

S1-H @ 25.0'-26.5'

5/2/6

3.6%

6/7/7

5.7%

8/6/10

4.6%

3/2/4

11.3%

4/4/1

17.8%

15/10/25

11.8% for 5.5"

14.0%

Chunks of granite in catcher

Angular, freshly broken chunks of granite

Layer of very dark grey cobbles at 18'

Sample Notes:

3" of gravelly topsoil

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FIELD LOG OF ROCK CORING

PROJECT: Bia Po'i Naokwaide Culvert Replacement BORING #: BH‐1

PROJECT LOCATION: North Fork, Idaho SHEET 1 OF 1

PROJECT NUMBER: 23‐147 DATE: 10/10/2023

DRILL METHOD: Rotary LOGGED BY: GHC CHECKED BY: TOTAL DEPTH (FT): 34'

DRILL RIG TYPE: CME 85 DRILLED BY: Aaron Delvalle (Haztech) DEPTH TO G.W.:

DRILL BIT SIZE/TYPE: 4" Hollow stem auger with rock core bit INCLINATION FROM ___13.1'___ FT AT TIME OF DRILLING

BOREHOLE BACKFILL: Cuttings and bentonite VERTICAL/BEARING: N/A ___________ FT AFTER ________ HRS

COMMENTS: ___________ FT AFTER ________ HRS

26.5__ 3443.5

1 1 58 1 71 1

30.0_ 3440.0

2 1 81 2.3 41 2

34.0_ 3436.0

END OF ROCK CORING

26.5' to 27.5'; Amphibolite; dark grey;

aphanitic; no foliation; slightly weathered;

strong.

27.5' to 28.0'; seam of angular and rounded rock and pebbles (rubble).

28.0' to 30.0'; same amphibolite.

Dark grey rock, possibly amphibolite

Quartz monzonite; pink phenocrysts in a matrix of white/black/grey; porphyritic; no foliation; slightly weathered; strong.

Very coarse grained granite or quartz monzonite.

P A C K

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T

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TS

LA

B T

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TS

D R

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NOTES

ROCK CORE MATERIAL DESCRIPTION

R

EC

O V

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Y, D

EP

TH

FT

EL

EV

FT

) Depth to Depth; Rock type; color; texture, grain size, foliation, weathering, strength, other.

At Discontinuities: Fracture Number, dip angle, type, width, infilling type/amount, surface shape/roughness.

R U N N O

B O X N O

FR

A C . F R

EQ

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FR

A C

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R E

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IN

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PT

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DESCRIPTION

OF MATERIALS

N (U

N C

O R

B

L O

W S/

FT

M O

IS

T

U R

E C

O N

T E

N

T OTHER FIELD OR

SAMPLE

INFORMATION

5.0

10.0

Geotechnical Engineering

32 DISCOVERY DRIVE

BOZEMAN, MT 59718

FAX (406) 582-5770

PHONE (406) 582-0221

Land Surveying Civil Engineering

Structural Engineering

LOG OF BORING

PROJECT: BPN Culverts JOB #: 23-147 DATE: 10/10/2023 PAGE: 1

LOCATION: North Fork, ID ELEVATION: 3470 DEPTH: 29.0' GW: N/A

DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: GHC BORING: BH-2

DRILLER: Aaron with Haztech CASING/HAMMER/SAMPLER: N/A/ 140#/ SSS

{0'-7.0'}: Alluvium Medium dense; grey; sandy GRAVEL with silt; dry.

{7.0'-10.0'}: Alluvium Dense; brown and grey; gravelly SAND with silt; dry.

Auger refusal at 10.0' bgs. Switch tooling to rock coring.

{10.0'-29.0'}: Bedrock See rock coring log for BH-2

General Notes:

1. Easy drilling

2. Hard spot.

3. Auger is scraping and squealing.

· SSS - 2.0'' O.D. Split Spoon Sample

· The beginning and ending depths of the individual soil layers are approximate.

End of Boring

15.0

20.0

25.0

30.0

35.0

S2-A @ 2.5'-4.0'

S2-B @ 5.0'-6.5'

3/6/6

2.7%

5/8/19

25/26/29

4.4%

FOR

2"

Sample Notes:

3" of sandy topsoil

10.0'-11.5'

0.0'-1.5' 6/16/17

SA

M

PL

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FIELD LOG OF ROCK CORING

PROJECT: Bia Po'i Naokwaide Culvert Replacement BORING #: BH‐2

PROJECT LOCATION: North Fork, Idaho SHEET 1 OF 1

PROJECT NUMBER: 23‐147 DATE: 10/10/2023

DRILL METHOD: Rotary LOGGED BY: GHC CHECKED BY: TOTAL DEPTH (FT): 29.0

DRILL RIG TYPE: CME 85 DRILLED BY: Aaron Delvalle (Haztech) DEPTH TO G.W.:

DRILL BIT SIZE/TYPE: 4" Hollow stem auger with rock core bit INCLINATION FROM ___N/A____ FT AT TIME OF DRILLING

BOREHOLE BACKFILL: Cuttings and bentonite VERTICAL/BEARING: N/A ___________ FT AFTER ________ HRS

COMMENTS: ___________ FT AFTER ________ HRS

10.0__ 3460.0

1 2 48 N/A 8 N/O

14.0_ 3456.0

2 2 72 10 10 1

18.0_

19.0_ 3451.0

_ 3 2 93 2.3 78 2

22.0_

24.0_ 3446.0

4 2 67 8 0 3

25.5_ 3444.5

5 3 112 1.8 81 4

28.0_

29.0_ 3441.0

END OF ROCK CORING

Quartz monzonite, same as above.

Quartz monzonite, same as above. Blockage in split; short run

Quartz monzonite, same as above. Some extra recovery due to previous blockage.

Amphibolite; dark grey with mottled light grey; aphanitic; no foliation; weathdered;

strong.

Quartz monzonite (fractured); pink phenocrysts in a matrix of white/black/grey; porphyritic; no foliation;

slightly weathered; strong.

Quartz monzo from

17.5' to 19.0'

D

EP

TH

FT

EL

EV

FT

ROCK CORE MATERIAL DESCRIPTION

P A C K

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ES

TS

co b b le s/ b o u ld e rs n o d ra w in g

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FT

/H

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R U N N O

B O X N O

R

EC

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Y, FR

A C . F R

EQ

R .Q .D

FR

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TU

R E

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IN

N U M B

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LI

TH

O

LO

G Y

Depth to Depth; Rock type; color; texture, grain size, foliation, weathering, strength, other.

At Discontinuities: Fracture Number, dip angle, type, width, infilling type/amount, surface shape/roughness.

LA

B T

ES

TS

Amphibolite cobbles and boulders; dark grey with mottled light grey; aphanitic; no foliation; weathered ; strong.

Ampibolite

Amphibolite from

14.0' to 17.5'

PT

H

(F T

G E

O L

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Y L

O G

DESCRIPTION

OF MATERIALS

N (U

N C

O R

B

L O

W S/

FT

M O

IS

T

U R

E C

O N

T E

N

T OTHER FIELD OR

SAMPLE

INFORMATION

5.0

10.0

Geotechnical Engineering

32 DISCOVERY DRIVE

BOZEMAN, MT 59718

FAX (406) 582-5770

PHONE (406) 582-0221

Land Surveying Civil Engineering

Structural Engineering

LOG OF BORING

PROJECT: BPN Culverts JOB #: 23-147 DATE: 10/11/2023 PAGE: 1

LOCATION: North Fork, ID ELEVATION: 3480 DEPTH: 30.0' GW: 15.0'

DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: GHC BORING: BH-4

DRILLER: Aaron with Haztech CASING/HAMMER/SAMPLER: N/A/ 140#/ SSS

{0'-10.0'}: Alluvium Medium; brown; gravelly SAND with silt;

dry.

{10.0'-15.0'}: Alluvium Medium; grey; gravelly SAND with silt;

moist.

{15.0'-21.0'}: Alluvium Very dense; medium grey; gravelly SAND with silt; moist.

{21.0'-30.0'}: Alluvium Very dense; grey; gravelly SAND with silt;

wet.

7/14/13

General Notes:

Brown cuttings.

Grey cuttings.

Scraping noise.

Water at 15.0' bgs.

· SSS - 2.0'' O.D. Split Spoon Sample

· The beginning and ending depths of the individual soil layers are approximate.

End of Boring

15.0

20.0

25.0

30.0

35.0

S4-A @ 5.0'-6.5'

S4-B @ 15.0'-16.5'

10/10/12

9/8/10

11.5%

4/3/4

25/39/43

14.1%

Sample Notes:

2" of sandy topsoil

Bent sampler

Decomposed granite gravels with some amphibole same

No recovery, bedrock.30.0'-31.5' 50 for

1"

25.0'-26.5' 50 for 5"

20.0'-21.5'

10.0'-11.5' 1/15/15

33/40/ 50 for

3"

7.5'-9.0'

2.5'-4.0'

0.0'-1.5'

SA

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APPENDIX B

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GRAIN SIZE DISTRIBUTION (ASTM D‐422)

Project: Bia Po'I Naokwaide Culvert Replacement Project Number: 23‐147 Sample Identification: BH1 S1‐A Soil Classification: Gravely Sand with Silt Date Sampled: 10/10/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 2.3% Gravel Portion (retained on #4 sieve): 25.8% Sand Portion (passing # 4 & retained on #200 sieve): 55.7% Fines Portion (passing #200 sieve): 18.5%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 100.0% 3/4" 100.0% 3/8" 88.0% #4 74.2% #10 57.7% #20 45.1% #40 37.5% #60 31.2% #100 25.5% #140 22.0% #200 18.5%

D10 0.04 mm D30 0.229 mm D60 2.383 mm

Cu 58.81 Cc 0.54

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive Bozeman, MT 59718

Phone (406) 582-0221

Project Number: 23‐147 Sample Identification: BH1 S1‐F Soil Classification: Gravely Sand with Silt Date Sampled: 10/10/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 17.8% Gravel Portion (retained on #4 sieve): 25.0% Sand Portion (passing # 4 & retained on #200 sieve): 62.9% Fines Portion (passing #200 sieve): 12.1%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 100.0% 3/4" 100.0% 3/8" 88.1% #4 75.0% #10 57.4% #20 38.4% #40 31.1% #60 25.4% #100 19.2% #140 15.2% #200 12.1%

D10 0.061 mm D30 0.392 mm D60 2.412 mm

Cu 38.97 Cc 1.03

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

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GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH1 S1‐G Soil Classification: Gravely Sand with Silt Date Sampled: 10/10/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 11.8% Gravel Portion (retained on #4 sieve): 26.3% Sand Portion (passing # 4 & retained on #200 sieve): 53.3% Fines Portion (passing #200 sieve): 20.5%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 94.2% 3/4" 91.5% 3/8" 83.0% #4 73.7% #10 64.6% #20 49.9% #40 40.1% #60 33.3% #100 27.9% #140 24.2% #200 20.5%

D10 0.036 mm D30 0.188 mm D60 1.638 mm

Cu 44.70 Cc 0.59

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

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GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH2 S2‐A Soil Classification: Gravely Sand with Silt Date Sampled: 10/10/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 2.7% Gravel Portion (retained on #4 sieve): 34.3% Sand Portion (passing # 4 & retained on #200 sieve): 47.1% Fines Portion (passing #200 sieve): 18.6%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 100.0% 3/4" 94.8% 3/8" 80.9% #4 65.7% #10 52.1% #20 41.7% #40 35.4% #60 30.0% #100 24.8% #140 21.3% #200 18.6%

D10 0.04 mm D30 0.249 mm D60 3.595 mm

Cu 89.27 Cc 0.43

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH2 S2‐B Soil Classification: Sandy Gravel with Silt Date Sampled: 10/10/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 4.4% Gravel Portion (retained on #4 sieve): 52.8% Sand Portion (passing # 4 & retained on #200 sieve): 34.7% Fines Portion (passing #200 sieve): 12.5%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 84.8% 3/4" 73.8% 3/8" 57.4% #4 47.2% #10 38.3% #20 30.7% #40 25.8% #60 21.8% #100 17.7% #140 14.9% #200 12.5%

D10 0.06 mm D30 0.792 mm D60 10.854 mm

Cu 180.80 Cc 0.96

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH3 S3‐A Soil Classification: Silty Sand with Gravel Date Sampled: 10/11/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 3.5% Gravel Portion (retained on #4 sieve): 18.9% Sand Portion (passing # 4 & retained on #200 sieve): 52.0% Fines Portion (passing #200 sieve): 29.1%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 100.0% 3/4" 100.0% 3/8" 93.7% #4 81.1% #10 67.3% #20 55.3% #40 47.7% #60 41.3% #100 35.7% #140 32.2% #200 29.1%

D10 0.025 mm D30 0.083 mm D60 1.303 mm

Cu 50.57 Cc 0.21

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH3 S3‐C Soil Classification: Silty Sand with Gravel Date Sampled: 10/11/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 7.6% Gravel Portion (retained on #4 sieve): 23.0% Sand Portion (passing # 4 & retained on #200 sieve): 51.8% Fines Portion (passing #200 sieve): 25.3%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 95.5% 3/4" 91.7% 3/8" 85.7% #4 77.0% #10 66.5% #20 56.2% #40 48.8% #60 41.7% #100 34.1% #140 29.7% #200 25.3%

D10 0.029 mm D30 0.108 mm D60 1.274 mm

Cu 42.92 Cc 0.31

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH3 S3‐E Soil Classification: Sandy Gravel with Silt Date Sampled: 10/11/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 11.7% Gravel Portion (retained on #4 sieve): 51.7% Sand Portion (passing # 4 & retained on #200 sieve): 47.7% Fines Portion (passing #200 sieve): 0.5%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 88.3% 3/4" 82.0% 3/8" 59.7% #4 48.3% #10 32.1% #20 20.3% #40 15.8% #60 9.1% #100 4.8% #140 2.5% #200 0.5%

D10 0.273 mm D30 1.794 mm D60 9.671 mm

Cu 35.33 Cc 1.22

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH4 S4‐A Soil Classification: Gravelly Sand with Silt Date Sampled: 10/11/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 11.5% Gravel Portion (retained on #4 sieve): 41.6% Sand Portion (passing # 4 & retained on #200 sieve): 36.7% Fines Portion (passing #200 sieve): 21.7%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 92.2% 3/4" 84.7% 3/8" 71.2% #4 58.4% #10 51.0% #20 42.6% #40 37.1% #60 32.4% #100 27.8% #140 24.9% #200 21.7%

D10 0.034 mm D30 0.197 mm D60 5.357 mm

Cu 154.96 Cc 0.21

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

Project Number: 23‐147 Sample Identification: BH4 S4‐B Soil Classification: Gravelly Sand with Silt Date Sampled: 10/11/23 Date Tested: 11/13/23 Tested By: JGK

Natural Moisture Content: 14.1% Gravel Portion (retained on #4 sieve): 44.9% Sand Portion (passing # 4 & retained on #200 sieve): 43.6% Fines Portion (passing #200 sieve): 11.4%

Sieve Percent Size Passing 4" 100.0% 3" 100.0% 2" 100.0% 1.5" 100.0% 1" 90.9% 3/4" 85.9% 3/8" 68.0% #4 55.1% #10 44.7% #20 32.8% #40 25.3% #60 19.9% #100 15.6% #140 13.4% #200 11.4%

D10 0.065 mm D30 0.689 mm D60 6.557 mm

Cu 100.11 Cc 1.11

Reviewed By: ___GHC________

Summary of Lab Test Data

4" 3" 2" 1" 1/2" #4 #10 #20 #40 #60 #100 #200 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 0.010.1110100

Pe rc en t P as si ng

GRAIN SIZE DISTRIBUTION

Grain Size (mm)

Gravels FinesSands

32 Discovery Drive

APPENDIX C

LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt

LIMITATIONS OF YOUR GEOTECHNICAL REPORT

GEOTECHNICAL REPORTS ARE PROJECT AND CLIENT SPECIFIC

Geotechnical investigations, analyses, and recommendations are project and client specific. Each project and each client have individual criterion for risk, purpose, and cost of evaluation that are considered in the development of scope of geotechnical investigations, analyses and recommendations. For example, slight changes to building types or use may alter the applicability of a particular foundation type, as can a particular client’s aversion or acceptance of risk. Also, additional risk is often created by scope‐of service limitations imposed by the client and a report prepared for a particular client (say a construction contractor) may not be applicable or adequate for another client (say an architect, owner, or developer for example), and vice‐versa. No one should apply a geotechnical report for any purpose other than that originally contemplated without first conferring with the consulting geotechnical engineer. Geotechnical reports should be made available to contractors and professionals for information on factual data only and not as a warranty of subsurface conditions, such as those interpreted in the exploration logs and discussed in the report.

GEOTECHNICAL CONDITIONS CAN CHANGE

Geotechnical conditions may be affected as a result of natural processes or human activity. Geotechnical reports are based on conditions that existed at the time of subsurface exploration. Construction operations such as cuts, fills, or drains in the vicinity of the site and natural events such as floods, earthquakes, or groundwater fluctuations may affect subsurface conditions and, thus, the continuing adequacy of a geotechnical report.

GEOTECHNICAL ENGINEERING IS NOT AN EXACT SCIENCE

The site exploration and sampling process interprets subsurface conditions using drill action, soil sampling, resistance to excavation, and other subjective observations at discrete points on the surface and in the subsurface. The data is then interpreted by the engineer, who applies professional judgment to render an opinion about over‐all subsurface conditions. Actual conditions in areas not sampled or observed may differ from those predicted in your report. Retaining your consultant to advise you during the design process, review plans and specifications, and then to observe subsurface construction operations can minimize the risks associated with the uncertainties associated with such interpretations. The conclusions described in your geotechnical report are preliminary because they must be based on the assumption that conditions revealed through selective exploration and sampling are indicative of actual

Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 2 conditions throughout a site. A more complete view of subsurface conditions is often revealed during earthwork; therefore, you should retain your consultant to observe earthwork to confirm conditions and/or to provide revised recommendations if necessary. Allied Engineering cannot assume responsibility or liability for the adequacy of the report’s recommendations if another party is retained to observe construction.

EXPLORATIONS LOGS SHOULD NOT BE SEPARATED FROM THE REPORT

Final explorations logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data.

Only final exploration logs and data are customarily included in geotechnical reports. These final logs should not be redrawn for inclusion in Architectural or other design drawings, because drafters may commit errors or omissions in the transfer process.

To…