Amendment 0001 -TN ERFO FS CHRKE804 2020-2(4).pdf

(x)

693C7326B000010 x x

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ASHBURN VA 20147

ATTN: CONSTRUCTION

693C73

SUITE E2-3-300

QUANTUM PARK, 22001 LOUDOUN COUNTY PKWY

EASTERN FEDERAL LANDS HIGHWAY DIVISION

FEDERAL HIGHWAY ADMINISTRATION

ASHBURN VA 20147

ATTN: ACQUISITIONS

693C73

SUITE E2-3-300

QUANTUM PARK, 22001 LOUDOUN COUNTY PKWY

EASTERN FEDERAL LANDS HIGHWAY DIVISION

FEDERAL HIGHWAY ADMINISTRATION

See Block 1405/12/20260001

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Project TN ERFO FS CHRKE804 2020-2(4):

The purpose of this Amendment is to:

1) Provide attached Geotechnical Report.

2) Extend the date of the Bid Opening from Thursday, May 14, 2026, to Thursday, May 21, 2026, at 2:00 pm EDT.

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Amendment 0001

Info Page 1 of 1

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

Amendment No. 0001 Project TN ERFO FS CHRKE804 2020-2(4)

Cherokee National Forest Solicitation: 693C73-26-B-000010

The purpose of this Amendment is to:

1) Provide attached Geotechnical Report.

2) Extend the date of the Bid Opening from Thursday, May 14, 2026, to Thursday, May 21, 2026, at 2:00 pm EDT.

Report of Geotechnical Exploration

FSR 45 & 67 Little Gassaway and

Sina Branch

Ocoee, Tennessee

S&ME Project No. 23810282

PREPARED FOR:

WSP USA, Inc.

13530 Dulles Technology Drive, Suite 300

Herndon, Virginia 20171

PREPARED BY:

S&ME, Inc.

4291 Highway 58

Chattanooga, Tennessee 37416

March 13, 2026

FSR 45 & 67 Little Gassaway and Sina Branch

Ocoee, Tennessee

S&ME Project No. 23810282

March 13, 2026 ii

Table of Contents

1.0 Introduction

2.0 Project Description

3.0 Exploratory and Testing Procedures

3.1 Soil Test Borings

3.2 Laboratory Testing

4.0 Site, Geologic, and Subsurface Conditions

4.1 Site Conditions

4.2 Geologic Conditions

4.3 Subsurface Conditions

4.3.1 Paving Materials

4.3.2 Fill Soils

4.3.3 Alluvial Soils

4.3.4 Residual Soils

4.3.5 Auger Refusal Materials

5.0 Laboratory Testing

6.0 Conclusions and Recommendations

6.1 Earthwork

6.1.1 Stripping

6.1.2 Subgrade Evaluation

6.1.3 Difficult Excavation

6.1.4 Earth Material Utilization and Fill Placement

6.1.5 Fill Density Testing

6.1.6 Groundwater

6.2 Final Subgrade Preparation

6.3 Foundations

6.3.1 Aquatic Organism Passage – Little Gassaway Mile Post 0.251 / Master Pin 194

6.3.2 Aquatic Organism Passage – Little Gassaway Mile Post 0.310 / Master Pin 196

6.3.3 Aquatic Organism Passage – Sina Branch Mile Post 6.55 / Master Pin 26

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March 13, 2026 iii

6.3.4 Aquatic Organism Passage – Sina Branch Mile Post 7.795 / Master Pin 45

6.3.5 Box Culvert – Sina Branch Mile Post 9.024 / Master Pin 53

6.3.6 General Foundation Recommendations

6.4 Retaining Wall – Little Gassaway Mile Post 2.3 / Master Pin 210

6.5 Slope Failure– Sina Branch Mile Post 6.825 / Master Point 030

6.5.1 Rock Buttress Repair Option

6.5.2 Anchored Slope Repair Option

6.6 Seismic Considerations (AASHTO 2020)

6.7 Corrosivity

7.0 Follow-Up Services

8.0 Limitations of Report

Appendix I Figures 1 and 2 – Site Location Plans

Figures 3 through 8 – Boring Location Plans

Geologic Maps

Appendix II Soil Log Legend

Rock Core Log Legend

Boring Logs

Core Photographs

Appendix III Lab Test Results

Appendix IV Figures 9 through 11 - Slope Stability Analysis Results

Figure 12 – Subsurface Profile – MP 2.3

Appendix V Site Photographs

Important Information About Your Geotechnical Engineering Report

Ocoee, Tennessee

S&ME Project No. 23810282

March 13, 2026 1

1.0 Introduction

The purpose of our services was to explore subsurface conditions at the site, provide laboratory testing, and provide a geotechnical engineering report including a retaining wall and rock slope design. Plans for the wall design will be submitted separately from this report. This report describes our understanding of the project, presents the results of the field exploration and laboratory testing, and discusses our conclusions and recommendations relative to the considerations discussed in this report. This report provides the following:

A summary of the project and provided information;

A summary of current site conditions, topography, and area geology;

A summary of the field exploration methods;

A summary of the subsurface conditions encountered in the test borings;

A summary of the laboratory test methods and results;

Recommendations for site preparation, including subgrade preparation, excavation, structural fill placement, and groundwater control;

Recommendations for foundation design and construction for each structure;

Results of slope stability analysis and recommendations for repair of the slope failure at Sina Branch Mile

Post 6.825;

Seismic hazard analysis of the sites following AASHTO LRFD Section 3.10; and

An Appendix with Site Location Plans, Boring Location Plans, individual boring logs for each test boring including rock core photos, individual laboratory test reports, slope stability analysis results, and site photographs.

2.0 Project Description

Initial project information was provided through emails and conversations with Mr. Matthew Martin of WSP USA, Inc. Appended to the emails were the following documents:

Design Scoping Report TN ERFO FS CHRK804 202-2 (1), by the Federal Highway Administration

(FHWA), May 2023.

Section B Supplies or Services and Prices/Costs, by FHWA (undated).

Section C Statement of Work, by FHWA (undated).

DGN files of the existing condition surveys for each site.

Based on the provided information, we understand there has been storm damage impacting Forest Service Roads

(FSR) 45 (Little Gassaway) and 67 (Sina Branch). On Little Gassaway, repairs include the installation of aquatic organism passages (AOP’s) at Mile Posts 0.251 and 0.310, as well as the construction of a retaining wall at Mile

Post 2.3. Repairs on Sina Branch include the construction of AOP’s at Mile Posts 6.55, and 7.795, the installation of a rock slope at Mile Post 6.825, and the construction of a box culvert at Mile Post 9.024. Two Site Location Plans, Figures 1 and 2, are included in the Appendix showing the general location of each of the Little Gassaway and Sina

Branch sites, respectively.

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S&ME Project No. 23810282

March 13, 2026 2

Based on the information provided, we understand the proposed box culvert located at Mile Post 9.024 on Sina

Branch will be a precast concrete structure bearing on shallow foundations. Based on conversations with the project team, we understand the preference for the retaining wall constructed at the slope failure located at Mile

Post 2.3 on Little Gassaway is a mechanically stabilized earth retaining wall structure. Lastly, we understand the proposed AOP’s at Mile Posts 6.55 and 7.795 of Sina Branch and Mile Posts 0.251 and 0.310 of Little Gassaway will consist of bottomless, half-dome corrugated metal pipes supported on a shallow concrete foundation.

The project information detailed in this report should be reviewed and confirmed by the appropriate team members. Modifications to our conclusions and recommendations may be required if the actual conditions vary from the project information and assumptions described herein.

3.0 Exploratory and Testing Procedures

3.1 Soil Test Borings

A member of S&ME’s professional staff made a site reconnaissance to observe site features and to mark the test boring locations. The locations of the borings, labeled LG-01 through LG-04 for Little Gassaway and SB-01 through SB-04 for Sina Branch, were selected at each site based on the existing site features, obstructions, and drill rig access. Members of the WSP’s survey subcontractor, Cannon and Cannon, later surveyed the locations of these borings. The approximate boring locations are shown on the Boring Location Plans (Figures No. 4 through 6) in the Appendix. Ground surface elevations at the boring locations were estimated to the nearest foot based on the approximate locations and interpolation between the contours shown on the provided topographic surveys.

These elevations should be considered approximate.

Due to the rocky nature of the overburden soils, we were not able to advance our soil test borings using hollow stem augers as originally proposed. Therefore, the soil test borings for this exploration were made using a casing advancer in general accordance with ASTM D5872, Standard Practice for Use of Casing Advancement Drilling

Methods for Geoenvironmental Exploration. Continuous soil sampling was performed in general accordance with

ASTM D1586, Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils until auger refusal was reached for each boring. During standard penetration testing, the sampler was first seated 6 inches and then driven an additional foot with blows of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the standard penetration resistance or N-value with units of blows per foot (bpf).

The samples obtained during the field exploration were visually classified by members of our professional staff in general accordance with ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual

Procedure). The purposes of this review were to check the field descriptions, visually estimate the relative percentages of the soils’ constituents (sand, clay, etc.), and evaluate the soil’s origin. The stratification lines shown on the appended Boring Logs represent the approximate boundaries between soil types, but the transitions may be more gradual than shown. The samples were then packaged, labeled for identification, and transported to our laboratory.

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In addition to split barrel sampling, one relatively undisturbed Shelby tube was obtained from a select boring location and depth. We were unable to obtain more Shelby tubes due to the granular nature of the soils. The borings were backfilled with bentonite grout before leaving the site.

3.2 Laboratory Testing

Selected soil samples were subjected to moisture content (ASTM D2216), Atterberg limits testing (ASTM D4318), grain size distribution (ASTM D1140), unconfined compression strength of rock (ASTM D2166), and corrosion testing including pH (ASTM G51), resistivity (ASTM G 187), chloride ion concentration (ASTM D 4327), and sulfate ion concentration (ASTM D4327). We were unable to perform triaxial testing because testable Shelby tube samples could not be obtained in the soil matrix.

4.0 Site, Geologic, and Subsurface Conditions

4.1 Site Conditions

Each of the eight sites is located in the southern Cherokee National Forest in eastern Tennessee. The sites at Mile

Posts 0.251, 0.310, and 2.3 are located along FSR 45 (Little Gassaway), while the sites at Mile Posts 6.55, 6.825, 7.697, and 9.024 are located along FSR 67 (Sina Branch). The sites along Little Gassaway at Mile Posts 0.251 and

0.310 are located at two culverts crossing Little Gassaway Creek, approximately 500 feet west of the Ocoee 2

Powerhouse. The site at Mile Post 2.3 is a failing slope further south along FSR 67, about 500 feet north of the spine of Chestnut Ridge. Mile Post 6.55 along FSR 67 is located at a culvert in a relatively wide valley formed by

Davis Branch. Mile Post 6.825 is a slope consisting of the toe eroding into an unnamed drainage feature adjacent to Davis Branch. The site at Mile Post 7.697 is a culverted creek crossing along a tributary of Davis Branch. Mile

Post 9.024 is located adjacent to an existing AOP, about ¼ mile east of the intersection of Sina Branch Road and

Sheeds Creek Road. Each site is located along a gravel or asphalt paved forest service road surrounded by mature trees.

4.2 Geologic Conditions

The project site lies within the Blue Ridge Physiographic Province (also known as the Unaka Physiographic

Province). The Blue Ridge, located along the eastern border of Tennessee, is a deeply dissected mountainous area of numerous steep mountain ridges (with elevations up to about 6,600 feet), basins, and trench valleys that intersect at all angles which give the area its rugged mountain character. This province is underlain by complexly folded and faulted igneous and metamorphic rock with some sedimentary rock. The Blue Ridge contains the highest elevations and the most rugged topography in the Appalachian Mountain system of eastern North

America.

Based on our review of the Geologic Map of East Tennessee dated 1953 - Plate 13, Cleveland, and Plate 14, Murphy (included in Appendix I), the borings performed along Sina Branch are underlain by bedrock of the

Sandsuck Formation of the Walden Creek Group. This formation consists of greenish-gray siltstone, silty shale, and fine-grained sandstone with thick lenticular beds of sandstone and quartz-pebble conglomerate that occurs in the middle part of the formation.

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S&ME Project No. 23810282

March 13, 2026 4

The borings performed along Little Gasaway are underlain by bedrock of the Great Smoky Group which is part of the Ocoee Supergroup. The Great Smoky Group is not divided into individual formations in the area of this site.

Where undivided, the Great Smoky Group is composed of the Anakeesta, Thunderhead Sandstone, and Elkmont

Sandstone Formations. These formations are typically composed of feldspathic, fine-grained sandstone inter-bedded with black slate, greywacke, quartz, and conglomerate.

4.3 Subsurface Conditions

The borings logs included in Appendix II should be reviewed for specific information at the individual boring locations. The depths and thicknesses of the subsurface strata indicated on the boring logs are generalized and the transition between materials may be more gradual than indicated. Information on actual subsurface conditions exists only at the specific boring locations and is relevant to the time the exploration was performed. Variations may occur and should be expected between and away from the boring locations. The stratification lines were used for our analytical purposes and, unless specifically stated otherwise, should not be used as the basis for design or construction cost estimates.

4.3.1 Paving Materials

Aggregate base was encountered in borings SB-01, SB-02, LG-03, and LG-04 to a depth of about 2 inches. Paving materials were not noted in the remaining borings which were performed in the unpaved shoulders of Little

Gassaway or Sina Branch.

4.3.2 Fill Soils

Fill was encountered in borings LG-01, LG-02, LG-04, SB-03, and SB-04 to depths ranging from about 2 ½ to 8 feet. Fill is material that has been transported to its present location by man. The fill was generally composed of gray and orange silts, sands and gravels. N-values in the granular fill soils ranged from 5 to 34 bpf, indicating a loose to dense relative density. One sample of fine-grained soil classified as a gravelly silt had an N-value of over

50 bpf, indicating a hard soil consistency.

The fill material extended to bedrock at about 6 feet below grade in boring LG-01. We have not been provided any information relative to when or how fill soils at each site were placed.

4.3.3 Alluvial Soils

Alluvial soils were encountered in borings SB-01, SB-03, and SB-04 below the aggregate base or fill layer to depths ranging from about 5 ½ to 12 feet. Alluvial soil is soil that has been transported to its present location by flowing water. The alluvial soils encountered in our test borings were typically composed of gray, silty sands and gravels. N-values in the alluvium ranged from 21 to over 50 bpf, indicating a medium dense to very dense relative density.

4.3.4 Residual Soils

Residual soils were encountered in borings LG-02, LG-03, LG-04, SB-01, and SB-02 either from the ground surface or below the fill soils. Residual soils were encountered to auger refusal depths ranging from about 5 to 11 ½ feet.

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S&ME Project No. 23810282

March 13, 2026 5

Residual soil forms from the in-place weathering of the underlying bedrock. The residual soils encountered at the site were typically composed of orange brown with gray silty gravels or sands and gravelly silts. N-values in the fine-grained residuum ranged from 4 bpf to over 50 bpf indicating a soft to hard consistency. N-values in coarse-grained residual soils also ranged from 4 to over 50 bpf, indicating very loose to very dense relative densities.

4.3.5 Auger Refusal Materials

Auger refusal materials were encountered in each of the borings at depths ranging from about 5 to 12 feet below the existing ground surface. Refusal occurs when materials are encountered that cannot be penetrated by the drilling equipment and is normally indicative of a very hard or very dense material, such as a boulder, a rock lens or pinnacle, or the upper surface of bedrock. Auger refusal discussed herein is based on conditions impenetrable to the drilling equipment for this project. Encountering auger refusal conditions with this particular equipment does not necessarily indicate conditions impenetrable to other equipment.

Rock was cored in each of the borings. The rock core samples collected were logged in the field. The recovery and rock quality designation (RQD) were determined prior to storing the samples. The rock core recovery is a measure of the length of core drilled to that recovered expressed as a percentage. The RQD is a measure of the rock quality based on the percentage of the rock core run containing pieces greater than 4 inches in length. The rock core recovery ranged from 20 to 100 percent but was typically greater than 50 percent. The RQD ranged from 0 to 100 percent but was typically in the 25 to 60 percent range. The rock cored from borings LG-01 through LG-03 and

SB-03 consisted of very dark gray slate. Light gray and brown arkosic sandstone was encountered in boring LG-04.

Greywacke sandstone was encountered in borings SB-01, SB-02, and SB-04.

5.0 Laboratory Testing

The results of the laboratory testing for this project are summarized in the following table with the exception of grain size distribution and corrosion series testing. Laboratory test reports are included in the Appendix III. The results of corrosion series testing are discussed in Section 6.7 of this report.

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S&ME Project No. 23810282

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Test Results Summary

Boring Sample

Type Depth (ft)

Natural

Moisture

Content (%)

Percent Finer than US No

200 Sieve (%)

Liquid

Limit

Plasticity

Index

Unconfined

Compressive

Strength (psi)

LG-01

Split Spoon 1-2.5 12.4 30.2 26 5 -

Rock Core 9.3-9.7 - - - - 7,076

LG-02

Split Spoon 6-7.5 3.0 - - - -

Rock Core 10.8-11.2 - - - - 11,758

LG-03 Split Spoon 3.5-5 9.0 12.4 29 6 -

LG-04

Split Spoon 2.5-4 9.0 - - - -

Split Spoon 4-5.5 10.1 - - - -

Split Spoon 6-7.5 11.1 - - - -

SB-01

Split Spoon 1-2.5 11.7 - - - -

Split Spoon 6-7.5 5.7 16.0 19 3 -

Split Spoon 8.5-10 8.5 - - - -

Rock Core 10.7-11.1 - - - - 21,842

SB-02

Split Spoon 1-2.5 4.9 - - - -

Split Spoon 5.5-8 14.4 23.5 23 4 -

Split Spoon 8.5-10 11.1 - - - -

Rock Core 14.5-14.9 - - - - 626

SB-03

Split Spoon 1-2.5 10.5 23.0 25 7 -

Split Spoon 6-7.5 13.1 22.0 31 8 -

Split Spoon 8.5-10 11.3 - - - -

Split Spoon 11-12.5 6.3 - - - -

Rock Core 14.3-14.7 - - - - 7,909

SB-04

Split Spoon 1-2.5 5.0 17.0 25 6 -

Split Spoon 3.5-5 0.1 - - - -

“-“ Test not performed

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6.0 Conclusions and Recommendations

6.1 Earthwork

6.1.1 Stripping

Aggregate base paving material should be stripped from the construction area. Aggregate base was encountered to a depth of about two inches in borings SB-01, and SB-02. However, both Little Gassaway and Sina Branch were paved with aggregate base. Therefore, this material was present at each site. We expect topsoil to be present in unexplored areas, particularly near drainage features.

6.1.2 Subgrade Evaluation

After completion of stripping in areas to receive fill, and once grade is achieved in cut areas, we recommend a member of our geotechnical engineering staff evaluate the stability of the exposed subgrade soils. Subgrade evaluations may include hand probing with a steel probe rod, hand auger borings, test pit excavations or proofrolling with a loaded dump truck or other heavy equipment. In general, unstable materials should be undercut to stable soils and backfilled with compacted structural fill unless otherwise directed by the geotechnical engineer or his representative.

Subgrade repair can be expected to be more extensive if grading operations are performed during wet periods of the year. Once areas that need remediation have been repaired, the site may be brought to grade with structural fill. Depending on prevailing weather conditions and the speed of contractor activities, subgrade evaluations may be required on multiple occasions.

6.1.3 Difficult Excavation

Based on the boring data obtained during the exploration, we expect material requiring difficult excavation may be encountered during foundation excavation at the proposed culvert and AOP structures. Depths to auger refusal are summarized in the following table.

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Auger Refusal Depth Summary

Boring Depth to Auger Refusal (ft)

LG-01 6.1

LG-02 7.5

LG-03 5.1

LG-04 7.3

SB-01 9.3

SB-02 11.4

SB-03 11.8

SB-04 6.4

In confined excavations such as foundations, removal of weathered rock typically requires the use of large backhoes and/or pneumatic spades. The difficulty of excavation will depend on the composition of the rock, the location and orientation of discontinuities and bedding, and the skill of the equipment operator.

6.1.4 Earth Material Utilization and Fill Placement

After subgrade evaluation/preparation and completion of any field-recommended remedial actions, areas to receive fill may be brought to design subgrade levels with structural fill. Structural fill is defined as inorganic natural soil with maximum particle sizes of about 4 inches and a Plasticity Index of 30 or less. Structural fill should be placed in relatively thin (4- to 8-inch) layers and compacted to at least 98 percent of the soil’s maximum dry density as determined by the standard Proctor compaction test (ASTM D698).

6.1.5 Fill Density Testing

In-place density testing must be performed as a check the previously recommended compaction criteria are achieved. We recommend density testing by a technician working under the direction of our project engineer.

6.1.6 Groundwater

Based on the test boring results, we do not expect that groundwater will present significant site development problems. However, perched groundwater conditions may occur at this site, particularly during periods of heavy rain. The contractor should provide adequate dewatering to maintain the groundwater level, if encountered, and surface water below the bottom of excavations, except when the excavation is in rock. Pumping from sumps constructed outside the excavation should be effective in dewatering the soils encountered in our exploration.

However, the dewatering methods selected should take into consideration the presence of gravel layers and pockets that will concentrate the groundwater flow in discreet zones. Water from the pumps should be discharged beyond the construction boundaries to limit its effect on construction activities.

6.2 Final Subgrade Preparation

Roadway subgrades are often disturbed between completion of site grading and final roadway construction due to weather, foundation installation, and other construction activities. For this reason, it is important the subgrades

Ocoee, Tennessee

S&ME Project No. 23810282

March 13, 2026 9 be evaluated just before final roadway grading. At that time, as much of the subgrade as practical should be proofrolled with a loaded dump truck in the presence of our representative. Any areas that deflect significantly under the proofrolling load, or which are otherwise assessed to be soft or unstable, should be undercut to firm materials. The undercut areas should be backfilled with compacted soil or crushed stone. Our representative can provide recommendations for repairing unstable areas that are observed.

6.3 Foundations

6.3.1 Aquatic Organism Passage – Little Gassaway Mile Post 0.251 / Master Pin 194

Based on the results of soil test boring LG-01, we expect intact rock will be encountered at or near the proposed foundation bearing elevation of the proposed aquatic organism passage at Little Gassaway Mile Post 0.251 /

Master Pin 194. We recommend the foundations be supported entirely on bedrock. If soil is encountered at proposed bearing elevations, this material should be undercut to expose intact bedrock. Once the excavations are completed and relatively free of loose debris, they should be backfilled with flowable fill or lean concrete to the design foundation bearing elevation. Foundation concrete may then be placed neat to the excavation.

Based on our analysis, foundations prepared in accordance with the recommendations of this report and bearing on bedrock, or on flowable fill, may be designed using an allowable bearing pressure of 3,000 pounds per square foot.

6.3.2 Aquatic Organism Passage – Little Gassaway Mile Post 0.310 / Master Pin 196

Based on the results of soil test boring LG-02, we expect intact bedrock, or residual soils will be encountered at or near the proposed foundation bearing elevation of the Aquatic Organism Passage at Little Gassaway Mile Post

0.310 / Master Pin 196. We recommend the foundations be supported entirely on rock. If fill or residual soils are encountered in areas at this proposed bearing elevation, this material should be undercut to expose intact bedrock. Once the excavations are completed and relatively free of loose debris, they should be backfilled with flowable fill or lean concrete to the design foundation bearing elevation. Foundation concrete may then be placed neat to the excavation.

Based on our analysis, foundations prepared in accordance with the recommendations of this report and bearing on bedrock, or on flowable fill, may be designed using an allowable bearing pressure of 3,000 pounds per square foot.

6.3.3 Aquatic Organism Passage – Sina Branch Mile Post 6.55 / Master Pin 26

Based on the results of soil test boring SB-01, we expect residual soils will be encountered at the proposed foundation bearing elevation at the Aquatic Organism Passage at Sina Branch Mile Post 6.55 / Master Pin 26.

Based on our analysis, shallow spread footings bearing on newly placed compacted soil fill or medium dense or higher relative density or stiff or higher consistency residual soil may be designed using an allowable soil bearing pressure of 2,500 pounds per square foot.

If a higher bearing pressure is required, the foundations may be undercut to bedrock and backfilled with flowable fill or lean concrete to the design bearing elevation. Foundation concrete may then be placed neat to the

Ocoee, Tennessee

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March 13, 2026 10 excavation. Foundations should bear on either rock or soil, not a combination of the two, due to the risk of differential settlement. Foundations bearing on bedrock, or on flowable fill, may be designed using an allowable bearing pressure of 3,000 pounds per square foot.

6.3.4 Aquatic Organism Passage – Sina Branch Mile Post 7.795 / Master Pin 45

Based on the results of soil test boring SB-03, we expect alluvial soils will be encountered at the proposed foundation bearing elevation at the Aquatic Organism Passage at Sina Branch Mile Post 7.697 / Master Pin 42.

Based on our analysis, shallow spread footings bearing on newly placed compacted soil fill or medium dense or higher relative density of stiff or higher consistency alluvial soil may be designed using an allowable soil bearing pressure of 2,500 pounds per square foot. If fill soils are encountered during foundation excavation, they should be undercut and backfilled with properly compacted structural fill to the design bearing elevation.

If a higher bearing pressure is required, the foundations may be undercut to bedrock and backfilled with flowable fill or lean concrete to the design bearing elevation. Foundation concrete may then be placed neat to the excavation. Foundations should bear on either rock or soil, not a combination of the two, due to the risk of differential settlement. Foundations bearing on bedrock, or on flowable fill, may be designed using an allowable bearing pressure of 3,000 pounds per square foot.

6.3.5 Box Culvert – Sina Branch Mile Post 9.024 / Master Pin 53

Based on the results of soil test boring SB-04, we expect intact rock will be encountered at or near the proposed foundation bearing elevation of the box culvert at Sina Branch Mile Post 9.024 / Master Pin 53. We recommend the foundations be supported entirely on rock. If residual soils are encountered in areas at this proposed bearing elevation, this material should be undercut to expose intact bedrock. Once the excavations are completed and relatively free of loose debris, they should be backfilled with flowable fill or lean concrete to the design foundation bearing elevation. Foundation concrete may then be placed neat to the excavation.

Based on our analysis, foundations prepared in accordance with the recommendations of this report and bearing on bedrock, or on flowable fill, may be designed using an allowable bearing pressure of 3,000 pounds per square foot.

6.3.6 General Foundation Recommendations

Foundation excavations should be backfilled with concrete the same day they are excavated. Footing concrete should be placed directly against the excavation so water cannot collect behind forms before backfilling. If soils exposed in the foundation excavations experience moisture variations prior to concrete placement, the affected bearing materials should be undercut as recommended by our geotechnical engineer. A 2- to 3-inch thick mud-mat of lean concrete may be used to protect the exposed support materials if the foundations cannot be backfilled with concrete the same day they are excavated. Although computed footing dimensions may be less, we recommend continuous footings be a minimum of 18 inches wide and isolated spread footings be a minimum of

36 inches wide. Foundations should bear at a minimum of 18 inches below subgrade to protect against frost penetration and to provide adequate confinement.

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The recommendations in this report are contingent on S&ME observing and evaluating the foundation bearing soils prior to placing concrete. Foundation subgrade observations should be performed by the geotechnical engineer, or his qualified representative, to confirm the recommendations provided in this report are consistent with the site conditions encountered. A Dynamic Cone Penetrometer (DCP) may be utilized to provide information that is compared to the data obtained in the geotechnical report. If unacceptable materials are encountered, the material should be excavated to stiff or higher consistency soils or remediated as recommended by the geotechnical engineer.

The recommendations in this report are contingent on S&ME observing and evaluating the foundation excavations prior to placing flowable fill or concrete. Foundation subgrade observations should be performed by the geotechnical engineer, or his qualified representative, in order to confirm the recommendations provided in this report are consistent with the site conditions encountered.

6.4 Retaining Wall – Little Gassaway Mile Post 2.3 / Master Pin 210

The proposed retaining wall at Little Gassaway Mile Post 2.3 / Master Pin 210 will be a mechanically stabilized earth (MSE) retaining wall. The proposed wall will include a face consisting of segmental retaining wall units with an uniaxial geogrid reinforced zone behind the block facing. Recommendations for MSE wall construction will be provided in mechanically stabilized earth wall drawings, Sheets R01 and R02, which will be issued under separate cover. A subsurface profile (Figure No. 12) at the proposed wall location is included in Appendix IV.

6.5 Slope Failure– Sina Branch Mile Post 6.825 / Master Point 030

6.5.1 Rock Buttress Repair Option

The slope failure at Sina Branch Mile Post 6.825 / Master Pin 030 has resulted in a significant loss of roadway shoulder as well as a portion of the travel lane (approximately 6 feet of horizontal retreat). As requested, S&ME analyzed the stability of this slope to evaluate potential repair options. The analysis included a back-analysis first to evaluate representative material properties based on an assumed factor of safety of approximately 1.0 at the time of original slope failure. This analysis is represented by Figure 9 in Appendix IV. A repair solution (with multiple geometries attempted) was then modeled to analyze global stability with a target Factor of Safety of 1.3.

The results of our analysis are shown on Figure 10 in Appendix IV. Based on the results of our analysis, the slope failure at Sina Branch can be repaired using a crushed stone and riprap buttress with a maximum slope inclination of 1.5 Horizontal to 1 Vertical (1.5H:1V). Given this maximum slope inclination, the design will need to consider the balance between the amount of repaired shoulder width at the top of slope and avoiding disturbance to the drainage channel present at the toe of the slope. These factors could require a variable shoulder width along the length of the repair depending on actual subsurface conditions and changes in channel direction.

Prior to rock buttress construction, we recommend undercutting the existing overburden soils which have been impacted by the slope’s failure. This material should be removed to underlying stiff or better consistency residual or alluvial soil or partially weathered rock. This excavation should be reviewed by the geotechnical engineer or his representative. Should the exposed partially weathered rock be steeply inclined, it may be necessary to excavate benches into the weathered rock prior to the placement of riprap until an effective inclination of 1.5H:1V is achieved. Prior to the placement of riprap, non-woven geotextile should be placed against the exposed soil slope

Ocoee, Tennessee

S&ME Project No. 23810282

March 13, 2026 12 to serve as separation prior to placement of any crushed stone. The stone should consist of TDOT Machined

Riprap Class B with an outside slope inclination of 1.5H:1V or flatter. Slope construction should be performed in accordance with TDOT Standard Specifications for Road and Bridge Construction (current version). Within the top one to two feet of the repair, we recommend capping the riprap with a layer of graded aggregate (TDOT Mineral

Aggregate Base Type B) to provide a level and compacted surface for vehicle traffic. This surface layer of aggregate base could be deeper, if necessary, to allow for installation of a guardrail along the top of the slope.

The repair should also consider important factors related to surface water runoff and drainage to help reduce potential erosion of the roadway and slope.

6.5.2 Anchored Slope Repair Option

Based on discussion with WSP, an alternative repair was considered and analyzed consisting of granular fill soil reinforced with percussion anchors. This option would involve re-grading the slope using soil material as opposed to crushed stone such as riprap. Following grading, the slope would be anchored in a pattern using shallow anchors driven into the slope and tensioned against the face, which would be dressed with an erosion control fabric. The results of our analysis indicate this slope repair option offers a potentially marginal Factor of Safety and could require significant anchorage to achieve the target Factor of Safety of 1.3. Moreover, soil compaction along this slope may not be practical due to the site constraints likely making it difficult for compaction equipment to reach the base of this failed slope without a significant amount of additional grading outside the failed slope.

However, this option remains an alternative that could be pursued while these limitations are taken into consideration.

6.6 Seismic Considerations (AASHTO 2020)

The soil profile present at each site has been evaluated for a seismic design classification utilizing standard penetration resistance (N-value) information in general accordance with AASHTO LRFD Bridge Design

Specifications, 2020 Section 3.10.3. Based on the results of our exploration and the geology of the area, we recommend a Site Class of C be used for the design of each of the proposed structures. The AASHTO manual contains a provision for assessing the use of site-specific values, provided a site-specific assessment is conducted.

S&ME can provide these services, if requested. For a site class of C for each structure, we determined the following design spectral acceleration parameters in accordance with AASHTO 3.10.2.1 provided in the following table.

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March 13, 2026 13

Spectral Acceleration Parameters

Structure Roadway Master Pin PGA SDS SD1

Aquatic Organism Passage Little Gassaway 194

0.145 0.318

0.117

Aquatic Organism Passage Little Gassaway 196

Retaining Wall Little Gassaway 210

Aquatic Organism Passage Sina Branch 026

0.148 0.322 Aquatic Organism Passage Sina Branch 045

Culvert Sina Branch 053

6.7 Corrosivity

To evaluate the corrosion potential of onsite soils, we reviewed the corrosivity lab test results and compared them to Table 5-15 Typical Numerical Corrosivity Scoring System of the FHWA-NHI-16-072 GEC 5 -Geotechnical Site

Characterization document. Corrosivity scores for each site are summarized in the following table. The lab tests are included in Appendix III.

Corrosion Potential Score Summary

Test Location Total Corrosivity Score Soil Corrosion Potential

LG-01 6 Mild

LG-02 6 Mild

LG-03 6 Mild

SB-02 6 Mild

SB-03 6 Mild

SB-04 6 Mild

7.0 Follow-Up Services

Our services should not end with the submission of this geotechnical report. S&ME should be kept involved throughout the design and construction process to maintain continuity and to determine if our recommendations are properly interpreted and implemented. To achieve this, we should review project plans and specifications with the designers to see that our recommendations are fully incorporated and have not been misinterpreted. We also should be retained by the owner to observe the site preparation and foundation construction.

S&ME’s familiarity with the site and foundation recommendations makes us a valuable part of your construction quality assurance team. S&ME recommends we be retained by the owner on a full-time basis to observe earthwork and foundation construction. Our personnel are uniquely qualified to recognize unanticipated ground conditions and can offer responsive remedial recommendations should these unanticipated conditions occur.

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8.0 Limitations of Report

This report has been prepared in accordance with generally accepted geotechnical engineering practice for specific application to this project. The conclusions and recommendations contained in this report are based upon applicable standards of our practice in this geographic area at the time this report was prepared. No other representation or warranty is express or implied.

We relied on project information given to us or assumed by us based on similar projects in the East Tennessee area to develop our conclusions and recommendations. If project information described in this report is not accurate, or if it changes during project development, we should be notified of the changes so that we can modify our recommendations based on this additional information, if appropriate.

Our conclusions and recommendations are based on limited data from a field exploration program. Subsurface conditions can vary widely between explored areas. Some variations may not become evident until construction.

If conditions are encountered which appear different than those described in our report, we should be notified.

This report should not be construed to represent subsurface conditions for the entire site.

Unless specifically noted otherwise, our field exploration program did not include an assessment of regulatory compliance, environmental conditions or pollutants or presence of any biological materials (mold, fungi, bacteria).

If there is a concern about these items, other studies should be performed. S&ME can provide a proposal and perform these services, if requested.

S&ME should be retained to review the final plans and specifications to check that earthwork, foundation, and other recommendations are properly interpreted and implemented. For additional information regarding the use and limitations of this report, please read the Important Information about your Geotechnical Engineering Report document located at the end of this report.

Appendices

Appendix I

Site Location Plans

Boring Location Plans

Geologic Maps

SCALE:

DATE:

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

FSR 45 - LITTLE GASSAWAY ROAD

CONASAUGA, TENNESSEE

SITE LOCATION PLAN – LITTLE GASSAWAY BORINGS

DRAWING FOR ILLUSTRATION PURPOSES ONLY

SOURCE: USGS TOPOGRAPHICAL MAP, PARKSVILLE TN 2022

Master Pin 196 Mile Post 0.31

Master Pin 194 Mile Post 0.251

Master Pin 210 Mile Post 2.3

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

FSR 67 – SINA BRANCH ROAD

CONASAUGA, TENNESSEE

SITE LOCATION PLAN – SINA BRANCH BORINGS

DRAWING FOR ILLUSTRATION PURPOSES ONLY

SOURCE: USGS TOPOGRAPHICAL MAP, DUCKTOWN TN 2022

Master Pin 026 Mile Post 6.55

Mile Post 030 Mile Post 6.825

Master Pin 045 Mile Post 7.795

Master Pin 053 Mile Post 9.024

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PINS 196 AND 194

MILE POSTS 0.251, 0.31

LG-01

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

FSR 45 - LITTLE GASSAWAY ROAD

CONASAUGA, TENNESSEE

LG-02

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PIN 210

MILE POST 2.3

LG-03

LG-04

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

FSR 45 - LITTLE GASSAWAY ROAD

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PIN 026

MILE POST 6.55

SB-01

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

FSR 67 – SINA BRANCH ROAD

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PIN 030

MILE POST 6.825

SB-02

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PIN 045

MILE POST 7.795

SB-03

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

PROJECT NUMBER

FIGURE NO.

NOT TO SCALE

10/17/2024

23810282

BORING LOCATION PLAN – MASTER PIN 053

MILE POST 9.024

SB-04

NOTES:

IMAGERY COURTESY OF WSP.

DRAWING FOR ILLUSTRATION PURPOSES ONLY

LEGEND: APPROXIMATE BORING LOCATION

Appendix II

Soil Log Legend

Rock Core Log Legend

Boring Logs

Core Photographs

Descriptive Order of Soil Strata: Geologic Disposition (i.e., Fill, Colluvium, Alluvium, etc.), ASTM Group Name (ASTM Group Symbol), quantified/qualified soil constituents, misc. constituents, consistency/density, color, organic description, moisture. ASTM group classifications is determined per ASTM D2487 where lab testing has been performed and ASTM D2488 where lab testing has not been performed.

SHELBY TUBE (ST) samples are obtained by hydraulically pushing a thin-walled tube (typically 3-inches in diameter) to obtain a relatively undisturbed sample for testing of fine-grained soils to determine engineering properties such as strength, compressibility, permeability, and density. Shelby tubes are sampled in general accordance with ASTM D1587 (AASHTO T207).

The STANDARD PENETRATION TEST (SPT) as defined by ASTM D1586 (or AASHTO T206) is a method to obtain a disturbed soil sample for examination and testing and to obtain relative density and consistency information. A standard 1.4-inch I.D./2-inch O.D. split-barrel sampler is driven three 6-inch increments with a 140 lb. hammer freely falling 30 inches. The hammer can either be of a trip, free-fall design, or actuated by a rope and cathead. The SPT N Value is determined by adding the number of blows from the 2nd and 3rd 6-inch increments. A normalized blowcount (N60) may be determined by the following equation: N60 = [ Rig Energy Ratio (%) / 60 ] * N.

SOIL PROPERTY SYMBOLS

N - Standard Penetration, bpf

NMC - Natural Moisture Content, %

F - Fines Content, %

LL - Liquid Limit, %

PL - Plastic Limit, %

PI - Plasticity Index, %

PPV - Pocket Penetrometer Value, tsf

Qu - Unconfined Compressive Strength gd - Dry Unit Weight, pcf

ASTM GROUP NAME (SYMBOL) AND GRAPHIC

FINE-GRAINED SOIL

(Relative Consistency)

N PPV

Very Soft < 2 bpf < 0.25 tsf

Soft 2 - 4 bpf > 0.25 - 0.5 tsf

Firm 5 - 8 bpf > 0.5 - 1.0 tsf

Stiff 9 - 15 bpf > 1.0 - 2.0 tsf

Very Stiff 16 - 30 bpf > 2.0 - 4.0 tsf

Hard > 30 bpf > 4.0 tsf

COARSE-GRAINED SOIL

(Relative Density)

N

Very Loose < 5 bpf

Loose 5 - 10 bpf

Medium Dense 11 - 30 bpf

Dense 31 - 50 bpf

Very Dense > 50 bpf

MINOR CONSTITUENTS

(% By Weight)

Percentage

Trace 0% - 10%

Little 11% - 20%

Some 21% - 35%

“And” > 36%

ORGANIC CONTENT OF SOIL

(Determined by ASTM D2974 or AASHTO T267)

Classification Percentage

With Organic Matter 4% - 15%

Organic Soil 16% - 30%

Peat > 30%

MOISTURE CONDITION

Dry Absense of moisture, dusty, dry to touch

Moist Damp but no visible water

Wet Visible free water, usually soil is below water table

Groundwater observation made anytime during the drilling process. Depending on time of reading and drilling methodologies, this value may be influenced by the drilling process.

Groundwater measurement soon after the drilling processes are complete, and the borehole is at final depth. Drilling fluids, if introduced during drilling, may influence this measurement.

Groundwater measurements made in a borehole hours to days after drilling is complete. Depending on subsurface conditions, elapsed time, drilling process, etc. this observation may reflect a stabilized level.

At Time of Drilling (ATD)

End of Drilling

After Drilling

FHWA NHI-16-072, Geotechnical Engineering Circular No. 5 “Geotechnical Site Characterization” ASTM Specifications D2487 and D2488 DOT Specifications & Design Manuals from NC, SC, OH, MI, IN, PA, VA.

REFERENCES:

(GM)

CLAYEY GRAVE

(GC)

CLAYEY GRAVE

WITH SILT (GC-GM

SPT

ST

ROCK QUALITY

Percent

>90–100

>75–90

>50–75

>25–50

0–25

Quality

Excellent

Good

Fair

Poor

Very Poor

L = 10” (254mm)

L = 0

HIGHLY

WEATHERED

DOES NOT MEET

SOUNDNESS

REQUIREMENT

L = 0

CENTERLINE

PIECES <4”

(100mm) & HIGHLY

WEATHERED

L = 7.5” (190.5mm)

L = 8” (203mm)

L = 0

NO

REC.

CORE RUN OR INTERNAL TOTAL LENGTH = 4’ (1220mm)

MECHANICAL

BREAK DUE TO

DRILLING PROCESS

LEGEND

SOUND

ROCK

UNSOUND

ROCK

Unfractured >10 ft.

Intact 10 ft. – 3 ft.

Slightly Fractured 3 ft. – 1 ft.

Moderately Fractured 12 in. – 4 in.

Fractured 4 in. – 2 in.

Highly Fractured < 2 in.

Extremely Strong Rock

Specimen can only be chipped with firm blows from the hammer end of a geological hammer.

> 36,250

Very Strong Rock

Specimen requires many firm blows from the hammer end of a geological hammer to fracture.

36,250 – 14,500

Strong Rock Specimen requires more than one firm blow of the point of a geological hammer to fracture.

14,500…