mt-a0300461_WarmanLoopRoad_RevisedFinalGeotechnicalReport.pdf

FINAL GEOTECHNICAL REPORT

MT BIGHORN 46(1)

Warman Loop Road

IDIQ Contract No. DTFH70-15-D-00007 Task Order No. 69056720F000015

Modification No. P00001 WFLHD Geotechnical Report 20-20

SK Geotechnical Project Number 19-3865G

Submitted by

2511 Holman Avenue P. O. Box 80190

Billings, Montana 59108-0910

Prepared for

Robert Peccia & Associates P. O. Box 5653

Helena, Montana 59604-5653

February 5, 2021

February 5, 2021 WFLHD Geotechnical Report 20-20 SK Geotechnical Project Number 19-3865G R1

Mr. Brad Thompson, PE Robert Peccia & Associates P. O. Box 5653 Helena, Montana 59604-5653 Via Email: brad@rpa-hln.com

Dear Mr. Thompson:

Re: Final Geotechnical Report, MT BIGHORN 46(1), Warman Loop Road, IDIQ Contract No.

DTFH70-15-D-00007, Task Order No. 69056720F000015, Modification No. P00001

The Final Geotechnical Report for the above-referenced project has been completed. This report presents the findings of our geotechnical evaluation for the Warman Loop Road project.

Introduction

Background. The Western Federal Lands Highway Division (WFLHD) is planning to improve Warman Loop Road, north of Fort Smith, Montana. SK Geotechnical was originally tasked to perform a pavement reconnaissance and prepare a preliminary geotechnical report for the project. The results of this work were submitted in our Preliminary Geotechnical Pavement Reconnaissance Report dated February 28, 2020.

For the current phase of the project, SK Geotechnical was tasked to develop and perform the final site investigation based off our preliminary work, develop a materials testing plan for the recovered samples to be performed jointly by SK Geotechnical and WFLHD's Vancouver, Washington office, analyze the field and laboratory data, and prepare a geotechnical evaluation report presenting the results of the field investigation and providing geotechnical recommendations for the project.

Project Description. The anticipated project is to either rehabilitate or reconstruct the existing pavement structure along the 4-mile long portion of Warman Loop Road running adjacent to Montana Highway MT 313. The Warman Loop Road project begins at its northeastern intersection with Montana Highway MT 313 at Station 10+31.55 and terminates at its southwestern intersection with MT 313 near Station 227+48.61. It is our understanding the existing asphalt concrete pavement was a cold mix that was placed sometime in the early 1990s, and is therefore about 30 years old. This section of road serves to allow outdoor recreationalists access to the Three Mile Access boat launch along the Bighorn River. According to the Montana Federal Lands Access Program (FLAP) Application submitted for the project, the road is also used by school district buses, law enforcement, and emergency first responders. Based on the Statement of Work, the project design for the roadway includes the following:

Rehabilitate or reconstruct the existing pavement structure to provide a new asphalt concrete pavement (ACP) final surface, 2511 Holman Avenue P. O. Box 80190

Billings, Montana 59108-0190 p: 406.652.3930; f: 406.652.3944 www.skgeotechnical.com

Robert Peccia & Associates February 5, 2021 Project 19-3865G Page 2

Replace the existing ACP surface on the Bighorn Canal Bridge and protecting the bridge deck to extend the decking life, Hydraulic sizing of culverts, replacing the existing culverts, and/or repairing existing culverts, Permanent traffic control devices including signage and striping, Guardrail installation, if needed, and

Staging and temporary traffic control to complete the work.

Scope of Work. Our scope of work is outlined in the Modification No. P00001 statement of work for MT BIGHORN 46(1), Warman Loop Road project. The purpose of this evaluation was to assist FHWA, Robert Peccia and Associates (RPA) and the selected contractor in evaluating existing pavement and subsurface soil conditions along the project, as well as provide geotechnical recommendations related to preparing plans and specifications for the project.

Results

General Site Topography and Geology. As can be seen on the attached partial Topographic Sketch, the beginning of the Warman Loop Road project is located at its eastern extent where it intersects MT 313 at Station 10+31.55. The project extends about 3 1/4 miles west before turning south and eventually reconnects to MT 313 at Station 227+48.61. We wish to point out that while the Statement of Work characterized Warman Loop Road as a 4-mile project, we observed the road is generally 4.2 miles long from start to finish.

A portion of the Geologic Map of the Lodge Grass 30' by 60' Quadrangle, Montana, Robert N. Bergatino, 2007, is attached. The map indicates the Warman Loop Road project is situated primarily in alluvial terrace deposits (Qat) associated with the Bighorn River and likely underlain by Thermopolis Shale/Fall River Sandstone (Kt), and Mowry Shale Formations (Km).

Drilling and Sampling. Seventeen subgrade borings (SB20-01 through SB20-17) were performed along the existing present traveled way (PTW) of Warman Loop Road. Subgrade Boring SB20-08 was performed to a depth of 10 1/2 feet for an existing fill slope, subgrade and culvert Borings SBC20-03 and SBC20-16 were performed to a depth of 15 1/2 feet near existing culvert crossings, while all other borings were performed to a depth of 5 1/2 feet. Photographs of the staked boring locations are attached and provide good visual representation of the alignment. Additional project photographs are available upon request.

The test borings were performed on the dates indicated on the boring logs and with a truck-mounted drilling rig by SK Geotechnical Corporation. Sampling for the borings was conducted in general accordance with ASTM D1586, "Penetration Test and Split-Barrel Sampling of Soils." Using this method, we advanced the borehole with a hollow-stem auger to the desired test depth. Then a 140-pound hammer falling 30 inches drove a standard 2-inch OD, split-barrel sampler a total penetration of 1 1/2 feet below the tip of the hollow-stem auger, which is referred to as a Standard Penetration Test (SPT). The SPT and blows for each 6-inch increment of penetration were recorded on the logs and are an index of soil strength characteristics. Shelby tube, asphalt, base, and bulk subgrade samples were collected from

Project 19-3865G Page 3 the borings. N-values representing the blow count total for the last foot of penetration are graphically illustrated on the boring logs. Photographs of the SPT samples are attached.

Existing Pavement Conditions. The condition of the existing pavement was observed and the results are presented in our Pavement Reconnaissance Report dated February 28, 2020. In general, we judged the existing pavement to be in poor to fair condition across the length of the project, with numerous types of pavement distress and fatigue cracking. Very poor pavement conditions were observed near the beginning and end of the project.

Our pavement condition observations are summarized in Table 1 following this page. As can be seen, pavement distress was rated as low, moderate, or severe as well as the corresponding type of distress.

These extents were recorded using a digital measuring instrument by Microdynamics, a DOT-Z1 PRO, however, the extents were not surveyed and tied into the project stationing. The extents should therefore be considered approximate.

Existing Pavement Conditions. Borings SB20-01 through SB20-17 performed in Warman Loop Road encountered approximately 2 to 8 1/4 inches of existing cold mix surfacing (CMS) underlain by 3 to 12 1/2 inches of crushed base course (CBC). Table 2 following Table 1 shows a summary of the pavement section and anticipated subgrade encountered at each boring. The existing CBC was judged to be mostly rounded and of moderate quality. Notably thin pavement sections were observed at Boring SB20-05 and

SB20-09.

Below the pavement section, the borings encountered a fairly similar subgrade generally consisting of lean clays, lean to fat clays, and fat clays to the termination depths of the borings ranging from 5 1/2 to 15 1/2 feet. Where the embankment had been raised above existing grade in some locations, such as Borings SBC20-03, SB20-05, SB20-06, and SB20-09, up to 1 1/2 feet of clayey gravel with sand fill was observed between the existing pavement section and the native subgrade. In Boring SB20-08, poorly graded gravel with silt and sand alluvium was also observed from 8 to 10 1/2 feet.

N-values in the fine-grained soils ranged from weight of hammer (WH) to 10 blows per foot (BPF), indicating the fine-grained soils were generally very soft to stiff. N-values in the coarse-grained soils ranged from 4 to 50 BPF, indicating the coarse-grained soils were very loose to dense.

Groundwater. Groundwater was not encountered in any of the borings to depths ranging from 5 to 15 feet at the time of the fieldwork. However, high moisture contents were recorded in the SPT samples, and some standing water was observed along the road near Station 86+93. Also, visible moisture was observed in some SPT samples at the depths noted on the Log of Boring sheets. The close proximity of the roadway to the Bighorn Canal will also influence moisture levels and groundwater in underlying soils along the eastern portion of Warman Loop Road. Other fluctuations in the groundwater levels can occur due to rainfall, snow melt, run-off, flooding, irrigation, and many other seasonal factors not evident during the drilling. These factors can create soft, wet subgrades that could be encountered during construction.

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Table 1. Pavement Distress Type and Approximate Extent

Approximate Stationa

Length (ft)

Width (ft)

Lane Pavement Distress Rating

Low Moderate Severe

12+64 35 10 LT 1 2

18+45 30 8 CL 5 1

20+56 90 9 RT 2 1

23+20 10 9 LT 2 1

26+37 55 8 CL 3 1, 2

29+01 50 9 LT 5 1

33+23 125 12 RT 1

37+98 60 9 RT 1, 3

46+96 40 20 BOTH 3 2, 5 1

47+36 60 15 RT 2 1

49+60 100 9 RT 2, 3 1

51+18 45 9 RT 1, 3

56+46 160 12 LT 4

68+61 30 8 CL 3

81+28 20 12 RT 1

81+81 30 9 LT 1, 3

83+92 100 15 LT 4 1, 3

86+56 80 20 BOTH 4

91+31 10 9 LT 3 1

92+90 75 20 BOTH 1, 3

95+54 15 20 BOTH 3 1

96+59 50 20 BOTH 4

98+18 75 9 RT 3 1

140+42 60 20 BOTH 1, 3

155+73 30 9 RT 1, 3

178+96 80 9 LT 3 1

182+66 32 9 RT 3 1

189+52 30 9 LT 3 1

194+27 10 20 BOTH 1, 3

195+86 10 15 RT 1, 5

198+50 210 15 RT 2, 5 1, 3

206+94 36 8 CL 2 1, 3

207+47 50 15 LT 1, 3

212+22 125 20 BOTH 1, 2, 3

216+98 40 20 BOTH 2

219+33 70 20 BOTH 5 1, 2

220+67 120 9 LT 1, 3

Total Length 440' 893' 915' a Location and extent of pavement distress estimated, not surveyed, and should therefore be considered approximate.

1. Fatigue Cracking 2. Potholes 3. Patches 4. Poor Drainage 5. Wide to Very Wide Cracks

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Table 2. Existing PTW Pavement and Anticipated Subgrade Conditions along Warman Loop Road

Boring SB20-01 SB20-02 SBC20-03 SB20-04 SB20-05 SB20-06 SB20-07 SB20-08 SB20-09

Date Drilled 7/6/2020 7/6/2020 7/7/2020 7/6/2020 7/7/2020 7/7/2020 7/7/2020 7/7/2020 7/8/2020

Station, Offset 12+31, 3'L 22+99, 5'R 36+18, 6'L 49+30, 5'R 62+26, 5'L 75+35, 5'R 86+93, 5'L 95+56, 4'R 113+58, 3'L

Existing Cold Mix Surfacing

3 1/2" 4 3/4" 6 3/4" 5 3/4" 3 3/4" 5 3/4" 6 1/4" 5 1/2" 3 1/4"

Existing Crushed Base Course

8 3/4" 12 1/4" 11 1/4" 11 3/4" 3" 4 3/4" 11 3/4" 12 1/2" 3 3/4"

Total Thickness 12 1/4" 17" 18" 17 1/2" 6 3/4" 10 1/2" 18" 18" 7"

Subgrade(1)

Description Lean Clay with

Sand Lean Clay with

Sand

Fill: Clayey Gravel with

Sand/Lean to Fat Clay

Lean Clay with Sand

Fill: Clayey Gravel with

Sand/Fat Clay with Sand

Fill: Clayey Gravel with

Sand/Fat Clay with Sand

Lean to Fat Clay

Lean Clay Fat Clay

ASTM Class CL CL GC/CL-CH CL GC/CH GC/ CH CL-CH CL CH

N-Values 7, 2 4, 5 14/8, 3 10, 7 6/3 50/9 8, 4 3, 4 8, 4

Consistency Firm to Soft Soft to Firm Medium

Dense/Firm to Soft

Stiff to Firm Loose/Soft Dense/Stiff Firm to Soft Soft Soft to Firm

Moisture Content 23.9, 25.7 20.3, 23.9 18.4, 27.5 16.4 19.3, 22.7 19.3, 25.8 21.8 21.3, 29.2 20.8, 27.2

Optimum Moisture Content (Approximate)

15.9 15.9 16.0 16.0 16.7 16.7 21.0 21.0 25.9

Groundwater Depth N/E N/E N/E N/E N/E N/E N/E N/E N/E

Risk of Subgrade Failure Due to Heavy Equipment

High High Moderate Moderate High Moderate High High High

(1) Anticipated subgrade that will be present beneath the proposed pavement section.

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Table 2. Existing PTW Pavement and Anticipated Subgrade Conditions along Warman Loop Road

(1) Anticipated subgrade that will be present beneath the proposed pavement section.

Boring SB20-10 SB20-11 SB20-12 SB20-13 SB20-14 SB20-15 SBC20-16 SB20-17

Average Date Drilled 7/8/2020 7/8/2020 7/8/2020 7/8/2020 7/8/2020 7/8/2020 7/9/2020 7/9/2020

Station, Offset 125+95, 5'R 139+98, 5'L 153+03, 7'R 166+82, 5'L 179+33, 6'R 192+65, 7'L 220+12, 3'R 224+08, 5'L

Existing Cold Mix Surfacing

6 1/2" 5 1/2" 4" 6 1/4" 4 1/2" 8 1/4" 2" 3 1/4" 5"

Existing Crushed Base Course

6 1/4" 5 1/4" 7 3/4" 9 1/2" 7 3/4" 4 1/2" 10 3/4" 14 3/4" 8 1/2"

Total Thickness 12 3/4" 10 3/4" 11 3/4" 15 3/4" 12 1/4" 12 3/4" 12 3/4" 18" 13 1/2"

Subgrade(1)

Description Fat Clay Lean Clay with Sand

Lean to Fat Clay

Fat Clay with Sand

Fat Clay with Sand

Lean Clay Lean to Fat

Clay Lean Clay with Sand

ASTM Class CH CL CL-CH CH CH CL CL-CH CL

N-Values 6, 4 8, 3 10, 5 8, 6 8, 3 8, 2 6, 10 6

Consistency Firm to Soft Firm to Soft Stiff to Firm Firm Firm to Soft Firm to Soft Firm to Stiff Firm

Moisture Content 20.5, 22.2 24.9 29.9 18.0, 29.1 27.5, 29.0 30.0 19.4, 30.4 21.7

Optimum Moisture Content (Approximate)

25.9 23.0 23.0 21.3 21.3 21.5 21.3 21.5

Groundwater Depth N/E N/E N/E N/E N/E N/E N/E N/E

Risk of Subgrade Failure Due to Heavy Equipment

High High Moderate High High High Moderate Moderate

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Laboratory Testing Program and Procedures

General. After completion of the borings, the samples were returned to our office for inventory before being sent to the WFLHD Vancouver laboratory for materials testing. The samples submitted included SPT, bulk subgrade, and Shelby tube samples. The existing asphalt and base course samples were kept at our laboratory in Billings, Montana, in the event that a cement treated base (CTB) mix design was desired after our pavement analysis. Table 3 below shows the test methods requested and performed by the WFLHD laboratory for the provided samples.

Table 3. Laboratory Test Methods

Test Method

Natural Moisture Content AASHTO T 255/T 265

Plasticity Index (Atterberg Limits) AASHTO T 89/T 90

Sieve Analysis AASHTO T 11/T 27

Moisture Density (Standard Proctor) AASHTO T 99

R-Value (300 PSI Exudation) WL1901

Consolidation Test AASHTO T 216/ASTM D2435

Corrosion Test AASHTO T 290

(1) Modified from standard AASHTO tests methods

Moisture Content Tests. Moisture content tests were performed on the SPT samples from the borings, as well as the Shelby tube, and bulk subgrade samples. The results of these tests are indicated on the attached Log of Boring Sheets and generally indicate the clay subgrade is moist to wet.

Base Course and Subgrade Classification and Proctor Tests. Classification tests consisting of full sieve and Atterberg limits were performed on the SPT, base course, bulk subgrade, and Shelby tube samples obtained from various borings at various depths. Tables 4 and 5 below provide summaries of the test results. Some samples of the subgrade were also selected for Proctor tests and the results are attached.

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Table 4. Summary of Base Course Samples Classification Tests

Boring Station, Offset

Depth (feet)

Atterberg Limits P200

ASTM

Classification

AASHTO

Classification

LL PL PI

SB20-01 12+31, 3'L 0.3 – 1 NP NP NP 8 GP-GM A-1-a

SB20-02 22+99, 5'R 0.4 – 1.4 17 16 1 10 GP-GM A-1-a

SBC20-03 36+18, 6'L 0.6 – 1.5 NP NP NP 7 GP-GM A-1-a

SB20-04 49+30, 5'R 0.5 – 1.5 NP NP NP 10 GP-GM A-1-a

SB20-05 62+26, 5'L 0.3 – 0.6 NP NP NP 11 GW-GM A-1-a

SB20-06 75+35, 5'R 0.5 – 0.9 NP NP NP 9 GP-GM A-1-a

SB20-07 86+93, 5'L 0.5 – 1.5 NP NP NP 13 GM A-1-a

SB20-08 95+56, 4'R 0.5 – 1.5 NP NP NP 9 GP-GM A-1-a

SB20-09 113+58, 3'L 0.3 – 0.6 22 14 8 12 GP-GC A-2-4

SB20-10 125+95, 5'R 0.5 – 1.1 NP NP NP 15 GM A-1-a

SB20-11 139+98, 5'L 0.5 – 0.9 19 15 4 9 GP-GC A-1-a

SB20-12 153+03, 7'R 0.3 – 1.0 NP NP NP 10 GP-GM A-1-a

SB20-13 166+82, 5'L 0.5 – 1.3 NP NP NP 10 GP-GM A-1-a

SB20-14 179+33, 6'R 0.4 – 1.0 20 15 5 12 GP-GC A-1-a

SB20-15 192+65, 7'L 0.7 – 1.0 21 15 6 17 GC-GM A-1-b

SBC20-16 220+12, 3'R 0.2 – 1.1 NP NP NP 8 GP-GM A-1-a

SB20-17 224+08, 5'L 0.3 – 1.5 NP NP NP 12 GP-GM A-1-a

Table 5. Summary of Subgrade Classification Tests

Borings Depth (feet)

Atterberg Limits P200

ASTM

Classification

AASHTO

Classification LL PL PI

SB20-01/SB20-02 1 – 4 37 15 22 82.5 CL A-6

SBC20-03 5 ½ – 6 ½ 43 19 24 87.0 CL-CH A-7-6

SBC20-03 11 ½ – 13 48 16 32 94.7 CL-CH A-7-6

SB20-05/SB20-06 2 ½ – 4 53 17 36 80.2 CH A-7-6

SB20-09/SB20-10 1 – 4 59 17 42 88.8 CH A-7-6

SB20-13/SB20-14 1 ½ – 4 58 18 40 83.8 CH A-7-6

SBC20-16 5 ½ – 6 ½ 72 20 52 89.1 CH A-7-6

SBC20-16 1 ½ – 8 47 18 29 85.6 CL-CH A-7-6

Based on the subgrade test results, one of the samples classified as lean clay with sand (CL), three as lean to fat clay (CL-CH), and four as fat clay and fat clay with sand (CH).

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Consolidation Test. Consolidation tests were performed on the two Shelby tube samples collected from borings SBC20-03 and SBC20-16. These test results are attached. Recommendations related to culvert foundation fill are provided later in this report.

R-Value Test. R-value tests were performed on bulk subgrade samples collected from various borings.

The results of these R-value tests are summarized in Table 6 below.

Table 6. Summary of R-Value Tests

Boring Depth (feet)

R-Value

SB20-01/SB20-02 1 – 4 16

SB20-05/SB20-06 2½ – 4 6

SB20-09/SB20-10 1 – 4 6

SB20-13/SB20-14 1½ – 4 7

SBC20-16 1½ – 8 9

Corrosion Test. Corrosion tests were performed on two composite subgrade samples collected from Borings SB20-05/SB20-06 and SB20-13/SB20-14. These test results were provided to RPA for culvert material selection.

Pavement Analysis and Recommendations

Pavement Analysis. Traffic data for the project was not provided for our pavement analysis. However, as indicated in our Geotechnical Pavement Reconnaissance Report dated February 28, 2020, minimal traffic was observed on Warman Loop Road. The traffic that was observed was almost entirely light automobile and pickup trucks. We therefore are assuming 50,000 ESALs over a period of 20 years for design. The Federal Lands Highway Project Development and Design Manual (PDDM) recommends this value as a minimum ESAL value for low volume roads, and in our opinion it is appropriate for Warman Loop Road.

Pavement Analysis. Alternative pavement sections were analyzed using an Excel spreadsheet based on the 1993 AASHTO Guide for Design of Pavement Structures. The following parameters were used for design.

Change in serviceability of 1.7, Standard deviation of 0.49, An inherent reliability of 75 percent, A design life of 20 years.

Laboratory tests were performed on five subgrade samples to determine R-values for each. As previously indicated in Table 6, these values ranged from 6 to 16 for the bulk subgrade samples. Using these values, an R-value analysis was performed to plot all R-values on a percent greater than curve. At the

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85th percentile, a value of 6.4 was obtained. However, when lean clay and fat clay subgrades are prevalent, the Montana Department of Transportation (MDT) assumes an R-value of 5 for design. Based on our experience, it is our opinion this lower R-value is more representative of the lean clay and fat clay subgrades in this area. An R-value of 5 equates to a Modulus of Subgrade Reaction (MR) equal to 3,250 pounds per square inch (psi), which we used for our analysis to determine alternative pavement sections.

We also measured the existing CMS and CBC thicknesses at each of the boring locations during our fieldwork. These thicknesses were summarized above in Table 2 and resulted in the following average existing pavement section.

Existing CMS 5"

Existing CBC 8½"

Total Thickness 13½"

This average section was used in our pavement design for Full Depth Recycling (FDR) rehabilitation and overlay pavement preservation.

Pavement Design. Based on a design MR of 3,250 psi and ESAL's of 50,000, the AASHTO pavement design guide indicates a required structural number (SN) of 2.66 is needed for the project. We developed four typical sections: one for pavement rehabilitation using FDR, one for pavement preservation using an overlay, and two for total reconstruction. Table 7 following this page shows our four recommended pavement sections.

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Table 7. Recommended Pavement Sections

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Pavement Rehabilitation. Typical Section 1 is full-depth recycling (FDR) of the existing CMS and CBC to a depth of 9 inches across the entire project. The pulverized material would then be moisture conditioned and recompacted to specifications. Hot asphalt concrete pavement (HACP) of 3 inches should then be placed over the compacted FDR. This approach would result in a minor 2- to 3-inch raise in grade and would keep construction equipment working on top of the existing materials rather than directly on the soft, wet clay subgrade. FDR reuses existing materials as well as provides new surfacing.

In our opinion, FDR rehabilitation is a good approach for the project and will provide better long-term performance than pavement preservation with an overlay. We recognize that the 9-inch FDR will extend through the pavement section and into the subgrade in isolated areas, such as Borings SB20-05 and

SB20-09.

We recommend assuming the low, moderate, and severe extents identified in the previous Table 1 will require digouts prior to the FDR. These approximate stations are listed below and have been included in the plan sheets.

Station 12+64 to 12+99 Station 18+45 to 18+75 Station 20+56 to 21+46 Station 23+20 to 23+30 Station 26+37 to 26+92 Station 29+01 to 29+51 Station 33+23 to 34+48 Station 37+98 to 38+58 Station 46+96 to 47+36 Station 47+36 to 47+96 Station 49+60 to 50+60 Station 51+18 to 51+63 Station 56+46 to 58+06 Station 68+61 to 68+91 Station 81+28 to 81+48 Station 81+81 to 82+11 Station 83+92 to 84+92 Station 86+56 to 87+36

Station 91+31 to 91+41 Station 91+90 to 93+65 Station 95+54 to 95+69 Station 96+59 to 97+09 Station 98+18 to 98+93 Station 140+42 to 141+02 Station 155+73 to 156+03 Station 178+96 to 179+76 Station 182+66 to 182+98 Station 189+52 to 189+82 Station 194+27 to 194+37 Station 195+86 to 195+96 Station 198+50 to 200+60 Station 206+94 to 207+30 Station 207+47 to 207+97 Station 212+22 to 213+47 Station 216+98 to 217+38 Station 219+33 to 220+03 Station 220+67 to 221+87

We estimate 37 locations resulting in approximately 2250 feet of alignment will require digouts. As previously indicated, these extents were not surveyed and therefore should be considered approximate.

This represents approximately 10 percent of the project, but 15 percent is recommended for budgeting to provide a contingency. Digouts for FDR rehabilitation are discussed in more detail later in this report.

Pavement Preservation. Typical Section 2 is for pavement preservation and basically consists of a 2-inch overlay. Prior to the overlay, however, the distressed pavement extents will need to be repaired and cracks sealed. Digouts are recommended for the moderate and severe extents indicated in previous

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Table 1. These approximate stations of digout extents for pavement preservation are listed below.

Station 12+64 to 12+99 Station 18+45 to 18+75 Station 20+56 to 21+46 Station 23+20 to 23+30 Station 26+37 to 26+92 Station 29+01 to 29+51 Station 33+23 to 34+48 Station 37+98 to 38+58 Station 46+96 to 47+36 Station 47+36 to 47+96 Station 49+60 to 50+60 Station 51+18 to 51+63 Station 68+61 to 68+91 Station 81+81 to 82+11 Station 83+92 to 84+92

Station 91+31 to 91+41 Station 91+90 to 93+65 Station 95+54 to 95+69 Station 98+18 to 98+93 Station 140+42 to 141+02 Station 155+73 to 156+03 Station 178+96 to 179+76 Station 182+66 to 182+98 Station 189+52 to 189+82 Station 194+27 to 194+37 Station 198+50 to 200+60 Station 206+94 to 207+30 Station 207+47 to 207+97 Station 212+22 to 213+47 Station 216+98 to 217+38 Station 219+33 to 220+03

For the moderate and severe extents, we estimate 31 locations resulting in approximately 1800 feet of the alignment will require digouts. This represents approximately 8 percent of the project, but 13 percent is recommended for budgeting and to provide a contingency. Digouts for pavement preservation are discussed in more detail later in this report.

A major disadvantage of pavement preservation is the majority of the project will only receive an overlay.

Although the existing cracks will be crack sealed prior to the overlay, we anticipate almost all of the cracks will reflect through the new HACP overlay within 2 to 4 years, and it will look similar to its current appearance. The overlay will provide more structural support of traffic, however.

Total Reconstruction. Typical Sections 3 and 4 are CBC and subbase sections for total reconstruction, respectively. Total reconstruction is the most expensive approach, although some of the existing pavement materials can likely be salvaged and reused as subbase. Total reconstruction will also require cutting to subgrade elevations, which will allow heavy rubber-tired equipment on the subgrade.

Repetitive traffic loads due to heavy equipment can create more unstable subgrades, increasing the extent of digouts and the risk of delays and change orders. When considering the suitability of rehabilitation and preservation of the existing pavement, it is our opinion total reconstruction is not warranted. These sections can be used for new approaches and or other extents as determined by the Project Manager.

Digouts for Unstable Subgrades. As shown in Table 2, several borings encountered soft subgrades across the project. All 17 borings are noted as having a medium to high risk of subgrade failure due to heavy rubber-tired construction traffic. The actual extent of the unstable subgrade is dependent on numerous variables, such as thin existing pavement sections, excessive moisture, and heavy construction equipment on the subgrade. If construction occurs during spring thaw, heavy snow melt, or rainy weather, then more subgrade areas are likely to be unstable. Less unstable areas are expected during fair to good summer and fall construction.

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We recommend providing the following stabilized pavement section for digout and unstable subgrade extents for the project.

Plant Mix Surfacing 3 inches Crushed base course, Type C or D 18 inches Geogrid, Stabilization Yes Separation-stabilization nonwoven geotextile, Class 1, Type C Yes

Stabilization geogrid should meet the requirements of Table 714-4 and nonwoven separation fabric should meet the requirements of Table 714-1, Class 1, Type C according to Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects, FP-14.

The actual extent of stabilized pavement sections for digouts should be determined by the Project Manager during construction. As previously discussed, digout extents are indicated in previous Table 1, and we further recommend providing a contingency of 5 percent.

For pavement rehabilitation, digouts for low, moderate, and severe distress extents will be performed prior to the 9-inch FDR. FDR will then pulverize and blend the existing asphalt and base course, which should then be moisture conditioned and recompacted. To further identify unstable subgrades, we recommend proof rolling the compacted recycled base course with a loaded tandem-axle dump truck (replicating paving equipment). Areas where deflections of 1/4-inch or more occur should be considered unstable, and additional digouts should be performed to provide the thicker digout section.

For pavement preservation, digouts for moderate and severe distress extents will be performed prior to placing the overlay. This construction equipment and traffic may cause additional pavement distress, and a contingency of 5 percent is recommended. The Project Manager will need to determine the actual extent of digouts during construction.

Geotechnical Analysis and Recommendations

Culverts. Numerous culverts are present along the project. It is our understanding the culverts near Station 50+88, 81+65, 168+40, and 220+12 will be replaced. Typically, the new culvert size will match the existing. The exception to this is the undersized 48-inch culvert for Warman Creek. At this location, a 5-foot by 9-foot box culvert will replace the existing culvert.

We observed settlement of the backfill above all of the culverts along the project, which has caused dips in the existing pavement surface. For new or replaced culverts, we recommend subexcavating 2 feet below bottom-of-bedding elevation. We recommend replacing the excavated material with foundation fill wrapped in Class 1, Type C nonwoven fabric. Wrapping the foundation fill will help reduce the piping of fines from the surrounding subgrade if it is open-graded.

For existing culverts that will not be replaced, the exact cause of the settlement is unknown. Even so, we recommend the backfill above the culvert be subexcavated and replaced above the top of the culvert to the subgrade with roadway aggregate.

Project 19-3865G Page 15

Cut Slopes. Significant cut slopes were not observed along the project, other than minor ditch cuts for drainage. For any cut slopes, we recommend 1:3 (vertical:horizontal) slopes for maintenance, better establishment of vegetation, reduced erosion, and roadside safety.

Fill Slopes. In general, fill slopes were not observed along the project, with the exception of the fill slope near Boring SB20-08. At this location, we observed an 8- to 10-foot tall embankment with slopes that were slightly steeper than 1:1. We observed some slope creep along the southern side of Warman Loop Road, likely from poorly compacted utility backfill on an overly steep fill slope. For this fill slope, and any fill slopes along the project, we would recommend the fill slopes as shown in Table 8. below, Table 8. Fill Slope Recommendations

Fill Slope Description and Location

Existing Fill Slope (V:H)2

Anticipated Subsurface

Conditions on Fill Side of Roadway3

Fill Slope Recommendations

(V:H)2

Fill Slopes up to 10 feet.1 Near Station 95+56

Existing fill:

Slightly steeper than 1:1

Lean Clay/Sandy Lean Clay/Poorly Graded

Gravel 1:3 fill slopes

1. Slope height measured vertical from ditch line to crest.

2. Slope inclinations listed as Vertical:Horizontal (V:H).

3. Subsurface conditions listed are those observed in the existing fill and interpreted from subsurface investigation locations. The actual soil profile in the fill will be variable, and the description is intended to describe the predominant soil/rock observed for the cuts.

We anticipate most fill for the project will be imported due to minimal cuts planned along the project.

We recommend imported unclassified borrow consist of A-1, A-3, and/or A-2-4 soils as outlined in section 704.06 Unclassified Borrow FP-14.

Earthwork. Based on our borings, we anticipate lean clays, lean to fat clays, and fat clays will make up the majority of the subgrade along the project. Clays are generally moisture sensitive and may rut or pump excessively if they become wet or if they are subjected to heavy vehicle traffic. This can create difficulties for equipment traversing the subgrade and increase production time. We therefore recommend minimizing construction traffic over exposed subgrade, such as in digout locations.

General

The analyses and recommendations submitted in this report are based upon our observations of the alignment and the data obtained from the soil borings performed at the locations indicated on the attached sketches. Often, variations occur between exposed topography and borings, the nature and extent of which do not become evident until additional exploration or construction is conducted. A reevaluation of the recommendations in this report should be made after performing on-site observations during construction to note the characteristics of any variations. The variations may result in additional

PARTIAL TOPOGRAPHIC SKETCH

Warman Loop Road

East of Fort Smith, Montana

Drawn by: MBMG/SK Date 12/23/20

Project: 19-3865G

Scale: None FIGURE

Sheet 1 of 1 1

Reference: Mountain Pocket Creek Quadrangle, Big Horn County, Montana. 7.5-Minute Topo Map, U.S. Geological Survey, North American Datum of 1983 (NAD83)

North

Beginning of Project Station 10+31.55

End of Project Station 227+48.61

PARTIAL GEOLOGIC SKETCH

Warman Loop Road

East of Fort Smith, Montana

Drawn by: MBMG/SKGeo Date 12-23-20

Project: 19-3865G

Scale: NTS FIGURE

Sheet 1 of 1 1

Geologic Map of the Lodge Grass 30' x 60' Quadrangle, Montana Montana Bureau of Mines and Geology - S. Vuke, E. Wilde, D. Lopez, R. Bergantino, 2007

North

Belle Fourche Shale

End of Project Station 227+48.61

Beginning of Project Station 10+31.55

Alluvium Alluvial Terrace Deposit

Thermopolis Shale/Fall River Sandstone

Mowry Shale

5-4-3

1-1-1

SPT1

SPT2

COLD MIX SURFACING (CMS): Approximately 3½" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 8¾" thick.

LEAN CLAY with SAND (CL), firm to soft, dark gray to brown, moist to wet, medium to low plasticity, homogeneous. (Alluvium)

At a depth of approximately 5', visible moisture observed in SPT sample.

Unable to obtain second subgrade bag due to limited cuttings. Second bag sampled from Boring SB20-02.

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

2' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.3 1.0

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 50.99" (45.347496°)

LONGITUDE (DEGREES): W -107° 48' 10.86" (-107.803017°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

12+31, 3'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

Location determined by recreational GPS.NOTES:

BORING SB20-01

COMPANY:

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P J

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Z

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IN

T \G

IN

T

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R A

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S \F

H W

A

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B R

A R

Y .G

LB

ri nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/6/2020

S A

M P

LE

R

7/6/2020

STATION, OFFSET:

PLASTIC LIMIT

PROJECT: 19-3865G Warman Loop Road, Montana Bighorn

8-6-2

1-2-3

SPT3

SPT4

CMS: Approximately 4¾" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), medium dense, brown, moist, fine- to coarse-grained, angular to subangular, homogeneous.

Approximately 12¼" thick.

LEAN CLAY with SAND (CL), soft to firm, brown to gray, moist, low to medium plasticity, homogeneous. (Alluvium)

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

2' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.4 1.4

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 49.73" (45.347146°)

LONGITUDE (DEGREES): W -107° 48' 25.64" (-107.807122°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

22+99, 5'R

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-02

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

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IN

T

\L

IB

R A

R

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S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/6/2020

S A

M P

LE

R

7/6/2020

STATION, OFFSET:

7-13-7

3-4-4

1-1-2

WH-WH-WH

1-3-3

WH-WH-2

2-5-5

SPT7

SPT8

SPT9

TW1

SPT10

SPT11

SPT12

SPT13

CMS: Approximately 6¾" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), medium dense, light brown to dark brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 11¼" thick.

FILL: Clayey Gravel with Sand (GC), medium dense, dark brown, moist, fine- to coarse-grained, subangular to subrounded, low plasticity, homogeneous.

LEAN to FAT CLAY (CL-CH), very soft to stiff, dark brown to brown, moist to wet, medium to high plasticity, homogeneous. (Alluvium)

At depths of approximately 7½' and 12½', visible moisture observed in SPT samples.

End of hollow-stem auger at 14', SPT sample performed to 15½'.

Water not encountered with 14' of hollow-stem auger.

2' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.6

1.5

2.5

15.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 53.47" (45.348187°)

LONGITUDE (DEGREES): W -107° 48' 43.22" (-107.812006°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 15.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

3" OD Split Spoon Thin Wall

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

36+18, 6'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SBC20-03

COMPANY:

F ile

: Z :\G

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T

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IN

T \P

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1-

\3

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L.

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Z

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IN

T \G

IN

T

\L

IB

R A

R

IE

S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/7/2020

S A

M P

LE

R

7/7/2020

STATION, OFFSET:

10-10-5

2-3-4

SPT5

SPT6

CMS: Approximately 5¾" thick.

BASE COURSE: Poorly Graded Gravel with Clay and Sand (GP-GC), medium dense, brown, moist, fine- to coarse-grained, angular to subangular, low plasticity, homogeneous. Approximately 11¾" thick.

LEAN CLAY with SAND (CL), stiff to firm, brown, moist to wet, low plasticity, homogeneous. (Alluvium)

At a depth of approximately 5½', visible moisture observed in SPT sample.

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

1½' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5

1.5

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 54.01" (45.348335°)

LONGITUDE (DEGREES): W -107° 49' 1.07" (-107.816963°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

49+30, 5'R

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-04

COMPANY:

F ile

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T

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IN

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1-

\3

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IN

T \G

IN

T

\L

IB

R A

R

IE

S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/6/2020

S A

M P

LE

R

7/6/2020

STATION, OFFSET:

6-4-2

WH-1-2

SPT14

SPT15

CMS: Approximately 3¾" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), brown to dark brown, moist, fine- to coarse-grained, angular to subangular, homogeneous.

Approximately 3" thick.

FILL: Clayey Gravel with Sand (GC), loose, brown, moist, fine- to coarse-grained, subangular to subrounded, low plasticity, homogeneous.

FAT CLAY with SAND (CH), soft, brown, moist, high plasticity, 2" seam of silty clay at approximately 5 feet.

(Alluvium) Unable to obtain second subgrade sample due to limited cuttings. Second bag sampled from Boring SB20-06.

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

2½' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.3 0.6

2.5

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 52.76" (45.347988°)

LONGITUDE (DEGREES): W -107° 49' 18.52" (-107.821812°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

62+26, 5'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-05

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

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C

T S

\3

1-

\3

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L.

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IN

T \G

IN

T

\L

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R A

R

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S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/7/2020

S A

M P

LE

R

7/7/2020

STATION, OFFSET:

6-13-37

3-4-5

SPT16

SPT17

CMS: Approximately 5¾" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 4¾" thick.

FILL: Clayey Gravel with Sand (GC), dense, brown to dark gray, moist, fine- to coarse-grained, subangular to subrounded, low plasticity, homogeneous.

FAT CLAY with SAND (CH), stiff, dark gray, moist, high plasticity, homogeneous. (Alluvium) End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

2' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5 0.9

2.5

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 55.47" (45.348743°)

LONGITUDE (DEGREES): W -107° 49' 36.45" (-107.826791°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

75+35, 5'R

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-06

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

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C

T S

\3

1-

\3

-W F

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Z

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IN

T \G

IN

T

\L

IB

R A

R

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S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/7/2020

S A

M P

LE

R

7/7/2020

STATION, OFFSET:

6-6-4

2-2-2

SPT18

SPT19

CMS: Approximately 6¼" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), medium dense, brown, moist, fine- to coarse-grained, angular to subangular, homogeneous.

Approximately 11¾" thick.

LEAN to FAT CLAY (CL-CH), firm to soft, brown to dark gray, moist, medium to high plasticity, homogeneous.

(Alluvium)

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

1' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5

1.5

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 50.85" (45.347457°)

LONGITUDE (DEGREES): W -107° 49' 50.81" (-107.83078°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

86+93, 5'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-07

COMPANY:

F ile

: Z :\G

IN

T

\G

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T \P

R O

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C

T S

\3

1-

\3

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T \G

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T

\L

IB

R A

R

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S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/7/2020

S A

M P

LE

R

7/7/2020

STATION, OFFSET:

9-5-2

1-2-1

1-2-2

WH-2-3

7-14-15

SPT20

SPT21

SPT22

SPT23

SPT24

CMS: Approximately 5½" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), loose, brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 12½" thick.

LEAN CLAY (CL), soft, brown, moist, low to medium plasticity, homogeneous. (Alluvium)

SANDY LEAN CLAY (CL), firm, brown, moist, low plasticity, homogeneous. (Alluvium)

POORLY GRADED GRAVEL with SILT and SAND (GP-GM), medium dense, light brown to brown, moist, fine-to coarse-grained, subrounded, homogeneous. (Alluvium)

End of hollow-stem auger at 9', SPT sample performed to 10½'.

Water not encountered with 9' of hollow-stem auger.

6' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5

1.5

6.0

8.0

10.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 47.25" (45.346458°)

LONGITUDE (DEGREES): W -107° 50' 1.76" (-107.833821°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 10.5'

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

95+56, 4'R

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-08

COMPANY:

F ile

: Z :\G

IN

T

\G

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T \P

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C

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1-

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IN

T \G

IN

T

\L

IB

R A

R

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S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/7/2020

S A

M P

LE

R

7/7/2020

STATION, OFFSET:

1-2-2

SPT25

SPT26

CMS: Approximately 3¼" thick.

BASE COURSE: Poorly Graded Gravel with Clay and Sand (GP-GC), reddish brown to brown, moist, fine- to coarse-grained, angular to subangular, low plasticity, homogeneous. Approximately 3¾" thick.

FILL: Clayey Gravel with Sand (GC), brown, moist, fine- to coarse-grained, angular to subangular, low plasticity, homogeneous.

FAT CLAY (CH), firm to soft, brown, moist, high plasticity, homogeneous. (Alluvium) End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

1½' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.3 0.6 0.8

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 39.07" (45.344186°)

LONGITUDE (DEGREES): W -107° 50' 23.42" (-107.839838°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

113+58, 3'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-09

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

JE

C

T S

\3

1-

\3

-W F

L.

G

Z

:\G

IN

T \G

IN

T

\L

IB

R A

R

IE

S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/8/2020

S A

M P

LE

R

7/8/2020

STATION, OFFSET:

5-3-3

1-2-2

SPT27

SPT28

CMS: Approximately 6½" thick.

BASE COURSE: Poorly Graded Gravel with Clay and Sand (GP-GC), loose, brown, moist, fine- to coarse-grained, angular to subangular, low plasticity, homogeneous.

Approximately 6¼" thick.

FAT CLAY (CH), firm to soft, brown, moist, high plasticity, homogeneous. (Alluvium)

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

1½' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5 1.1

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 39.13" (45.344204°)

LONGITUDE (DEGREES): W -107° 50' 40.74" (-107.84465°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

LIQUID LIMIT

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

125+95, 5'R

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-10

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

JE

C

T S

\3

1-

\3

-W F

L.

G

Z

:\G

IN

T \G

IN

T

\L

IB

R A

R

IE

S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/8/2020

S A

M P

LE

R

7/8/2020

STATION, OFFSET:

6-5-3

2-2-1

SPT29

SPT30

CMS: Approximately 5½" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 5¼" thick.

LEAN CLAY with SAND (CL), firm to soft, brown, moist to wet, low plasticity, homogeneous. (Alluvium)

At a depth of approximately 5½', visible moisture observed in SPT sample.

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

1½' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.5 0.9

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 38.89" (45.344137°)

LONGITUDE (DEGREES): W -107° 51' 0.39" (-107.850108°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 5.5'

AFTER DRILLING

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

4.25" HSA

139+98, 5'L

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

NOTES:

BORING SB20-11

COMPANY:

F ile

: Z :\G

IN

T

\G

IN

T \P

R O

JE

C

T S

\3

1-

\3

-W F

L.

G

Z

:\G

IN

T \G

IN

T

\L

IB

R A

R

IE

S \F

H W

A

LI

B R

A R

Y nt ed

: 1 2/

/2

SK Geotech LOGGER: Brandon Western

Hot, Sunny

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

N/A

WEATHER:

Automatic

WATER CONTENT (%)

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/8/2020

S A

M P

LE

R

7/8/2020

STATION, OFFSET:

6-7-3

1-2-3

SPT31

SPT32

CMS: Approximately 4" thick.

BASE COURSE: Poorly Graded Gravel with Silt and Sand (GP-GM), brown, moist, fine- to coarse-grained, angular to subangular, homogeneous. Approximately 7¾" thick.

LEAN to FAT CLAY (CL-CH), stiff to firm, dark gray, moist, medium to high plasticity, homogeneous. (Alluvium) Decomposing odor in SPT sample 32, and in clay cuttings.

End of hollow-stem auger at 4', SPT sample performed to 5½'.

Water not encountered with 4' of hollow-stem auger.

2' to dry cave in.

Boring then backfilled, and road surface patched with cold mix asphalt.

0.3 1.0

5.5

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 45° 20' 39.03" (45.344175°)

LONGITUDE (DEGREES): W -107° 51' 18.66" (-107.855182°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH:…