Attachment 1 - FLH Soil Identification Guidelines_2017 December FINAL.pdf

Federal Lands Highway

Soil Description and Identification Guidelines

Drilling BPA RFQ # 69056720Q000012 Attachment 1

FLH Soil Description and Identification GuidelinesDecember 2017 i

CONTENTS

SECTION 1 – INTRODUCTION

1.1 REFERENCED PROCEDURES

1.2 BORING IDENTIFICATION

1.3 STRATIFICATION

1.4 ORDER OF DESCRIPTORS

SECTION 2 – SOIL IDENTIFICATION

2.1 COARSE-GRAINED SOILS – GRAVEL & SAND (<50% FINES)

2.2 FINE-GRAINED SOIL – SILT & CLAY (≥ 50% FINES)

2.2.1 INORGANIC FINE-GRAINED SOIL

2.2.2 ORGANIC FINE-GRAINED SOIL

2.3 PEAT

2.4 COBBLES AND BOULDERS

SECTION 3 – SOIL DESCRIPTORS

3.1 APPARENT DENSITY AND CONSISTENCY

3.2 COLOR

3.3 MOISTURE

3.4 PARTICLE SIZE AND ANGULARITY (COARSE-GRAINED SOIL)

3.5 PLASTICITY (FINE-GRAINED SOIL)

3.6 STRUCTURE

3.7 OTHER DESCRIPTORS

3.7.1 HCl REACTION

3.7.2 CEMENTATION

3.7.3 MICA CONTENT

3.7.4 FROZEN SOIL

3.7.5 REMARKS

3.8 GROUNDWATER OBSERVATIONS

SECTION 4 – REFERENCES

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RFQ # 69056720Q000018 Attachment 9

SECTION 1 – INTRODUCTION

This guide outlines the standard practice for field identification of soil on Federal Lands Highway (FLH) projects. The intent of this guide is to produce consistent and uniform field descriptions for soil by FLH personnel and consultants working on FLH projects.

1.1 REFERENCED PROCEDURES

Soil identification, for engineering purposes, is based on the distribution and behavior of the fine-grained and coarse-grained soil constituents. In this guide, soil descriptions are based on modified procedures outlined in ASTM D 2488 - Standard Practice for Description and Identification of Soils (Visual-Manual Procedure) and Publication No. FHWA NHI-01-031, Subsurface Investigations - Geotechnical Site Characterization Reference Manual (2002). It is important to distinguish that the soil descriptions described herein are based on soil visual-manual identification and differ from precise soil classification according to classification systems such as the Unified Soil Classification System (USCS) (ASTM D 2487) and the AASHTO Classification System (AASHTO M 145). The visual-manual identification utilizes visual observation and simple manual tests to identify the characteristics of the soil constituents whereas soil classification is based on prescribed laboratory tests to determine particle size characteristics, liquid limit, and plasticity index. After laboratory testing has been completed, USCS Group Symbols are added behind the group name to indicate that it is a classification in accordance with ASTM D 2487 based on the laboratory test results.

AASHTO soil classifications may be added to the boring log at the discretion of the project geotechnical engineer or engineering geologist. The AASHTO soil classifications are determined in accordance with AASHTO M 145 based on the results of prescribed laboratory tests.

1.2 BORING IDENTIFICATION

Identify each boring with an alphanumeric identification (Boring ID) that includes the two-digit year the boring was completed followed by a dash and then a two-digit boring number. Letters used in the Boring ID should either describe the boring type, instrumentation installed, or location of the boring. Use the same total number of digits in all boring identifications for each project.

The following abbreviations are recommended:

BH Conventional boring MW Monitoring well

SG Subgrade boring VW Vibrating wire piezometer

CP Cone penetrometer test hole SI Slope inclinometer casing

PM Pressuremeter test hole TD Time domain reflectometer

DT Dilatometer test hole SA ShapeAccelArray

Example Boring IDs are listed and described below:

BH14-01 indicates boring number 1 drilled in 2014, SG14-22 indicates subgrade boring number 22 drilled in 2014, VW14-04 indicates boring number 4 drilled in 2014 with a vibrating wire piezometer installation, SI14-22 indicates boring number 22 drilled in 2014 with slope inclinometer casing installation, TD14-01 indicates boring number 1 drilled in 2014 with a time domain reflectometer installation.

1.3 STRATIFICATION

Describe the first sample in every stratum using a full description as described under Section 1.4 Order of Descriptors. On subsequent samples, list changes to any of the descriptors from the first sample in that layer, if applicable (e.g. more boulders up to 3 feet and wet).

Use a stratification line to separate adjacent layers on the field logs where the group name of the major constituent changes or where the geological origin of the material changes. Stratification lines may also be used if more than two of the descriptors change between samples.

A solid horizontal line is used when a stratigraphic change is observed within a sample. A dashed horizontal line is used when a change occurs between samples and it is not observed, or when the driller notes a change in drilling behavior between samples. Place the dashed line midway between samples if the location of the change is unknown by drilling behavior.

Indicate the thickness and type of groundcover encountered at the boring location. For example, the uppermost layer may be described as follows:

• Asphalt Concrete (0.5 ft thick)

• Topsoil (0.4 ft thick)

• Duff/leaf litter (0.2 ft thick)

• Aggregate Roadway Surfacing (0.5 ft thick)

For borings through paved surfaces, record asphalt concrete (AC) or Portland cement concrete (PCC) pavement thickness and base course thickness when present.

Geologic origin or unit may be added if the information is available from geologic maps or the unit can be easily identified based on known area geology. When samples are interpreted as fill materials, or the geologic origin or unit is known, note it at the end of the sample description, e.g., Glacial lake deposit or e.g., Fill. Do not include geologic origin or unit for fill material.

Groundwater observations must also be recorded on the boring logs. See Section 3.8 for guidance on recording groundwater, when encountered.

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1.4 ORDER OF DESCRIPTORS

The protocol for field identification of soil is to describe the soil properties in the following order:

soil group NAME (main constituent in CAPS) (USCS group symbol) (when based on laboratory test results), consistency (fine grained soils) or apparent density (coarse grained soils), color, moisture, particle size and angularity (coarse grained soils), plasticity (fine grained soils), structure, additional remarks (performance of drill rig, HCL reaction, mica content, presence of cobbles/boulders, etc.). AASHTO classification (when required). Geologic origin or unit (when required).

Some examples of this field logging protocol are as follows:

Well-graded GRAVEL (GW) with cobbles and boulders up to 14 inches, very dense, light brown, wet, fine to coarse, subrounded, homogeneous, drilling action indicates boulders encountered from 5 to 9 feet. A-1-a. Fill.

Sandy SILT (ML), loose, gray, moist, nonplastic, laminated horizontal layers of light and dark gray less than 1/8 inch thick, weak HCL reaction. A-4. Glacial lake deposit.

Fat CLAY, medium stiff, gray, wet, high plasticity, 1/16 inch lenses of fine sand every 6 to 12 inches. Glacial lake deposit.

Poorly-graded SAND (SP), loose to medium dense, brown, wet, medium to coarse, subrounded to subangular, homogeneous. Glacial outwash.

Silty SAND, very loose, gray, wet, fine, homogeneous, augers sunk 10 inches after disconnecting from drill head.

COBBLES and BOULDERS up to 3 feet in a silty sand matrix, wet, subrounded. Silty sand is medium dense, brown, wet, fine to medium. Driller remarks increased drilling resistance below 13 feet.

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SECTION 2 – SOIL IDENTIFICATION

Soil identification is based on the portion of the soil sample that will pass a 3-inch (75 mm) sieve.

Fines are defined as soil particles that pass a No. 200 sieve (0.075 mm opening), i.e., silt and clay sized particles.

The first step in identifying soils is to categorize the sample into one of the two broad categories listed below:

• Coarse Grained Soils: Soils that contain less than 50% fines. These soils are composed primarily of sand and gravel. See Subsection 2.1.

• Fine Grained Soils: Soils that contain 50% or more fines. These soils are composed primarily of silt and clay. See Subsection 2.2.

Peat is a highly organic soil that does not fall into either of the categories listed above. Peat is material composed primarily of vegetative tissue in various stages of decomposition that has a fibrous to amorphous texture, dark brown to black color, a spongy consistency, and an organic odor. See Subsection 2.3 for guidance on describing peat.

Soil identification does not take into account the presence of cobbles and boulders (plus 3 inch material) within the soil mass. See Subsection 2.4 for guidance on describing layers with cobbles and/or boulders.

2.1 COARSE-GRAINED SOILS – GRAVEL & SAND (<50% FINES)

Coarse-grained soils have less than 50% fines. Coarse-grained soils are identified by estimating the percentages of gravel, sand, and fines, and determining the characteristics of the fine-grained material. The particle sizes of gravel, sand, and fines are defined in Exhibit 2.1-A.

Exhibit 2.1-A PARTICLE SIZE DEFINITIONS FOR GRAVEL, SAND, AND

FINES

Component Grain Size Limits

Gravel #4 to 3-inch Sieve (4.75 mm to 75 mm opening)

Sand #200 to #4 Sieve (0.075 mm to 4.75 mm opening)

Fines Smaller than #200 Sieve (0.075 mm opening)

The percentage of fines in the soil should be estimated as: 5% or less, 10%, or 15% or more.

Exhibit 2.2.1-A in Subsection 2.2.1 can be used to identify the soil group of the fines.

Identify coarse grained soil as well-graded if it has a wide range of particle sizes and substantial amounts of the intermediate particle sizes. Identify coarse grained soil as poorly graded if it

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contains predominantly one size (uniformly graded) or if it has a wide range of sizes with some intermediate sizes obviously missing (gap graded).

Once the major component is identified, use the flow chart in Exhibit 2.1-B to determine the soil group name.

Exhibit 2.1-B FLOW CHART FOR IDENTIFICATION OF COARSE-GRAINED

SOIL (AFTER ASTM D 2488)

2.2 FINE-GRAINED SOIL – SILT & CLAY (≥ 50% FINES)

Fine grained soils have 50% or more fines. Identify inorganic fine-grained soil according to Subsection 2.2.1. If there is enough organic content in the soil to influence the soil properties, identify the soil as organic fine-grained soil according to Subsection 2.2.2.

2.2.1 INORGANIC FINE-GRAINED SOIL

Fine-grained soils are separated into four basic groups based on physical characteristics of dry strength, dilatancy, and toughness. These physical characteristics are summarized in Exhibit 2.2.1-A. Field index tests can be performed on a representative handful-sized sample consisting of material smaller than the No. 40 sieve to determine physical characteristics of fine-grained soil.

The field index tests outlined in Exhibit 2.2.1-B should be performed for each soil unit encountered. When describing and identifying similar soil samples, it is generally not necessary to follow all of the procedures for field index testing as outlined in Exhibit 2.2.1-B.

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Exhibit 2.2.1-A FIELD IDENTIFICATION OF INORGANIC FINE-GRAINED SOIL

Soil Group Dry Strength Dilatancy Toughness

SILT (ML) None to Low Slow to Rapid Low or thread cannot be formed elastic SILT (MH) Low to Medium None to Slow Low to Medium lean CLAY (CL) Medium to High None to Slow Medium fat CLAY (CH) High to Very High None High

Exhibit 2.2.1-B FIELD METHODS TO IDENTIFY INORGANIC FINE-GRAINED

SOILS (AFTER ASTM D 2488)

FIELD TEST

Field Test Procedure

Description Criteria

DRY STRENGTH

Field Test Procedure: From the sample select enough of the specimen to mold a 1-inch diameter ball. Mold the material until it has the consistency of putty, adding water as necessary. Make at least three specimens about ½ inch (13 mm) in diameter. All the specimens to dry in air, sunlight or other means at temperatures below 140°F (60°C). Test the dry strength of the balls by crushing between the thumb and forefinger.

No dry strength The dry specimen crumbles into powder with mere pressure of handling.

Low dry strength The dry specimen crumbles into powder with some finger pressure.

Medium dry strength The specimen breaks into pieces or crumbles with considerable finger pressure.

High dry strength The specimen cannot be broken with finger pressure, but will break into pieces when pressed between the thumb and a hard surface.

Very high dry strength The specimen cannot be broken between the thumb and a hard surface.

DILATANCY

Field Test Procedure: Select enough material from the sample to mold a ball about ½ inch in diameter. Mold the material, adding water as needed, until it has a soft but not sticky consistency. Smooth the ball onto the palm of the hand with a soil knife or spatula. Shake the specimen horizontally striking the side of the hand vigorously against the other hand multiple times. Note the reaction of water appearing on the surface of the soil (dilatancy sheen). Squeeze the sample by closing the hand or pinching the soil between the fingers, and observe disappearance of sheen.

No dilatancy No visible change in the specimen.

Slow dilatancy Water appears slowly on the surface of the specimen during shaking and does not disappear or disappears slowly upon squeezing.

Rapid dilatancy Water appears quickly on the surface of the specimen during shaking and disappears quickly upon squeezing.

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FIELD TEST

Field Test Procedure

Description Criteria

TOUGHNESS AND PLASTICITY

Field Test Procedure: Following completion of the dilatancy test, the specimen is shaped into an elongated pat and rolled by hand on a smooth surface or between the palms into a thread about 1/8 inch in diameter.

The specimen should be repeatedly folded back together into a ball and rerolled until the thread crumbles when it reaches a diameter of 1/8 inch - this is near the soil plastic limit. Note the pressure required to roll the thread and the strength of the thread. After reaching the plastic limit, lump the pieces of thread back together and knead until the lump crumbles. Note the toughness of the material during kneading.

Low toughness Only slight pressure is required to roll the thread near the plastic limit. The thread and the lump are weak and soft.

Medium toughness Medium pressure is required to roll the thread to near the plastic limit. The thread and the lump have medium stiffness.

High toughness Considerable pressure is required to roll the thread to near the plastic limit. The thread and the lump have very high stiffness.

Nonplastic 1/8-inch (3-mm) diameter thread cannot be rolled at any water content.

Low plasticity The thread can barely be rolled and the lump cannot be formed when drier than the plastic limit.

Medium plasticity The thread is easy to roll and not much time is required to reach the plastic limit.

The thread cannot be rerolled after reaching plastic limit. The lump crumbles when drier than the plastic limit.

High plasticity It takes considerable time rolling and kneading to reach the plastic limit. The thread can be rerolled several times after reaching the plastic limit. The lump can be formed without crumbling when drier than the plastic limit.

Once the soil group has been determined, estimate the percentages of sand and gravel contained in the field sample to the nearest 5% (by weight) and use the flow chart in Exhibit 2.2.1-C to determine the soil group name.

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Exhibit 2.2.1-C FLOW CHART FOR IDENTIFICATION OF INORGANIC FINE-

GRAINED SOIL (AFTER ASTM D 2488)

2.2.2 ORGANIC FINE-GRAINED SOIL

If the soil has more than 50% fines and contains enough organic particles to influence the soil properties, identify it as an organic fine-grained soil. Organic soils usually have a dark brown to black color and may have an organic odor. Often, organic soils will change colors, for example from black to brown, when exposed to the air. Organic soils will not have a high toughness or plasticity. The thread for the toughness test will be spongy. It will be difficult to differentiate between organic silt and organic clay. Once it has been determined that the soil is an organic fine-grained soil, estimate the percentage of fines, sand, and gravel in the field sample using the same procedures as for inorganic fine-grained soil. Then use the flow chart in Exhibit 2.2.2-A (from ASTM D 2488) to determine the soil group name.

Exhibit 2.2.2–A FLOW CHART FOR IDENTIFICATION OF ORGANIC FINE-GRAINED

SOIL (AFTER ASTM D 2488)

2.3 PEAT

Soils that are composed primarily of vegetative tissue in various stages of decomposition that have a fibrous to amorphous texture, usually are dark brown to black, spongy consistency, and have distinctive organic odor are designated as a highly organic soil called peat. Peat is not subjected to any further identification procedures. Include color, moisture, odor, and any other relevant descriptors in the descriptive information for the sample.

2.4 COBBLES AND BOULDERS

Soil identification is based on the minus 3-inch material and therefore does not take into account the presence of cobbles and boulders within the soil mass. Cobbles and boulders are defined as follows:

• Cobbles – particles of rock that will pass a 12-inch (300 mm) square opening and be retained on a 3-inch (75 mm) sieve

• Boulders – particles of rock that will not pass a 12-inch (300 mm) square opening.

When cobbles and/or boulders are detected, either visually within a test pit or indicated by drilling action or core recovery, report it on the field logs with the maximum dimension indicated.

Cobbles and/or boulders may be listed as the main soil constituent if the layer consists primarily of cobbles and/or boulders. An example description of the main constituents follows:

• COBBLES and BOULDERS up to 3 feet in a silty sand matrix

When cobbles and/or boulders are not the main constituent in the layer, report it on the field logs following the main soil constituents. Indicate the maximum dimension of boulders encountered.

Add notes at the end of the description indicating the depths where cobbles and boulders are encountered.

Descriptors to be used include:

• with cobbles – when only cobbles are present

• with boulders up to xx inches/feet – when only boulders are present

• with cobbles and boulders up to xx inches/feet – when both cobbles and boulders are present.

SECTION 3 – SOIL DESCRIPTORS

3.1 APPARENT DENSITY AND CONSISTENCY

The standard penetration test (SPT) is an in-situ field test (ASTM D 1586) that is widely used to approximate apparent density of cohesionless soil and consistency of cohesive soil. Use Exhibits 3.1-A and 3.1-B to describe apparent density or consistency, respectively, based on the uncorrected “standard penetration resistance” or “N-value”.

The standard penetration tests consists of driving a 2-inch (50 mm) outside diameter split barrel sampler below the bottom of the borehole using a 140 pound (623 N) hammer with a 30-inch (760

mm) drop. The sampler is driven a total of 18 inches (450 mm) and the number of blows is recorded for each 6-inch (150 mm) increment. The first increment is recorded as a “seating drive” of the sampler, and the sum of the number of blows required to advance the second and third increments is the “standard penetration resistance” or the “N-value” reported in blows per foot.

ASTM D 1586 indicates refusal if one of the following occurs:

1. A total of 50 blows is applied during any one of the 6-inch increments,

2. A total of 100 blows has been applied, or

3. There is no observed advance of the sampler during application of 10 successive blows of the hammer.

If the sampler sinks under the weight of the rods, or the weight of the rods and the hammer, record the depth of penetration and drive the sampler through the rest of the test interval. Record the blow count as either weight of rods (WR) or weight of hammer (WH).

The type of hammer used to drive the sampler (e.g. automatic trip hammer, cathead and safety hammer, cathead and donut hammer) should be recorded on the boring log. Report the hammer efficiency on the boring log if recent test data is available. Also, record the use of non-standard samplers (e.g. 3 inch (75 mm) split barrel samplers) on the boring log. In U.S. practice, it is normal to omit the inside liner in the standard 2-inch O.D. split-barrel sampler. Therefore, in the case that liners are used it must be noted on the boring log.

Exhibit 3.1-A APPARENT DENSITY Exhibit 3.1-B CONSISTENCY

Apparent Density of Coarse Grained Soil (Gravel and Sand)

Consistency of Fine Grained Soil (Silt and Clay)

SPT N-value (blows per foot)

Apparent Density

SPT N-value (blows per foot) Consistency

0 to 4 Very Loose 0 to 1 Very Soft

5 to 10 Loose 2 to 4 Soft 11 to 30 Medium Dense 5 to 8 Firm 31 to 50 Dense 9 to 15 Stiff

> 50 Very Dense 16 to 30 Very Stiff >30 Hard

3.2 COLOR

Soil color is not a specific engineering property, but may be an indicator of other significant geologic processes that may be occurring within the soil mass. Color may also aid in the subsurface correlation of soil units. Soil color should be determined in the field at the natural moisture content. Use basic color descriptions (i.e., brown, gray, black, green, white, yellow, red, etc.). Describe mixed colors by using a dash between the two basic colors (e.g., gray-green). Describe different shades or tints of basic colors by adding the terms light or dark in front of the basic color, for example, light brown.

Use Munsell color descriptions only when specified for a particular project.

The term mottled can be used to describe soil marked with spots of color; usually a result of the groundwater table rising and lowering in the soil column, causing reduction and oxidation of minerals in the soil. When using the term mottled, a color should be added to the description (e.g.

mottled orange-red). The term streaked can be used to describe soils with a homogeneous texture but having color patterns which change and are not considered mottled.

3.3 MOISTURE

Make a visual estimation of the relative moisture content of the soil during the field identification.

Describe the field moisture content of the soil based on the criteria outlined in Exhibit 3.3-A.

Exhibit 3.3-A CRITERIA FOR DESCRIBING MOISTURE CONDITION

Moisture Description Criteria

Dry Absence of moisture; dusty; dry to the touch

Moist Damp but no visible water

Wet Visible free water

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3.4 PARTICLE SIZE AND ANGULARITY (COARSE-GRAINED SOIL)

For coarse-grained soil (i.e., sand, gravel, cobbles and boulders) as the main constituent, include descriptors of particle size and angularity in the field description.

Conform to the field description of particle size of coarse-grained soil outlined in Exhibit 3.4-A.

The coarse-grained soil identification does not take into account the presence of cobbles and boulders within the soil mass, which are often encountered in coarse-grained soil deposits. See Subsection 2.4 for guidance on describing cobbles and boulders. A range of grain size descriptors may be used when appropriate (e.g. fine to medium).

Exhibit 3.4-A PARTICLE SIZE DEFINITION FOR COARSE GRAINED SOILS

Component Grain Size Limits

GRAVEL

Coarse Gravel ¾ – 3” (19 – 75 mm)

Fine Gravel #4 Sieve – ¾” (4.75 – 19 mm)

SAND

Coarse Sand #10 – #4 Sieve (2.00 – 4.75 mm)

Medium Sand #40 – #10 Sieve (0.425 – 2.00 mm)

Fine Sand #200 – #40 Sieve (0.075 – 0.425 mm)

Conform to the criteria as outlined in Exhibit 3.4-B and shown in Exhibit 3.4-C for the field description of angularity of the coarse sized particles of a soil (boulders, cobbles, gravel, and coarse sand). A range of angularity descriptors may be used when appropriate (e.g.

subrounded to rounded).

Exhibit 3.4-B CRITERIA FOR THE FIELD DESRIPTION OF ANGULARITY

(AFTER ASTM D 2488).

Description Criteria

Angular Coarse grained particles have sharp edges and relatively plane sides with unpolished surfaces

Subangular Coarse grained particles are similar to angular description but have rounded edges

Subrounded Coarse grained particles have nearly plane sides but have well rounded corners and edges

Rounded Coarse grained particles have smoothly curved sides and no edges

Exhibit 3.4-C ANGULARITY EXAMPLES (AFTER ASTM D 2488)

3.5 PLASTICITY (FINE-GRAINED SOIL)

Plasticity is an important index property of soil and should be included in the description of all fine-grained soil. The range of the plasticity index can be estimated by using the results of the toughness test (ASTM D 2488) as outlined in Exhibit 2.2.1-B.

3.6 STRUCTURE

Soil often contains depositional or physical features that are referred to as soil structure. These features should be described following the criteria as outlined in Exhibit 3.6-A.

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Exhibit 3.6-A CRITERIA FOR DESCRIBING SOIL STRUCTURE

Description Criteria Stratified

Alternating layers of varying material or color with layers at least 0.25 inch (6

mm) thick; note thickness and inclination.

Laminated*

Alternating layers of varying material or color with layers less than 0.25 inch (6 mm) thick; note thickness and inclination.

Fissured*

Breaks along definite planes of fracture with little resistance to fracturing.

Slickensided*

Fracture planes appear polished or glossy, sometimes striated.

Blocky*

Cohesive soil that can be broken down into smaller angular lumps which resists further breakdown.

Disrupted

Soil structure is broken and mixed. Infers that material has moved substantially - landslide debris.

Homogeneous

Same color and appearance throughout.

Lensed

Inclusion of small pockets of different soil, such as small lenses of sand scattered through a mass of clay; note thickness

*Note: Do not use laminated, fissured, slickensided, or blocky for coarse-grained soils.

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3.7 OTHER DESCRIPTORS

When applicable, use additional descriptors to describe specific geologic conditions encountered in the sample or non-soil material (i.e., HCl reaction, cementation, mica, gypsum, surface coatings on coarse-grained particles, roots, root holes, odor, etc.). Guidelines for additional descriptors are provided in this Section. Do not include these additional descriptors unless they are relevant to the geology at the site. Include remarks on the performance of the drill or comments made by the driller when the conditions change between samples as described in Subsection 3.7.5.

3.7.1 HCl REACTION

HCl reaction should be tested when the soil may contain carbonate minerals. Calcium carbonate is a common cementing agent in soil. To test for the presence of acidic reaction, the soil sample should be tested with dilute (3% to 10%) HCl. Report the reaction of the soil sample with HCl in accordance with the criteria outlined in Exhibit 3.7.1-A. Only include a description of the soil reaction to HCL when the sample has been tested.

Exhibit 3.7.1-A SOIL REACTION TO HYDROCHLORIC ACID

HCl Reaction Description Criteria

No HCl Reaction No visible reaction

Weak HCl Reaction Some reaction with bubbles forming slowly

Strong HCl Reaction Violent reaction with bubbles forming immediately

3.7.2 CEMENTATION

If the soil particles are cemented, report the cementation of the soil sample in accordance with the criteria outlined in Exhibit 3.7.2-A. Only include a description of the soil cementation if the sample is cemented; however, it may be appropriate to indicate no cementation if adjacent samples or other soil layers encountered on the site have cemented particles.

Exhibit 3.7.2-A SOIL CEMENTATION

Description Criteria

Weak cementation Sample crumbles or breaks with handling or little finger pressure

Moderate cementation Sample crumbles or breaks with considerable finger pressure

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Strong cementation Sample will not crumble or break with finger pressure

3.7.3 MICA CONTENT

Only include a description of the mica content if mica has been identified in the sample. Mica is common in residual soils and it has been found to affect compressibility and strength/stability, especially for cut slopes, and it also affects the compaction characteristics of fill/backfill. When the soil includes mica minerals, include one of the following expressions:

• slightly micaceous – few shiny flakes

• micaceous – common throughout the soil

• highly micaceous – soil is almost all mica.

3.7.4 FROZEN SOIL

When frozen soil is encountered in areas that have seasonal frost penetration use the following expression:

• frozen from xx to xx feet

When frozen soil is encountered in areas that have permafrost the project geotechnical engineer or engineering geologist may specify the use of ASTM D 4083 Description of Frozen Soils (Visual- Manual Procedure) for a systematic description of frozen soil and ice layers.

3.7.5 REMARKS

Include remarks on the performance of the drill or comments made by the driller when the conditions change between samples, such as water or fluid circulation, heaving sands, caving or sloughing of auger holes or test pits, difficulty in augering, etc.

Examples of additional remarks that may be included are:

• driller remarks cobbles and boulders from 25 to 30 feet based on drill chatter

• roots encountered from 1 to 4 feet

• driller remarks more drilling resistance below 13 feet

• driller remarks loss of water circulation from 18’ to 20’

3.8 GROUNDWATER OBSERVATIONS

Groundwater observations are not a specific soil sample descriptor; however, the water table is an important consideration in almost any type of geotechnical design and therefore, it should be sought out in any type of geotechnical investigation.

As a general rule of thumb, water levels and borehole cave-in depths should be checked and recorded in the remarks section of the log in the following cases, as applicable:

• when advancing the borehole after wet soil samples are encountered (e.g. water level observed at 16 feet during drilling).

• if borehole is stopped at the end of the work shift, and before resuming drilling (e.g. water level observed at 17 feet and casing is at 20.5 feet at end of work shift on 9/2/15, water level observed at 16.5 feet before resuming drilling on 9/3/15).

• after reaching the bottom of the borehole before pulling the augers/casing out of the ground (e.g. water level observed at 18 feet upon completion of boring with augers in).

• and after pulling the augers/casing out of the ground (e.g. water level observed at 17.5 feet immediately after withdrawal of augers).

• at a set time after completion of the hole (e.g. water level observed at 15 feet 24 hours after withdrawal of augers).

Generally, do not record water levels if drilling fluid is used to advance the hole.

Record the time and date that water level is measured.

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SECTION 4 – REFERENCES

AASHTO M 145. 2004. Classification of Soils and Soil-Aggregate Mixtures for Highway

Construction Purposes. American Association of State Highway and Transportation Officials.

8p.

ASTM D 1586. 2011. Standard Test Method for Standard Penetration Test (SPT) and Split- Barrel Sampling of Soils. ASTM International. 9p.

ASTM D 2487. 2010. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System). ASTM International. 12p.

ASTM D 2488. 2006. Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). ASTM International. 11p.

ASTM D 4083. 2007. Standard Practice for Description of Frozen Soils (Visual-Manual Procedure). ASTM International. 6p.

USDOT-FHWA, 2002. Subsurface Investigations - Geotechnical Site Characterization Reference Manual, Publication No. FHWA NHI-01-031.

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2.2.2 ORGANIC FINE-GRAINED SOIL

3.8 GROUNDWATER OBSERVATIONS

SECTION 4 – REFERENCES