Geotechnical_Report.pdf

REPORT OF SUBSURFACE EXPLORATION

AND GEOTECHNICAL EVALUATION

PROPOSED PEDESTRIAN BRIDGE

FORT BRAGG, NORTH CAROLINA

BUILDING & EARTH PROJECT NO: RD180249

PREPARED FOR:

STANTEC

JUNE 20, 2018

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Table of Contents

1.0 PROJECT & SITE DESCRIPTION

2.0 SCOPE OF SERVICES

3.0 GEOTECHNICAL SITE CHARACTERIZATION

3.1 GEOLOGY

3.2 EXISTING SURFACE CONDITIONS

3.3 SUBSURFACE CONDITIONS

EXISTING FILL

RESIDUAL SOILS

AUGER REFUSAL

GROUNDWATER

4.0 SITE DEVELOPMENT CONSIDERATIONS

4.1 INITIAL SITE PREPARATION

4.2 SUBGRADE EVALUATION

4.3 MOISTURE SENSITIVE SOILS

4.4 STRUCTURAL FILL

4.5 EXCAVATION CONSIDERATIONS

5.0 FOUNDATION RECOMMENDATIONS

5.1 DRIVEN PRE-CAST CONCRETE PILES

5.2 PILE CAPACITY VERIFICATION

6.0 RETAINING WALL CONSIDERATIONS

7.0 CONSTRUCTION MONITORING

8.0 CLOSING AND LIMITATIONS

APPENDIX

Subsurface Exploration and Geotechnical Evaluation, Proposed Pedestrian Bridge, Fort Bragg, North Carolina Project No: RD180249, June 20, 2018

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1.0 PROJECT & SITE DESCRIPTION

The proposed pedestrian bridge is planned over Reilly Road, south of the intersection of Ardennes Street and Reilly Road in Fort Bragg, North Carolina. The new bridge will provide access to the Smoke Bomb Hill Shopette from the housing areas located west of Reilly Road. Based on the provided plans, the proposed bridge will have a span of about 400.75 feet and a width of 10 feet. The proposed bridge is estimated to have a total foundation loads ranging from approximately 100 kips to 445 kips. The bridge will be supported by stair towers located on either side of Reilly Road. The stair towers are substantial and include a double flight of stairs, as well as handicap access ramps.

A schematic of the pedestrian bridge provided by Stantec is presented below.

2.0 SCOPE OF SERVICES

The authorized subsurface exploration was performed on June 7 and 8, 2018 in conformance with our proposal RD20138, dated March 8, 2018. Notice to proceed was provided by Mr. Will Bynum on April 30, 2018.

The purpose of the geotechnical exploration was to determine general subsurface conditions at specific boring locations and to gather data on which to base a geotechnical evaluation with respect to the proposed construction. The subsurface exploration for this project consisted of four (4) soil test borings. The site was drilled using a GeoProbe 7822DT drill rig equipped with an automatic hammer.

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The soil boring locations were determined in the field by a representative of our staff estimating distances from existing site features. As such, the boring locations shown on the Boring Location Plan attached to this report should be considered approximate.

The soil samples recovered during our site investigation were visually classified and specific samples were selected by the project engineer for laboratory analysis. The laboratory analysis consisted of:

Test ASTM No. of Tests

Natural Moisture Content D2216 8

Atterberg Limits D4318 4

Material Finer Than No. 200 Sieve by Washing D1140 4 Table 1: Scope of Laboratory Tests

The results of the laboratory analysis are presented on the enclosed Boring Logs and in tabular form in the Appendix of this report. Descriptions of the laboratory tests that were performed are also included in the Appendix.

The information gathered from the exploration was evaluated to determine a suitable foundation type for the proposed structure. The information was also evaluated to help determine if any special subgrade preparation procedures will be required during the earthwork phase of the project.

The results of the work are presented within this report that addresses:

Summary of existing surface conditions.

A description of the subsurface conditions encountered at the boring locations.

Site preparation considerations including material types to be expected during the pedestrian bridge construction/installation and mass grading as well as recommendations regarding handling and treatment of unsuitable soils, if encountered.

Compaction requirements and recommended criteria to establish suitable surfaces for structural backfill.

Boring logs detailing the materials encountered with soil classifications, penetration values, and groundwater levels (if measured).

Presentation of laboratory test results.

Recommendations for support of the new structure.

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Presentation of the estimated total and differential settlement.

Plans and maps showing the location of the project and our onsite work.

3.0 GEOTECHNICAL SITE CHARACTERIZATION

The following discussion is intended to create a general understanding of the site from a geotechnical engineering perspective. It is not intended to be a discussion of every potential geotechnical issue that may arise, nor to provide every possible interpretation of the conditions identified. The following conditions and subsequent recommendations are based on the assumption that significant changes in subsurface conditions do not occur between boreholes. However, anomalous conditions can occur due to variations in existing fill that may be present at the site, or the geologic conditions at the site, and it will be necessary to evaluate the assumed conditions during site grading and foundation installation.

3.1 GEOLOGY

Based on the available geologic information, the site is located within the Middendorf Formation of the Cretaceous age. This formation consists of sand, sandstone, and mudstone that are gray to pale grain with an orange cast in color. Clay balls and iron-cemented concretions are common in this formation, with discontinuous beds laterally and cross-bedding.

The conditions encountered in the borings generally correlate with the published geologic information.

3.2 EXISTING SURFACE CONDITIONS

The borings located on the east side of Reilly Road are located in a landscaped area for the Smoke Bomb Hill Shopette. The borings are located in a strip of grass that is located between the parking lot sidewalk (to the east) and the drive-thru for the shopette. The grass strip is about 10 feet wide and slopes downward from the sidewalk to the drive-thru. There is about 3 feet of fall between the sidewalk and the drive thru at the south side near boring B-02 and increases to about 5 feet near B-01. Borings B-03 and B-04 are located on the west side of Reilly Road in an active construction site.

The construction site is fenced in and is controlled by Sauer, Inc. Sauer granted us access to the boring locations. The west side of Reilly Road slopes downward from Marion Street toward Reilly Road. Maximum relief in this area is less than 2 feet. The construction area has been stripped to remove the existing ground cover.

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3.3 SUBSURFACE CONDITIONS

A generalized stratification summary has been prepared using data from the soil test borings and is presented in the table below. The stratification depicts the general soil conditions and strata types encountered during our field investigation.

Stratum No.

Typical Thickness Description Consistency

1 3 – 4 in. Topsoil (all borings except B-03) N/A

2 4.3 – 9 ft. Existing Fill – Silty Sand (SM), Silty Clayey Sand (SC-SM), and Clayey Sand (SC)

Typically Very Loose to Medium Dense

3 13.7 – 43.2 ft.

Residual Soils – Silty Sand (SM), Clayey Sand (SC), and Poorly Graded Sand with Silt (SP-SM)

Typically Very Loose to Medium Dense

Table 2: Stratification Summary

Subsurface soil profiles have also been prepared based on the data obtained at the specific boring locations. The subsurface soil profiles are presented in the Appendix. For specific details on the information obtained from individual soil borings, please refer to the Boring Logs included in the Appendix. The elevations of the borings indicated in this report were estimated based on the provided Existing Conditions Plan prepared by US Army Corps of Engineers, undated.

EXISTING FILL

Previously placed fill material was encountered in all of the borings. The fill was encountered at the surface or below the layer of topsoil (where encountered), and extended to depths of approximately 4.6 to 9 feet below the existing surface. The fill consisted of reddish brown, brown, dark brown, and gray silty sand (SM), clayey sand (SC), and silty clayey sand (SC-SM). Standard Penetration Test (SPT) N-values within the fill layer ranged from 3 to 28.

Atterberg Limits tests performed on selected fill soil samples exhibited low plasticity with Liquid Limits (LL) of 19 and 21 and Plasticity Indices (PI) of 3 and 6. The moisture content of the existing fill material tested ranged from approximately 10 to 14 percent. Wash No.

200 sieve tests performed on the selected fill material tested indicated that the samples contained approximately 21 and 35 percent fines.

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RESIDUAL SOILS

Residual soils, materials formed by the in-place weathering of the parent bedrock, were encountered in all borings. The residual soils consisted of silty sand (SM), clayey sand (SC), and poorly graded sand with silt (SP-SM). The sandy soils were encountered below the fill layer and extended to boring termination depths. N-values within the sandy soils typically ranged from 2 to 22, indicating very loose to medium dense relative density of the soils.

Atterberg Limits tests performed on selected sandy soil samples exhibited low to medium plasticity with Liquid Limits (LL) of 26 and 52 and Plasticity Indices (PI) of 10 and 31. The moisture content of the residual soils tested ranged from approximately 20 to 27 percent.

Wash No. 200 sieve tests performed on the selected residual samples tested indicated that the samples contained approximately 23 and 46 percent fines.

AUGER REFUSAL

Auger refusal is the drilling depth at which the borehole can no longer be advanced using soil drilling procedures. Auger refusal can occur on hard soil, boulders, buried debris or bedrock. Coring is required to sample the material below auger refusal. Auger refusal was not encountered in any of the borings. All of the borings were advanced to their planned termination depths.

GROUNDWATER

At the time of drilling, groundwater was encountered at approximately 10 feet (approx.

elevation 277 feet) below existing grades in boring B-03. Water levels reported are accurate only for the time and date that the borings were drilled. Long term monitoring of the boreholes was not included as part of our subsurface exploration. The borings were backfilled the same day that they were drilled.

4.0 SITE DEVELOPMENT CONSIDERATIONS

A grading plan was not provided at the time of this report. We assume that limited cut and fill (less than 3 feet) will be required to reach finished grades. We understand construction will consist of installation of foundations for support of the pedestrian bridge that will be constructed at the site.

Based on our evaluation of the subsurface soil information, and the anticipated foundation loads, it appears that construction with a driven pile foundation system is feasible. The site development recommendations outlined below are intended for development of the site to support construction with a driven pile system.

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If a different type of foundation system is preferred, Building & Earth should be allowed to review the site development recommendations to verify that they are appropriate for the preferred foundation system.

The primary geotechnical concern for this project is:

Moisture sensitive silty sands and clayey sands encountered at each boring location. These soils are prone to losing stability and strength with slight increases in soil moisture contents.

Loose sandy soils encountered at the boring locations at various depths.

Recommendations addressing the site conditions are presented in the following sections.

4.1 INITIAL SITE PREPARATION

All topsoil and deleterious materials should be removed from the proposed construction areas. Approximately 3 to 4 inches of topsoil were observed in all of the borings except B-03. A geotechnical engineer should observe stripping and grubbing operations to evaluate that all unsuitable materials are removed from locations for proposed construction.

Since the proposed pedestrian bridge will cross an existing road, buried structures could be encountered such as utility lines. If encountered, depending on the type of utility, location, and existing condition, some utilities may need to be relocated. If existing utility lines are left in place, they should be considered during the design of the proposed pedestrian bridge.

Materials disturbed during clearing operations should be stabilized in place or, if necessary, undercut to undisturbed materials and backfilled with properly compacted, approved structural fill.

During site preparation activities, the contractor should identify borrow source materials that will be used as structural fill and provide samples to the testing laboratory so that conformance to the Structural Fill requirements outlined below and appropriate moisture-density relationship curves can be determined.

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4.2 SUBGRADE EVALUATION

We recommend that the project geotechnical engineer or a qualified representative evaluate the subgrade after the site is prepared. Some unsuitable or unstable areas may be present in unexplored areas of the site. All areas that will require fill or that will support the bridge should be carefully proofrolled with a heavy (40,000 # minimum), rubber-tired vehicle at the following times.

After an area has been stripped, and undercut if required, prior to the placement of any fill.

After grading an area to the finished subgrade elevation in the bridge or access ramps area.

After areas have been exposed to any precipitation, and/or have been exposed for more than 48 hours.

Some instability may exist during construction, depending on climatic and other factors immediately preceding and during construction. If any soft or otherwise unsuitable soils are identified during the proofrolling process, they must be undercut or stabilized prior to fill placement or bridge construction. All unsuitable material identified during the construction shall be removed and replaced in accordance with the Structural Fill section of this report.

4.3 MOISTURE SENSITIVE SOILS

Moisture sensitive silty sands (SM) and clayey sands (SC) encountered at the boring locations. These soils will degrade if allowed to become saturated. Therefore, not allowing water to pond by maintaining positive drainage and temporary dewatering methods (if required) is important to help avoid degradation and softening of the soils.

The contractor should anticipate some difficulty during the earthwork phase of this project if moisture levels are moderate to high during construction. Increased moisture levels will soften the subgrade and the soils may become unstable under the influence of construction traffic. Accordingly, construction during wet weather conditions should be avoided, as this could result in soft and unstable soil conditions that would require ground modification, such as in place stabilization or undercutting.

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4.4 STRUCTURAL FILL

Requirements for structural fill on this project are as follows:

Soil Type

USCS

Classification Property Requirements Placement Location

Sand and Gravel

GW, GP, GM,

SW, SP, SM or combinations

Maximum 2” particle size All locations and depths with proper drainage

Clay CL, SC, GC LL<50, PI<25, d 100 pcf All locations and depths

Clay CH N/A Not suitable for structural fill

Silt ML, MH N/A Not suitable for structural fill

On-site soils

SM, SC, SC-SM,

SP-SM As listed above As listed above

Table 3: Structural Fill Requirements

Notes:

1. LL indicates the soil Liquid Limit; PI indicates the soil Plasticity Index; d indicates the maximum dry density as defined by the density standard outlined in the table below.

2. Laboratory testing of the soils proposed for fill must be performed in order to verify their conformance with the above recommendations.

3. Any fill to be placed at the site should be reviewed by the geotechnical engineer.

Placement requirements for structural fill are as follows:

Specification Requirement

Lift Thickness Maximum 8-inch loose lifts when compacted with large heavy compaction equipment. Maximum 6-inch loose lifts when compacted with lightweight compaction equipment (thinner lifts may be required in confined locations).

Density Minimum of 98 percent of maximum dry density as defined by ASTM D698 at all locations and depths.

Moisture

± 2 percent of optimum moisture as defined by ASTM D698 for cohesive soils. For cohesionless soils with greater than 12 percent passing the US Standard No. 200 sieve, ± 3 of optimum moisture as defined above. Moisture requirement is waived for cohesionless soils with less than 12 percent passing the No. 200 sieve.

Density Testing Frequency

One test per 5,000 sf in pavement areas with minimum of 3 tests per lift. One test per 200 feet of trench backfill with minimum of 2 tests per lift.

Table 4: Structural Fill Placement Requirements

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4.5 EXCAVATION CONSIDERATIONS

All excavations performed at the site should follow OSHA guidelines for temporary excavations. Excavated soils should be stockpiled according to OSHA regulations to limit the potential cave-in of soils.

Groundwater was encountered at a depth of approximately 10 feet in one of the four borings. It should be noted that fluctuations in the water level could occur due to seasonal variations in rainfall. The contractor must be prepared to remove groundwater seepage from excavations if encountered during construction. Excavations extending below groundwater levels will require dewatering systems (such as well points, sump pumps or trench drains). The contractor should evaluate the most economical and practical dewatering method.

5.0 FOUNDATION RECOMMENDATIONS

Estimated loading information was provided by Mr. Jonathan Kilcrease with Stantec in an email dated June 11, 2018. Based on the provided information, we understand the foundation loads will vary from approximately 100 to 445 kips. If actual loading conditions exceed the anticipated loads, our office should be contacted so that our recommendations can be reviewed.

Based on the conditions encountered during our field investigation, and the expected loading, we recommend the proposed pedestrian bridge be supported on deep foundations. The deep foundations considered for this project are driven pre-cast concrete piles. Pile sizes, estimated capacities, spacing and capacity verification recommendations are provided in the following sections.

5.1 DRIVEN PRE-CAST CONCRETE PILES

Analyses were performed based on the field data and laboratory test results with regard to a pile foundation. The estimated allowable pile capacities are as follows. An efficiency factor (to account for capacity reductions caused by group effects) of 1.0 should be used for center-to-center pile spacings of five pile diameters or more. Factors decrease linearly to 0.8 for a spacing of three pile diameters, which is the minimum recommended spacing.

The pile capacities presented below were estimated using APILE® 5.0 software developed by Ensoft Inc. The structural capacity of the piles has not been considered in our analysis.

The results are included in the Appendix.

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Estimated Single Pre-Cast Square Concrete Driven Pile Capacity (TONS)

Pile Size (inch)

Penetration Depth (ft)

Ultimate Skin Friction (Tons)

Ultimate End Bearing (Tons)

Ultimate Compressive

Capacity (Tons)

Allowable Compressive

Capacity (Tons) (FS=2)

12 x 12 45 93 37 130 65 14 x 14 45 120 50 170 85 16 x 16 45 145 65 210 105

Table 5: Pre-Cast Concrete Driven Pile Axial Capacities

Notes:

* Capacities are soil-pile related capacities and consideration should be given to the structural integrity of the pile member ** This capacity does not include load due to downdrag- see discussion below

An efficiency factor (to account for capacity reductions caused by group effects) of 1.0 should be used for center-to-center pile spacings of five pile diameters or more. Factors decrease linearly to 0.8 for a spacing of three pile diameters, which is the minimum recommended spacing.

We recommend planned fill be placed in advance of pile driving to help reduce the effects of downdrag (negative friction and reduced capacity) on the pile. Negative skin friction is a downward shear drag acting on piles due to downward movement of surrounding soil strata relative to the pile. For such movement of the soils to occur, a segment of the pile must penetrate a compressible soil stratum that consolidates. At this site, the downward drag would be caused by the placement of additional fill over the compressible zone.

Therefore, in the event that fill heights are greater than those assumed in this report, Building & Earth should be retained to review the changes and, if necessary, modify our recommendations.

The pile minimum penetration depth is estimated by considering the conditions encountered in the field, but the depth to a sufficiently hard stratum can vary and will require some adaptation during construction. A minimum pile length of 45 feet is recommended with a minimum of 2 piles per pile cap. This would limit post construction settlements to less than 1 inch.

The driving criteria should be established at the time of construction based on the characteristics of the pile driving hammer used and the required pile capacity. Each pile should be driven to the desired tip elevation and driving resistance should be monitored without interruption in the driving operations.

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We recommend the pile driving be monitored by the geotechnical engineer or his representative. Sometimes, premature refusal occurs due to poor performance of the hammer rather than from soil resistance. Any changes in hammer blow counts should be carefully examined before making any decisions about the pile penetration.

Pile driving vibrations should be controlled to reduce the possibility of damage to nearby structures. The maximum particle velocity typically recommended to prevent damage to structures is 0.5 inch per second. Peak particle velocities in excess of 0.25 inch per second could densify near surface cohesionless soils causing cracks in structures supported on these soils. Therefore, we recommend that peak particle velocities at nearby structures be limited to 0.25 inch per second. A study should be performed on nearby structures prior to pile driving to document the pre-construction condition.

Accurate records of the final tip elevation and driving resistances should be obtained during the pile driving operations. Supplemental techniques like pre-drilling or jetting may reduce the pile capacity and should be avoided. Some pile heaving may be experienced during installation of adjacent displacement type piles. It is therefore recommended that the tip elevation of the pile be recorded and if significant heave is noted after driving subsequent piles, provisions must be made for reseating them.

Proper site preparation, construction techniques, and quality control are critical to the integrity of the deep foundation system. These construction efforts should be monitored and documented by a representative of the geotechnical engineer.

5.2 PILE CAPACITY VERIFICATION

Pile capacities should be verified at the start of construction, before production piles are cast, through dynamic pile testing with the use of a Pile Driving AnalyzerTM (PDA) per ASTM D4945. Dynamic testing is more economical than static load testing and will enable several piles to be quickly tested across the site. We recommend that at least three test piles be driven at production pile locations at the site. The piles should be tested during initial installation then re-struck at a minimum of 5 days after installation to determine their capacity.

We recommend the test piles have at least 3 feet of “stick-up” above the existing ground surface so test equipment can be attached. During production pile installation, an Engineering Technician working under the direction of the Geotechnical Engineer should monitor all pile driving to verify that the piles are encountering expected driving resistances and note any damage or other concerns during installation.

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Pile driving hammers having rated energies in the range of 30 to 60 ft-kips should be suitable for the pile installation. However, prior to the start of construction, a wave equation analysis should be performed to verify that the proposed driving system (i.e., hammer type/size) is capable of driving the piles to the desired depth without damage.

Potential pile driving complications should be considered during the design and planning phase, and the pile driving contractor should be informed during the bid process of potential problems such as vibration concerns or possible subsurface debris.

6.0 RETAINING WALL CONSIDERATIONS

Based on the provided plans, retaining walls are planned east and west of the proposed pedestrian bridge at the access ramps. Information regarding the retaining walls was not provided at the time of this report. The design and global stability analysis of the walls are beyond the scope of this report.

7.0 CONSTRUCTION MONITORING

Field verification of site conditions is an essential part of the services provided by the geotechnical consultant. In order to confirm our recommendations, it will be necessary for Building & Earth personnel to make periodic visits to the site during site grading.

Typical construction monitoring services are listed below.

Periodic observations and consultations by a member of our engineering staff during site grading.

Continuous monitoring during structural fill placement or undercutting.

Field density tests during structural fill placement.

Monitoring and inspection of driven pile construction.

Reinforcing steel inspections.

8.0 CLOSING AND LIMITATIONS

This report was prepared for Stantec, for specific application to the Proposed Pedestrian Bridge located in Fort Bragg, North Carolina. The information in this report is not transferable. This report should not be used for a different development on the same property without first being evaluated by the engineer.

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The recommendations in this report were based on the information obtained from our field exploration and laboratory analysis. The data collected is representative of the locations tested. Variations are likely to occur at other locations throughout the site.

Engineering judgment was applied in regards to conditions between borings. It will be necessary to confirm the anticipated subsurface conditions during construction.

This report has been prepared in accordance with generally accepted standards of geotechnical engineering practice. No other warranty is expressed or implied. In the event that changes are made, or anticipated to be made, to the nature, design, or location of the project as outlined in this report, Building & Earth must be informed of the changes and given the opportunity to either verify or modify the conclusions of this report in writing, or the recommendations of this report will no longer be valid.

The scope of services for this project did not include any environmental assessment of the site or identification of pollutants or hazardous materials or conditions. If the owner is concerned about environmental issues Building & Earth would be happy to provide an additional scope of services to address those concerns.

This report is intended for use during design and preparation of specifications and may not address all conditions at the site during construction. Contractors reviewing this information should acknowledge that this document is for design information only.

An article published by the Geoprofessional Business Association (GBA), titled Important Information About Your Geotechnical Report, has been included in the Appendix. We encourage all individuals to become familiar with the article to help manage risk.

Appendix Table of Contents

GEOTECHNICAL INVESTIGATION METHODOLOGIES

DRILLING PROCEDURES – STANDARD PENETRATION TEST (ASTM D1586)

BORING LOG DESCRIPTION

DEPTH AND ELEVATION

SAMPLE TYPE

SAMPLE NUMBER

BLOWS PER INCREMENT, REC%, RQD%

SOIL DATA

SOIL DESCRIPTION

GRAPHIC

REMARKS

SOIL CLASSIFICATION METHODOLOGY

KEY TO LOGS

KEY TO HATCHES

BORING LOCATION PLAN

SUBSURFACE SOIL PROFILES

BORING LOGS

LABORATORY TEST PROCEDURES

DESCRIPTION OF SOILS (VISUAL-MANUAL PROCEDURE) (ASTM D2488)

NATURAL MOISTURE CONTENT (ASTM D2216)

ATTERBERG LIMITS (ASTM D4318)

MATERIAL FINER THAN NO. 200 SIEVE BY WASHING (ASTM D1140)

LABORATORY TEST RESULTS

Table A-1: General Soil Classification Test Results

APILE CALCULATIONS

IMPORTANT INFORMATION ABOUT THIS GEOTECHNICAL-ENGINEERING REPORT

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GEOTECHNICAL INVESTIGATION METHODOLOGIES

The subsurface exploration, which is the basis of the recommendations of this report, has been performed in accordance with industry standards. Detailed methodologies employed in the investigation are presented in the following sections.

DRILLING PROCEDURES – STANDARD PENETRATION TEST (ASTM D1586)

At each boring location, soil samples were obtained at standard sampling intervals with a split-spoon sampler. The borehole was first advanced to the sample depth by augering and the sampling tools were placed in the open hole. The sampler was then driven 18 inches into the ground with a 140-pound automatic hammer free-falling 30 inches. The number of blows required to drive the sampler each 6-inch increment was recorded. The initial increment is considered the “seating” blows, where the sampler penetrates loose or disturbed soil in the bottom of the borehole.

The blows required to penetrate the final two (2) increments are added together and are referred to as the Standard Penetration Test (SPT) N-value. The N-value, when properly evaluated, gives an indication of the soil’s strength and ability to support structural loads.

Many factors can affect the SPT N-value, so this result cannot be used exclusively to evaluate soil conditions.

The SPT testing was performed using a drill rig equipped with an automatic hammer.

Automatic hammers mechanically control the height of the hammer drop, and doing so, deliver higher energy efficiency (90 to 99 % efficiency) than manual hammers (60 % efficiency) which are dropped using a manually operated rope and cathead system. Because historic data correlations were developed based on use of a manual hammer, it is necessary to adjust the N-values obtained using an automatic hammer to make these correlations valid. Therefore, an energy correction factor of 1.3 was applied to the recorded field N-values from the automatic hammer for the purpose of our evaluation. The N-values discussed or mentioned in this report and shown on the boring logs are recorded field values.

Samples retrieved from the boring locations were labeled and stored in plastic bags at the jobsite before being transported to our laboratory for analysis. The project engineer prepared Boring Logs summarizing the subsurface conditions at the boring locations.

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BORING LOG DESCRIPTION

Building & Earth Sciences, Inc. used the gINT software program to prepare the attached boring logs. The gINT program provides the flexibility to custom design the boring logs to include the pertinent information from the subsurface exploration and results of our laboratory analysis. The soil and laboratory information included on our logs is summarized below:

DEPTH AND ELEVATION

The depth below the ground surface and the corresponding elevation are shown in the first two columns.

SAMPLE TYPE

The method used to collect the sample is shown. The typical sampling methods include Split Spoon Sampling, Shelby Tube Sampling, Grab Samples, and Rock Core. A key is provided at the bottom of the log showing the graphic symbol for each sample type.

SAMPLE NUMBER

Each sample collected is numbered sequentially.

BLOWS PER INCREMENT, REC%, RQD%

When Standard Split Spoon sampling is used, the blows required to drive the sampler each 6-inch increment are recorded and shown in column 5. When rock core is obtained the recovery ration (REC%) and Rock Quality Designation (RQD%) is recorded.

SOIL DATA

Column 6 is a graphic representation of four different soil parameters. Each of the parameters use the same graph, however, the values of the graph subdivisions vary with each parameter.

Each parameter presented on column 6 is summarized below:

N-value- The Standard Penetration Test N-value, obtained by adding the number of blows required to drive the sampler the final 12 inches, is recorded . The graph labels range from 0 to 50.

Qu – Unconfined Compressive Strength estimate from the Pocket Penetrometer test in tons per square foot (tsf). The graph labels range from 0 to 5 tsf.

Atterberg Limits – The Atterberg Limits are plotted with the plastic limit to the left, and liquid limit to the right, connected by a horizontal line. The difference in the plastic and liquid limits is referred to as the Plasticity Index. The Atterberg Limits test results are also included in the Remarks column on the far right of the boring log. The Atterberg Limits graph labels range from 0 to 100%.

Moisture – The Natural Moisture Content of the soil sample as determined in our laboratory.

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SOIL DESCRIPTION

The soil description prepared in accordance with ASTM D2488, Visual Description of Soil Samples. The Munsel Color chart is used to determine the soil color. Strata changes are indicated by a solid line, with the depth of the change indicated on the left side of the line and the elevation of the change indicated on the right side of the line. If subtle changes within a soil type occur, a broken line is used. The Boring Termination or Auger Refusal depth is shown as a solid line at the bottom of the boring.

GRAPHIC

The graphic representation of the soil type is shown. The graphic used for each soil type is related to the Unified Soil Classification chart. A chart showing the graphic associated with each soil classification is included.

REMARKS

Remarks regarding borehole observations, and additional information regarding the laboratory results and groundwater observations.

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SOIL CLASSIFICATION METHODOLOGY

Major Divisions Symbols

Group Name & Typical Description Lithology Group

Coarse Grained

Soils

More than

50% of material is larger than

No. 200 sieve size

Gravel and Gravelly coarse fraction is larger than No. 4 sieve

Clean Gravels

(Less than 5% fines)

GW Well-graded gravels, gravel – sand mixtures, little or no fines

GP Poorly-graded gravels, gravel – sand mixtures, little or no fines

Gravels with Fines

(More than 12% fines)

GM Silty gravels, gravel – sand – silt mixtures

GC Clayey gravels, gravel – sand – clay mixtures

Sand and Sandy coarse fraction is smaller than

No. 4 sieve

Clean Sands

(Less than 5% fines)

SW Well-graded sands, gravelly sands, little or no fines

SP Poorly-graded sands, gravelly sands, little or no fines

Sands with Fines

(More than 12% fines)

SM Silty sands, sand – silt mixtures

SC Clayey sands, sand – clay mixtures

Fine Grained material is smaller than No. 200 sieve size

Silts and Clays

Liquid Limit less than 50

Inorganic ML Inorganic silts and very find sands, rock flour, silty or clayey fine sands or clayey silt with slight plasticity

CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

Organic OL Organic silts and organic silty clays of low plasticity

Silts and Clays

Liquid Limit greater than

50 sieve

Inorganic MH Inorganic silts, micaceous or diatomaceous fine sand, or silty soils

CH Inorganic clays of high plasticity

Organic OH Organic clays of medium to high plasticity, organic silts

Highly Organic Soils PT Peat, humus, swamp soils with high organic contents

Table 1: Soil Classification Chart (based on ASTM D2487)

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SOIL CLASSIFICATION METHODOLOGY

* - Modified based on 80% hammer efficiency

Building & Earth Sciences classifies soil in general accordance with the Unified Soil Classification System (USCS) presented in ASTM D2487. Table 1 and Figure 1 exemplify the general guidance of the USCS. Soil consistencies and relative densities are presented in general accordance with Terzaghi, Peck, & Mesri’s (1996) method, as shown on Table 2, when quantitative field and/or laboratory data is available. Table 2 includes Consistency and Relative Density correlations with N-values obtained using either a manual hammer (60 percent efficiency) or automatic hammer (90 percent efficiency). The Blows Per Increment and SPT N-values displayed on the boring logs are the unaltered values measured in the field. When field and/or laboratory data is not available, we may classify soil in general accordance with the Visual Manual Procedure presented in ASTM D2488.

Non-cohesive: Coarse-Grained Soil Cohesive: Fine-Grained Soil

SPT Penetration (blows/foot) Relative

Density

SPT Penetration (blows/foot)

Consistency

Estimated Range of Unconfined Compressive

Strength (tsf)

Automatic Hammer*

Manual Hammer

Automatic Hammer*

Manual Hammer < 2 < 2 Very Soft < 0.25

0 - 3 0 - 4 Very Loose 2 - 3 2 - 4 Soft 0.25 – 0.50

3 - 8 4 - 10 Loose 3 - 6 4 - 8 Medium Stiff 0.50 – 1.00

8 - 23 10 - 30 Medium Dense 6 - 12 8 - 15 Stiff 1.00 – 2.00

23 - 38 30 - 50 Dense 12 - 23 15 - 30 Very Stiff 2.00 – 4.00

> 38 > 50 Very Dense > 23 > 30 Hard > 4.00

Table 2: Soil Consistency and Relative Density (based on Terzaghi, Peck & Mesri, 1996)

0 10 20 30 40 50 60 70 80 90 100 P la st ic it y In d ex

P

I) Liquid Limit (LL)

CH or OH

MH or OH

CL or OL

ML or OLCL-ML7

Figure 1: Plasticity Chart (based on ASTM D2487)

Page | A-6

KEY TO LOGS

Standard Penetration Test ASTM D1586 or

AASHTO T-206

Dynamic Cone Penetrometer (Sower DCP)

ASTM STP-399

Soil Particle Size U.S. Standard

Boulders Larger than 300 mm N.A.

Cobbles 300 mm to 75 mm N.A.

Shelby Tube Sampler

ASTM D1587

No Sample Recovery

Gravel 75 mm to 4.75 mm 3-inch to #4 sieve

Coarse 75 mm to 19 mm 3-inch to ¾-inch sieve

Fine 19 mm to 4.75 mm ¾-inch to #4 sieve

Rock Core Sample

ASTM D2113

Groundwater at Time of Drilling

Sand 4.75 mm to 0.075 mm #4 to #200 Sieve

Coarse 4.75 mm to 2 mm #4 to #10 Sieve

Medium 2 mm to 0.425 mm #10 to #40 Sieve

Auger Cuttings

Groundwater as Indicated

Fine 0.425 mm to 0.075 mm #40 to #200 Sieve

Fines Less than 0.075 mm Passing #200 Sieve

Silt Less than 5 µm N.A.

Clay Less than 2 µm N.A.

Table 1: Symbol Legend Table 2: Standard Sieve Sizes

Standard Penetration Test Resistance calculated using ASTM D1586 or AASHTO T-

206. Calculated as sum of original, field recorded values.

A measure of a soil’s plasticity characteristics in general accordance with ASTM D4318. The soil Plasticity Index (PI) is representative of this characteristic and is bracketed by the Liquid Limit (LL) and the Plastic Limit (PL).

Unconfined compressive strength, typically estimated from a pocket penetrometer. Results are presented in tons per square foot (tsf).

Percent natural moisture content in general accordance with ASTM D2216.

Table 3: Soil Data

Hollow Stem Auger Flights on the outside of the shaft advance soil cuttings to the surface. The hollow stem allows sampling through the middle of the auger flights.

Descriptor

Meaning Mud Rotary /

Wash Bore A cutting head advances the boring and discharges a drilling fluid to support the borehole and circulate cuttings to the surface. Trace Likely less than 5%

Solid Flight Auger Flights on the outside bring soil cuttings to the surface. Solid stem requires removal from borehole during sampling.

Few 5 to 10% Little 15 to 25%

Hand Auger Cylindrical bucket (typically 3-inch diameter and 8 inches long) attached to a metal rod and turned by human force.

Some 30 to 45% Mostly 50 to 100%

Table 4: Soil Drilling Methods Table 5: Descriptors

Page | A-7

KEY TO LOGS

Manual Hammer The operator tightens and loosens the rope around a rotating drum assembly to lift and drop a sliding, 140-pound hammer falling 30 inches.

Automatic Trip Hammer An automatic mechanism is used to lift and drop a sliding, 140-pound hammer falling 30 inches.

Dynamic Cone Penetrometer (Sower DCP) ASTM STP-399

Uses a 15-pound steel mass falling 20 inches to strike an anvil and cause penetration of a 1.5-inch diameter cone seated in the bottom of a hand augered borehole. The blows required to drive the embedded cone a depth of 1-3/4 inches have been correlated by others to N-values derived from the Standard Penetration Test (SPT).

Table 6: Sampling Methods

Non-plastic A 1/8-inch thread cannot be rolled at any water content.

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

Medium The thread is easy to roll and not much time is required to reach the plastic limit. The thread cannot be re-rolled after reaching the plastic limit. The lump crumbles when drier than the plastic limit.

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

Table 7: Plasticity

Dry Absence of moisture, dusty, dry to the touch.

Moist Damp but no visible water.

Wet Visible free water, usually soil is below water table.

Table 8: Moisture Condition

Stratified Alternating layers of varying material or color with layers at least ½ inch thick.

Laminated Alternating layers of varying material or color with layers less than ¼ inch thick.

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

Slickensides Fracture planes appear polished or glossy, sometimes striated.

Blocky Cohesive soil that can be broken down into small angular lumps which resist further breakdown.

Lensed Inclusion of small pockets of different soils, such as small lenses of sand scattered through a mass of clay.

Homogeneous Same color and appearance throughout.

Table 9: Structure

Page | A-8

KEY TO HATCHES

Hatch Description Hatch Description Hatch Description

GW - Well-graded gravels, gravel – sand mixtures, little or no fines Asphalt Clay with Gravel

GP - Poorly-graded gravels, gravel – sand mixtures, little or no fines Aggregate Base Sand with Gravel

GM - Silty gravels, gravel – sand – silt mixtures Topsoil Silt with Gravel

GC - Clayey gravels, gravel – sand – clay mixtures Concrete Gravel with Sand

SW - Well-graded sands, gravelly sands, little or no fines Coal Gravel with Clay

SP - Poorly-graded sands, gravelly sands, little or no fines CL-ML - Silty Clay Gravel with Silt

SM - Silty sands, sand – silt mixtures Sandy Clay Limestone

SC - Clayey sands, sand – clay mixtures Clayey Chert Chalk

ML - Inorganic silts and very find sands, rock flour, silty or clayey fine sands or clayey silt with slight plasticity

Low and High Plasticity Clay Siltstone

CL - Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

Low Plasticity Silt and Clay Till

OL - Organic silts and organic silty clays of low plasticity

High Plasticity Silt and Clay

Sandy Clay with Cobbles and Boulders

MH - Inorganic silts, micaceous or diatomaceous fine sand, or silty soils Fill Sandstone with Shale

CH - Inorganic clays of high plasticity Weathered Rock Coral

OH - Organic clays of medium to high plasticity, organic silts Sandstone Boulders and Cobbles

PT - Peat, humus, swamp soils with high organic contents Shale Soil and Weathered

Rock

Table 1: Key to Hatches Used for Boring Logs and Soil Profiles

Page | A-9

BORING LOCATION PLAN

Bo rin g Lo ca tio n M ap

BE

S Pr oj ec t #

RD

Ad dr es s:

Re ill y Ro ad , S o f K ed en bu rg

S t.

D ra w in g So ur ce

St an te c Ci ty

Fo rt

Br ag g, N

C Cl ie nt

St an te c Fi gu re

Pr oj ec t:

Pr op os ed P ed es tri an

B rid ge

N B-

Ap pr ox im at e Bo rin g

Lo ca tio n

B- 03 B-

B-

B-

Page | A-10

SUBSURFACE SOIL PROFILES

Page | A-11

BORING LOGS

Page | A-12

LABORATORY TEST PROCEDURES

A brief description of the laboratory tests performed is provided in the following sections.

DESCRIPTION OF SOILS (VISUAL-MANUAL PROCEDURE) (ASTM D2488)

The soil samples were visually examined by our engineer and soil descriptions were provided. Representative samples were then selected and tested in accordance with the aforementioned laboratory-testing program to determine soil classifications and engineering properties. This data was used to correlate our visual descriptions with the Unified Soil Classification System (USCS).

NATURAL MOISTURE CONTENT (ASTM D2216)

Natural moisture contents (M%) were determined on selected samples. The natural moisture content is the ratio, expressed as a percentage, of the weight of water in a given amount of soil to the weight of solid particles.

ATTERBERG LIMITS (ASTM D4318)

The Atterberg Limits test was performed to evaluate the soil’s plasticity characteristics. The soil Plasticity Index (PI) is representative of this characteristic and is bracketed by the Liquid Limit (LL) and the Plastic Limit (PL). The Liquid Limit is the moisture content at which the soil will flow as a heavy viscous fluid. The Plastic Limit is the moisture content at which the soil is between “plastic” and the semi-solid stage. The Plasticity Index (PI = LL - PL) is a frequently used indicator for a soil’s potential for volume change. Typically, a soil’s potential for volume change increases with higher plasticity indices.

MATERIAL FINER THAN NO. 200 SIEVE BY WASHING (ASTM D1140)

Grain-size tests were performed to determine the partial soil particle size distribution. The amount of material finer than the openings on the No. 200 sieve (0.075 mm) was determined by washing soil over the No. 200 sieve. The results of wash #200 tests are presented on the boring logs included in this report and in the table of laboratory test results.

Page | A-13

LABORATORY TEST RESULTS

The results of the laboratory testing are presented in the following table.

Boring Location Sample Depth

(ft) LL PL PI % Passing

#200 Sieve Moisture

Content (%) B-01 0 – 2 19 16 3 21.1 11.1

B-01 2 – 4 - - - - 10.5

B-01 4 – 6 - - - - 10.4

B-02 6 – 8 26 16 10 23.2 26.7

B-03 10 – 12 52 21 31 45.5 20.2

B-03 13.5 – 15 - - - - 21.6

B-04 0 – 2 21 15 6 34.5 14.0

B-04 2 – 4 - - - - 10.8 Table A-1: General Soil Classification Test Results

Soils with a Liquid Limit (LL) greater than 50 and Plasticity Index (PI) greater than 25 usually exhibit significant volume change with varying moisture content and are considered to be highly plastic.

Page | A-14

APILE CALCULATIONS

12 inch Square Pre Cast Pile.ap6o

APILE for Windows, Version 2014.6.2

Serial Number : 230082818

A Program for Analyzing the Axial Capacity and Short term Settlement of Driven Piles under Axial Loading.

(c) Copyright ENSOFT, Inc., 1987 2014

All Rights Reserved

This program is licensed to :

Building and Earth Sciences Birmingham, Alabama

Path to file locations : R:\Raleigh\Projects\2018 Projects\RD180249 (GEO) Pedestrian Bridge of Reilly Road, Fort Bragg Stantec\Calculations\APILE\Pre Cast Concrete Piles\

Name of input data file : 12 inch Square Pre Cast Pile.ap6d Name of output file : 12 inch Square Pre Cast Pile.ap6o Name of plot output file : 12 inch Square Pre Cast Pile.ap6p

Time and Date of Analysis

Date: June 19, 2018 Time: 14:04:14

* INPUT INFORMATION *

Pre Cast Pile 12x12

DESIGNER : JR

JOB NUMBER : RD180249

METHOD FOR UNIT LOAD TRANSFERS :

FHWA (Federal Highway Administration) Unfactored Unit Side Friction and Unit Side Resistance are used.

COMPUTATION METHOD(S) FOR PILE CAPACITY :

FHWA (Federal Highway Administration)

TYPE OF LOADING :

COMPRESSION

PILE TYPE :

Precast concrete pile (Square/Rectangular/Orthogonal)

DATA FOR AXIAL STIFFNESS :

MODULUS OF ELASTICITY = 0.290E+08 PSI

CROSS SECTION AREA = 144.00 IN2

NONCIRCULAR PILE PROPERTIES :

TOTAL PILE LENGTH, TL = 45.00 FT.

PILE STICKUP LENGTH, PSL = 0.00 FT.

ZERO FRICTION LENGTH, ZFL = 5.00 FT.

PERIMETER OF PILE = 48.00 IN.

TIP AREA OF PILE = 1.00 IN2

INCREMENT OF PILE LENGTH

USED IN COMPUTATION = 1.00 FT.

SOIL INFORMATIONS :

LATERAL EFFECTIVE FRICTION BEARING

SOIL EARTH UNIT ANGLE CAPACITY

DEPTH TYPE PRESSURE WEIGHT DEGREES FACTOR

FT. LB/CF

0.00 SAND 1.00 115.00 32.00 10.00

7.00 SAND 1.00 115.00 32.00 10.00

7.00 SAND 1.00 115.00 29.00 8.00

10.00 SAND 1.00 115.00 29.00 8.00

10.00 SAND 1.00 55.00 29.00 8.00

28.00 SAND 1.00 55.00 29.00 8.00

28.00 SAND 1.00 59.00 34.00 15.00

100.00 SAND 1.00 59.00 34.00 15.00

MAXIMUM MAXIMUM UNDISTURB REMOLDED

UNIT UNIT SHEAR SHEAR BLOW UNIT SKIN UNIT END

FRICTION BEARING STRENGTH STRENGTH COUNT FRICTION BEARING

KSF KSF KSF KSF KSF KSF

0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00 0.10E+08* 0.10E+08* 0.00 0.00 0.00 0.00 0.00

* MAXIMUM UNIT FRICTION AND/OR MAXIMUM UNIT BEARING

WERE SET TO BE 0.10E+08 BECAUSE THE USER DOES NOT

PLAN TO LIMIT THE COMPUTED DATA.

LRFD FACTOR LRFD FACTOR

ON UNIT ON UNIT

DEPTH FRICTION BEARING

FT.

0.00 1.000 1.000

7.00 1.000 1.000

7.00 1.000 1.000

10.00 1.000 1.000

10.00 1.000 1.000

28.00 1.000 1.000

28.00 1.000 1.000

100.00 1.000 1.000

* COMPUTATION RESULT *

* FED. HWY. METHOD *

PILE TOTAL SKIN END ULTIMATE

PENETRATION FRICTION BEARING CAPACITY

FT. KIP KIP KIP

0.00 0.0 1.4 1.4

1.00 0.0 2.8 2.8

2.00 0.0 5.8 5.8

3.00 0.0 8.7 8.7

4.00 0.0 11.6 11.6

5.00 0.7 14.5 15.2

6.00 2.2 15.3 17.4

7.00 3.9 15.3 19.2

8.00 5.6 14.5 20.1

9.00 7.3 13.2 20.5

10.00 9.1 13.3 22.5

11.00 11.1 13.3 24.5

12.00 13.2 13.3 26.5

13.00 15.4 13.3 28.7

14.00 17.7 13.3 31.0

15.00 20.0 13.3 33.4

16.00 22.5 13.3 35.8

17.00 25.1 13.3 38.4

18.00 27.7 13.3 41.0

19.00 30.4 13.3 43.8

20.00 33.3 13.3 46.6

21.00 36.2 13.3 49.5

22.00 39.2 13.3 52.5

23.00 42.3 13.3 55.7

24.00 45.5 13.3 58.9

25.00 48.8 13.3 62.2

26.00 52.2 13.3 65.5

27.00 55.7 27.7 83.4

28.00 59.3 43.4 102.7

29.00 64.3 59.2 123.5

30.00 70.7 73.5 144.2

31.00 77.3 73.5 150.8

32.00 84.1 73.5 157.6

33.00 91.0 73.5 164.5

34.00 98.1 73.5 171.6

35.00 105.4 73.5 178.9

36.00 112.8 73.5 186.4

37.00 120.4 73.5 194.0

38.00 128.2 73.5 201.8

39.00 136.2 73.5 209.7

40.00 144.3 73.5 217.8

41.00 152.6 73.5 226.1

42.00 161.1 73.5 234.6

43.00 169.7 73.5 243.2

44.00 178.5 73.5 252.1

45.00 187.5 73.5 261.0

AN ASTERISK WILL BE PLACED IN THE END BEARING COLUMN

IF THE TIP RESISTANCE IS CONTROLLED BY THE FRICTION

OF SOIL PLUG INSIDE AN OPEN ENDED PIPE PILE.

* COMPUTE LOAD DISTRIBUTION AND LOAD SETTLEMENT *

* CURVES FOR AXIAL LOADING *

T Z CURVE NO. OF DEPTH TO CURVE LOAD TRANSFER PILE MOVEMENT

NO. POINTS FT. PSI IN.

1 10 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.1000E 01 0.0000E+00…