W912HN-22-B-4008_FIO_GEOTECH AMD3.pdf

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Project Innovation Outpost, Fort Bragg Officer’s Club Renovation

October 2020 ben.wyszynski Text Box

JUNE 2021

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GEOTECHNICAL REPORT

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ECS Southeast, LLP Geotechnical Engineering Report Lafayette Ballroom Addition

Totten Street & Armistead Street Fort Bragg, North Carolina

ECS Project No. 33:5411

December 14, 2020

December 14, 2020

Ms. Shanelle Sims Griggs Raymond Engineering 1224 Royal Drive Conyers, GA 30094

ECS Project No. 33:5411

Reference: Geotechnical Engineering Report

Lafayette Ballroom Addition Totten Street & Armistead Street Fort Bragg, North Carolina

Dear Ms. Griggs:

ECS Southeast, LLP (ECS) has completed the subsurface exploration, laboratory testing, and geotechnical engineering analyses for the above-referenced project. Our services were performed in general accordance with our agreed to scope of work. This report presents our understanding of the geotechnical aspects of the project along with the results of the field exploration and laboratory testing conducted, and our design and construction recommendations.

It has been our pleasure to be of service to Raymond Engineering during the design phase of this project.

We would appreciate the opportunity to remain involved during the continuation of the design phase, and we would like to provide our services during construction phase operations as well to verify subsurface conditions assumed for this report. Should you have any questions concerning the information contained in this report, or if we can be of further assistance to you, please contact us.

Respectfully submitted, ECS Southeast, LLP

Barnabas Bwambale, Ph.D., P.E. Winslow E. Goins, P.E.

Geotechnical Department Manager Principal Engineer BBwambale@ecslimited.com WGoins@ecslimited.com

12/14/20 mailto:BBwambale@ecslimited.com mailto:WGoins@ecslimited.com mailto:WGoins@ecslimited.com

Lafayette Ballroom Addition December 14, 2020 ECS Project No. 33:5411 Page i

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Site Information

2.2 Proposed Construction

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 Field Exploration

3.2 Laboratory Testing

3.3 Subsurface Characterization

3.4 Groundwater Observations

4.0 DESIGN RECOMMENDATIONS

4.1 Foundations

4.2 Slabs On Grade

4.3 Pavements

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 Subgrade Preparation

5.1.1 Previous Site Development

5.1.2 Demolition

5.1.3 Stripping and Grubbing

5.1.4 Proofrolling

5.1.5 Site Temporary Dewatering

5.2 Earthwork Operations

5.3 Foundation and Slab Observations

5.4 Utility Installations

6.0 CLOSING

APPENDICES

Appendix A – Drawings & Reports

• Site Location Diagram

• Boring Location Diagram

Appendix B – Field Operations

• Reference Notes for Boring Logs

• Subsurface Exploration Procedure: Standard Penetration Test (SPT)

• Boring Logs B-1 through B-5

Appendix C – Laboratory Testing

• Laboratory Test Results Summary

ECS Project No. 33:5411 Page 1

EXECUTIVE SUMMARY

The following summarizes the main findings of the exploration, particularly those that may have a cost impact on the planned development. Further, our principal recommendations are summarized.

Information gleaned from the executive summary should not be utilized in lieu of reading the entire geotechnical report.

• Provided the subgrades are prepared as recommended in this report, the planned building may be supported by conventional shallow foundations consisting of column or strip footings bearing on compacted structural fill and natural soils sized using a net allowable soil bearing pressure of 2,000 psf.

• Very loose near-surface soils were encountered in the borings. These soils should be densified in place by first rolling with 10-ton vibratory smooth-drum roller. Depending on the final foundation elevations, undercutting these very loose soils may still be necessary.

• ECS should be retained to review the design documents for conformance with our recommendations.

• ECS should be retained for construction materials testing and special inspections to facilitate proper implementation of our recommendations.

ECS Project No. 33:5411 Page 2

1.0 INTRODUCTION

The purpose of this study was to provide geotechnical information for the design of the proposed Lafayette Ballroom building addition in Fort Bragg, North Carolina. The recommendations developed for this report are based on project information supplied by Raymond Engineering.

Our services were provided in accordance with our Proposal No. 33:4637-GP dated November 5, 2020, as authorized by Raymond Engineering on November 13, 2020, which includes our Terms and Conditions of Service.

This report contains the procedures and results of our subsurface exploration and laboratory testing programs, review of existing site conditions, engineering analyses, and recommendations for the design and construction of the project.

The report includes the following items.

• Observations from our site reconnaissance including current site conditions.

• A brief review of the published geologic conditions.

• A description of the field exploration and laboratory tests performed and a characterization of the subsurface conditions.

• Recommended allowable soil bearing pressure for conventional shallow foundations.

• Recommendations for slab-on-grade design and construction.

• Recommendations for design and construction of the pavements.

• Evaluation of the on-site soil characteristics encountered in the soil borings, including suitability of the on-site materials for reuse as engineered fill, compaction requirements and suitable material guidelines.

• Logs of the soil borings and results of the laboratory tests performed.

2.0 PROJECT INFORMATION

2.1 SITE INFORMATION

The subject site is the Fort Bragg Officer’s Club located immediately south of the intersection of Totten Street and Armistead Street in Fort Bragg, North Carolina. The site location is shown n Figure 2.1.1 and indicated on the Site Location Diagram in Appendix A.

The site is currently developed with an existing building, asphalt pavements, pavers, concrete walkways, and landscaped areas. The existing ground surface is relatively flat, and we anticipate that the lowest finished floor elevation will be the same as that of the existing building.

Due to the developed nature of the site, the boring locations were adjusted in the field to avoid existing underground and overhead utilities. The approximate boring locations are indicated on the Boring Location Diagram in Appendix A.

ECS Project No. 33:5411 Page 3

Figure 2.1.1. Site Location

2.2 PROPOSED CONSTRUCTION

The project will consist of a one- and two-story extension on the west side of the existing one-story ballroom. The project will also include addition of a new mezzanine floor within the existing building. The planned building addition will be a steel-framed structure consisting of structural steel columns and beams and open-web steel joists. It is anticipated that the columns will be supported on shallow reinforced concrete spread footings with an anticipated maximum unfactored design load of approximately 120 kips in the two-story area.

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 FIELD EXPLORATION

Our exploration procedures are explained in greater detail in Appendix B including the insert titled Subsurface Exploration Procedures. Our scope of work included drilling five borings. Our borings were located with a handheld GPS unit and their approximate locations are shown on the Boring Location Diagram in Appendix A.

ECS Project No. 33:5411 Page 4

3.2 LABORATORY TESTING

Each sample was visually classified on the basis of texture and plasticity in accordance with ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedures) and including USCS classification symbols, and ASTM D2487 Standard Practice for Classification for Engineering Purposes (Unified Soil Classification System (USCS)). After classification, the samples were grouped in the major zones noted on the boring logs in Appendix B. The group symbols for each soil type are indicated in parentheses along with the soil descriptions. The stratification lines between strata on the logs are approximate; in situ, the transitions may be gradual.

The laboratory testing consisted of selected tests performed on samples obtained during our field exploration operations. Classification and index property tests performed on representative soil samples included four natural moisture content tests, four percent passing sieve number 200 (wash sieve) tests, and one Atterberg limits tests.

3.3 SUBSURFACE CHARACTERIZATION

The site is located within the Coastal Plain physiographic province. The Coastal Plain is typically characterized by marine, alluvial, and aeolian sediments that were deposited during periods of fluctuating sea levels and moving shorelines. Basal formations are typical of those laid down in a shallow sloping sea bottom; dense sand, consolidated clay, limestone, chalk, marl, claystone, and sandstone. Overburden soils include marine interbedded gravel, sand, silt, and clay. Many of the clays have been preconsolidated by desiccation from frequent rising and lowering of the sea level and groundwater table. Alluvial gravel, sand, silt, and clay are typically present near rivers and creeks.

The generalized subsurface conditions encountered in the borings are described below. For soil stratification at a particular test location, the respective boring log found in Appendix B should be reviewed.

Approximate Depth (ft.) Stratum Description Ranges of

SPT(1) N-values (bpf)

0 to 0.5 (Surface Cover) N/A The borings encountered approximately 4 to 6 inches of topsoil N/A

0.5 to 8 I Very Loose to Medium Dense SAND (SP, SP-SM) 3 to 12(2)

8 to 20 II Loose to Medium Dense SAND (SM, SP-SM, SP, SC, SC-SM) with an intermittent layer of Very Stiff SILT (ML) 5 to 25

Notes:

(1) Standard Penetration Testing

(2) Predominantly Very Loose to Loose SAND (SPT N-values of 3 to 6 bpf). Medium Dense SAND (SPT N-value of 12 bpf) was encountered in Boring B-5 from about 5.5 to 8 feet below existing grades.

3.4 GROUNDWATER OBSERVATIONS

Water levels were measured in our borings as noted on the boring logs in Appendix B. Groundwater was not encountered in the borings during our field exploration to the depths explored. Variations in the long-term water table may occur as a result of changes in precipitation, evaporation, surface water runoff, construction activities, and other factors.

ECS Project No. 33:5411 Page 5

4.0 DESIGN RECOMMENDATIONS

4.1 FOUNDATIONS

Provided subgrades and structural fills are prepared as recommended in this report, the proposed structure can be supported by shallow foundations including column footings and continuous wall footings. We recommend the foundation design use the following parameters:

Design Parameter Column Footing Wall Footing

Net Allowable Bearing Pressure(1) 2,000 psf 2,000 psf Acceptable Bearing Soil Material Stable Natural Soil or Compacted Structural Fill

Minimum Width 30 inches 18 inches Minimum Footing Embedment Depth (below slab or finished grade) (2) 12 inches 12 inches

Estimated Total Settlement (3) Less than 1 inch Less than 1 inch

Estimated Differential Settlement (4) Less than ½ inch between columns Less than ½ inch

Notes:

(1) Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above the base of the foundation.

(2) For bearing considerations and frost penetration requirements.

(3) Based on anticipated structural loads. If final loads are different, ECS must be contacted to update foundation recommendations and settlement calculations.

(4) Based on maximum loads and variability in borings. Differential settlement can be re-evaluated once the foundation plans are more complete.

4.2 SLABS ON GRADE

The on-site natural soils are considered suitable for support of the lowest floor slabs. Assuming the lowest finished floor elevation is around the current site elevations, it appears that the slabs for the structure will bear on the near-surface Stratum I soils and/or approved structural fill. These materials are suitable for the support of a slab-on-grade; however, there may be areas of soft or yielding soils that should be removed and replaced with compacted structural fill in accordance with the recommendations included in this report. The following graphic depicts our soil-supported slab recommendations:

Figure 4.2.1 Slab-on-Grade Section

1. Drainage Layer Thickness: 4 inches, minimum

2. Drainage Layer Material: GRAVEL (GP, GW), SAND containing <12% fines (SP, SW, SP-SM, SW-SM)

2. Subgrade Compacted to at least 98% of the Maximum Dry Density per ASTM D698

Concrete Slab Vapor Barrier

Granular Capillary Break

Compacted Subgrade

ECS Project No. 33:5411 Page 6

Subgrade Modulus: Provided the Structural Fill and Granular Drainage Layer are constructed in accordance with our recommendations, the slab may be designed assuming a modulus of subgrade reaction, k1 of 175 psi/in (pci). The modulus of subgrade reaction value is based on 1 ft by 1 ft plate load test data and CBR correlations for similar soils.

Vapor Barrier: Before the placement of concrete, a vapor barrier may be placed on top of the granular drainage layer to provide additional protection against moisture penetration through the floor slab. When a vapor barrier is used, special attention should be given to surface curing of the slab to reduce the potential for uneven drying, curling and/or cracking of the slab. Depending on proposed flooring material types, the structural engineer and/or the architect may choose to eliminate the vapor barrier.

Slab Isolation: Soil-supported slabs should be isolated from the foundations and foundation-supported elements of the structure so that differential movement between the foundations and slab will not induce excessive shear and bending stresses in the floor slab. Where the structural configuration prevents the use of a free-floating slab such as in a drop down footing/monolithic slab configuration, the slab should be designed with suitable reinforcement and load transfer devices to avoid overstressing of the slab.

4.3 PAVEMENTS

Design Traffic Loading: We understand design traffic will be limited to light duty passenger vehicles in addition to occasional garbage trucks and food delivery trucks. The peak-hour light duty traffic is anticipated to include up to 60 passenger vehicles. We have assumed up to 1 garbage truck and 1 food delivery truck per week. Based on these assumptions, we estimate design traffic loading will be less than 15,000 ESALs in 20 years.

Subgrade Characteristics: Based on the results of our borings, it appears that the soils that will be exposed as pavement subgrades consist mainly of SAND (SP-SM, SP). California Bearing Ratio (CBR) testing was not performed as part of this study. For section thickness design purposes, a CBR value of 8 has been selected.

The pavement design assumes subgrades consist of suitable materials evaluated by ECS and placed and compacted to at least 98 percent of the maximum dry density as determined by the standard Proctor test (ASTM D 698) in accordance with the project specifications.

Minimum Material Thicknesses: Pavements for the project are expected to consist of light duty parking and drive-thru areas. In general, light duty sections are appropriate for vehicular traffic and parking areas.

We recommend the following minimum pavement sections for the project.

PROPOSED PAVEMENT SECTIONS

MATERIAL FLEXIBLE PAVEMENT RIGID PAVEMENT

Portland Cement Concrete (f’c = 4000 psi, air-entrained) - 6 inches

Asphaltic Concrete Surface Course (S9.5B) 2 inches -

Aggregate Base Course 6 inches 6 inches

ECS Project No. 33:5411 Page 7

ECS should be allowed to review these recommendations and make appropriate revisions based upon the formulation of the final traffic design criteria for the project. It is important to note that the design sections do not account for construction traffic loading.

It should also be noted that these design recommendations may not satisfy the North Carolina Department of Transportation traffic guidelines. Any roadways constructed for public use and to be dedicated to the State for repair and maintenance must be designed in accordance with the State requirements.

Large, front loading trash dumpsters frequently impose concentrated front wheel loads on pavements during loading. This type of loading typically results in rutting of bituminous pavements and ultimately pavement failures and costly repairs. Therefore, we suggest that the pavements in trash drive-thru areas utilize the aforementioned Portland Cement Concrete (PCC) pavement section. Appropriate steel reinforcing and jointing should also be incorporated into the design of PCC pavements.

The soil subgrade should be smooth-rolled and proofrolled prior to ABC placement. Areas that pump, rut, or are otherwise unstable should be re-compacted or undercut and replaced. The ABC should conform to the gradation, liquid limit, plasticity index, resistance to abrasion, and soundness per Section 1005 of the 2012 NCDOT Standard Specifications for Roads and Structures.

The ABC should be placed and be compacted in accordance with Section 520 of the 2012 NCDOT Standard Specifications for Roads and Structures. The ABC should be placed in a single lift. It should be spread after end-dumping on previously-placed ABC to prevent rutting and degradation of the relatively clean sand subgrade soils by rubber-tired dump trucks. The ABC should be compacted to at least 98 percent of its modified Proctor maximum dry unit weight per ASTM D1557 or AASHTO T180 (as modified by NCDOT), provided nuclear density testing is performed. Otherwise, at least 100% compaction is recommended.

To confirm that the specified degree of compaction is being obtained, field compaction testing should be performed in each ABC lift by the geotechnical engineer’s representative. We recommend that compaction tests be performed at a minimum frequency of one test per 5,000 square feet per lift in pavement areas.

Minimum Material Lift Thickness: The minimum lift thickness for S9.5B is 1.0 inch and the maximum lift thickness for S9.5B is 1.5 inches. For sections with more than 1.5 inches of S9.5B surface asphalt, it should be placed in two lifts of equal thickness. Asphalt pavement S9.5B should be compacted to least 90.0 percent of the material’s specific gravity Gmm.

Drainage: An important consideration with the design and construction of pavements is surface and subsurface drainage. Where standing water develops, either on the pavement surface or within the aggregate base course layer, softening of the subgrades and other problems related to the deterioration of the pavement can be expected. This is particularly important at the site due to the moisture sensitive near-surface soils. Furthermore, good drainage should help reduce the possibility of the subgrade materials becoming saturated during the normal service period of the pavement.

ECS Project No. 33:5411 Page 8

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 SUBGRADE PREPARATION

5.1.1 Previous Site Development

When reviewing our recommendations, please note that there are existing structures on this site, and that previous grading activities have occurred on the site. Our experience with previously graded sites indicates that unexpected conditions can exist that were not encountered by the soil test borings.

Unexpected conditions could include areas of soft or loose fill, debris-laden fill, and other obstructions or conditions. These conditions should be addressed by on-site engineering evaluation by ECS during construction.

5.1.2 Demolition

Site demolition should include the removal of the existing underground utilities, and any other buried structures from the proposed construction areas. Any underground utilities that may exist within the proposed building addition area should be relocated, and any within proposed pavement areas should be evaluated by the design team and relocated or filled with grout, if necessary. Excavations or cavities resulting from demolition should be backfilled with compacted structural backfill.

5.1.3 Stripping and Grubbing

The subgrade preparation should consist of stripping vegetation, rootmat, topsoil, and any soft or unsuitable materials from the 10-foot expanded building and 5-foot expanded pavement limits, where practical. The borings encountered approximately 4 to 6 inches of topsoil. ECS should be retained to verify that topsoil and unsuitable surficial materials have been removed prior to the placement of structural fill or construction of structures.

5.1.4 Proofrolling

After removing unsuitable surface materials, cutting to the proposed grade, and prior to the placement of any structural fill or other construction materials, the exposed subgrade should be examined by the geotechnical engineer or authorized representative. The exposed subgrade should be thoroughly densified in place using a 10-ton, self-propelled, vibratory smooth drum roller due to the very loose to loose sands encountered in the borings at the anticipated subgrade elevations. The exposed subgrade should then be proofrolled with approved construction equipment having a minimum axle load of 10 tons (e.g., fully loaded tandem-axle dump truck). The areas subject to proofrolling should be traversed by the equipment in two perpendicular (orthogonal) directions with overlapping passes of the vehicle under the observation of the geotechnical engineer or authorized representative. This procedure is intended to assist in identifying any localized yielding materials.

ECS Project No. 33:5411 Page 9

Where proofrolling identifies areas that are unstable or “pumping” subgrade those areas should be repaired prior to the placement of any subsequent structural fill or other construction materials. Methods of stabilization include undercutting, moisture conditioning, or chemical stabilization. The situation should be discussed with ECS to determine the appropriate procedure. Test pits may be excavated to explore the shallow subsurface materials to help in determining the cause of the observed unstable materials, and to assist in the evaluation of appropriate remedial actions to stabilize the subgrade.

Undercut excavations should be backfilled with properly placed and compacted structural fill. Use of geotextiles and select granular fill may be recommended by ECS during construction to reduce the required undercut depths and/or aid in stabilization of subgrades.

5.1.5 Site Temporary Dewatering

Based upon our subsurface exploration at this site, as well as significant experience on sites in nearby areas of similar geologic setting, we believe construction dewatering at this site will be mainly limited to removing accumulated rainwater and some minor seepage from the support of excavation.

Dewatering operations, if required, can be handled using conventional submersible pumps directly in the excavation or temporary trenches to direct the flow of water and to remove water from the excavation.

If temporary sump pits are used, we recommend they be established at an elevation 3 to 5 feet below the bottom of the excavation subgrade or bottom of footing. A perforated 55-gallon drum or other temporary structure could be used to house the pump.

5.2 EARTHWORK OPERATIONS

Structural Fill: Prior to placement of structural fill, representative bulk samples (about 50 pounds) of on-site and/or off-site borrow should be submitted to ECS for laboratory testing, which will typically include Atterberg limits, natural moisture content, grain-size distribution, and moisture-density relationships (i.e., Proctors) for compaction. Import materials should be tested prior to being hauled to the site to determine if they meet project specifications. Alternatively, Proctor data from other accredited laboratories can be submitted if the test results are within the last 90 days.

Satisfactory Structural Fill Materials: Materials satisfactory for use as structural fill should consist of inorganic soils with the following engineering properties and compaction requirements.

STRUCTURAL FILL INDEX PROPERTIES

Subject Property

Building and Pavement Areas LL < 40, PI < 20

Max. Particle Size 3 inches

Max. Organic Content 2% by dry weight

ECS Project No. 33:5411 Page 10

STRUCTURAL FILL COMPACTION REQUIREMENTS

Subject Requirement

Compaction Standard Standard Proctor, ASTM D698

Required Compaction 98% of Max. Dry Density within top 12 inches, and 95% elsewhere

Moisture Content -3 to +3 % points of the soil’s optimum value

Loose Thickness 8 inches prior to compaction

On-Site Borrow Suitability: The on-site soils meeting the classifications for recommended satisfactory structural fill, plus meeting the restrictions on organic content and debris, may be used as structural fill.

We anticipate that most soils encountered in the borings within the anticipated excavation depths will be satisfactory for use as compacted structural fill. On-site soils used as structural fill will require careful moisture control to achieve compaction and stability.

Fill Placement: Fill materials should not be placed on frozen soils, on frost-heaved soils, and/or on excessively wet soils. Borrow fill materials should not contain frozen materials at the time of placement, and frozen or frost-heaved soils should be removed prior to placement of structural fill or other fill soils and aggregates. Excessively wet soils or aggregates should be scarified, aerated, and moisture conditioned.

5.3 FOUNDATION AND SLAB OBSERVATIONS

Protection of Foundation Excavations: Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time. Therefore, foundation concrete should be placed the same day that excavations are made. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, a 1 to 3-inch thick “mud mat” of “lean” concrete should be placed on the bearing soils before the placement of reinforcing steel.

Footing Subgrade Observations: Most of the soils at the foundation bearing elevation are anticipated to be suitable for support of the proposed structure. It is important to have ECS observe the foundation subgrade prior to placing foundation concrete, to confirm the bearing soils are what was anticipated.

Slab Subgrade Verification: A representative of ECS should be called to observe exposed subgrades within the expanded building limits prior to structural fill placement to assure that adequate subgrade preparation has been achieved. Proofrolling using a drum roller or loaded dump truck should be performed in their presence at that time. Once subgrades have been determined to be firm and stable, structural fill can be placed.

ECS Project No. 33:5411 Page 11

If there will be a significant time lag between the site grading work and final grading of concrete slab areas prior to the placement of the design floor slab section materials, a representative of ECS should be called to verify the condition of the prepared soil subgrade. Prior to final floor slab section construction, the soil subgrade may require scarification, moisture conditioning, and re-compaction to restore stable conditions.

5.4 UTILITY INSTALLATIONS

Utility Subgrades: The soils encountered in our exploration are expected to be generally suitable for support of utility pipes. The pipe subgrades should be observed and probed for stability by ECS. Any loose or unsuitable materials encountered should be removed and replaced with suitable compacted Structural Fill, or pipe stone bedding material.

Utility Backfilling: The granular bedding material (often AASHTO #57 stone) should be at least 4 inches thick, but not less than that specified by the civil engineer’s project drawings and specifications. We recommend that the bedding materials be placed up to the springline of the pipe. Fill placed for support of the utilities, as well as backfill over the utilities, should satisfy the requirements for structural fill and fill placement.

Excavation Safety: Excavations and slopes should be constructed and maintained in accordance with OSHA excavation safety standards. The contractor is solely responsible for designing, constructing, and maintaining stable temporary excavations and slopes. The contractor’s responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. ECS is providing this information solely as a service to our client. ECS is not assuming responsibility for construction site safety or the contractor’s activities; such responsibility is not being implied and should not be inferred.

ECS Project No. 33:5411 Page 12

6.0 CLOSING

ECS has prepared this report to guide the geotechnical-related design and construction aspects of the project. We performed these services in accordance with the standard of care expected of professionals in the industry performing similar services on projects of like size and complexity at this time in the region.

No other representation, expressed or implied, and no warranty or guarantee is included or intended in this report.

The description of the proposed project is based on information provided to ECS by Raymond Engineering.

If any of this information is inaccurate or changes, either because of our interpretation of the documents provided or site or design changes that may occur later, ECS should be contacted so we can review our recommendations and provide additional or alternate recommendations that reflect the proposed construction.

We recommend that ECS review the project plans and specifications so we can confirm that those plans/specifications are in accordance with the recommendations of this geotechnical report.

Field observations, and quality assurance testing during earthwork and foundation installation are an extension of, and integral to, the geotechnical design. We recommend that ECS be retained to apply our expertise throughout the geotechnical phases of construction, and to provide consultation and recommendation should issues arise.

ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in this report.

APPENDIX A – Diagrams & Reports

Site Location Diagram Boring Location Diagram

Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

²

RAYMOND CONSTRUCTION

LAFAYETTE BALLROOM ADDITION

TOTTEN ST. & ARMISTEAD ST., FORT BRAGG, NC

Site Location Diagram

0 3,0001,500 Feet

12/14/2020

ENGINEER

SCALE

33:5411

FIGURE 1

PROJECT NO.

SHEET

DATE

BB

AS NOTED

B-3

B-4

B-1

B-2 B-5

Service Layer Credits: Esri, HERE, Garmin, (c) OpenStreetMap contributors

²

Legend Approximate boring locations

RAYMOND CONSTRUCTION

LAFAYETTE BALLROOM ADDITION

TOTTEN ST. & ARMISTEAD ST., FORT BRAGG, NC

Boring Location Diagram

0 10050 Feet

12/14/2020

ENGINEER

SCALE

33:5411

FIGURE 2

PROJECT NO.

SHEET

DATE

BB

AS NOTED

APPENDIX B – Field Operations

Reference Notes for Boring Logs Subsurface Exploration Procedure: Standard Penetration Test (SPT) Boring Logs B-1 through B-5

REFERENCE NOTES FOR BORING LOGS

MATERIAL1,2

1Classifications and symbols per ASTM D 2488-17 (Visual-Manual Procedure) unless noted otherwise.

2To be consistent with general practice, “POORLY GRADED” has been removed from GP, GP-GM, GP-GC, SP, SP-SM, SP-SC soil types on the boring logs.

3Non-ASTM designations are included in soil descriptions and symbols along with ASTM symbol [Ex: (SM-FILL)].

4Typically estimated via pocket penetrometer or Torvane shear test and expressed in tons per square foot (tsf).

5Standard Penetration Test (SPT) refers to the number of hammer blows (blow count) of a 140 lb. hammer falling 30 inches on a 2 inch OD split spoon sampler required to drive the sampler 12 inches (ASTM D 1586). “N-value” is another term for “blow count” and is expressed in blows per foot (bpf). SPT correlations per 7.4.2 Method B and need to be corrected if using an auto hammer.

6The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in granular soils. In clay and cohesive silts, the determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally employed.

7Minor deviation from ASTM D 2488-17 Note 14.

8Percentages are estimated to the nearest 5% per ASTM D 2488-17.

Reference Notes for Boring Logs (10-14-2020).doc © 2020 ECS Corporate Services, LLC. All Rights Reserved

COHESIVE SILTS & CLAYS

UNCONFINED

COMPRESSIVE

STRENGTH, QP4

<0.25

0.25 - <0.50

0.50 - <1.00

1.00 - <2.00

2.00 - <4.00

4.00 - 8.00

>8.00

SPT5

(BPF)

CONSISTENCY7

(COHESIVE)

GRAVELS, SANDS & NON-COHESIVE SILTS

SPT5

DENSITY

<5 5 - 10

11 - 30 31 - 50

>50

Very Loose Loose

Medium Dense Dense

Very Dense

WATER LEVELS6

RELATIVE

AMOUNT7

Trace

With

Adjective (ex: “Silty”)

COARSE

GRAINED

(%)8

<5

FINE

GRAINED

(%)8

<5

DRILLING SAMPLING SYMBOLS & ABBREVIATIONS

PARTICLE SIZE IDENTIFICATION

DESIGNATION PARTICLE SIZES

Hollow Stem Auger Power Auger (no sample) Bulk Sample of Cuttings Wash Sample Shelby Tube Sampler Split Spoon Sampler

Rock Quality Designation % Rock Sample Recovery % Rock Core, NX, BX, AX Rock Bit Drilling Pressuremeter TestSS

ST

WS

BS

PA

HSA

RQD

PM

RD

RC

REC

Boulders Cobbles

Gravel:

Sand:

Silt & Clay (“Fines”) Fine Medium

Coarse Fine Coarse

0.074 mm to 0.425 mm (No. 200 to No. 40 sieve) <0.074 mm (smaller than a No. 200 sieve)

0.425 mm to 2.00 mm (No. 40 to No. 10 sieve)

2.00 mm to 4.75 mm (No. 10 to No. 4 sieve)

4.75 mm to 19 mm (No. 4 sieve to ¾ inch) ¾ inch to 3 inches (19 mm to 75 mm) 3 inches to 12 inches (75 mm to 300 mm) 12 inches (300 mm) or larger

>50 31 - 50 16 - 30

9 - 15 5 - 8 3 - 4 <3

Very Hard Hard

Very Stiff

Stiff Firm Soft

Very Soft

ASPHALT

CONCRETE

GRAVEL

TOPSOIL

VOID

BRICK

AGGREGATE BASE COURSE

GW

GP

GM

GC

SW

SP

SM

SC

ML

MH

CL

CH

OL

OH

PT

WELL-GRADED GRAVEL

gravel-sand mixtures, little or no fines

POORLY-GRADED GRAVEL

gravel-sand mixtures, little or no fines

SILTY GRAVEL

gravel-sand-silt mixtures

CLAYEY GRAVEL

gravel-sand-clay mixtures

WELL-GRADED SAND

gravelly sand, little or no fines

POORLY-GRADED SAND

gravelly sand, little or no fines

SM SILTY SAND

sand-silt mixtures

CLAYEY SAND

sand-clay mixtures

SILT

non-plastic to medium plasticity

ELASTIC SILT

high plasticity

LEAN CLAY

low to medium plasticity

FAT CLAY

high plasticity

ORGANIC SILT or CLAY non-plastic to low plasticity

ORGANIC SILT or CLAY high plasticity

PEAT

highly organic soils

WL (First Encountered)

WL (Completion)

WL (Seasonal High Water)

WL (Stabilized)

FILL POSSIBLE FILL PROBABLE FILL ROCK

FILL AND ROCK

25 - 45

10 - 20

30 - 45

10 - 25

SUBSURFACE EXPLORATION PROCEDURE:

STANDARD PENETRATION TEST (SPT) - ASTM D 1586

Split-Barrel Sampling

The Standard Penetration Test (SPT) is the most frequently used subsurface exploration test performed worldwide. This test provides samples for identification purposes, as well as a measure of penetration resistance, or N-value. The SPT N-value (or blow counts), when corrected and correlated, can be used to approximate the engineering properties of soils for geotechnical design and engineering purposes.

Involves driving a 2-inch outer diameter split-barrel (split-spoon) sampler into the soil by dropping a 140-lb hammer a height of 30 inches at the desired test depth.

Recording the number of hammer blows required to drive the split-spoon sampler a distance of 18 to 24 inches (in 3 or 4 increments of 6 inches each).

The SPT N-value (blows per foot) is determined by summing the blow counts for the 2nd and 3rd six-inch internals.

The boring is advanced* to the desired depths and additional SPTs are performed.

SPT tests are typically performed at 2½-foot intervals within the upper 10 feet of the boring and 5-foot intervals thereafter.

Soil samples are obtained at each test depth for visual classification and laboratory testing.

The drill rig is equipped with either an automatic hammer or a rope and cathead driving assembly. The automatic hammer generally delivers more energy to the sampler than the standard cathead assembly.

Although the differences in energy will vary, it is common to assume the automatic hammer delivers about 1.3 times the energy of the cathead assembly.

The uncorrected N-values recorded in the field are typically reported on the soil test boring logs.

*Drilling methods may vary, but the predominant drilling methods used for SPT are the open hole fluid rotary (mud rotary) drilling and hollow-stem auger drilling.

SPT Procedure:

DE

PT

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

S-6

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[4"] (SP) FINE TO MEDIUM SAND, brown to tan, moist, very loose to loose

(SM) SILTY FINE TO MEDIUM SAND, tan to orange, moist, loose to medium dense

(ML) SANDY SILT, gray, moist, very s

END OF DRILLING AT 20.0 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6"

3-3-2 (5)

2-2-2 (4)

2-3-3 (6)

3-4-6 (10)

4-9-11 (20)

4-9-12 (21)

Plas c Limit Water Content Liquid Limit X─────────⚫─────────△

21 20.1 [75.4%]

CLIENT:

Raymond Construc on

PROJECT NAME:

Lafaye e Ballroom Addi on

PROJECT NO.: BORING NO.:

33:5411 B-1

DRILLER/CONTRACTOR:

Carolina Drilling

SHEET:

SITE LOCATION:

To en Street & Armistead Street, Fort Bragg, North Carolina 28307

LOSS OF CIRCULATION

NORTHING: EASTING: STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

NE

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

Track CME 45

Nov 18 2020

Nov 18 2020

LOGGED BY:

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

HSA

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION BLOWS/FT

ROCK QUALITY DESIGNATION & RECOVERY

RQD

REC

CALIBRATED PENETROMETER TON/SF

[FINES CONTENT] %

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

S-6

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"]

(SP-SM) FINE TO MEDIUM SAND WITH

SILT, tan, orange, moist, very loose to loose

(SM) SILTY FINE TO MEDIUM SAND,

orange, tan, moist, medium dense

(SP-SM) FINE TO MEDIUM SAND WITH

SILT, tan, gray, moist, loose

(SP) FINE TO MEDIUM SAND, tan, moist, loose

END OF DRILLING AT 20.0 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6"

2-2-1 (3)

2-2-2 (4)

2-2-3 (5)

3-5-7 (12)

3-2-3 (5)

4-4-5 (9)

Plas c Limit Water Content Liquid Limit X─────────⚫─────────△

6.3 [8.9%]

CLIENT:

Raymond Construc on

PROJECT NAME:

Lafaye e Ballroom Addi on

PROJECT NO.: BORING NO.:

33:5411 B-2

DRILLER/CONTRACTOR:

Carolina Drilling

SHEET:

SITE LOCATION:

To en Street & Armistead Street, Fort Bragg, North Carolina 28307

LOSS OF CIRCULATION

NORTHING: EASTING: STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

NE

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

Track CME 45

Nov 18 2020

Nov 18 2020

LOGGED BY:

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

HSA

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION BLOWS/FT

ROCK QUALITY DESIGNATION & RECOVERY

RQD

REC

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

S-6

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"] (SP) FINE TO MEDIUM SAND, tan, orange, moist, very loose to loose

(SM) SILTY FINE TO MEDIUM SAND,

orange, moist, loose

(SP-SM) FINE TO MEDIUM SAND WITH

SILT, orange, moist, loose

(SM) SILTY FINE TO MEDIUM SAND,

orange, moist, medium dense

END OF DRILLING AT 20.0 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6"

1-2-2 (4)

2-2-3 (5)

2-2-3 (5)

3-2-4 (6)

4-3-4 (7)

4-7-7 (14)

Plas c Limit Water Content Liquid Limit X─────────⚫─────────△

CLIENT:

Raymond Construc on

PROJECT NAME:

Lafaye e Ballroom Addi on

PROJECT NO.: BORING NO.:

33:5411 B-3

DRILLER/CONTRACTOR:

Carolina Drilling

SHEET:

SITE LOCATION:

To en Street & Armistead Street, Fort Bragg, North Carolina 28307

LOSS OF CIRCULATION

NORTHING: EASTING: STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

NE

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

Track CME 45

Nov 18 2020

Nov 18 2020

LOGGED BY:

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

HSA

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION BLOWS/FT

ROCK QUALITY DESIGNATION & RECOVERY

RQD

REC

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

S-6

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"] (SP) FINE TO MEDIUM SAND, brown to orange, moist, very loose to loose

(SC-SM) SILTY CLAYEY SAND, orange, gray, moist, loose

END OF DRILLING AT 20.0 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6"

2-3-3 (6)

1-2-2 (4)

2-3-2 (5)

2-3-3 (6)

4-4-6 (10)

2-3-4 (7)

Plas c Limit Water Content Liquid Limit X─────────⚫─────────△

19.7 [39.7%]

CLIENT:

Raymond Construc on

PROJECT NAME:

Lafaye e Ballroom Addi on

PROJECT NO.: BORING NO.:

33:5411 B-4

DRILLER/CONTRACTOR:

Carolina Drilling

SHEET:

SITE LOCATION:

To en Street & Armistead Street, Fort Bragg, North Carolina 28307

LOSS OF CIRCULATION

NORTHING: EASTING: STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

NE

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

Track CME 45

Nov 18 2020

Nov 18 2020

LOGGED BY:

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

HSA

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION BLOWS/FT

ROCK QUALITY DESIGNATION & RECOVERY

RQD

REC

CALIBRATED PENETROMETER TON/SF

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

S-6

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"] (SP) FINE TO MEDIUM SAND, tan, brown, moist, very loose

(SP) FINE TO MEDIUM SAND, trace gravel, tan, orange, moist, medium dense (SC) CLAYEY FINE TO MEDIUM SAND, red, orange, moist, medium dense

(SM) SILTY FINE TO MEDIUM SAND,

orange, moist, medium dense

END OF DRILLING AT 20.0 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6"

2-1-2 (3)

3-1-2 (3)

3-5-7 (12)

3-8-17 (25)

4-6-6 (12)

5-7-6 (13)

Plas c Limit Water Content Liquid Limit X─────────⚫─────────△

15.4 [27.0%]

CLIENT:

Raymond Construc on

PROJECT NAME:

Lafaye e Ballroom Addi on

PROJECT NO.: BORING NO.:

33:5411 B-5

DRILLER/CONTRACTOR:

Carolina Drilling

SHEET:

SITE LOCATION:

To en Street & Armistead Street, Fort Bragg, North Carolina 28307

LOSS OF CIRCULATION

NORTHING: EASTING: STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

NE

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

Track CME 45

Nov 18 2020

Nov 18 2020

LOGGED BY:

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

HSA

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION BLOWS/FT

ROCK QUALITY DESIGNATION & RECOVERY

RQD

REC

CALIBRATED PENETROMETER TON/SF

APPENDIX C – Laboratory Testing

Laboratory Test Results Summary

S-6 20.1 75.4

S-1 6.3 8.9

S-6 19.7 22 18 4 39.7

S-4 15.4 27

Client:

Laboratory Testing Summary

Sample

Source

Sample

Number

Depth

(feet)

MC

Soil Type

Atterberg Limits Percent

Passing

No. 200

Sieve

Moisture - Density

LBR (%)

Organic

Content (%)

LL PL PI

Maximum

Density (pcf)

Optimum

Moisture (%)

B-1 18.5-20

B-2 1-2.5

B-4 18.5-20

B-5 8.5-10

Notes: See test reports for test method, *ASTM D2488 Definitions:

MC: Moisture Content, Soil Type: USCS (Unified Soil Classification System), LL: Liquid Limit, PL: Plastic Limit, PI: Plasticity Index, CBR: California Bearing Ratio, OC: Organic Content

Project: Lafayette Ballroom Addition Project No.: 33:5411 Raymond Construction Date Reported:

Office / Lab Address Office Number / Fax

ECS Southeast LLP - Fayetteville 6151 Raeford Road

Suite A Fayetteville, NC 28304

(910)401-3288

(910)323-0539

Tested by Checked by Approved by Date Received djohnson djohnson djohnson

*ML

*SP-SM

SC-SM

*SC