S02_Attachment - 876CM3025 Salibury NC Annex II BID SET Geotech Report.pdf

10121 Pineville Distribution St, Pineville, North Carolina 28134 | phone 704-504-1717 | fax 305-249-8479 www.summit-companies.com

REPORT OF GEOTECHNICAL SUBSURFACE EXPLORATION

SALISBURY NATIONAL CEMETERY

501 STATESVILLE BLVD. & 202 GOVERNMENT RD.

SALISBURY, NORTH CAROLINA

SUMMIT PROJECT NO. 7884.G0011

Prepared For:

Mr. Mark Shumpert KCI Technologies, Inc.

3014 Southcross Blvd

Rock Hill, SC 29730 Email: Mark.Shumpert@kci.com

Prepared By:

SUMMIT Engineering, Laboratory & Testing, Inc. (SUMMIT) 10121 Pineville Distribution Street

Pineville, North Carolina 28134

August 25, 2023 i

10121 Pineville Distribution Street, Pineville, North Carolina 28134 www.summit-companies.com

August 25, 2023

Mr. Mark Shumpert KCI Technologies, Inc.

3014 Southcross Blvd Rock Hill, SC 29730 Email: Mark.Shumpert@kci.com

Subject: Report of Geotechnical Subsurface Exploration Salisbury National Cemetery 501 Statesville Blvd. & 202 Government Rd.

Salisbury, North Carolina SUMMIT Project No. 7884.G0011

Dear Mr. Shumpert:

SUMMIT Engineering, Laboratory & Testing, Inc. (SUMMIT) has completed a geotechnical subsurface exploration for the Salisbury National Cemetery site located at 501 Statesville Blvd. & 202 Government Rd. in Salisbury, North Carolina. This subsurface exploration was performed in general accordance with our Proposal No. 7884.G0011 dated July 12, 2023, and subsequent conversations and email correspondence. This report contains a brief description of the project information provided to us, general site and subsurface conditions revealed during our geotechnical subsurface exploration and our general recommendations regarding foundation design and construction.

SUMMIT appreciates the opportunity to be of service to you on this project. If you have any questions concerning the information presented herein or if we can be of further assistance, please feel free to call us at (704) 504-1717.

Sincerely yours, SUMMIT Engineering, Laboratory & Testing, Inc.

Christian Payne L. Brian Cantrell, P.E.

Assistant Project Manager Geotechnical Dept. Manager

8/25/2023

Christian Payne Stamp

Report of Geotechnical Subsurface Exploration SUMMIT Project No. 7884.G0011 Salisbury National Cemetery August 25, 2023 ii www.summit-companies.com

TABLE OF CONTENTS

SECTION Page

EXECUTIVE SUMMARY ................................................................................................................................. iv

1.0 INTRODUCTION

1.1. Site and Project Description

1.2. Purpose of Subsurface Exploration

2.0 EXPLORATION PROCEDURES

2.1. Field Exploration

3.0 AREA GEOLOGY AND SUBSURFACE CONDITIONS

3.1. Physiography and Area Geology

3.2. Generalized Subsurface Stratigraphy

3.2.1. Surface Materials

3.2.2. Alluvial Soils

3.2.3. Existing Fill Soils

3.2.4. Residual Soils

3.2.5. Partially Weathered Rock and Auger Refusal

3.2.6. Groundwater Level Measurements

3.3. Summary of Laboratory Testing

Laboratory Testing Services

4.0 EVALUATIONS AND RECOMMENDATIONS

4.1. General

4.2. Shallow Foundation Recommendations

4.3. Retaining Wall Recommendations (if used)

4.4. Temporary and Permanent Dewatering

4.5. Seismic Site Class

4.6. Low to Moderate Plasticity Moisture Sensitive Soils (CL and MH)

4.7. Wet Weather Conditions

4.8. Floor Slabs

4.9. Pavements Subgrade Preparation

4.10. Cut and Fill Slopes

5.0 PAVEMENT RECOMMENDATIONS

Flexible Pavement Section

Rigid Duty Pavement Sections

6.0 CONSTRUCTION CONSIDERATIONS

6.1. Abandoned Utilities/Structures

6.2. Site Preparation

6.3. Difficult Excavation

6.4. Temporary Excavation Stability

6.5. Structural Fill

6.6. Suitability of Excavated Soils for Re-Use

6.7. Engineering Services During Construction

7.0 RELIANCE AND QUALIFICATIONS OF REPORT

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APPENDIX 1 - Figures

Site Vicinity Map (Figure 1) Boring Location Plan (Figure 2)

APPENDIX 2 – Mechanical Boring Logs

APPENDIX 3 - Asphalt Cores & Hand Auger Borings and Photos

APPENDIX 4 – Summary of Laboratory Testing iv www.summit-companies.com

EXECUTIVE SUMMARY

SUMMIT has completed a geotechnical subsurface exploration for the Salisbury National Cemetery project. The purpose of this exploration was to obtain general information regarding the subsurface conditions and to provide geotechnical recommendations regarding foundation support of the proposed construction. This exploration consisted of eighteen (18) soil test borings (identified as B-1 through B-12, SW-13, and SW-14 through B-18) and six (6) asphalt cores with hand augers (identified as C-1 through C-6). The approximate test locations are shown in Figures 2 and 3 provided in Appendix 1. The following geotechnical engineering information was obtained as a result of the soil test borings:

• Surface Materials Soil Borings – Surficial organic (topsoil) soils were observed at the existing ground surface of the borings with estimated thicknesses ranging from approximately 3 to 4 inches.

• Surface Materials Asphalt Cores – Surficial asphalt was observed at the existing ground surface of the cores with estimated thicknesses ranging from approximately 1.25 to 3 inches.

Base material was observed below the asphalt with estimated thicknesses ranging from approximately 5 to 12.5 inches.

• Alluvial Soils - Alluvial (water-deposited) soils were encountered beneath the surface materials in Boring B-1 to an approximate depth of 3 feet below the existing ground surface.

When sampled, the alluvial soils generally consisted of sandy silts (ML).

• Existing Fill Soils – Existing fill (disturbed) soils were encountered beneath the surface materials in Borings B-18, C-3, and C-5 at approximate depths of 1, 1.2, and 1 foot below the existing ground surface. When sampled, the existing fill soils generally consisted of silty sands (SM) and lean clays (CL).

• Residual Soils – Residual (undisturbed) soils were encountered below the surface materials, existing fill soils, or alluvial soils and extended to either the maximum boring termination depth or partially weathered rock (PWR). These residual soils generally consisted of elastic silts (MH), sandy silts (ML), and silty sands (SM). The Standard Penetration Resistances (SPT N-values) in the residual soils ranged from 0 to 26 bpf.

• Partially Weathered Rock (PWR) and Auger Refusal – Partially weathered rock (PWR) conditions were encountered in five (5) of the borings at approximate depths ranging from 1 to 17 feet below the existing ground surface. Mechanical auger refusal conditions were encountered in four (4) of the borings at approximate depths ranging from 5.6 to 19.1 feet below the existing ground surface. Hand auger refusal was encountered in all the asphalt cores/hand augers at approximate depths ranging from 0.83 to 2.33 feet below the existing ground surface.

• Groundwater Levels – At the time of drilling, groundwater was observed in Borings B-1 and B-2 at approximate depths of 7 and 9 feet below the existing ground surface. After waiting v www.summit-companies.com more than 24 hours, water was not observed in Boring SW-13.

• Foundation Support – Based on the results of our borings, the proposed structures can be adequately supported on shallow foundation systems provided site preparation and compacted fill recommendation procedures outlined in this report are implemented concerning unsuitable soils such as alluvial soils, existing fill soils, and soils with N-values less than 6 bpf. An allowable net bearing pressure of up to 2,000 pounds per square foot (psf) can be used for design of the foundations bearing on approved undisturbed residual soils, or on structural fill compacted to at least 95 percent of its Standard Proctor maximum dry density.

• Seismic Site Class – We have determined the Seismic Site Classification for this project site in accordance with Chapter 20 of ASCE 7 “Minimum Design Loads Criteria for Buildings and Other Structures, Site Class Definitions using SPT N-Values. We recommend this project be designed using a Seismic Site Class of “E” (Soft Clay soil profile) as defined in Table 20.3-1.

• Special Construction Considerations: Special considerations are warranted concerning alluvial soils, existing fill soils, and soils with SPT N-values less than 7 bpf. Dependent on final grades, the contractor can anticipate that some undercutting and/or foundation extension may be necessary through unsuitable soils if encountered during grading and construction.

Should unsuitable soils be encountered during the grading and construction activities, these soils should be inspected in the field by a Geotechnical Engineer-of-Record and/or their designee prior to remediation. Additional testing such as test pit excavations and/or hand auger borings may be required in order to further explore these soil conditions, depths and locations.

o Alluvial Soils: Alluvial (water-deposited) soils were encountered beneath the surface materials in Boring B-1 to an approximate depth of 3 feet below the existing ground surface. Alluvial soils are typically encountered in or near drainage features, pond bottoms, creeks and in low-lying areas. Alluvial soils are generally loose and/or under-compacted and, as such, are typically unsuitable for supporting the proposed construction. Therefore, remediation may be required wherever alluvial soils are encountered during grading activities.

o Existing Fill Soils: At the time of this report, no relevant information (documentations) regarding previous grading activities, prior materials testing, and/or geotechnical engineering services was provided for our review. Boring B-18 encountered undocumented fill soils (fill soils not monitored and tested during placement).

Undocumented fill poses risks associated with undetected deleterious materials within the fill soils and/or deleterious material at the interface between the fill soils and residual soils.

o Soils with SPT N-values less than 6 bpf: Soils that exhibited SPT N-values less than 6 bpf are considered not suitable for the direct support of the proposed construction. These soil conditions were encountered in sixteen (16) of the borings at various depths.

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Depending on the final design grades, if the lower consistency soils are present in the near-surface (i.e., upper 1.5 to 3 feet), some undercutting, re-working or stabilization may be required. Stabilization measures could potentially consist of using a geogrid and subsequent layers of stone or using soil bridge lifts (in non-structural areas). Specific stabilization recommendations can typically be developed at the time of construction through routine field engineering decisions.

o Difficult Excavation: The results of the borings indicated that the excavation of residual soils is possible with conventional excavating techniques. However, please note that partially weathered rock (PWR) conditions were encountered in five (5) of the borings and mechanical auger refusal conditions were encountered in four (4) of the borings performed for this exploration. Dependent on final grades and locations, the contractor should anticipate the excavations of PWR and auger refusal conditions will require specialized equipment and procedures.

Please note that the information provided in this executive summary is intended to be a brief overview of project information and recommendations from the geotechnical report. The information in the executive summary should not be used without first reading the geotechnical report in its entirety and the recommendations described therein.

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1.0 INTRODUCTION

1.1. Site and Project Description

The Salisbury National Cemetery site is located at 501 Statesville Blvd. & 202 Government Rd. in

Salisbury, North Carolina. A vicinity map showing the project’s general location is provided as

Figure 1. The subject property is approximately 30 acres comprised of Rowan County Tax Parcel

ID Numbers 1008583 and 015505. At the time of our field exploration, the subject site was a mix of paved roadways and wooded, undeveloped land.

The Client (KCI Technologies, Inc.) provided SUMMIT a plan sheet prepared by Architura

Corporation, that indicated the configurations of the proposed construction planned for this project. Based on the provided information, we understand the project is planned to include an expansion of the existing cemetery.

At the time of report preparation, SUMMIT had not been provided structural details of the planned construction indicating proposed loads, foundation bearing elevations, or finished floor elevations. For this report, SUMMIT assumed the proposed structures will be supported on a shallow foundation system consisting of spread, strip, and/or combined footings and that wall loads will be on the order of 1 to 3 kips per foot. Also, grading plans were not available at the time of this report and we have assumed that maximum cut/fill depths will be on the order of 1 to 3 feet over the existing ground surface.

1.2. Purpose of Subsurface Exploration

The purpose of this exploration was to obtain general geotechnical information regarding the subsurface conditions and to provide general preliminary recommendations regarding the geotechnical aspects of site preparation and foundation design. This report contains the following items:

• General subsurface conditions, www.summit-companies.com

• Boring logs and an approximate “Boring Location Plan”,

• Suitable foundation types,

• Allowable bearing pressures for design of shallow foundations,

• Anticipated excavation difficulties during site grading and/or utility installation,

• Remedial measures to correct unsatisfactory soil conditions during site development, as needed,

• Drainage requirements around structures and under floor slabs, as needed,

• Construction considerations,

• Pavement subgrade support guidelines and pavement sections,

• Seismic Site Classification based on SPT N-values.

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2.0 EXPLORATION PROCEDURES

2.1. Field Exploration

SUMMIT visited the site on July 27th, August 1st, 2nd, and 9th of 2023 and performed a subsurface exploration that consisted of eighteen (18) soil test borings (identified as B-1 through B-12, SW-

13, and B-14 through B-18). The approximate locations of the borings are shown on the Figure 2

- “Boring Location Plan” provided in Appendix 1. The borings were located by professionals from our office using the provided plan, recreation-grade handheld GPS, existing topography, and aerial maps as reference. Since the boring locations were not surveyed, the location of the borings should be considered approximate.

The soil test borings were performed using an ATV-mounted CME 550X drill rig and extended to approximate depths of 5.6 to 25 feet below the existing ground surface. Hollow-stem, continuous flight auger drilling techniques were used to advance the borings into the ground. Standard

Penetration Tests (SPT) were performed within the mechanical borings at designated intervals in general accordance with ASTM D 1586. The SPT “N” value represents the number of blows required to drive a split-barrel sampler 12 inches with a 140-pound hammer falling from a height of 30 inches. When properly evaluated, the SPT results can be used as an index for estimating soil strength and density. In conjunction with the penetration testing, representative soil samples were obtained from each test location and returned to our laboratory for visual classification in general accordance with ASTM D 2488. Water level measurements were attempted at the termination of drilling. The results of these tests are presented on the individual boring logs provided in Appendix 2 at the respective test depth.

Asphalt cores were performed using a Milwaukee 4097 Diamond Core with asphalt cores ranging from approximately 1.25 to 3 inches in thickness. Hand auger borings were advanced to approximate depths of 0.83 to 2.33 feet below each asphalt core. Split-barrel soil samples were recovered from each of the mechanical borings for soil classification and potential laboratory testing. Within each of the hand auger borings, the soil cuttings were only described for general field reference and should be considered approximate due to the degree of sample disturbance www.summit-companies.com inherent with hand auger testing. The results of these tests are presented on “Asphalt Cores &

Hand Auger Borings” provided in Appendix 3 at the respective test depth.

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3.0 AREA GEOLOGY AND SUBSURFACE CONDITIONS

3.1. Physiography and Area Geology

The subject property is located in Salisbury, North Carolina, which is located in the south central

Piedmont Physiographic Province. The Piedmont Province generally consists of well-rounded hills and ridges which are dissected by a well-developed system of draws and streams. The Piedmont

Province is predominantly underlain by metamorphic rock (formed by heat, pressure and/or chemical action) and igneous rock (formed directly from molten material) which were initially formed during the Precambrian and Paleozoic eras. The volcanic and sedimentary rocks deposited in the Piedmont Province during the Precambrian era were the host of the metamorphism and were generally changed to gneiss and schist. The more recent Paleozoic era had periods of igneous emplacement, with episodes of regional metamorphism resulting in the majority of the rock types seen today.

The topographic relief found throughout the Piedmont Province has developed from differential weathering of theses igneous and metamorphic rock formations. Ridges developed along the more easily weathered and erodible rock. Because of the continued chemical and physical weathering, the rocks in the Piedmont Province are generally covered with a mantle of soil that has weathered in-place from the parent bedrock below. These soils have variable thicknesses and are referred to as residual soils, as they are the result of in-place weathering. Residual soils are typically fine-grained and have a higher clay content near the ground surface because of the advanced weathering. Similarly, residual soils typically become more coarse-grained with increasing depth because of decreased weathering. As weathering decreases with depth, residual soils generally retain the overall appearance, texture, gradation and foliations of their parent rock.

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3.2. Generalized Subsurface Stratigraphy

General subsurface conditions observed during our geotechnical exploration are described herein. For more detailed soil descriptions and stratifications at a particular field test location, the respective “Boring Logs”, provided in Appendix 2 should be reviewed. The horizontal stratification lines designating the interface between various strata represents approximate boundaries. Transitions between different strata in the field may be gradual in both the horizontal and vertical directions. Therefore, subsurface stratigraphy between test locations may vary.

3.2.1. Surface Materials

Surficial organic (topsoil) soils were observed at the existing ground surface with thicknesses ranging from approximately 3 to 4 inches. The surficial organic soil depths provided in this report and on the individual “Boring Logs” are based on observations of field personnel and should be considered approximate. Please note that the thickness of surface materials at the site should be expected to vary, and measurements necessary for detailed quantity estimation were not performed for this report. For planning purposes, we suggest considering a topsoil thickness of about 12 inches to account for existing vegetation and shallow roots.

Surficial Organic Soil is typically a dark-colored soil material containing roots, fibrous matter, and/or other organic components, and is generally unsuitable for engineering purposes. SUMMIT has not performed any laboratory testing to determine the organic content or other horticultural properties of the observed surficial organic soils. Therefore, the phrase “surficial organic soil” is not intended to indicate suitability for landscaping and/or other purposes.

Asphalt cores were performed in the existing roadways with thicknesses ranging from 1.5 to 3 inches. Base material was observed below the asphalt with estimated thicknesses ranging from 5 to 12.5 inches. The surficial asphalt and base material depths provided in this report and on the individual “Boring Logs” in Appendix 3 are based on observations www.summit-companies.com of field personnel and should be considered approximate. Please note that the thickness of surface materials at the site should be expected to vary, and measurements necessary for detailed quantity estimation were not performed for this report.

The following table summarizes the locations and approximate depths of the asphalt and base material in the cores/hand augers performed for this exploration.

Summary Table of Asphalt Cores and Base Material Depths

Boring No.

Asphalt Core

Approx. Depth, (inches)1

Base Material

Approx. Depth, (inches)1

C-1 1.25 6.75

C-2 3.0 5.0

C-3 2.25 12.25

C-4 2.0 6.0

C-5 2.25 9.75

C-6 1.75 9.25

1Depths were measured from the existing ground surface at the time drilling was performed.

3.2.2. Alluvial Soils

Alluvial (water-deposited) soils were encountered beneath the surface materials in Boring

B-1 to an approximate depth of 3 feet below the existing ground surface, respectively.

When sampled, the alluvial soils generally consisted of sandy silts (ML). The Standard

Penetration Resistances (SPT N-values) in the alluvial soils ranged from # to # blows per foot (bpf).

Alluvial soils are typically encountered in or near drainage features, pond bottoms, creeks and in low-lying areas. Alluvial soils are generally loose and/or under-compacted and, as such, are typically unsuitable for supporting the proposed construction. Therefore, remediation may be required wherever alluvial soils are encountered during grading activities. The design team may want to consider evaluating the extent of the alluvial soils prior to or during grading activities. The extent of the alluvial soils should be inspected in the field by the Geotechnical Engineer-of-Record or and/or their designee. Additional www.summit-companies.com testing such as test pit excavations and/or hand auger borings may be required in order to further explore these soil conditions.

3.2.3. Existing Fill Soils

Existing fill (disturbed) soils were encountered beneath the surface materials in Borings

B-1, C-3, and C-5 to approximate depths of 1, 1.2, and 1 foot below the existing ground surface. When sampled, the existing fill soils generally consisted of lean clays (CL) and silty sands (SM)

If fill soils are encountered at other locations in the field during construction, the fill soils should be inspected by the Geotechnical Engineer-of-Record and/or their designee, with respect to the criteria outlined in Section 5.0 of this report.

3.2.4. Residual Soils

Residual (undisturbed) soils were encountered below the surface materials, alluvial and existing fill soils and extended to either the maximum termination depth, partially weathered rock (PWR), or auger refusal. These residual soils generally consisted of stiff elastic silts (MH), soft to very stiff sandy silts (ML), and very loose to medium dense silty sands (SM). The Standard Penetration Resistances (SPT N-values) in the residual soils ranged from 0 to 26 bpf.

3.2.5. Partially Weathered Rock and Auger Refusal

Partially weathered rock (PWR) conditions were encountered in five (5) of the borings at approximate depths ranging from 1 to 17 feet below the existing ground surface. PWR is defined as soil-like material exhibiting SPT N-values in excess of 100 bpf. When sampled, the PWR generally breaks down into silty sands (SM) with rock fragments.

Mechanical auger refusal conditions were encountered in five (5) of the borings at approximate depths ranging from 5.6 to 19.1 feet below the existing ground surface.

Hand auger refusal was encountered in all the asphalt cores/hand augers at approximate depths ranging from 0.83 to 2.33 feet below the existing ground surface. Auger refusal is www.summit-companies.com defined as material that could not be penetrated by the drilling equipment used during our field exploration. Materials that might result in auger refusal include large boulders, rock ledges, lenses, seams or the top of parent bedrock. Core drilling techniques would be required to evaluate the character and continuity of the refusal material. However, rock coring was beyond the scope of this exploration and not performed.

The following table summarizes the approximate depths that PWR and auger refusal conditions were encountered in the borings performed for this exploration.

Summary Table of Partially Weathered Rock and Auger Refusal Depths

Boring No.

Partially Weathered Rock

Approx. Depth, (feet)1 Auger Refusal Approx. Depth, (feet)1

B-1 12 15

B-2 17 ---

B-12 17 19.1

B-17 3 5.6

B-18 1 7.5

C-1 --- 2.0*

C-2 --- 1.2*

C-3 --- 2.33*

C-4 --- 0.83*

C-5 --- 2.0*

C-6 --- 2.33* 1Depths were measured from the existing ground surface at the time drilling was performed.

*Hand Auger Refusal

“---“ When PWR or auger refusal conditions were not encountered in the borings.

3.2.6. Groundwater Level Measurements

At the time of drilling, groundwater was observed in Borings B-1 and B-2 at approximate depths of 7 and 9 feet, respectively. After waiting more than 24 hours, water was not observed in Boring SW-13. Please note moisture conditions of the soil samples were noted within some of the borings and moisture conditions within the soils may be an indication of the presence of groundwater. Also, moist to wet soil conditions can be an www.summit-companies.com indication that some manipulation (scarifying and drying) of the soil may be required in order to obtain the specified compaction during grading operations. It should also be noted that groundwater levels tend to fluctuate with seasonal and climatic variations, as well as with some types of construction operations. Therefore, water may be encountered during construction at depths not indicated in the borings performed for this exploration.

3.3. Summary of Laboratory Testing

SUMMIT was on site on August 1st and 2nd, 2023 and performed additional geotechnical services that consisted of retrieving bulk soil samples at pre-selected locations. The primary purpose of this exploration was to obtain additional information concerning onsite soils and engineering properties for pavement recommendations. The approximate location of the bulk soil sample are presented on Figure 2A, “Boring Location Plan” provided in Appendix 4.

Laboratory Testing Services

While on site, SUMMIT collected one (1) composite bulk soil sample from mechanical augers in the vicinity of soil Boring B-8. The soil samples were transported to SUMMIT’s laboratory for visual examination and laboratory testing. The laboratory testing was performed to better evaluate the onsite soils’ maximum dry unit weight and USCS soil classification. The laboratory testing performed included one (1) Atterberg Limit test (ASTM D 4318), one (1) Sieve Analysis w/o Hydrometer test (ASTM D 422), one (1) Standard Proctor test (ASTM D 698), and one (1)

California Bearing Ratio test (ASTM D 1833). The laboratory test results are summarized in the following table and are included in Appendix 4 of this report.

Additional lab testing was assigned to determine USCS soil classifications for selected soil samples. A total of seventeen (17) Atterberg Limit Test (ASTM D 4318), Sieve Analysis w/o

Hydrometer tests (ASTM D 422), and Moisture Contents (ASTM D 2216) are to be performed and added as an addendum to this report at a later date.

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Summary of Laboratory Testing

Boring No.

Sample Depth (feet)

Moisture Content

Soil Class.

USCS

Atterberg Limit Test Results

Sieve Analysis Results

California Bearing Ratio at

95% Max Density

Liquid Limit

Plastic Limit

Plasticity Index

Percent Passing

#40 Sieve

Percent Passing

#200 Sieve

B-8 0-5 27.7 ML 42 39 3 39.5 60.5 4.7

Based on our laboratory test results, the maximum dry unit weight of the one (1) bulk sample is

94.0 pounds per cubic foot (pcf) with an optimum moisture of 26.7%. The California Bearing

Ratio was based off 95% compaction of the max dry unit weight which resulted in a 4.7% CBR value. SUMMIT recommends that structural fill exhibit a maximum dry unit weight of at least 90 pcf, as determined by a Standard Proctor compaction test (ASTM-D698). Additionally, we recommend that structural fill be compacted to a minimum of 95 percent of the soil's Standard

Proctor maximum dry density (ASTM D 698) at/or near optimum moisture content (±2 percent).

Based on the laboratory results the tested areas will likely require some reworking in accordance with sections 5.5 and 5.6 of this report for use as structural fill.

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4.0 EVALUATIONS AND RECOMMENDATIONS

4.1. General

Our preliminary evaluation and recommendations are based on the project information outlined previously and on the data obtained from the field and laboratory testing program. If the structural loading, geometry, or proposed building locations are changed or significantly differ from those outlined, or if conditions are encountered during construction that differ from those encountered by the borings, SUMMIT requests the opportunity to review our recommendations based on the new information and make the necessary changes.

Grading plan information with proposed foundation bearing elevations was not available for our review at the time of this report. Finish grade elevations of proposed construction in conjunction with the proposed foundation bearing elevation can have a significant effect on design and construction considerations. SUMMIT should be provided the opportunity to review the project grading plans prior to their finalization with respect to the recommendations contained in this report.

4.2. Shallow Foundation Recommendations

Based on the results of the soil test borings, and our assumptions regarding site grading and assumed structural building loads, the proposed structures can be adequately supported on shallow foundation systems provided site preparation and compacted fill recommendation procedures outlined in this report are implemented concerning unsuitable soils such as alluvial soils, existing fill soilsand soils with N-values less than 6 bpf. An allowable net bearing pressure of up to 2,000 pounds per square foot (psf) can be used for design of the foundations bearing on approved undisturbed residual soils, or on approved structural fill compacted to at least 95 percent of its Standard Proctor maximum dry density. Please refer to section 5.0 of this report for more information.

Provided the procedures and recommendations outlined in this report are implemented and using the assumed loads, we have estimated a total settlement of less than 1 inch for footing www.summit-companies.com design pressures of 2,000 psf.

To avoid punching type bearing capacity failure, we recommend wall foundation widths of 18 inches or more. Exterior foundations and foundations in unheated areas should be designed to bear at least 12 inches below finished grade for frost protection. To reduce the effects of seasonal moisture variations in the soils, for frost protection and for bearing capacity, it is recommended that all foundations be embedded at least 12 inches below the lowest adjacent grade.

All footing excavations and undercutting remediation operations should be inspected by the

Geotechnical Engineer-of-Record or and/or their designee to confirm that suitable soils are present at and below the proposed bearing elevation and that the backfill operations are completed with the recommendations of this report. This evaluation may include hand-auger and DCP testing. If DCP testing encounters lower penetration resistances than anticipated or unsuitable materials are observed beneath the footing excavations, these bearing soils should be corrected per the Geotechnical Engineer-of-Record’s recommendations.

4.3. Retaining Wall Recommendations (if used)

Design Parameters for backfill properties (i.e., friction angle, earth pressure coefficients) should use the values in the table below. These parameters are based on suitable soils with a minimum moist unit weight of 120 pcf. SUMMIT should be retained to test the actual soils used for construction to verify these design assumptions. To reduce long term creep or deflections to the wall system, desirable wall backfill soils should be used. These include non-plastic, granular soils

(sands and gravels). However, these soils may not be available on site.

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Soil Parameters for Wall Backfill

Backfill Type

Allowable Bearing Capacity

(psf)

Friction Angle (deg)

Modulus of Subgrade Reaction

(pci)

Active Earth Pressure

Coefficient Ka

Passive Earth

Pressure Coefficient

Kp

Coefficient of Earth

Pressure at Rest Ko

Slide Friction

Residuum 2,000 28° 200 0.361 2.77 0.531 0.4

Fill 2,000 24 o 150 0.421 2.37 0.593 0.4

Additional Testing is Required to verify these estimated designed parameters.

Soils classified as elastic silts (MH) and/or fat clays (CH) shall not be used for wall backfill or in the retained zone as shown in Table 1610.1 of the 2018 IBC. If on-site soils are used as backfill within the reinforced zone, the wall designer should address the need for wall drainage and the possibility of long-term, time-dependent movement or creep in their design.

At the time of report preparation, we were not provided retaining wall plans or specifications.

Therefore, we request the opportunity to review the wall plans and specifications once they are finalized and make any necessary changes to our recommendations. Also, we recommend an external stability analysis (including global stability) of the proposed wall(s) be conducted once the site layout and wall geometry is complete.

4.4. Temporary and Permanent Dewatering

At the time of drilling, groundwater levels were observed in two (2) of the borings at approximate depths ranging from 7 to 9 feet below the existing ground surface. Should groundwater be encountered while performing excavations associated with the construction, the contractor should be prepared to promptly remove/dewater the water from the general construction area.

Pump(s) should remain on standby to handle groundwater as necessary. Details concerning dewatering should be discussed with the geotechnical engineer and agreed upon with the contractor prior to proceeding with construction. Also, depending on the groundwater conditions, the contractor may need to contact a professional that specializes in designing a groundwater control system.

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The groundwater levels should be kept a minimum of five (5) feet below the bottom of the proposed excavation elevation. Dewatering shall be performed until the construction is completed. If water is encountered, pumping must be maintained continuously from sumps and/or well points for any beneficial dewatering to be derived and a back-up pump should also be maintained on-site. Discontinuous pumping will result in softening of the subgrade soils and additional undercutting may be required. The contractor should also be prepared to implement additional dewatering procedures in the event water levels rise to the point it impacts construction.

Positive site drainage shall be maintained away from all working areas at all times to prevent ponding of water that could soften and disturb the subgrade materials. The contractor shall be prepared to implement alternative dewatering techniques should the need arise. All subgrade surfaces and fill surfaces should be adequately sloped to provide positive drainage as construction progresses. Undercutting due to softening of subgrade soils as a result of improper temporary dewatering will be the contractor’s responsibility.

Note: Depending on final grades and groundwater level conditions, permanent dewatering system(s) may need to be installed and maintained during and after construction. Also, the contractor will also need to consult with the project’s environmental specialist concerning the disposal of groundwater.

4.5. Seismic Site Class

SUMMIT has determined the Seismic Site Classification for this project site in accordance with

Chapter 16, Section 1613.5.2 of the 2018 North Carolina Building Code, Site Class Definitions using SPT N-Values. We recommend this project be designed using a Seismic Site Class of “E”

(Soft Clay soil profile as defined in Table 1613.5.4 Site Class Definitions.

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4.6. Low to Moderate Plasticity Moisture Sensitive Soils (CL and MH)

Low to moderate plasticity and moisture sensitive lean clay (CL) soils were encountered in one

(1) of the hand auger borings and elastic silt (MH) soils were encountered in four (4) of the mechanical borings performed during this exploration. These fine-grained soils are susceptible to moisture intrusion and can become soft when exposed to weather and/or water infiltration.

Consequently, some undercutting and/or reworking (drying) of the near-surface soils may be required depending upon the site management practices and weather conditions present during construction.

Should these materials be left in-place, special consideration should be given to providing positive drainage away from the structure and discharging roof drains a minimum of 5 feet from the foundations to reduce infiltration of surface water to the subgrade materials.

Note: Since Low to Moderate Plasticity and Moisture Sensitive Soils can become remolded (i.e., softened) under the weight of repeated construction traffic and changes in moisture conditions, these soils should be evaluated and closely monitored by the Geotechnical Engineer-of-Record or and/or their designee prior to and during fill placement. Additional testing and inspections of moisture sensitive soils may be warranted such as laboratory testing, field density (compaction) testing, hand auger borings with dynamic cone penetrometer (DCP) testing and/or test pit excavations.

4.7. Wet Weather Conditions

Contractors should be made aware of the moisture sensitivity of the near soils and potential compaction difficulties. If construction is undertaken during wet weather conditions, the surficial soils may become saturated, soft, and unworkable. The contractor can anticipate reworking and/or recompacting soils may be needed when excessive moisture conditions occur.

Additionally, subgrade stabilization techniques, such as chemical (lime or lime-fly ash) treatment, may be needed to provide a more weather-resistant working surface during construction.

Therefore, we recommend that consideration be given to construction during the dryer months.

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Surface runoff should be drained away from excavations and not allowed to pond. Concrete for foundations should be placed as soon as practical after the excavation is made. That is, the exposed foundation soils should not be allowed to become excessively dry or wet before placement of concrete. Bearing soils exposed to moisture variations may become highly disturbed resulting in the need for undercutting prior to placement of concrete. If excavations must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, we recommend that a 2- to 4-inch-thick “mud-mat” of lean (2000 psi) concrete be placed on the bearing soils before work stops for the night.

SUMMIT recommends that special care be given to providing adequate drainage away from the building areas to reduce infiltration of surface water to the base course and subgrade materials.

If these materials are allowed to become saturated during the life of the slab section, a strength reduction of the materials may result causing a reduced life of the section.

4.8. Floor Slabs

Slab-on-grade floor systems may be supported on approved residual soils, or newly compacted fill, provided the site preparation and fill placement procedures outlined in this report are implemented. Depending upon the amount of cuts and/or fills, unsuitable soils such as alluvial soils, existing fill soils, and areas which deflect, rut or pump excessively during proof-rolling may require remediation as described in Section 6.2.

The proposed slab-on-grade floor slab should be designed to withstand the planned dead and live loads. Based on the use of granular fill material, soils encountered in our borings and our experience, a modulus of subgrade reaction (k) of 125 pci can be used to design the floor slab supported on the subgrade soils. A higher modules value may be available once the structural soils and/or supporting soils has been identified. We recommend a minimum of 4-inch thickness of crushed stone (NCDOT ABC stone gradation or equivalent) compacted to a minimum of 98 percent of the material’s Standard Proctor maximum dry density (ASTM D 698) be placed as floor slab base course.

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Immediately prior to constructing a floor slab, the areas should be proof-rolled to detect any softened, loosened or disturbed areas that may have been exposed to wet weather or construction traffic. Areas that are found to be disturbed or indicate pumping action during the proof-rolling should be undercut and replaced with adequately compacted structural fill. This proof-rolling should be observed by a SUMMIT staff professional or a senior soils technician under his/her direction. Proof-rolling procedures are outlined in the “Site Preparation” section of this report.

4.9. Pavements Subgrade Preparation

The pavement sections can be adequately supported on approved non-high plasticity residual soils, or newly compacted fill, provided the site preparation and fill placement procedures outlined in this report are implemented. Immediately prior to constructing the pavement section, we recommend that the areas be proofrolled to detect any softened, loosened or disturbed areas that may have been exposed to wet weather or construction traffic. Areas that are found to be disturbed or indicate instability during the proofrolling should be undercut and replaced with adequately compacted structural fill or repaired as recommended by the Geotechnical Engineer-of-Record. This proofrolling should be observed by a SUMMIT professional or a senior soils technician under his/her direction. Proofrolling procedures are outlined in the “Site Preparation” section of this report.

Due to the presence of near surface low to moderate plasticity lean clays (CL) and elastic silts

(MH), remediation of pavement subgrade soils may be recommended (as determined by the

Geotechnical Engineer-of-Record during construction) including undercutting and replacement with additional NCDOT ABC stone. Alternatively, lime stabilization of pavement subgrade may be a more economical option and SUMMIT can provide lime stabilization mix design services if requested. This may be more pronounced depending on the time of the year and seasonal conditions at the time of pavement construction. We recommend contingency for some remediation efforts for the subgrade soils be considered during the planning stage.

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4.10. Cut and Fill Slopes

Permanent project slopes should be designed with geometry of 3 horizontal to 1 vertical (3H:1V) or flatter. The tops and bases of all slopes should be located 10 feet or more from structural limits and 5 feet or more from parking limits. Fill slopes should be constructed utilizing properly compacted, structural fill according to the recommendations provided in this report. In addition, fill slopes should be overbuilt and cut to finished grade during construction to achieve proper compaction on the slope face. All slopes should be seeded, stabilized and maintained after construction and adhere to local, state and federal municipal standards, if applicable.

Immediately prior to constructing the project slopes, the areas should be proof-rolled to detect any softened, loosened or disturbed areas that may have been exposed to wet weather or construction traffic. Areas that are found to be disturbed or indicate pumping action during the proof-rolling should be undercut and replaced with adequately compacted structural fill. This proof-rolling should be observed by a SUMMIT staff professional or a senior soils technician under his/her direction. Proof-rolling procedures are outlined in the “Site Preparation” section of this report.

Structural fill should not be placed on a subgrade with a slope steeper than 5 horizontal to 1 vertical (5H:1V), unless the fill is confined by an opposing slope, such as in a ravine. Otherwise, where steeper slopes exist, the subgrade should be benched to allow for fill placement on a horizontal surface.

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5.0 PAVEMENT RECOMMENDATIONS

Pavement strength is normally calculated and designed based on NCDOT Design Methodology using what is called a Structural Number (SN). A pavements’ SN was calculated based on the thickness of an individual pavement component multiplied by the component’s Strength

Coefficient. The Strength Coefficient is assigned based on empirical information gathered by various highway agencies to include the SCDOT. In general, the Strength Coefficient is the highest for hot laid compacted asphalt (0.44 per inch) and lower for graded aggregate base course (0.14 per inch).

The following data was used during our pavement analysis:

• California bearing ratio (CBR) value: 4.7 – based on laboratory results

• Daily Traffic o Standard estimated 1 to 2 large trucks/day (2-axel tractor, 1-axel trailer) o Heavy estimated 3 to 4 large trucks /day (2-axel tractor, 1-axel trailer)

• 20-year Design Life.

CBR and Recommended SSV

Item Recommended

Value

California Bearing Ratio (CBR) (AASHTO T 193) 4.7

Soil Support Value 3.7

• Should the anticipated vehicular loading conditions change, SUMMIT should be given the opportunity to review our pavement recommendation and to make any necessary changes or revision.

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Flexible Pavement Section

• Based on normal vehicle traffic, the estimated California Bearing Ratio (CBR) and Soil

Support Value (SSV), and estimated single axle loads (ESALs) based on 1 to 2 large trucks with 2-axel tractor, 1-axel trailer vehicles per day for light duty pavement and 3 to 4 large trucks with 2-axel tractor, 1-axel trailer vehicles per day for heavy duty pavement.

SUMMIT has recommended the following flexible pavement sections for this project.

Recommended Asphalt Light and Heavy Duty Pavement Section

Material

Light Duty

Thickness

(Inches)

Heavy Duty

Thickness

(Inches)

Hot Mix Asphalt (HMA) Surface 1.5 2.0

Hot Mix Asphalt (HMA) Base 2.0 2.0

Gravel Aggregate Base Course (GABC) 6 6

TOTAL RECOMMENDED PAVEMENT THICKNESS 9.5 10

Rigid Duty Pavement Sections

For the Rigid pavement sections, we recommend a rigid pavement section of Flex 550 concrete

(4000 psi) consisting of:

Recommended Rigid Heavy Duty Pavement Section

Material

Light Duty

Thickness, Inches

Heavy Duty

Thickness, Inches

4,000 psi Concrete 6 8

Crushed Aggregate Base Course (98% compaction) --- 4

All new pavement components should meet the latest NCDOT requirements (Standard Specifications for Highway Construction, Latest Edition).

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6.0 CONSTRUCTION CONSIDERATIONS

6.1. Abandoned Utilities/Structures

SUMMIT recommends that any existing utility lines and foundations be removed from within proposed building and pavement areas. The utility backfill and foundation material should be removed and the subgrade in the excavations should be inspected by a geotechnical professional prior to fill placement. The subgrade inspection should consist of visual observations, probing with a steel rod and/or performing hand auger borings with Dynamic Cone Penetrometer tests to explore their suitability of receiving structural fill. Once the excavations are inspected and approved, they should be backfilled with adequately compacted structural fill. Excavation backfill under proposed new foundations should consist of properly compacted structural fill, crushed stone, flowable fill or lean concrete as approved by the Geotechnical Engineer-of-Record.

6.2. Site Preparation

Based on the results of our borings, and dependent on final grades, the contractor can anticipate that some undercutting and/or foundation extension through existing fill soils and soils with N-values less than 6 bpf may be required prior to building construction and/or fill placement. If these soils are encountered during the grading activities, the extent of the undercut required should be determined in the field by the Geotechnical Engineer-of-Record and/or their designee.

Additional testing such as test pit excavations and/or hand auger borings may be required to further explore these soil conditions, depths and locations.

Topsoil, organic laden/stained soils, construction debris and other unsuitable materials should be stripped/removed from the proposed construction limits. Stripping and clearing should extend 10 feet or more beyond the planned construction limits. Upon completion of the stripping operations, we recommend areas planned for support of foundations, floor slabs, parking areas, slope areas and structural fill be proof-rolled with a loaded dump truck or similar pneumatic tired vehicle (minimum loaded weight of 20 tons) under the observations of a staff professional. After www.summit-companies.com excavation of the site has been completed, the exposed subgrade in cut areas should also be proof-rolled. The proof-rolling procedures should consist of four complete passes of the exposed areas, with two of the passes being in a direction perpendicular to the proceeding ones. Any areas which deflect, rut or pump excessively during proof-rolling or fail to “tighten up” after successive passes should be undercut to suitable soils and replaced with compacted fill.

The extent of any undercut required should be determined in the field by a SUMMIT staff professional or engineer while monitoring construction activity. After the proof-rolling operation has been completed and approved, final site grading should proceed immediately.