S02 -Ft Jackson 31 20 01 Geotechnical Engineering Report.pdf

Report Cover Page

Ft. Jackson Burial Expansion

Columbia, SC

Geotechnical Engineering Report

November 1, 2024 | Terracon Project No. 73245103

Prepared for:

VCI Builders, Inc.

56 Louis Prima Dr, Ste B

Covington, LA 70433

521 Clemson Road

Columbia, South Carolina 29229

P (803) 741-9000

Terracon.com

Facilities | Environmental | Geotechnical | Materials

Report Cover Letter to Sign

November 1, 2024

VCI Builders, Inc.

56 Louis Prima Dr, Ste B

Covington, LA 70433

Attn: Mr. Jordan Vandermeer

P: 479-225-8170

E: Jordan.vandermeer@valiint.com

Re: Geotechnical Engineering Report

Ft. Jackson Burial Expansion

101 Main Street

Columbia, SC

Terracon Project No. 73245103

Dear Mr. Vandermeer:

We have completed the scope of Geotechnical Engineering services for the above referenced project in general accordance with Terracon Proposal No. P73235XXX, dated

July 18, 2024, authorized by VCI Purchase Order Agreement dated August 16, 2024.

This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations and pavements the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon

Luke L. Groth, E.I.T. Phillip A. Morrison, P.E.

Staff Engineer Senior Geotechnical Engineer, APR

SC Registration No. 17275

Luke Groth https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAhHm05XBgo8qX-3-USr4GVCDUHvUK1e9Y https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAhHm05XBgo8qX-3-USr4GVCDUHvUK1e9Y https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAhHm05XBgo8qX-3-USr4GVCDUHvUK1e9Y https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAhHm05XBgo8qX-3-USr4GVCDUHvUK1e9Y https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAxwa3358JGXxADCH9AFO6x32zhLjHzPzq

Ft. Jackson Burial Expansion | Columbia, SC

Facilities | Environmental | Geotechnical | Materials i

Table of Contents Introduction Project Description Site Conditions Geotechnical Characterization Seismic Site Class Corrosivity Geotechnical Overview Earthwork

Site Preparation Subgrade Preparation Fill Material Types Fill Placement and Compaction Requirements Utility Trench Backfill Grading and Drainage Earthwork Construction Considerations Construction Observation and Testing

Shallow Foundations Design Parameters – Compressive Loads Design Parameters – Overturning and Uplift Loads Foundation Construction Considerations

Pavements General Pavement Comments Pavement Design Parameters Pavement Section Thicknesses General Design Recommendations Pavement Maintenance

General Comments

Figures GeoModel

Attachments

Exploration and Testing Procedures Site Location and Exploration Plans

Exploration and Laboratory Results

Supporting Information

Facilities | Environmental | Geotechnical | Materials ii

Note: This report was originally delivered in a web-based format. Blue Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

Refer to each individual Attachment for a listing of contents.

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Facilities | Environmental | Geotechnical | Materials 1

Introduction

This report presents the results of our subsurface exploration and Geotechnical

Engineering services performed for the proposed columbarium expansion and roadway renovations at the Fort Jackson National Cemetery, located at 101 Main Street in

Columbia, SC. The purpose of these services was to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions

■ Groundwater conditions

■ Seismic site classification per IBC

■ Site preparation and earthwork

■ Foundation design and construction

■ Pavement design and construction

The geotechnical engineering Scope of Services for this project included the advancement of test borings and laboratory testing, engineering analysis, and preparation of this report. Site Location and Exploration Plan presents the site and boring locations, respectively. The boring logs and the results of the laboratory testing performed on soil samples obtained from the site during our field exploration are included in Exploration and Laboratory Results.

Project Description

Our initial understanding of the project was presented in our proposal and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Information

Provided

The following were provided for our use in preparing this report:

■ An email request for proposal by Mr. Vandermeer on July

11, 2024. The request included a description of the site location, scope of the work, and boring locations.

■ Specifications for Geotechnical Investigations

■ Plans of a similar development at Fort Gibson

■ Civil drawings by VCI dated 10/18/24

Project

Description

The project includes the addition of a new columbarium to the existing development and roadway renovations of the Fort

Jackson National Cemetery near Columbia, SC.

Facilities | Environmental | Geotechnical | Materials 2

Item Description

Proposed

Structure

The structures associated with the expansion include two rows of five columbarium structures in radial pattern. The structures have a length of about 30 feet and a width of about 6 feet. The walls are 5-foot tall, double-sided concrete structures.

Finished Floor

Elevation

Based on the provided plans, the finished floor elevation of the columbarium structures ranges from 417 amsl in the western end to 412 amsl in the eastern end.

Maximum Loads

Anticipated structural loads were not provided. In the absence of information provided by the design team, we assume that the wall load of the columbarium is 3 kips per linear foot (klf).

Grading/Slopes

Based on the provided grading plan, the proposed grades will be very near the existing grade, with less than a foot of cut at the roadway expansion at Procession Lane and less than a foot of fill at the opposite side of the columbarium expansion.

Below-Grade

Structures None indicated.

Free-Standing

Retaining Walls None indicated.

Pavements

Based on conversation with Mr. Vandermeer, primary pavement work planned in the columbarium area will be the replacement of the one lane of the existing road and a concrete sidewalk.

Parallel parking areas are planned along Procession Lane. The roadways and parking spaces will be constructed in this area using a flexible (asphalt) section. Moderate vehicular traffic is anticipated for the roadways and light vehicular traffic is anticipated for the parking areas. We anticipate the pavement design period is 20 years.

Terracon should be notified if any of the above information is inconsistent with the planned construction, as modifications to our recommendations may be necessary.

Site Conditions

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Facilities | Environmental | Geotechnical | Materials 3

Parcel

Information

The project site is located at 101 Main Street in Columbia, SC.

The approximate center of the site is located at 80°05’50.62” N, 80°50’50.62” W For additional information, see Site Location.

Existing

Improvements

The planned construction area of the columbarium area is undeveloped. It is bounded on its north and east sides by asphalt roadways. On the west side is an existing columbarium.

Current Ground

Cover

Based on our site reconnaissance, the columbarium area is wooded with pine trees.

Existing

Topography

Based on the provided topographic plan, the elevations of the columbarium area range from 420 feet amsl on its southwest side to 412 feet amsl on its north side along the roadway.

Area Geology

The site is located in the upper Coastal Plain physiographic province of South Carolina. The Coastal Plain is a wedge-shaped cross-section of water and wind deposited soil. Its thickness ranges from a featheredge at the surface contact of the

Piedmont (Fall Line) to several thousand feet at the present day coastline. The sediments range in age from the Cretaceous and

Tertiary periods at the contact with the bedrock to the recent period at the present coastline. The sediments include clays, silts, sands, and gravels, as well as organics.

Geotechnical Characterization

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of the site. Conditions observed at each exploration point are indicated on the individual logs. The individual logs can be found in

Exploration Results and the GeoModel can be found in Figures.

As part of our analyses, we identified the following model layers within the subsurface profile. For a more detailed view of the model layer depths at each boring location, refer to the GeoModel.

Model

Layer Layer Name General Description

1 Loose Sand Very loose to loose, fine to medium grained, well graded sand with silt

Facilities | Environmental | Geotechnical | Materials 4

Model

Layer Layer Name General Description

2 Dense Sand Loose to medium dense, fine to medium grained, well graded sand with silt

The borings were advanced in the dry using hollow stem auger drilling techniques that allow for short term groundwater observations to be made while drilling. Groundwater was not encountered within the maximum drilling depth at the time of our field exploration. Groundwater conditions may change because of seasonal variations in rainfall, runoff, and other conditions not apparent at the time of drilling. Long-term groundwater monitoring was outside the scope of services for this project.

Laboratory tests were conducted on selected soil samples and the test results are presented in Exploration and Laboratory Results. Moisture contents and fines contents were determined at selected depths within borings across the site. The moisture contents of the sandy soils ranged from about 6 to 7 percent. The fines contents of the sandy soil ranged between 10 and 12 percent.

A chemical analysis (pH, sulfates, chloride ion, and electrical resistivity) was performed on a composite sample from the upper 5 feet of borings located in the columbarium area. The results of the test are presented in Corrosivity.

Seismic Site Class

The seismic design requirements for buildings and other structures are based on Seismic

Design Category. Site Classification is required to determine the Seismic Design

Category for a structure. The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of

ASCE 7 and the International Building Code (IBC).

To determine the seismic site class, Terracon initially screened the site soil profile to determine whether any of the following conditions were satisfied which would require the site to be classified as Site Class F. These include:

■ Soils vulnerable to potential failure or collapse under seismic loading, such as liquefiable soils, quick and highly sensitive clays, and collapsible weakly cemented soils.

■ More than 10 feet thick, peats and/or highly organic clays.

■ More than 25 feet thick, very high plasticity clays of Plasticity Index (PI) > 75.

■ More than 120 feet thick, soft/medium clays with undrained shear strength less than 1,000 psf.

Facilities | Environmental | Geotechnical | Materials 5

Based on the data from soil test boring, we do not anticipate the conditions listed above are present. From the boring data and our experience from previous work performed in the area, our professional opinion is that a Seismic Site Classification of D can be considered for the project. Subsurface explorations at this site were extended to a maximum depth of 20 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth.

Corrosivity

The table below lists the results of laboratory soluble sulfate, soluble chloride, electrical resistivity, and pH testing. The values may be used to estimate potential corrosive characteristics of the on-site soils with respect to contact with the various underground materials which will be used for project construction.

Corrosivity Test Results Summary

Boring

Sample

Depth

(feet)

Soil

Description

Soluble

Sulfate

(mg/kg)

Soluble

Chloride

(mg/kg)

Electrical

Resistivity

(Ω-cm) pH

B-1 to

B-3 1 to 5

Well graded sand with silt 40 47 8,342 5.95

Results of soluble sulfate testing can be classified in accordance with ACI 318 – Building

Code Requirements for Structural Concrete. Numerous sources are available to characterize corrosion potential to buried metals using the parameters above.

ANSI/AWWA is commonly used for ductile iron, while threshold values for evaluating the effect on steel can be specific to the buried feature (e.g., piling, culverts, welded wire reinforcement, etc.) or agency for which the work is performed. Imported fill materials may have significantly different properties than the site materials noted above and should be evaluated if expected to be in contact with metals used for construction.

Consultation with a NACE certified corrosion professional is recommended for buried metals on the site.

Geotechnical Overview

The site appears to be generally suited for the proposed construction based upon geotechnical conditions encountered in the test borings, provided that the recommendations provided in this report are implemented in the design and construction phases of this project.

Facilities | Environmental | Geotechnical | Materials 6

Our subsurface exploration indicated the development area to have a generally uniform soil profile, consisting of typically loose, well graded sand with silt to the 20-foot maximum depth of the borings. With some improvement, these conditions can be compatible with the planned development. Presuming the foundations bear on firm native soils or on new structural fill supported by these materials, the structures can be supported by conventional spread/strip footings with tolerable settlement estimates.

Shallow Foundations addresses support of the structures bearing on these soil conditions.

As discussed previously, the near surface soils are generally sands with silt (fines contents of less than 12 percent) that extend to moderate depths. Soils of this type can provide very good subgrade support for the new structures and pavements proposed for this site. However, the borings indicate that these soils are typically loose. Removal of the stumps and roots of existing trees will further loosen the surficial soils. Based on the existing topography and the depth of the loose soils, we anticipate that they will be present at the subgrade throughout the site. Therefore, in-place densification will be needed to increase their density and prepare them for any subsequent fill placement and floor slab/pavement support. In deep areas of very loose soils, partial removal and replacement may be needed to fully compact the loose zone. The object should be to provide at least 3 feet of densified soil below the pavements and floor slabs.

The on-site shallow excavated soils (well graded sand with silt) less debris and organics are generally satisfactory for use as structural fill below the structural areas provided the target density is achieved. The surficial soils had moisture contents of 6 to 7 percent at the time of our field sampling, likely near the optimum moisture content level. Given their moderately low fines and natural moisture content, some difficulty in retaining moisture should be expected during earthwork operations when working with these materials. As such, the contractor should expect elevated effort to initially moisture condition the soils and to maintain the moisture once correct levels are reached. The contractor selected for this project should have tillers and deep soil mixers as well as water trucks to wet fill/subgrade material and to maintain moisture levels until confining loads can be placed (i.e. base course material pavements, sidewalks, etc.).

Groundwater was not encountered within the maximum depths of exploration during or at the completion of drilling. Therefore, groundwater is not expected to negatively affect the earthwork.

Pavements addresses the design of pavement sections for use in the repair and expansion applications. The recommendations contained in this report are based upon the results of data presented herein, engineering analyses, and our current understanding of the proposed project.

The recommendations contained in this report are based upon the results of field and laboratory testing (presented in the Exploration Results), engineering analyses, and

Facilities | Environmental | Geotechnical | Materials 7 our current understanding of the proposed project. General Comments provides an understanding of the report limitations.

Earthwork

Earthwork is anticipated to include clearing and grubbing, excavations, and engineered fill placement. The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria, as necessary, to render the site in the state considered in our geotechnical engineering evaluation for foundations and pavements.

Site Preparation

Prior to placing fill, existing vegetation, topsoil, stumps and root systems should be removed. Complete stripping of the topsoil should be performed in the proposed columbarium and pavement areas.

Although no evidence of fill or underground facilities (such as septic tanks, cesspools, basements, and utilities) was observed during the exploration and site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed, and the excavation thoroughly cleaned prior to backfill placement and/or construction.

Buried utilities should be removed. Existing utilities that are to be abandoned should be removed or filled with grout. The excavations resulting from foundation and utility removal should be properly backfilled with compacted structural fill as described in “Fill

Material Types” and “Fill Compaction Requirements”, below. Utilities that are to remain in service should be accurately located horizontally and vertically to minimize conflict with new foundation construction and their backfill evaluated and repaired, as necessary.

Subgrade Preparation

As indicated by the borings, the soil profile is composed of generally loose sand with some fines. These materials in their present state are not satisfactory to support the proposed structure and pavements but can be densified in-place to increase their density and improve their support carrying characteristics. Based on the fines content of these soils ranging from about 10 to 12 percent, in-place densification will be effective to a depth of about 1-½ to 2 feet. The exposed subgrades in the cut and fill areas should be densified to at least 95 percent of the soil’s standard Proctor maximum dry un it weight to a depth of least 1 foot below the subgrade level. The densification of the sand will require the use of a heavy vibratory roller with a minimum energy rating of 60,000 foot-

Facilities | Environmental | Geotechnical | Materials 8 pounds. The number of passes needed to achieve the desired densification will depend on several factors including soil moisture, percentage of fines in the soil, and the applied energy.

The effectiveness of the densification should be evaluated in the field. This should include density testing of the compacted sands prior to fill placement, both at the surface and at 1 foot below this level. As noted above, a minimum relative density of 95 percent of the soil’s standard Proctor maximum dry unit weight should be achieved at a depth of at least 1 foot below the subgrade level. It should be expected that moisture content adjustment, generally wetting the subgrade, will be necessary to faci litate densification based on the results of laboratory testing. We expect the in-situ moisture contents of the near surface soils are likely well below optimum.

To further evaluate the compaction effort and to look for areas of deep-seated unstable conditions, the subgrades in the at-grade areas and areas receiving fill should be proofrolled with an adequately loaded vehicle such as a fully loaded, tandem-axle dump truck. Cut areas should be proofrolled after they have been excavated to their proposed subgrade levels and compacted as needed. Proofrolling should be performed after a suitable period of dry weather to avoid degrading an otherwise acceptable subgrade. The proofrolling should be performed under the observation of the Geotechnical Engineer or representative. Areas excessively deflecting under the proofroll should be delineated and subsequently addressed by the Geotechnical Engineer.

The site soils are composed of primarily sandy soils. Traffic exposure to dried subgrades can destabilize otherwise satisfactory conditions, requiring remedial work to repair them.

Periodic wetting of the subgrades will substantially aid the maintenance of a stable subgrade. Wetting will also aid in the control of sand dust. We note that conditions of the subgrade can vary between the time of exploration and the time of construction;

therefore, the actual method of subgrade preparation should be determined at the time of construction.

Fill Material Types

Material property requirements for use as structural fill are noted in the table below:

Soil Type USCS Classification Acceptable Location for

Placement

Imported Structural Fill 1 SW, SM, SC All locations and elevations

On-Site Soils (less organics and debris) SW, SW-SM All locations and elevations

1. Structural fill should consist of approved materials free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a

Facilities | Environmental | Geotechnical | Materials 9

Soil Type USCS Classification Acceptable Location for

Placement frozen subgrade. A sample of each material type should be submitted to the

Geotechnical Engineer for evaluation prior to use on this site.

Fill Placement and Compaction Requirements

Structural fill should meet the following compaction requirements.

Item Description

Maximum Lift Thickness

8 inches or less in loose thickness when heavy, self-propelled compaction equipment is used

4 inches in loose thickness when hand-guided equipment

(i.e., jumping jack or plate compactor) is used

Minimum Compaction

Requirements 1

95% of the material’s standard Proctor maximum dry unit weight (ASTM D 698)

Water Content Range 1 -3% to +3% of optimum, for the on-site sands. Off site materials may require a narrower range.

1. We recommend that structural fill be tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved.

Utility Trench Backfill

Any soft or unsuitable materials encountered at the bottom of utility trench excavations should be removed and replaced with structural fill or bedding material in accordance with public works specifications for the utility to be supported. This recommendation is particularly applicable to utility work requiring grade control and/or in areas where subsequent raising of the grade could cause settlement in the subgrade supporting the utility. Trench excavation should not be conducted below a downward 1:1 projection from existing foundations without engineering review of shoring requirements and geotechnical observation during construction.

On-site materials are generally suited as backfill of utility and pipe trenches from 1 foot above the top of the pipe to the final ground surface, provided the material is free of organic matter and deleterious substances.

Trench backfill should be mechanically placed and compacted as discussed earlier in this report. Compaction of initial lifts should be accomplished with hand-operated tampers or

Facilities | Environmental | Geotechnical | Materials 10 other lightweight compactors. Flooding or jetting for placement and compaction of backfill is not recommended.

Grading and Drainage

All grades must provide effective drainage away from the building during and after construction and should be maintained throughout the life of the structure. The roof should have gutters/drains with downspouts that discharge directly into the storm drain system.

Earthwork Construction Considerations

The site soils are generally loose well graded sand with silt. Shallow excavations for the proposed structure are anticipated to be compatible with conventional construction equipment.

Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of grade-supported improvements such as pavements. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over or adjacent to construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted prior to floor slab construction.

Groundwater was not encountered within the maximum depths of exploration during or at the completion of drilling. Therefore, groundwater is not expected to negatively affect the earthwork.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part

1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local and/or state regulations.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety or the contractor's activities; such responsibility shall neither be implied nor inferred.

Excavations or other activities resulting in ground disturbance have the potential to affect adjoining properties and structures. Our scope of services does not include review of available final grading information or consider potential temporary grading performed by the contractor for potential effects such as ground movement beyond the project limits. A preconstruction/ precondition survey should be conducted to document nearby

Facilities | Environmental | Geotechnical | Materials 11 property/infrastructure prior to any site development activity. Excavation or ground disturbance activities adjacent or near property lines should be monitored or instrumented for potential ground movements that could negatively affect adjoining property and/or structures.

Construction Observation and Testing

The earthwork efforts should be observed by the Geotechnical Engineer (or others under their direction). Observation should include documentation of adequate removal of surficial materials (vegetation, topsoil, and pavements), evaluation and remediation of existing fill materials, as well as proofrolling and mitigation of unsuitable areas delineated by the proofroll.

Each lift of compacted fill should be tested, evaluated, and reworked, as necessary, as recommended by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least one test for every 2,500 square feet of compacted fill in the building areas and 5,000 square feet in pavement areas. Where not specified by local ordinance, one density and water content test should be performed for every 100 linear feet of compacted utility trench backfill and a minimum of one test performed for every 12 vertical inches of compacted backfill.

In areas of foundation excavations, the bearing subgrade should be evaluated by the

Geotechnical Engineer. If unanticipated conditions are observed, the Geotechnical

Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

Shallow Foundations

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Design Parameters – Compressive Loads

Item Description

Maximum Net Allowable Bearing

Pressure 1, 2 2,000 psf

Facilities | Environmental | Geotechnical | Materials 12

Required Bearing Stratum 3 Densified native soils or compacted structural fill

Minimum Foundation Dimensions ■ Columns: 24 inches

■ Continuous: 18 inches

Ultimate Passive Resistance 4

(equivalent fluid pressures) 300 pcf

Sliding Resistance 5 0.35 ultimate coefficient of friction

Minimum Embedment below

Finished Grade 6 12 inches

Estimated Total Settlement from

Structural Loads 2 Less than about 1 inch

Estimated Differential Settlement 2, 7 About ½ of total settlement

1. The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation.

Values assume that exterior grades are no steeper than 20% within 10 feet of structure.

2. Values provided are for maximum loads noted in Project Description.

Additional geotechnical consultation will be necessary if higher loads are anticipated.

3. Loose soils may require in-place densification per the recommendations presented in Earthwork and below in Foundation Construction

Considerations.

4. Use of passive earth pressures require the sides of the excavation for the spread footing foundation to be nearly vertical and the concrete placed neat against these vertical faces or that the footing forms be removed and compacted structural fill be placed against the vertical footing face. Assumes no hydrostatic pressure.

5. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Frictional resistance for granular materials is dependent on the bearing pressure which may vary due to load combinations. For fine-grained materials, lateral resistance using cohesion should not exceed ½ the dead load.

6. Embedment necessary to minimize the effects of frost and/or seasonal water content variations. For sloping ground, maintain depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure.

7. Differential settlements are noted for equivalent-loaded foundations and bearing elevation as measured over a span of 50 feet.

Facilities | Environmental | Geotechnical | Materials 13

Design Parameters – Overturning and Uplift Loads

Shallow foundations subjected to overturning loads should be proportioned such that the resultant eccentricity is maintained in the center-third of the foundation (e.g., e < b/6, where b is the foundation width). This requirement is intended to keep the entire foundation area in compression during the extreme lateral/overturning load event.

Foundation oversizing may be required to satisfy this condition.

Uplift resistance of spread footings can be developed from the effective weight of the footing and the overlying soils with consideration to the IBC basic load combinations.

Foundation Construction Considerations

As noted in Earthwork, the footing excavations should be evaluated under the observation of the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

Sensitive soils exposed at the surface of footing excavations may require surficial compaction with hand-held dynamic compaction equipment prior to placing structural fill, steel, and/or concrete. Should surficial compaction not be adequate, construction of a working surface consisting of either crushed stone or a lean concrete mud mat may be required prior to the placement of reinforcing steel and construction of foundations.

If unsuitable bearing soils are observed at the base of the planned footing excavation, the excavation should be extended deeper to suitable soils, and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. The lean concrete replacement zone is illustrated on the sketch below.

Item Description

Soil Moist Unit Weight 110 pcf

Soil weight included in uplift resistance

Soil included within the prism extending up from the top perimeter of the footing at an angle of 20 degrees from vertical to ground surface

Facilities | Environmental | Geotechnical | Materials 14

Overexcavation for structural fill placement below footings should be conducted as shown below. The overexcavation should be backfilled up to the footing base elevation, with structural fill placed, as recommended in Earthwork.

In-place densification of the subgrade should improve the shallow soil conditions.

However, if there are deeper areas of loose soils encountered by footing excavations that remain in loose condition, these portions of footing subgrades may require repair prior to the placement of reinforcement and concrete. This can likely be accomplished by compacting the material in-place. Any loose areas identified during footing evaluation should be densified in place to at least 95 percent of standard Proctor maximum dry unit weight at footing subgrade level. As with densifying the site subgrades, some moisture conditioning may be needed to facilitate compaction. The required depth to be compacted should be determined by the geotechnical engineer at the time of construction as it is likely to vary from area to area across the site. Density tests should be performed to check the percent compaction that is attained.

Facilities | Environmental | Geotechnical | Materials 15

Pavements

General Pavement Comments

Pavement designs are provided for the traffic conditions and pavement life conditions as noted in Project Description and in the following sections of this report. A critical aspect of pavement performance is site preparation. Pavement designs noted in this section must be applied to the site which has been prepared as recommended in

Earthwork.

Pavement Design Parameters

Traffic information was not available from our client. We understand that l ight to moderate vehicular traffic with occasional heavy trucks (deliveries, maintenance vehicles, etc.) is anticipated for the development. We anticipate the pavement design period is 20 years. We have considered two traffic volumes, parking areas and drives.

For the parking spaces, we have assumed the equivalent single axle load (ESALs) to be

15,000 ESALs. The drives are assumed to receive 75,000 ESALs. IF available, the actual traffic information should be provided to confirm that the noted ESALs are sufficient.

A California Bearing Ratio (CBR) of 5 was used for the subgrade for the asphaltic concrete (AC) pavement designs. A modulus of subgrade reaction of 120 pci was used for the portland cement concrete (PCC) pavement designs. The value was empirically derived based upon our experience with the sandy subgrade soils and our expectation of the quality of the subgrade as prescribed by the Subgrade Preparation conditions as outlined in Earthwork. A modulus of rupture of 580 psi was used in design for the concrete (based on correlations with a minimum 28-day compressive strength of 4,000 psi).

Pavement Section Thicknesses

The following table provides our opinion of minimum thickness for AC sections:

Asphaltic Concrete Design

Layer Thickness (inches) 1

Parking Spaces Drives

AC 2, 3 2 3-½ 3

Aggregate Base 6 8

Facilities | Environmental | Geotechnical | Materials 16

Layer Thickness (inches) 1

Parking Spaces Drives

1. See above and Project Description for more specifics regarding traffic assumptions.

2. All materials should meet the current South Carolina Department of

Transportation (SCDOT) Standard Specifications for Highway Construction.

■ Asphaltic Surface - SCDOT Type C Asphaltic Cement Concrete: Section

■ Asphaltic Intermediate - SCDOT Type C Asphaltic Cement Concrete:

Section 403

■ Aggregate Base - SCDOT Macadam Base Course: Section 305

3. A minimum 1-½-inch surface course should be used on ACC pavements.

The following table provides our estimated minimum thickness of PCC pavements.

Portland Cement Concrete Design

Layer Thickness (inches) 1

Sidewalks 3

PCC 2 5

Aggregate Base 4

1. See Project Description for more specifics regarding traffic classifications.

2. All materials should meet the current South Carolina Department of

Transportation (SCDOT) Standard Specifications for Highway Construction.

◼ Concrete Pavement – SCDOT Portland Cement Concrete: Section 501

3. Subjected to light-duty traffic.

General Design Recommendations

Edge restraints (i.e., concrete curbs or aggregate shoulders) should be planned along curves and areas of maneuvering vehicles.

Although not required for structural support, a minimum 4-inch thick base course layer is recommended to help reduce potential for slab curl, shrinkage cracking, and subgrade pumping through joints. Proper joint spacing will also be required to prevent excessive slab curling and shrinkage cracking. Joints should be sealed to prevent entry of foreign material and doweled where necessary for load transfer. PCC pavement details for joint spacing, joint reinforcement, and joint sealing should be prepared in accordance with

ACI 330 and ACI 325.

Facilities | Environmental | Geotechnical | Materials 17

Where practical, we recommend early-entry cutting of crack-control joints in PCC pavements. Cutting of the concrete in its “green” state typically reduces the potential for micro-cracking of the pavements prior to the crack control joints being formed, compared to cutting the joints after the concrete has fully set. Micro-cracking of pavements may lead to crack formation in locations other than the sawed joints, and/or reduction of fatigue life of the pavement.

Openings in pavements, such as decorative landscaped areas, are sources for water infiltration into surrounding pavement systems. Water can collect in the islands and migrate into the surrounding subgrade soils thereby degrading support of the pavement.

Islands with raised concrete curbs, irrigated foliage, and low permeability near-surface soils are particular areas of concern. The civil design for the pavements with these conditions should include features to restrict or collect and discharge excess water from the islands. Examples of features are edge drains connected to the stormwater collection system, longitudinal subdrains, or other suitable outlets and impermeable barriers preventing lateral migration of water such as a cutoff wall installed to a depth below the pavement structure.

Care should be taken that patched areas are saw cut to achieve a smooth edge and that at least 2 sides of the patch are at right angles to the direction of traffic. Tack coat should be placed on the exposed pavement edges, prior to placing the asphalt material.

The actual depth of the patch thickness should be determined by the geotechnical engineer at the time of construction. Areas where unsuitable conditions are located should be repaired by replacing the materials with properly compacted fill.

Pavement Maintenance

The pavement sections represent minimum recommended thicknesses and, as such, periodic upkeep should be anticipated. Preventive maintenance should be planned and provided for through an on-going pavement management program. Maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment. Pavement care consists of both localized (e.g., crack and joint sealing and patching) and global maintenance (e.g., surface sealing). Additional engineering consultation is recommended to determine the type and extent of a cost-effective program. Even with periodic maintenance, some movements and related cracking may still occur, and repairs may be required.

Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements:

■ Final grade adjacent to paved areas should slope down from the edges at a minimum 2%.

Facilities | Environmental | Geotechnical | Materials 18

■ Subgrade and pavement surfaces should have a minimum 2% slope to promote proper surface drainage.

■ Install pavement drainage systems surrounding areas anticipated for frequent wetting.

■ Install joint sealant and seal cracks immediately.

■ Seal all landscaped areas in or adjacent to pavements to reduce moisture migration to subgrade soils.

■ Place compacted, low permeability backfill against the exterior side of curb and gutter.

■ Place curb, gutter and/or sidewalk directly on clay subgrade soils rather than on unbound granular base course materials.

General Comments

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration.

Variations will occur between exploration point locations or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the

Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and any work product is limited to our client and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Facilities | Environmental | Geotechnical | Materials 19

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly affect excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety and cost estimating including excavation support and dewatering requirements/design are the responsibility of others.

Construction and site development have the potential to affect adjacent properties. Such impacts can include damages due to vibration, modification of groundwater/surface water flow during construction, foundation movement due to undermining or subsidence from excavation, as well as noise or air quality concerns. Evaluation of these items on nearby properties are commonly associated with contractor means and methods and are not addressed in this report. The owner and contractor should consider a preconstruction/precondition survey of surrounding development. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

Figures

Contents:

GeoModel

Attachments

Exploration and Testing Procedures

Field Exploration

Six (6) test borings were drilled on October 2, 2024. The borings were drilled to depths of 15 to 20 feet bgs at the approximate location shown on Exploration Plan.

Boring Layout and Elevations: Terracon personnel provided the boring layout using handheld GPS equipment (estimated horizontal accuracy of about ±10 feet) and referencing existing site features. Approximate ground surface elevations were interpolated from the provided topographic plan. If elevations and a more precise boring layout are desired, we recommend borings be surveyed.

Subsurface Exploration Procedures: We advanced the borings with a track-mounted, rotary drill rig using continuous flight hollow stem augers. Four samples were obtained in the upper 10 feet of each boring and at intervals of 5 feet thereafter. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon was driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration Test

(SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. We observed and recorded groundwater levels during drilling and sampling. For safety purposes, all borings were backfilled with auger cuttings after their completion. Pavements were patched with cold-mix asphalt and/or pre-mixed concrete, as appropriate.

We also observed the boreholes while drilling and at the completion of drilling for the presence of groundwater. Groundwater was not observed at these times in the boreholes.

The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a Geotechnical Engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials observed during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

Laboratory Testing

The project engineer reviewed the field data and assigned laboratory tests. The laboratory testing program included the following types of tests:

■ Moisture Content

■ Fines Content

■ Chemical analyses – pH, sulfates, chloride ion, electrical resistivity

The laboratory testing program often included examination of soil samples by an engineer. Based on the results of our field and laboratory programs, we described and classified the soil samples in accordance with the Unified Soil Classification System.

Site Location and Exploration Plans

Site Location Plan

Exploration Plans (2 Pages)

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Site Location

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Exploration Plan (1 of 2)

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Exploration Plan (2 of 2)

Exploration and Laboratory Results

Boring Logs (B-1 through B-6)

Summary of Laboratory Testing

422.67

TOPSOIL, (4 inches) WELL GRADED SAND WITH SILT (SW-SM), fine to medium grained, brown to light brown, loose

Boring Terminated at 20 Feet

Boring Log No. B-1

W at er L ev el

O b se rv at io n s

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L a ye r

0.3

20.0

3-3-5 N=8

2-3-4 N=7

3-2-5 N=7

3-3-3 N=6

4-5-4 N=9

4-3-6 N=9

4170 Percival Road | Columbia, SC

Terr…