Attachment 13 - 544-329 Geotech Report.pdf

Report of Geotechnical Study

WJB Dorn Medical Center Outpatient Optometric Treatment Center 6439 Garners Ferry Road Columbia, South Carolina

Prepared For:

Charlotte Engineers, LLP 5838 Monroe Road

Charlotte, North Carolina

By:

FROEHLING & ROBERTSON, INC.

18 Woods Lake Road Greenville, South Carolina 29607

F&R Project No. 65V‐0148

January 25, 2018

Appendix K

Corporate HQ: 3015 Dumbarton Road Richmond, Virginia 23228 T 804.264.2701 F 804.264.1202 www.fandr.com

VIRGINIA • NORTH CAROLINA • SOUTH CAROLINA • MARYLAND • DISTRICT OF COLUMBIA

A Minority‐Owned Business

Engineering Stability Since 1881

18 Woods Lake Road Greenville, South Carolina 29607 T 864.271.2840 I F 864.271.8124

F&R Project No. 65V‐0148

Charlotte Engineers, LLP

5838 Monroe Road

Charlotte, North Carolina

Attn: Mr. Michael Eaves, LEED AP

Re: Report of Geotechnical Study WJB Dorn Medical Center Outpatient Optometric Treatment Center 6439 Garners Ferry Road Columbia, South Carolina

Dear Mr. Eaves:

The enclosed report presents the results of the subsurface exploration program and geotechnical engineering evaluation undertaken by Froehling & Robertson, Inc. (F&R), in connection with the proposed WJB Dorn Medical Center Outpatient Optometric Treatment Center project. Our services were performed in general accordance with F&R Proposal No. 1865‐00204G dated

November 27, 2017.

The report presents our understanding of the project, reviews our exploration procedures, describes the general subsurface conditions at the boring locations, and presents our evaluations and recommendations.

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center F&R Project No. 65V‐0148 Columbia, South Carolina

We have enjoyed working with you on this project, and we are prepared to assist you with the recommended quality assurance monitoring and testing services during construction. Please contact us if you have any questions regarding this report or if we may be of further service.

Sincerely, Benedictus K. Azumah, P.E. Marving L. Farmer, P.E.

Geotechnical Services Manager Branch Manager, Senior Engineer

BKA/MLF

Email Distribution: MEaves@Charlotteengineers.com

F:\Projects 65V\65V‐0148 (Charlotte Engineers, LLP ‐ WJB Dorn Dept of VA ‐ Outpatient Optometric Treatment Center)\Reports\65V‐

0148.GEO1 (Charlotte Engineers, LLP. ‐ WJB Dorn Dept of VA ‐ Outpatient Optomentric Treatment Center).docx

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

January 25, 2018

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TABLE OF CONTENTS

SECTION PAGE

EXECUTIVE SUMMARY

1.0 PURPOSE & SCOPE OF SERVICE

2.0 PROJECT INFORMATION

2.1 SITE LOCATION AND DESCRIPTION

2.2 PROJECT INFORMATION AND PROPOSED CONSTRUCTION

3.0 EXPLORATION PROCEDURES

3.1 SUBSURFACE EXPLORATION

3.2 LABORATORY TESTING

4.0 REGIONAL GEOLOGY AND SUBSURFACE CONDITIONS

4.1 GENERAL

4.2 REGIONAL GEOLOGY

4.3 GENERALIZED SUBSURFACE CONDITIONS

4.3.1 Surficial Materials

4.3.2 Fill Soils

4.3.3 Coastal Plain Deposits

4.4 LABORATORY TEST RESULTS

4.5 GROUNDWATER DATA

5.0 DESIGN RECOMMENDATIONS

5.1 GENERAL

5.2 SHALLOW FOUNDATION DESIGN

5.3 ESTIMATED FOUNDATION SETTLEMENT

5.4 SHRINK‐SWELL, FROST DEPTH AND BEARING CONSIDERATIONS

5.5 CONCRETE SLABS‐ON‐GRADE

5.6 PAVEMENT DESIGN RECOMMENDATIONS

5.7 SEISMIC SITE CLASSIFICATION

6.0 CONSTRUCTION RECOMMENDATIONS

6.1 GENERAL

6.2 SITE PREPARATION

6.3 CONTROLLED STRUCTURAL FILL PLACEMENT AND COMPACTION

6.4 SHALLOW FOUNDATION CONSTRUCTION

6.5 SURFACE WATER CONTROL

6.6 EXCAVATION CHARACTERISTICS

6.7 NON‐STRUCTURAL FILL

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6.8 GROUNDWATER CONDITIONS

6.9 EXCAVATIONS

7.0 CONTINUATION OF SERVICES

8.0 LIMITATIONS

APPENDICES

APPENDIX I

Site Vicinity Map (Figure No. 1) Boring Location Plan (Figure No. 2)

APPENDIX II

Key to Soil Classification Soil Classification Chart

Boring Logs (B‐01 through B‐08) Subsurface Profiles A and B (2 Sheets)

APPENDIX III

Laboratory Test Results (1 Sheet)

Atterberg Limits (1 Sheet) Moisture Density Relationship (4 Sheets)

APPENDIX IV

GBA Publication “Important Information About Your Geotechnical Engineering Report”

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

EXECUTIVE SUMMARY

This Executive Summary is provided as a brief overview of our geotechnical engineering evaluation for the project and is not intended to replace more detailed information contained elsewhere in this report. As an overview, this summary inherently omits details that could be very important to the proper application of the provided geotechnical design recommendations. This report should be read in its entirety prior to implementation into design and construction.

The proposed 15,000 sf, one‐story Outpatient Optometric Treatment Center project is located at 6439 Garners Ferry Road in Columbia, South Carolina.

Our subsurface exploration included 8 soil test borings to depths ranging from 5 to 30 feet. Our soil test borings primarily indicated the presence of generally very loose to medium dense Clayey Sand (SC) fill soils from 1 to 8.5 feet in thickness underlain by natural soils. Groundwater was encountered at three of our boring locations at depths ranging from 24 to 29 feet during our exploration.

We anticipate the near‐surface soils at the site can be excavated with backhoes, front‐ end loaders or other similar equipment using conventional means and methods.

Based on the subsurface conditions at the site we recommend that any shallow column and wall foundations be designed for a maximum net allowable bearing pressure of 3,000 pounds per square foot (psf), for foundations bearing in approved subgrade soils. The recommended bearing pressure provides a factor of safety of at least 3 against general bearing capacity failure. With proper footing sizing, we estimate that footing settlement can be limited to less than one inch.

Based on the available subsurface data from our exploration and in general accordance with Section 20.3 of ASCE 7‐10, a Seismic Site Class “D” should be used for further evaluations relative to earthquake load design.

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January 25, 2018

1.0 PURPOSE & SCOPE OF SERVICE

The purpose of the subsurface exploration and geotechnical engineering evaluation is to explore the subsurface conditions in the area of the proposed optometric treatment center and to provide geotechnical engineering recommendations. Froehling & Robertson, Inc. (F&R) provided our

Proposal No. 1865‐00204G dated November 27, 2017, to Charlotte Engineers, LLP, in response to the proposal request and the provided project details.

F&R’s scope of services included the following:

A site reconnaissance to observe existing surface conditions and layout proposed boring locations.

Coordination of public underground utility location with SC811.

Review and summary of readily available geologic and subsurface information relative to the project site.

Completion of eight SPT borings, designated as B‐01 through B‐08, located within the proposed development area. The borings were advanced to termination depths ranging from approximately 5 to 30 feet below the existing ground surface. The exploration included making observations for the presence of groundwater and dense soil strata and measuring their depths below the existing ground surface

Evaluation of the Seismic Site Class in accordance with the 2015 International

Building Code and based on our subsurface exploration program.

Performing soil laboratory testing for classification purposes using Wash 200 (ASTM

D1140 without hydrometer), Atterberg limit tests (ASTM D4318), natural water content determinations (ASTM D2216), standard Proctor test (ASTM D698), and

California Bearing Ratio test (ASTM D1883)

Preparation of this report summarizing our work on the project including a description of the subsurface conditions encountered, recommendations for earthwork including site excavation characteristics, and placement and compaction of load‐bearing reusable on‐site soils. The report also provides recommendations for shallow foundation design including a net allowable soil bearing pressure, bearing elevations, floor slab design parameters, suitable friction angles between bearing

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

January 25, 2018 elevation soils and foundations, shrink‐swell potential of on‐site soils and recommendations for flexible pavement sections for use on the project. Boring location plans, boring logs, subsurface profiles, and laboratory test results are also included in this report.

F&R’s geotechnical services did not include topographic or field surveying, development of quantity estimates, preparation of plans and specifications, or the identification and evaluation of wetlands or other environmental aspects of the project site.

2.0 PROJECT INFORMATION

2.1 Site Location and Description

William Jennings Bryan (WJB) Dorn Veterans Affairs Medical Center is located at 6439 Garners

Ferry Road in Columbia, South Carolina. An existing ‘U’ shaped asphalt parking lot is present on the north side of an access driveway new the south side of the complex. The site for the proposed

Optometric Treatment Center is located at the southern corner of the medical center complex and existing parking area. The site is approximately 3.8 acres and has a generally flat topography with a slight downward slope from the north to the south. Ground surface elevations range from approximately Elevations (El.) 242 near the access driveway to around El. 233 near the property boundary. The site is generally open, grass‐covered, and with a few mature trees. An existing gravel‐covered parking lot, a few storage containers, and miscellaneous items are also present at the site. In addition, an existing earth‐filled embankment, about five feet tall, is present along a portion of the western limits of the site.

The site location is shown on the attached Figure No. 1 ‐ Site Vicinity Map, included in Appendix

I. F&R obtained site information from the project details including the Site Grading Plan dated

November 21, 2017, by HDR, Inc., we received from your office. Additional site information was obtained through our review of available aerial photography and during our site visit.

2.2 Project Information and Proposed Construction

The proposed project includes the construction of a new Outpatient Optometric Treatment Center near the western side of the site. New access driveway and parking areas will be constructed on the east and south sides of the new building. In addition, a storm water management (SWM) facility will be constructed on the east side of the new parking lot and will extend to the southern side of the site.

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The proposed treatment center building will be a single‐story structure with a height of 19’‐10” and a floor plan area of about 15,000 square feet (sf). Construction of the building will consist of concrete slab‐on‐grade, steel framing, brick veneer, and steel panel roofing. The proposed driveway and parking areas will be asphalt paved and have capacity for about 75 cars. The SWM facility will be less than 5 feet deep. Concrete paved sidewalks and a dumpster pad are also included in the proposed site devilment.

Finished floor elevation and structural loading for the proposed construction was not provided to F&R at the time of this report. However, F&R anticipates site grading to include less than 5 feet of cut and fill for the building and pavement areas. We anticipate a finished floor elevation of around El 238 and maximum column and wall foundation loads for the building will be less than 100 kips and 10 kips per linear feet, respectively. F&R also assumes eight individual trips per car for vehicular traffic loading purposes, therefore, we estimate an average daily traffic

(ADT) of up to 600 cars. This includes up to 30 heavy trucks or buses per day, which will account for 5 percent of the total daily traffic.

As part of the project planning requirements, F&R was requested to perform a geotechnical exploration of the site to evaluate the subsurface conditions for the proposed development.

F&R obtained the site information from our correspondence with Charlotte Engineers, LLP, on

November 27, 2017.

3.0 EXPLORATION PROCEDURES

3.1 Subsurface Exploration

The subsurface exploration was conducted by our drilling sub‐consultant, W. Walker

Environmental Services, LLC, of West Columbia, South Carolina, from December 27 to 28, 2017.

A field representative from F&R was onsite during drilling operations.

The drill rig used for this project was a truck‐mounted, CME 45B equipped with an automatic hammer. The test holes were advanced using 2.25” I.D. augers. The Standard Penetration Test

(SPT) was performed at the boring locations in general accordance with ASTM D1586.

The subsurface exploration program consisted of eight SPT borings, designated as Borings B‐01 through B‐08. The borings were located within the proposed new treatment center building and

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

January 25, 2018 parking area footprint. The locations of these borings were in general accordance with the proposed boring location described in our proposal.

SPTs were performed almost continuously from the existing ground surface to a maximum depth of 10 feet. Thereafter, boreholes were advanced and SPT performed at approximate 5‐foot intervals to their termination depths of 5 to 30 feet below the existing ground surface. A bulk soil sample was obtained from the auger cuttings at Boring B‐06. Approximate boring locations are identified on Figure No. 2 – Boring Location Plan, which is included in Appendix I of this report.

Boring locations were staked at the site by F&R personnel using a hand‐held GPS unit. As such, the boring locations should be considered approximate.

Soil samples were obtained with a standard 2” O.D. and 30” long split‐spoon sampler with each

SPT being driven with a 140‐lb automatic hammer falling 30 inches. The number of blows required to drive the sampler each 6‐inch increment of penetration was recorded and are shown on the boring logs. The first six‐inch increment is used to seat the sampler with the sum of the second and third penetration increments being termed the SPT value, “N.” A representative portion of each disturbed split‐spoon sample was collected with each SPT, placed in a glass jar, and returned to our laboratory for review.

The recovered split‐spoon samples were visually classified by F&R engineers in general accordance with the ASTM D2488. The boring logs provided in Appendix II show the subsurface conditions encountered on the dates and at the approximate locations indicated.

By the nature of the work performed, the drilling activities result in disturbances to the site. The completed boreholes performed were backfilled with drilling spoils upon completion for safety.

The borehole backfill may subside at some time following our work. F&R assumes no responsibility for borehole subsidence after completion of the field exploration and departing the site. For continued safety, the boreholes should be occasionally observed by others with any needed additional backfilling then being performed.

3.2 Laboratory Testing

For geotechnical considerations, select split‐spoon soil samples and bulk soil samples from the soil test borings were subjected to laboratory classification testing. This testing included Wash 200

(ASTM D1140 without hydrometer), Atterberg limits test (ASTM D4318), natural water content determinations (ASTM D2216), standard Proctor tests (ASTM D698), and California Bearing Ratio

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Test (ASTM D1883). Based on the results of these tests, the soil samples were then classified in general accordance with Unified Soil Classification System (ASTM D2487).

Laboratory test results are provided in Appendix III.

4.0 REGIONAL GEOLOGY AND SUBSURFACE CONDITIONS

4.1 General

The subsurface conditions discussed in the following paragraphs and those shown on the attached boring logs represent an estimate of the subsurface conditions based on interpretation of the field and laboratory data using normally accepted geotechnical engineering judgments. Subsurface profiles for the project stratigraphy have been prepared for convenience only. Given the wide spacing between boring locations, it is anticipated that subsurface conditions may vary between each boring location.

Strata breaks designated on the boring logs represent approximate boundaries between soil types. The transitions between different soil strata are usually less distinct than those shown on the boring logs. Although individual soil test borings are representative of the subsurface conditions at the boring locations on the dates shown, they are not necessarily indicative of subsurface conditions at other locations or at other times. Data from the specific soil test borings are shown on the individual boring logs included in Appendix II. Subsurface profiles in the area of the proposed apartment buildings, parking lot, driveway, and detention pond areas are also included in Appendix

III.

4.2 Regional Geology

The site is located within the Upper Cretaceous Middendorf Formation deposits of the Coastal

Plain physiographic province according to the Geologic Map of South Carolina (2005). The Upper

Cretaceous Middendorf Formation deposits are reportedly underlain by mainly the residual soils and rock of the Carolina terrane (slate belt) of the Piedmont. The Carolina terrane is also known to have been separate from North America during Late Proterozoic and Cambrian time according to the fossil evidence.

The Upper Cretaceous Middendorf Formation soil materials are alluvial deposited materials generally consisting mostly of micaceous, kaolinitic sands with lenses of clay with variable thickness. The sands are mostly coarse sand to granule size, angular to sub‐angular and poorly

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

January 25, 2018 sorted, but some fine‐grained, fairly well‐sorted sand does occur. These sediments represent alluvial or upper delta‐plain environments.

The upper part of the Carolina terrane generally consist of residual soils derived from the chemical and physical weathering of the predominantly clastic rocks. The boundary between soil and rock is not sharply defined. This transitional zone, termed “Partially Weathered Rock,” is normally found overlying the parent bedrock. The degree of weathering is facilitated by fractures, joints, and by the presence of less resistant rock types. Consequently, the profile of the Partially Weathered Rock and hard rock is quite irregular and erratic, even over short, horizontal distances.

The lower part of the Carolina terrane generally consist of intermediate to felsic pyroclastic rocks that are collectively greater than about 2 miles in thickness, and it has been interpreted as a sequence of ashflow tuffs, possibly deposited in a sub‐aerial environment.

The topography of the Coastal Plain is generally flat with ground surface elevations varying from approximately just above sea level in the east to about 500 feet in the west.

4.3 Generalized Subsurface Conditions

Subsurface data obtained from the soil borings are presented in the following paragraphs.

Complete boring logs are presented in Appendix II.

4.3.1 Surficial Materials

Boring B‐07 encountered approximately 4 inches of crushed stone at the ground surface. Borings

B‐01 through B‐06 and Boring B‐08 generally encountered approximately 3 inches of surficial organic soil at the ground surface.

Surficial Soil is typically a dark‐colored soil material containing roots, fibrous matter, and or other organic components, and is generally unsuitable for engineering purposes. F&R has not performed any laboratory testing to determine the organic content or other horticultural properties of the observed Surficial Soil materials. Therefore, the term Surficial Soil is not intended to indicate suitability for landscaping and or other purposes.

The Surficial Soil depths provided in this report are based on driller observations and should be considered approximate. We note that the transition from Surficial Soil to underlying materials

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

January 25, 2018 may be gradual, and therefore the observation and measurement of Surficial Soil depths is subjective. Actual Surficial Soil depths should be expected to vary.

4.3.2 Fill Soils

Borings B‐02 through B‐05 and B‐07 encountered fill soils below the ground surface from depths of approximately 1‐foot to 8.5 feet below the ground surface. The fill soils generally consisted of very loose to medium dense Clayey Sand (SC) containing various amounts of roots and rock fragments. Standard Penetration Resistances (N‐values) in the fill soils ranged from 5 to 15 blows per foot (bpf).

4.3.3 Coastal Plain Deposits

Coastal Plain soil deposits were encountered in Borings B‐01 through B‐08, below the fill soils and ground surface to the boring termination depths. The sampled coarse‐grained soils generally classified as medium dense to very dense Clayey Sand (SC) and Silty Sand (SM), Clayey Gravel

(GC), and Poorly Graded Sand with Silt (SP‐SM). Fine‐grained soils encountered in the borings generally classified as very stiff to hard Sandy Lean Clay (CL) and Sandy Fat Clay (CH). These soil samples were generally moist in the upper 23 to 28 feet and generally wet below these depths.

The SPT resistance (N‐values) in the Coastal Plain soil deposits ranged from 7 to 100 bpf.

4.4 Laboratory Test Results

Laboratory tests performed on a few representative soil samples indicate that these materials are moist to the depths explored, of moderate plasticity having liquid limits ranging from 38 to

48, and plasticity indices ranging from 15 to 19. These soils exhibit a moderate potential for moisture‐related volume change (shrink‐swell behavior). The natural moisture contents measured in several samples ranged from 13.5 to 19.7 percent.

A standard Proctor test was performed on a bulk soil sample obtained from Boring

B‐06. The sample classified as Silty Sand (SM) in accordance with ASTM D2487. The optimum moisture content for compaction of this soil sample was 114.1 percent and maximum dry density was 116.9 pcf. The natural moisture content measured in the bulk sample was 14.1 percent.

Laboratory California Bearing Ratio (CBR) testing was performed on the bulk sample from Boring

B‐06. We obtained laboratory a CBR value of 16.1 with a swell value of 0.04 percent for the soil compacted to approximately 95% of its Standard Proctor maximum dry density.

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4.5 Groundwater Data

Groundwater was encountered in Borings B‐01, B‐04, and B‐05 at an approximate depth of 28 feet during drilling. After removal of drilling augers, the borings were left open for a period of about 24 hours after which we measured stabilized groundwater levels. Stabilized groundwater level readings in Borings B‐01, B‐04, and B‐05 ranged from depths of approximately 24 to 29 feet below the ground surface. The remaining borings remained dry.

The presence of groundwater was evaluated at each boring location by visually judging the moisture content of the recovered split‐spoon soil samples and by dropping a weighted tape measure down the borehole.

Groundwater levels fluctuate with seasonal changes, periods of heavy or little rainfall, and other factors. Therefore, our evaluations of the groundwater level do not reveal the actual year‐round groundwater conditions.

5.0 DESIGN RECOMMENDATIONS

5.1 General

The following findings and recommendations are based on our observations at the site, interpretation of the field and laboratory data obtained during our subsurface exploration, and our experience with similar subsurface conditions and projects. Soil penetration data has been used to evaluate the subsurface conditions based on established correlations. Subsurface conditions in unexplored locations may vary from those encountered. If the proposed optometric treatment center layout or footprint are changed, F&R requests that we be advised so that our design recommendations can be re‐evaluated.

Determination of an appropriate foundation system for a given structure is dependent on the proposed structural loads, soil conditions, and construction constraints such as proximity to other structures, etc. The subsurface exploration aids the geotechnical engineer in determining the soil stratum appropriate for structural support. This determination includes considerations with regard to both allowable bearing capacity and compressibility of the soil strata.

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5.2 Shallow Foundation Design

The proposed treatment center may be supported on shallow foundation systems bearing on approved natural soils, or newly placed controlled structural fill subgrades. We do not recommend supporting the new foundations on the existing fill soils.

Based on our assumed structural loading condition, the proposed building finished floor elevations, site grading depths, as well as the encountered subsurface conditions, we recommend that the treatment center foundations be designed for a net allowable bearing pressure of 3,000 pounds per square foot (psf) for foundations bearing on approved subgrades. To reduce the possibility of localized shear failures, spread and strip foundations should be a minimum of 2 feet and 1.5 feet wide, respectively.

We recommend the use of a friction factor of 0.35 between bearing elevations and foundations.

This factor considers that concrete foundation elements will be placed in direct contact with suitable on‐site soils.

5.3 Estimated Foundation Settlement

Based on the subsurface data, site grading, our assumed finished floor elevation and structural loading conditions, we estimate total foundation settlements would be less than 1‐inch, with differential settlement of ½ of the estimated total settlement. The magnitude of differential settlements will be influenced by the variability of underlying soils across the footprint of the structures and the variation of foundation loads.

Our settlement analysis was performed based on an anticipated maximum structural load of 100 kips. The settlement analysis was based on a conventional shallow foundation bearing at a depth of at least 2 feet below the planned finished floor elevations and designed for an allowable soil bearing pressure of 3,000 psf. Actual settlements experienced by the building and the time required for these soils to settle will be influenced by undetected variations in subsurface conditions, final structural loads, final ground surface grades, and the quality of fill placement and foundation construction.

5.4 Shrink‐Swell, Frost Depth and Bearing Considerations

We recommend any near surface unsuitable fill soils at foundation bearing grades be removed and replaced with suitable structural fill soils. Suitable soils used as new structural fill soils are expected to have low to moderate plasticity.

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January 25, 2018

Based on our exploration, some of the coarse‐grained on‐site soils such as the Silty Sand (SM) and

Clayey Sand (SC) soils encountered during our subsurface exploration are close to being classified as fine‐grained soils. Therefore, it is possible that fine‐grained soils having similar degrees of plasticity will be present at the site. Based on our general experience in the project vicinity, we anticipate these coarse‐grained or potential fine‐grained soils, where present in foundation bearing grades, may exhibit a moderate potential for moisture‐related volume change (shrink‐swell behavior).

Accordingly, we recommend that exterior footings be constructed at least 24 inches below adjacent grades in order to reduce the effect of shrink‐swell, frosting, and shear puncture. Alternatively, exterior footing subgrades consisting of high plasticity fine‐grained soils may be undercut 2 feet and replaced with flowable fill, or lean concrete.

In order to further reduce the potential of shrink‐swell soil behavior, we recommend the ground surface near the building foundations be graded such that surface water does not accumulate near the foundations. Roof drainage downspouts should be routed into appropriate drainage channels or directed well away from the building.

5.5 Concrete Slabs‐On‐Grade

The floor slabs may be designed as a slab‐on‐grade supported on suitable undisturbed natural soil or new controlled structural fill subgrades. Slab‐on‐grade support is contingent upon successful completion of the subgrade evaluation process as described in the Site Preparation section of this report (Section 6.2). A modulus of subgrade reaction (k) of 150 pounds per square inch per inch

(psi/inch) may be used for design of the floor slab bearing on an approved subgrade.

A six‐inch thick layer of South Carolina Department of Transportation (SCDOT) Open Graded

Coarse Aggregate No. 57 or No. 78 should be placed beneath the floor slab. This granular base would function as a leveling and load distributing material as well as a capillary break beneath the slab.

A vapor retarder should be used beneath slabs that will be covered by tile, wood, carpet, impermeable coatings, and or if other moisture‐sensitive equipment or materials will be in contact with the slab. However, the use of vapor retarders may result in excessive curling of concrete slabs during curing. We refer the concrete slab designer to ACI 302.1R‐04, Sections

4.1.5 and 11.11, for further discussion on vapor retarders, curling, and the means to lessen potential concrete shrinkage and curling.

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January 25, 2018

Proper jointing of the concrete slabs‐on‐grade is also essential to reduce cracking. ACI suggests that unreinforced, plain concrete slabs may be jointed at spacing of 24 to 36 times the slab thickness, up to a maximum spacing of 15 feet. Slab construction should incorporate isolation joints along walls and column locations (if applicable) to allow minor movements to occur without damage. Utility or other construction excavations in the prepared subgrade should be backfilled to a controlled fill criterion to provide uniform support. Hopping

5.6 Pavement Design Recommendations

We anticipate that the proposed pavement areas will consist of both light‐duty asphalt and heavy‐duty asphalt. The light‐duty asphalt pavement section should be used where traffic is expected to primarily consist of autos and occasional light service vehicles such as in parking stalls. The heavy‐duty asphalt pavement section should be used where traffic will also consist of light and heavy service vehicles such as in driveways and areas that will see heavy truck traffic.

If concrete pavements are anticipated in vehicular traffic areas, F&R should be contacted so that we can provide additional appropriate design recommendations.

We established our pavement design recommendations based on the AASHTO layer coefficient method considering the soil conditions described in this report. We also considered an ADT loading of up to 600 cars including up to 30 heavy trucks, buses, or other delivery vehicles. Our pavement design considers a design period of 20 years. Please note that flexible pavement designed for a period of about 20 years should consider that application of new or replacement surface course will be performed at sometime around 10 years.”

The California Bearing Ratio (CBR) test result we obtained for the bulk pavement subgrade soil sample from Boring B‐06 is presented in Appendix IV. Pavement designs are normally based on a Design CBR (DCBR) value that is based on the soaked CBR value. The DCBR value used for this project is 10 based on the laboratory data.

Using the above referenced traffic conditions and the DCBR value, the following light‐duty and heavy‐duty asphalt pavement sections are recommended for the project:

Charlotte Engineers, LLP WJB Dorn Medical Center Outpatient Optometric Treatment Center

Table 5.6.1: Pavement Section Design

Pavement Section Light‐Duty Asphalt Pavement (inches)

Heavy‐Duty Asphalt Pavement (inches)

Type C Asphalt Surface Course 2.0 1.5

Type C Asphalt Intermediate Course ‐ 2.0

Graded Aggregate Base Course 6.0 6.0

It is recommended that any proposed dumpsters be supported on a minimum 6‐inch thick concrete pad on a minimum 6‐inch thick Graded Aggregate Base Course. Concrete should have a minimum compressive strength of 4,000‐psi and be air entrained. The pad should project horizontally in front of the dumpster such that the front wheels of any service truck are supported by the concrete pad during loading and unloading of the dumpster.

The above pavement sections are considered as minimum design recommendations. In general, long‐term pavement performance requires good drainage, performance of periodic maintenance activities, and particular attention to subgrade preparation. Pavement materials and installation procedures should conform with the applicable sections of the South Carolina DOT Standard

Specifications for Highway Construction (2007 Edition). Materials, weather limitations, placement and compaction are specified under appropriate sections of this publication.

Grading the site such that surface water is directed away from pavements and by construction of swales adjacent to the pavements is recommended. This will be required in areas of this site were pavement subgrades will be in cut areas or areas where the ground surface slopes towards the pavement. Pavements should be graded such that surface water is directed towards the outer limits of the paved area or to catch basins located such that surface water does not remain on the pavement.

5.7 Seismic Site Classification

The seismic site class evaluations presented herein reference American Society of Civil Engineers

(ASCE) 7‐10 as specified by Section 1613.3.2 of the International Building Code (IBC) 2015.

Chapter 20.1 of ASCE 7‐10 entails an evaluation of the top 100 feet of the subsurface soil profile in order to determine the seismic site class.

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January 25, 2018

The deepest soil boring for this project was terminated at a depth of 30 feet for foundation design considerations. Based on the data we collected from our subsurface exploration and on our experience in the area, a Site Class D is recommended for this project site.

F&R notes that the recommended Site Class is based on information available at the time this report was written. If this classification should be so onerous to the project cost that further study is warranted, we can perform a site‐specific geo‐physical survey to attain sufficient detail to further define the project’s seismic Site Class definition. This additional testing would be beyond the currently authorized scope of services for this project.

6.0 CONSTRUCTION RECOMMENDATIONS

6.1 General

The principal purpose of this section is to comment in general on the items related to earthwork and associated geotechnical engineering aspects of construction that should be expected for this project. It is recommended that F&R’s geotechnical engineer be retained to provide soil‐engineering services during the construction phases of the project and perform appropriate evaluations to help assure that conditions encountered during construction are similar to conditions encountered in the borings. The geotechnical engineer can also assist in interpretation of differing subsurface conditions that may be encountered and recommend remedial work, if needed.

6.2 Site Preparation

The entire construction area should be stripped of existing vegetation, surficial organic soils, debris or any other deleterious materials to a minimum of 5 feet outside the proposed apartment complex construction areas and 2 feet behind the curb lines for paved areas. Depressions or low areas resulting from stripping operations should be backfilled with approved soil and compacted in accordance with the recommendations presented in this report. Existing buried utilities and deleterious materials should be completely removed from within the footprint of the proposed new structures and replaced with approved soil.

During grading operations, hidden features in the substratum, such as organic laden soils, or other deleterious materials may be encountered within the proposed construction area.

Generally, such features will require removal. Details regarding the removal of deleterious

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January 25, 2018 materials should be determined on a case‐by‐case basis and; therefore, contract documents should include a contingency cost for the removal of such subsurface features.

We recommend site preparation be monitored by the geotechnical engineer or his representative to verify that the recommendations presented herein are implemented. Prior to fill placement and or at‐grade construction, areas to provide support for foundations, floor slabs, pavements and structural fills should be proofrolled under the supervision of the geotechnical engineer or his representative. Proofrolling should be performed with a fully loaded tandem‐axle dump truck or similar piece of rubber‐tired equipment with a minimum loaded weight of 20 tons. The purpose of the proofrolling is to detect the existence of any soft, very loose, or wet, near‐surface materials or unsuitable soils that may require undercutting. Areas that deflect, rut, or pump excessively during proofrolling, and which cannot be densified in‐place by further rolling, should be remediated as directed by the geotechnical engineer or his representative and approved by the Owner. Some localized undercutting and or recompaction should be anticipated and; therefore, contract documents should include a contingency cost for localized undercutting and recompaction.

6.3 Controlled Structural Fill Placement and Compaction

Prior to fill placement, representative samples of each engineered fill material should be collected and tested by F&R to determine the material’s moisture‐density characteristics

(including, the maximum dry density, optimum water content, gradation and Atterberg limits).

These tests are needed for quality control of the controlled structural fill and to determine if the fill material meets project specification requirements.

Controlled structural fill in structural areas should be free of organics, roots, or other deleterious materials; should not contain more than five percent (by weight) organic material; should not have a plasticity index (PI) greater than 25; or have a maximum dry density less than 90 pounds per cubic foot. Soils not meeting these criteria may be used in landscaped or non‐structural areas. Compacted structural fill should consist of material classified as CL, ML, SC or SM per ASTM

D2487, or others as approved by the geotechnical engineer. CH and MH materials are generally not recommended for use as structural fill due to their low strength characteristics and moisture sensitivity, but may be approved on a case‐by‐case basis. Soils imported from off‐site sources should also meet similar classification requirements and be approved by the geotechnical engineer prior to use. Successful reuse of the excavated, on‐site soils as controlled structural fill will depend on the water content and the plasticity of the soils encountered during excavation.

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Once fill placement begins, a qualified soils technician should perform field density tests to document the degree of compaction being obtained in the field. Structural fills should be placed in thin (8‐ to 10‐inch) loose lifts and compacted to the following recommendations:

Upper 18 inches below the final subgrade elevation:

100% of the soil’s standard Proctor maximum dry density (ASTM Test Method

D698) at or near optimum water content: maximum deviation of ±3 percent.

Depths below 18 inches:

98% of the soil’s standard Proctor maximum dry density (ASTM Test Method

D698) at or near optimum water content: maximum deviation of ±3 percent.

Some manipulation of the water content (such as wetting or drying) may be required during the filling operation to obtain the required degree of compaction. The manipulation of the water content is highly dependent on weather conditions and site drainage conditions. Therefore, the grading contractor should be prepared to both dry and wet the fill materials to obtain the specified compaction during grading. Regular one‐point Proctor tests should be conducted in an attempt to verify that the most representative Proctor curve is being selected. Sufficient density tests should be performed to confirm the required compaction of the fill material.

The contractor should exercise care after these soils have been compacted. If water is allowed to stand on the surface, these soils may become saturated. Movement of construction traffic on saturated subgrades can cause rutting that may destroy the fill's integrity. Once the integrity of the subgrade is destroyed, mobility of construction traffic becomes difficult or impossible.

Therefore, the fill surface should be sloped to achieve positive drainage and to minimize water from ponding on the surface.

If the surface becomes excessively wet, fill operations should be halted and our geotechnical engineer consulted for guidance. Testing of the fill material and compaction monitoring by our engineering technician is recommended during fill placement operations.

6.4 Shallow Foundation Construction

To document suitable bearing within the actual foundation excavation, we recommend that the near‐surface bearing soils be evaluated by performing hand auger borings with DCP testing equipment or other suitable methods prior to foundation installation. Any unsuitable soils

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January 25, 2018 detected during this evaluation should be undercut and remediated as directed by the geotechnical engineer. Depending on final design grades, some localized undercutting and or recompaction should be anticipated.

We recommend that individual foundations be concreted as soon after the evaluation as possible to minimize the potential disturbance of the bearing soils. If the foundation excavation subgrade soils must remain exposed overnight or during inclement weather, we recommend that a 2‐ to

4‐inch thick “mud‐mat” of lean concrete be placed on the bearing soils, taking care to maintain the required thickness of foundation concrete and the design top of footing elevation.

The foundation bearing area should be free of any very loose or soft material, standing water, and debris at the time of concrete placement. Concrete should not be placed on soils that have been softened by precipitation or frost heave. Exposure of the subgrade materials to the environment may weaken these soils at the foundation bearing level. If the foundation excavations remain open for long periods of time, or during inclement weather, re‐evaluation of the subgrade materials by the geotechnical engineer or his representative should be performed prior to steel, concrete, or stone placement.

6.5 Surface Water Control

If free water is allowed to stand on stable subgrade soils, these soils can absorb water, swell, and experience a reduction in their support capability. As a result, we recommend that the subgrade surface be graded to provide positive drainage away from the construction areas and towards suitable drainage handling areas, such as a perimeter ditch, French drain, culvert, or retention pond.

Due to the presence of moisture‐sensitive soils, trapped or perched water conditions could develop during periods of inclement weather and during seasonally wet periods. Such conditions could cause seepage into excavations and deeper cuts. Therefore, grading of the project should be performed in such a manner to prevent ponding of water and promote runoff away from construction areas. In addition, if site grading is performed during the seasonally wet months or after extended periods of inclement weather, wet and water softened near surface soil conditions should be expected.

6.6 Excavation Characteristics

We anticipate the near‐surface soils at the site can be excavated with backhoes, front‐end loaders

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January 25, 2018 or other similar equipment using conventional means and methods. Typically, material with an

N‐value of 50 blows per 3 to 6 inches of penetration can be excavated with moderate to heavy effort using appropriately sized equipment, such as a large track‐hoe (e.g., Caterpillar 330 with rock teeth).

6.7 Non‐Structural Fill

Soils not meeting the requirements for Controlled Structural Fill could be used for backfill in

“green” areas. However, it may not be economically feasible to dry soils that are found to be excessively wet during the excavation procedures. Such conditions may require the use of off‐site borrow for backfill.

Placement and compaction of non‐structural fill materials in green areas should be in accordance with the recommendations provided in Section 6.3; however, the required minimum compaction could be reduced to at least 90 percent of the standard Proctor (ASTM D698) maximum dry density.

6.8 Groundwater Conditions

Groundwater for the purposes of this report is defined as water encountered below the existing ground surface. Based on the data obtained during our exploration program, groundwater encountered in Borings B‐01, B‐04, and B‐05 at an approximate depth of 28 feet during drilling with approximate depths ranging from 24 to 29 feet for final readings. It is unlikely that groundwater would be encountered during excavation for shallow foundation construction.

However, grading activities and foundations construction may encounter a perched groundwater condition. The contractor should be prepared to dewater locations where surface water or a perched water condition is encountered. The contractor should be responsible for the design and installation of any dewatering systems required for this project.

Groundwater levels tend to fluctuate with seasonal and climatic variations as well as with some types of construction operations. Generally, the highest groundwater levels occur in late winter and early spring and the lowest levels occur in late summer and early fall. Depending on time of construction, groundwater may be encountered at shallower depths and locations not explored during this study. If encountered during construction, engineering personnel from our office should be notified immediately.

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January 25, 2018

6.9 Excavations

Mass excavations and other excavations required for construction of this project must be performed in accordance with the United States Department of Labor, Occupational Safety and

Health Administration (OSHA) guidelines (29 CFR 1926, Subpart P, Excavations) or other applicable jurisdictional codes for permissible temporary side‐slope ratios and or shoring requirements. The OSHA guidelines require daily inspections of excavations, adjacent areas and protective systems by a “competent person” for evidence of situations that could result in cave‐ ins, indications of failure of a protective system, or other hazardous conditions.

Excavated soils, equipment, building supplies, etc., should be placed away from the edges of the excavation at a distance equaling or exceeding the depth of the excavation. F&R cautions that the actual excavation slopes will need to be evaluated frequently each day by the “competent person” and flatter slopes or the use of shoring may be required to maintain a safe excavation depending upon excavation specific circumstances. The contractor is responsible for providing the “competent person” and all aspects of site excavation safety. F&R can evaluate specific excavation slope situations if we are informed and requested by the owner, designer or contractor’s “competent person.”

7.0 CONTINUATION OF SERVICES

F&R recommends that we be retained for professional and construction materials testing services during construction of the project. Our continued involvement on the project helps provide continuity for proper implementation of the recommendations discussed herein.

Additionally, we request the opportunity to review the foundation plans and project specifications when these construction documents approach completion. This review evaluates whether the recommendations and comments provided herein have been understood and properly implemented. The above listed services are not part of the currently authorized scope of services.

8.0 LIMITATIONS

There are important limitations to this and all geotechnical studies. Some of these limitations are discussed in the information prepared by the Geoprofessional Business Association (GBA), which is included in Appendix IV. We recommend that you review the GBA information.

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This report has been prepared for the exclusive use of Charlotte Engineers, LLP, or their agents, for specific application to the proposed WJB Dorn Medical Center Outpatient Treatment Center project located at 6439 Garners Ferry Road in Columbia, South Carolina, in accordance with generally accepted soil…