7164A_NGIP_Ph._II_Access_Road_Geotechnical_Report_072423.pdf

3620 Pelham Rd, PMB #292 Phone: 864-329-0013 Greenville, SC 29615-5044 FAX: 864-329-0014

REPORT OF GEOTECHNICAL EXPLORATION

Proposed Access Road

North Greenwood Industrial Park Ph. II US Highway 25

Hodges, Greenwood County, SC D&F Job No. 13984.01

GeoTrack Project No. 23-7164A

Prepared For:

1319 Highway 72/221 East

Greenwood, SC 29649

Attention: Mr. Brent Robertson, PE

July 24, 2023

3620 Pelham Road, PMB #292 Phone: 864-329-0013 Greenville, SC 29615-5044 FAX: 864-329-0014

July 24, 2023

Davis & Floyd, Inc.

1319 Highway 72/221 East Greenwood, SC 29649

Attention: Mr. Brent Robertson, PE (broberts@davisfloyd.com)

Re: Report of Geotechnical Exploration Proposed Access Road North Greenwood Industrial Park Phase II US Highway 25

Hodges, Greenwood County, SC D&F Job No. 13984.01

GeoTrack Project No. 23-7164A

Ladies and Gentlemen:

GeoTrack Technologies, Inc. has completed a geotechnical exploration for the referenced industrial park access road. The exploration was performed in general accordance with GeoTrack Proposal No. P23-2373, dated May 25, 2023, as authorized by Mr. Robertson on June 1, 2023.

The purposes of the exploration were to evaluate the site soil conditions and provide geotechnically-related design and construction recommendations for development of the approximately 2,400 linear feet of new access road. This report presents our understanding of the project, the subsurface exploration performed, the results and our recommendations.

SUMMARY OF FINDINGS AND RECOMMENDATIONS

The following is an outline of our exploration findings and recommendations for the proposed access road. These recommendations are discussed in more detail in the report text.

• Five borings (R-1 through R-5) were performed along the proposed Phase II Access Road centerline. The borings encountered about 3 to 4 inches of topsoil at the ground surface.

Due to most of the road alignment being heavily wooded, stripping to remove topsoil and tree roots will likely average on the order of 8 to 12 inches.

• Natural, residual soils were encountered beneath the topsoil in each of the borings. The residual soils consist of firm to very stiff sandy silts and sandy clays.

• None of the borings encountered partially weathered rock or auger refusal above the planned boring termination depths of 15 to 30 feet below the existing ground surface.

Based on the boring results, extensive difficult excavation due to partially weathered rock and mass rock appears unlikely.

• None of the borings encountered groundwater at the time of drilling or after a period of 24 hours. Thus, groundwater should not influence the proposed road construction.

mailto:broberts@davisfloyd.com

Report of Geotechnical Exploration, GeoTrack Project No. 23-7164A NGIP Ph. II Access Road, Greenwood Co., SC July 24, 2023

• The on-site residual soils appear satisfactory for use as structural fill. Depending on prevailing weather conditions, some moisture adjustment (wetting or drying) of this material may be required prior to reuse as structural fill.

• Based on the soil conditions encountered and estimated potential future traffic loads, we recommend that the industrial park roads consist of at least 8 inches of stone base, 2.5 inches of asphalt binder and 1.5 inches of asphalt surface. If a full-depth pavement section is utilized, we recommend 5 inches of asphalt binder and 3 inches of asphalt surface.

PROJECT DESCRIPTION

We have been provided a North Greenwood Industrial Park-Master Plan, dated November 2022, by Davis & Floyd. The drawing shows an approximately 2,400 linear feet long connector road extending west to east perpendicular to US Highway 25 along the southern boundary of the proposed North Greenwood Industrial Park (NGIP). Although we have not been provided road sections, we anticipate maximum cuts and fills on the order of about 10 feet. The NGIP Master Plan by Davis & Floyd shows three industrial buildings (manufacturing and/or warehousing) for future Phase II ranging in size from about 50,000 to 250,000 square feet. The semi-tractor trailer traffic (frequency and loads) will depend on the industries that occupy the buildings.

SCOPE OF EXPLORATION

The subsurface exploration included a site reconnaissance, and five soil test borings (R-1 through R-5) along the proposed access road at locations requested by Davis & Floyd. The approximate boring locations are shown on the Boring Location Plan in the Appendix. The borings were located with a hand-held GPS unit using coordinates from Google Earth. Ground surface elevations at the boring locations were estimated from 10-foot contours shown on the Master Plan. Because of the methods used to locate the borings and the widely spaced contours, the referenced locations and elevations are approximate.

The soil test borings were performed with a Diedrich D-50 drill mounted on a track rig, and the borings were extended to planned termination depths of 15 to 30 feet below existing grades using hollow stem augers. Standard Penetration Tests were performed at selected depth intervals with an automatic hammer to collect soil samples. A geotechnical engineer reviewed the data and visually classified the soil samples. Groundwater levels were checked in the borings at the time of drilling and after a period of 24 hours, and then the boreholes were backfilled with soil cuttings.

The boring results are summarized in the attached Boring Records. A more detailed description of our exploration procedures is also attached.

EXPLORATION RESULTS

SITE CONDITIONS

The proposed industrial park is located east of US Highway 25 in Greenwood County near Hodges, South Carolina. The proposed access road will be generally situated along the southern boundary of the proposed industrial park extending from west to east from Highway 25. The road alignment is mostly heavily wooded with pine trees. Based on contours shown on the NGIP Master Plan and elevations provided by Davis & Floyd, the ground surface along the access road varies from about 600 feet at US Highway 25 to just over 610 feet before its intersection with the connector road of phase I and to about 590 feet towards the eastern end of the proposed access road near Lot 3.

SUBSURFACE CONDITIONS

Surface Materials The borings encountered about 3 to 4 inches of topsoil and root mat at the ground surface. Due to tree roots, some variability of the thickness of surface materials should be expected across the site.

Residuum Residual soils were encountered beneath the topsoil in each of the borings to the pre-planned termination depths. Residual soils are natural soils derived from the in-place weathering of the parent bedrock. The residual soils were classified as firm to very stiff sandy silts and sandy clays.

Standard penetration resistances ranged from 6 to 30 blows per foot (bpf).

Partially Weathered Rock and Auger Refusal None of the borings encountered partially weathered rock (material with penetration resistances greater than 100 bpf) or auger refusal (typically indicates the presence of mass rock) within the boring depths of 15 to 30 feet.

Groundwater Groundwater was not encountered in the borings at the time of drilling or after a period of 24-hours. Groundwater levels fluctuate with changes in seasons and rainfall levels. Thus, future levels may rise significantly. However, it appears unlikely that groundwater will influence the proposed project.

RECOMMENDATIONS

LIMITATIONS

Our conclusions and recommendations are based on the project described above and the data obtained from our fieldwork. The recommendations are based on generally accepted geotechnical engineering practice in South Carolina at the time of the report. No other warranties are expressed or implied.

The borings performed at this site represent the subsurface conditions only at the exploration and test locations. Some variation in the subsurface conditions should be expected between the boring locations due to natural variations and previous agricultural activities. Consequently, subsurface conditions may be encountered during road construction that will require alternative recommendations.

EARTHWORK

Site Preparation We anticipate that site stripping will average on the order of 8 to 12 inches to remove topsoil and extensive tree root systems. Stripped topsoil should be wasted in landscaped areas or hauled off-site.

Subgrade Evaluation After the site is stripped, a qualified geotechnical representative should evaluate the exposed subgrade of areas that are to receive fill and areas that are at final subgrade. The evaluation will help identify soft areas not identified during stripping, and should include proofrolling with a loaded dump truck, pan or similar pneumatic tired vehicle, where possible. During the proofrolling, areas that excessively rut or deflect (pump) should be undercut to satisfactory soils, or other corrective actions should be implemented. Micaceous soils present at or near final subgrade can be susceptible to disturbance and may “fluff” if not confined by other soils or stone base. If that occurs, the micaceous soils should be removed and replaced with less micaceous soils.

Fill Placement Structural fills will be required for pavement embankments. Structural fill should be compacted to at least 95 percent of the soil’s maximum dry density obtained from the Standard Proctor Compaction Test (ASTM D-698). We recommend increasing the compaction to 98 percent in the upper 18 inches beneath the roads. To achieve the recommended compaction, the moisture content should generally be maintained within about three percent plus or minus of the optimum moisture content and the loose lift thickness should not exceed about 8 to 10 inches.

Except for the topsoil, the overburden soils (Unified Soil Classifications of ML and CL) encountered in the borings appear satisfactory for use as structural fill. It may be necessary to adjust the moisture content to achieve sufficient compaction, as a result of natural soil moisture or weather conditions immediately before construction. Part-time observation of fill placement should be performed during mass grading and include checking the compaction by performing density tests. The test frequency can be selected by the geotechnical engineer based on the areas to be filled and the construction schedule.

Excavation Difficulty The borings encountered moderate consistency soils to the planned termination depths of 15 to 30 feet. Maximum cut depths are expected on the order of 10 feet during mass grading. The depth to partially weathered rock and mass rock can be highly variable in the Upstate of South Carolina.

Thus, although unlikely, there is some potential that isolated difficult excavation could be encountered during mass grading of the roads and in deep trench excavations. Mass excavation of partially weathered rock can normally be accomplished with some pre-loosening with a ripper attached to a bulldozer, and trench excavation can be accomplished with a large-tracked excavator.

Excavation of mass rock typically requires blasting or pneumatic equipment, such as a hoe ram.

Slopes Based on our experience with similar subsurface conditions, we recommend permanent cut and fill slopes no steeper than 2H:1V (horizontal to vertical). We also recommend that temporary slopes be inclined no steeper than about 1.5H:1V, depending on specific soil conditions in the excavations and OHSA requirements. We assess the residual soils at the site to meet the description of a Type C soil based on OSHA Standard 29 CFR (Soil Classification – 1926 Subpart P Appendix A).

It is difficult to construct soil fill slopes to 2H:1V without creating a loose poorly compacted zone near the slope face. For this reason, we recommend that the fill slopes be slightly over-built, and then cut back to firm, well compacted soils prior to applying a vegetative cover. The crest areas should also be sloped to prevent surface water run-off from flowing over the slope face.

RETAINING WALLS

Segmental retaining walls may be required for road embankments. If required, we recommend designing the walls based on an estimated angle of internal friction of 28 degrees, no soil cohesion, and a soil unit weight of 120 pounds per cubic foot (pcf) for properly compacted structural fill.

PAVEMENT THICKNESS DESIGN

The soils encountered in the borings are assessed as firm to very stiff relative to pavement support characteristics. The subgrade soils can be expected to provide adequate pavement support when properly moisture-conditioned and compacted. The pavement thickness design should be based on an estimated California Bearing Ratio (CBR) of between about 4 and 6. The recommended heavy duty pavements sections contained in Table should be satisfactory for approximately 200,000 Equivalent 18,000 pound Single Axle Loads (ESALs) over a theoretical 20-year design period. If greater pavement loading is anticipated, then we recommend increasing the asphalt pavement section thickness. The pavements should be constructed in accordance with the South Carolina Department of Transportation (SCDOT) Standard Specifications for Highway Construction.

Table 1. Pavement Thickness Recommendations

The residual soils and properly compacted fill at the site will exhibit generally favorable long-term strength characteristics beneath completed pavements (as long as they are compacted properly and the pavement has adequate drainage). Exposed micaceous soils and clayey soils may be locally

MATERIAL

RECOMMENDED

THICKNESSES

(Inches)

RECOMMENDED FULL-

DEPTH THICKNESSES

(Inches)

SCDOT

SPECIFICATION

SECTION

Stabilized Aggregate or Macadam Base Course 8 N/A 305

Type C Asphalt Concrete Intermediate Course 2.5 5 402

Type C Asphalt Concrete Surface Course 1.5 3 403 unstable under rubber-tired construction equipment and variations in surface moisture conditions.

Therefore, it may be necessary to scarify and re-compact the subgrades immediately before pavement construction, or implement other measures, such as undercutting and replacement, to maintain subgrade stability before or during construction. The exposed subgrade should be evaluated in a manner described in the Earthwork Section, before placing crushed stone or pavement.

CLOSING

GeoTrack Technologies, Inc. appreciates the opportunity to assist you during this phase of the project. Please call if there are any questions concerning this report, or if you need additional assistance.

Respectfully submitted, GeoTrack Technologies, Inc.

Ashish Kumar Staff Professional akumar@geotracksc.com

Kenneth W. Weinel, P.E.

Senior Professional South Carolina P.E. No. 15921 kweinel@geotracksc.com

APPENDIX

Boring Location Plan Boring Records

Exploration Procedures

- Approximate Boring Location Ref: NGIP - Master Plan By Davis & Floyd

Boring Location Plan NGIP Phase II Access Road

Hodges, Greenwood County, SC GeoTrack Project No.: 23-7164A

Pelham Rd, PMB #292 Greenville, SC 29615 Phone: (864)329-0013

R-1

R-5

R-3

R-4

R-2

3.5

8.5

13.5

SS-1

SS-2

SS-3

SS-4

SS-5

0.25

Topsoil and Root Mat - 3 Inches

Residuum - Firm to Stiff Red, Yellow, White and Black Fine Sandy Silt (ML)

Boring Terminated at 15 Feet

Split Spoon Shelby Tube Rock Core, 1-1/8"

NQ

CU

CT

MATERIAL DESCRIPTION

Rotary Wash Rock Core

Rock Core, 1-7/8" Cuttings Continuous Tube

North Greenwood Industrial Park Access Rd Hodges, Greenwood County, SC GeoTrack Project No. 23-7164

BORING No. R-1

BORING RECORDBORING RECORD

597.5

595.0

592.5

590.0

587.5

585.0

582.5

580.0

577.5

575.0

572.5

570.0

N V al ue

Drilling Method: HSA Hammer Type: Automatic

Notes:

Independence Drilling - Diedrich D-50

D ep th (f t)

LEGEND

0.0

Water Level: Dry ATD; Dry after 24 hrs

E le va tio n (f t)

RW

RC

20 40

SAMPLER TYPE DRILLING METHOD

SS

ST

AWG

1s t 6 in

2n d

6i n

3r d

6i n

Date Drilled: 6/15/23

S am pl e

D ep th (f t)

STD. PENETRATION TEST DATA

(blows/ft)

Boring Location: See Boring Location Plan

Hollow Stem Auger Continuous Flight Augers Driving Casing

5 10

3620 Pelham Road, PMB #292 Greenville, SC 29615

(864) 329-0013

S am pl e

N o.

/T yp e

G ra p h ic L o g

HSA

CFA

DC

Ground Elevation: 600 ft

Boring Diameter: 6 in

B O

R

IN

G R

E C

O R

D

A N

G

IP

A C

C E

S S

R O

A D

.G P

J G

E O

T R

A C

K .G

T

7/

3/

8.5

13.5

SS-1

SS-2

SS-3

SS-4

SS-5

0.33

Topsoil and Root Mat - 4 Inches

Residuum - Very Stiff Reddish Brown Fine Sandy Clay (CL)

Stiff Red and Yellowish Brown Fine Sandy Silt (ML)

Boring Terminated at 15 Feet

Split Spoon Shelby Tube Rock Core, 1-1/8"

NQ

CU

CT

MATERIAL DESCRIPTION

Rotary Wash Rock Core

Rock Core, 1-7/8" Cuttings Continuous Tube

North Greenwood Industrial Park Access Rd Hodges, Greenwood County, SC GeoTrack Project No. 23-7164

BORING No. R-2

BORING RECORDBORING RECORD

597.5

595.0

592.5

590.0

587.5

585.0

582.5

580.0

577.5

575.0

572.5

570.0

N V al ue

Drilling Method: HSA Hammer Type: Automatic

Notes:

Independence Drilling - Diedrich D-50

D ep th (f t)

LEGEND

0.0

Water Level: Dry ATD; Dry after 24 hrs

E le va tio n (f t)

RW

RC

20 40

SAMPLER TYPE DRILLING METHOD

SS

ST

AWG

1s t 6 in

2n d

6i n

3r d

6i n

Date Drilled: 6/15/23

S am pl e

D ep th (f t)

STD. PENETRATION TEST DATA

(blows/ft)

Boring Location: See Boring Location Plan

Hollow Stem Auger Continuous Flight Augers Driving Casing

5 10

3620 Pelham Road, PMB #292 Greenville, SC 29615

(864) 329-0013

S am pl e

N o.

/T yp e

G ra p h ic L o g

HSA

CFA

DC

Ground Elevation: 600 ft

Boring Diameter: 6 in

B O

R

IN

G R

E C

O

A N

G

IP

A C

C E

S S

R O

A D

.G P

J G

E O

T R

A C

K .G

8.5

13.5

18.5

SS-1

SS-2

SS-3

SS-4

SS-5

SS-6

0.33

Topsoil and Root Mat - 4 Inches

Residuum - Stiff Reddish Brown and Yellowish Brown Fine Sandy Silt (ML)

Stiff Red, Yellow and Gray Fine Sandy Silt

(ML)

Stiff Yellowish Brown, Red and Gray Slightly Micaceous Fine Sandy Silt (ML)

Boring Terminated at 20 Feet

Split Spoon Shelby Tube Rock Core, 1-1/8"

NQ

CU

CT

MATERIAL DESCRIPTION

Rotary Wash Rock Core

Rock Core, 1-7/8" Cuttings Continuous Tube

North Greenwood Industrial Park Access Rd Hodges, Greenwood County, SC GeoTrack Project No. 23-7164

BORING No. R-3

BORING RECORDBORING RECORD

597.5

595.0

592.5

590.0

587.5

585.0

582.5

580.0

577.5

575.0

572.5

570.0

N V al ue

Drilling Method: HSA Hammer Type: Automatic

Notes:

Independence Drilling - Diedrich D-50

D ep th (f t)

LEGEND

0.0

Water Level: Dry ATD; Dry after 24 hrs

E le va tio n (f t)

RW

RC

20 40

SAMPLER TYPE DRILLING METHOD

SS

ST

AWG

1s t 6 in

2n d

6i n

3r d

6i n

Date Drilled: 6/15/23

S am pl e

D ep th (f t)

STD. PENETRATION TEST DATA

(blows/ft)

Boring Location: See Boring Location Plan

Hollow Stem Auger Continuous Flight Augers Driving Casing

5 10

3620 Pelham Road, PMB #292 Greenville, SC 29615

(864) 329-0013

S am pl e

N o.

/T yp e

G ra p h ic L o g

HSA

CFA

DC

Ground Elevation: 600 ft

Boring Diameter: 6 in

B O

R

IN

G R

E C

O

A N

G

IP

A C

C E

S S

R O

A D

.G P

J G

E O

T R

A C

K .G

8.5

13.5

18.5

23.5

28.5

SS-1

SS-2

SS-3

SS-4

SS-5

SS-6

SS-7

SS-8

0.33

Topsoil and Root Mat - 4 Inches

Residuum - Very Stiff Reddish Brown Fine Sandy Silt (ML)

Stiff Red, Yellow and Gray Fine Sandy Silt

(ML)

Stiff to Very Stiff Reddish Brown and Gray Slightly Micaceous Fine Sandy Silt (ML)

Boring Terminated at 30 Feet

Split Spoon Shelby Tube Rock Core, 1-1/8"

NQ

CU

CT

MATERIAL DESCRIPTION

Rotary Wash Rock Core

Rock Core, 1-7/8" Cuttings Continuous Tube

North Greenwood Industrial Park Access Rd Hodges, Greenwood County, SC GeoTrack Project No. 23-7164

BORING No. R-4

BORING RECORDBORING RECORD

599.5

597.0

594.5

592.0

589.5

587.0

584.5

582.0

579.5

577.0

574.5

572.0

N V al ue

Drilling Method: HSA Hammer Type: Automatic

Notes:

Independence Drilling - Diedrich D-50

D ep th (f t)

LEGEND

0.0

Water Level: Dry ATD; Dry after 24 hrs

E le va tio n (f t)

RW

RC

20 40

SAMPLER TYPE DRILLING METHOD

SS

ST

AWG

1s t 6 in

2n d

6i n

3r d

6i n

Date Drilled: 6/15/23

S am pl e

D ep th (f t)

STD. PENETRATION TEST DATA

(blows/ft)

Boring Location: See Boring Location Plan

Hollow Stem Auger Continuous Flight Augers Driving Casing

5 10

3620 Pelham Road, PMB #292 Greenville, SC 29615

(864) 329-0013

S am pl e

N o.

/T yp e

G ra p h ic L o g

HSA

CFA

DC

Ground Elevation: 602 ft

Boring Diameter: 6 in

B O

R

IN

G R

E C

O

A N

G

IP

A C

C E

S S

R O

A D

.G P

J G

E O

T R

A C

K .G

8.5

13.5

18.5

23.5

SS-1

SS-2

SS-3

SS-4

SS-5

SS-6

SS-7

0.25

Topsoil and Root Mat - 3 Inches

Residuum - Very Stiff Reddish Brown Fine Sandy Clay (CL)

Stiff Red and Yellowish Brown Slightly Micaceous Fine Sandy Silt (ML)

Firm Red and Gray Slightly Micaceous Fine Sandy Silt (ML)

Boring Terminated at 25 Feet

Split Spoon Shelby Tube Rock Core, 1-1/8"

NQ

CU

CT

MATERIAL DESCRIPTION

Rotary Wash Rock Core

Rock Core, 1-7/8" Cuttings Continuous Tube

North Greenwood Industrial Park Access Rd Hodges, Greenwood County, SC GeoTrack Project No. 23-7164

BORING No. R-5

BORING RECORDBORING RECORD

587.5

585.0

582.5

580.0

577.5

575.0

572.5

570.0

567.5

565.0

562.5

560.0

N V al ue

Drilling Method: HSA Hammer Type: Automatic

Notes:

Independence Drilling - Diedrich D-50

D ep th (f t)

LEGEND

0.0

Water Level: Dry ATD; Dry after 24 hrs

E le va tio n (f t)

RW

RC

20 40

SAMPLER TYPE DRILLING METHOD

SS

ST

AWG

1s t 6 in

2n d

6i n

3r d

6i n

Date Drilled: 6/16/23

S am pl e

D ep th (f t)

STD. PENETRATION TEST DATA

(blows/ft)

Boring Location: See Boring Location Plan

Hollow Stem Auger Continuous Flight Augers Driving Casing

5 10

3620 Pelham Road, PMB #292 Greenville, SC 29615

(864) 329-0013

S am pl e

N o.

/T yp e

G ra p h ic L o g

HSA

CFA

DC

Ground Elevation: 590 ft

Boring Diameter: 6 in

B O

R

IN

G R

E C

O

A N

G

IP

A C

C E

S S

R O

A D

.G P

J G

E O

T R

A C

K .G

EXPLORATION AND TESTING PROCEDURES

Soil Test Borings: Soil sampling and penetration testing for this project were performed in accordance with ASTM D 1586. The borings were advanced with hollow-stem, continuous flight augers and, at standard intervals, soil samples were obtained with a standard 1.4-inch I.D., 2 inch O.D., split-tube sampler. The sampler was first seated six (6) inches to penetrate any loose cuttings, then driven an additional foot with blows of a 140 pound hammer falling 30 inches or with an automatic safety hammer. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the "Standard Penetration Resistance" (N-Value). The Standard Penetration Resistance, when properly evaluated, is an index to soil consistency, strength, density, and ability to support foundations.

Representative portions of each soil sample were placed in glass jars or re-sealable plastic bags and transported to our laboratory. The samples were then visually classified by an engineer to supplement the driller's field classifications. Test Boring Records are attached indicating the soil descriptions and Standard Penetration Resistances.