SW6240107_Soils/Geotechnical Report_20240205

Raeford S115kV -
Re
Geotechnical Engineering Report
May 17, 2023 I Terracon Project No. 70235048. Revl
Prepared for:
Duke Energy
410 South Wilmington Street
Raleigh, North Carlina 27601
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May 17, 2023
Duke Energy
410 South Wilmington Street
Raleigh, North Carlina 27601
Attn: Beth Steffens - Senior Engineer
P: [phone]
E: [e-mail]
Re: Geotechnical Engineering Report
Raeford South 115kV - Rebuild Substation
1600 Oakdale Gin Road
Raeford, North Carolina
Terracon Project No. 70235048.Rev1
Dear Ms. Steffens:
We have completed the scope of Geotechnical Engineering services for the above
referenced project in general accordance with Terracon Proposal No. P70235048.Rev2
dated March 6, 2023. This report presents the findings of the subsurface exploration and
provides geotechnical recommendations concerning earthwork and the design and
construction of foundations and floor slabs for 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, \,,`1 i i 1////
\\ CAROI,
Terracon �\Q`��ES S j e O• y%
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5/17/2023 •
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Hugo Santana, PE Andi ew A. Nash, PE
Geotechnical Project Engineer Geotechnical Department Manager
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina ,I ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Table of Contents
Introduction 1
Project Description 1
Site Conditions 3
Geotechnical Characterization 3
Seismic Site Class 4
Corrosivity 5
Geotechnical Overview 5
Earthwork 6
Site Preparation 6
Site Remediation 7
Fill Material Types 7
Fill Placement and Compaction Requirements 7
Grading and Drainage 8
Earthwork Construction Considerations 8
Construction Observation and Testing 9
Shallow Foundations 10
Design Parameters - Compressive Loads 10
Design Parameters - Overturning and Uplift Loads 11
Foundation Construction Considerations 11
Deep Foundations 12
Drilled Shaft Design Parameters 12
MFAD Parameters 17
Drilled Shaft Lateral Loading 22
Drilled Shaft Construction Considerations 24
Gravel-Surfaced Drives and Parking 25
Subgrade Preparation 25
Design Recommendations 25
Ingress and Egress Pavement Sections 26
Maintenance 27
General Comments 27
Figures
GeoModel
Attachments
Exploration and Testing Procedures
Site Location and Exploration Plans
Exploration and Laboratory Results
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Supporting Information
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 .ierracon 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.
Facilities I Environmental I Geotechnical I Materials ii

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Introduction
This report presents the results of our subsurface exploration and Geotechnical
Engineering services performed for the proposed Raeford South 115kV - Rebuild
Substation to be located at 1600 Oakdale Gin Road in Raeford, North Carolina. 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
The geotechnical engineering Scope of Services for this project included the
advancement of test borings, laboratory testing, engineering analysis, and preparation
of this report.
Drawings showing the site and boring locations are shown on the Site Location and
Exploration Plan, respectively. The results of the laboratory testing performed on soil
samples obtained from the site during our field exploration are included on the boring
logs and/or as separate graphs in the Exploration Results section.
Project Description
Our initial understanding of the project was provided 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
The following documents were provided to us by Duke Energy.
RFP Geotech_RaefordSouth.pdf
Raeford South 115 KV - Prelim Layout-boring locates.pdf;
Information Boring plan
Provided Raeford-TLine-Borings.kmz; Boring Plan
Geotechnical Service Specification.pdf
Soil Boring Data.xlsx
130695 look-up-and-live-brochure-8-7-2014 reduced.pdf
Facilities I Environmental I Geotechnical I Materials 1

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Item Description
The project includes the addition of new equipment to the
Project existing substation along the 115kV side. Additional
Description transmission line structures to accommodate the new
equipment.
Foundations will need to be constructed for the new equipment.
Proposed We anticipate the installation of shallow and deep foundations to
Structure support the structures. We anticipate the installation of deep
foundations to support the transmission line structures.
Finished Floor Not provided, assumed to be close to the existing substation
Elevation elevation.
The following loads were provided in the RFP provided:
Transformers: 150 kips
Control Enclosure: 100 kips
Maximum Loads Switchgear Enclosure: 100 kips
Equipment Piers: Moment - 878 kip-ft
Shear - 11.64 kips
Compression - 20.7 kips
Grading/Slopes Minimal cuts and fills (less than 5 feet) will be required to
develop final grade.
Below-Grade
Structures None anticipated.
Free-Standing
Retaining Walls None anticipated.
We anticipate low-volume, aggregate-surfaced access roads will
have primarily light maintenance vehicles, but the roads will be
designed for a maximum vehicle load of 80,000 lbs. for fire
Access Road truck access. A traffic loading of 2,500 18-kip equivalent single
axle loads (ESALs) over is assumed.
The pavement design period is 20 years.
Terracon should be notified if any of the above information is inconsistent with the
planned construction, especially the grading limits, as modifications to our
recommendations may be necessary.
Facilities I Environmental I Geotechnical I Materials 2

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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.
Item Description
The project is located along 1600 Oakdale Gin Road in Raeford,
Parcel North Carolina.
Information Latitude/Longitude (approximate): 34.95977, -79.21119
See Site Location
Existing The site is located at the existing Raeford South 115kV
Improvements Substation.
Current Ground
Gravel, maintained grass and agricultural fields.
Cover
Existing Based on the aerial imagery and available topography
Topography information, the site appears to be relatively flat.
The subject site is located in the Coastal Plain Physiographic
Province, Middendorf Formation. The Coastal Plain soils consist
mainly of marine sediments that were deposited during
Site Geology successive periods of fluctuating sea level and moving shoreline.
The soils include sands, silts, and clays with irregular deposits of
shells, which are typical of those lain down in a shallow sloping
sea bottom. Recent alluvial sands, silts, and clays are typically
present near rivers and creeks.
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
the Exploration Results and the GeoModel can be found in the Figures attachment of
this report.
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.
Facilities I Environmental I Geotechnical I Materials 3

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina rr ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Model
Layer
Layer Name General Description
1 Surface Gravel, Topsoil and Cultivated Topsoil
2 Sand Silty/Clayey Sand and Poorly Graded Sand Soils; Loose
to Dense
3 Lean Clay Sandy Lean CLAY; Soft to Very Stiff
4 Fat Clay Sandy Fat CLAY; Stiff to Hard
The boreholes were observed while drilling for the presence and level of groundwater. The
boreholes were observed while drilling and at the completion of drilling for the presence
and level of groundwater. Groundwater was encountered at depths of 4 to 6 feet below the
existing ground surface. The water levels observed in the boreholes can be found on the
boring logs in Exploration Results.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall,
runoff and other factors not evident at the time the borings were performed. Therefore,
groundwater levels during construction or at other times in the life of the structure may
be higher or lower than the levels indicated on the boring logs. The possibility of
groundwater level fluctuations should be considered when developing the design and
construction plans for the project.
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). Based on the soil properties observed
at the site and as described on the exploration logs and results, our professional opinion
is for that a Seismic Site Classification of D be considered for the project. Subsurface
explorations at this site were extended to a maximum depth of 45 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.
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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
Sample Soil Soluble Soluble Electrical
Boring Depth Sulfate Chloride Resistivity pH
(feet) Description (mg/kg) (mg/kg) (fl-cm)
TB-1 1 — 4 Sandy Lean 5 88 13,423 5.7
CLAY
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
Based on project test boring information, shallow subsurface conditions consist of soft to
stiff sandy lean clay and medium dense to dense silty/clayey sand soils. At this time,
structure types and locations have not been finalized; however, based on the results of
our subsurface exploration, potential structures may be supported on conventional
spread and strip footings with a net allowable bearing pressure of 2,500 psf with some
localized repairs expected and when prepared as described in this report.
The loose near surface soils at the site will likely require remedial work at the time of
site preparation and earthwork. We recommend vibratory rolling of the exposed soils
after completion of topsoil stripping. Additional remedial measures in the existing near
surface soils may still be required depending upon the amount of fill to be placed at the
site and the moisture condition of the soils at the time of construction. The remedial
measures will potentially include over-excavation and replacement or the use of
subgrade stabilization fabric in conjunction with sand fill.
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
The near surface soils moisture sensitive and could become unstable, especially after
precipitation events, as well as with typical earthwork and construction traffic. The
effective drainage should be completed early in the construction sequence and
maintained after construction to avoid potential issues. If possible, the grading should
be performed during the warmer and drier times of the year. If grading is performed
during the winter months, an increased risk for possible undercutting and replacement of
unstable subgrade will persist. Additional site preparation recommendations, including
subgrade improvement and fill placement, are provided in the Earthwork section.
The recommendations contained in this report are based upon the results of field and
laboratory testing (presented in the Exploration Results), engineering analyses, and
our current understanding of the proposed project. The General Comments section
provides an understanding of the report limitations.
Earthwork
Earthwork is anticipated to include excavations and 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 floor
slabs.
Site Preparation
Prior to placing fill, existing vegetation, topsoil, and root mats should be removed.
Complete stripping of the topsoil should be performed in the proposed substation and
driveway areas.
Following stripping of topsoil, ground improvement will be required for the very loose to
loose near surface sand. In-place compaction should be performed using a medium to
heavy weight vibratory sheepsfoot roller in areas to receive fill or at the subgrade
elevation in cut areas. The roller should make at least six passes, with the second set of
three passes perpendicular to the first set of three passes. In-place compaction should
be performed during a period of dry weather to avoid degrading an otherwise suitable
subgrade.
The subgrade should be proofrolled with an adequately loaded vehicle such as a fully-
loaded tandem-axle dump truck. The proofrolling should be performed under the
direction of the Geotechnical Engineer. Areas excessively deflecting under the proofroll
should be delineated and subsequently addressed by the Geotechnical Engineer. We
expect that some localized areas may require additional over excavation and
replacement prior to receiving fill due to loose/soft conditions. Excessively wet or dry
material should either be removed or moisture conditioned and recompacted.
Facilities I Environmental I Geotechnical I Materials 6

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Site Remediation
The following recommendations are for the pavement sections of the new access road.
Following stripping of topsoil, the area should be undercut to 2 feet below final subgrade
within the pavement areas and 5 feet beyond the lateral limits of the pavement areas.
Once materials have been removed, the entire area should be compacted in place and
proofrolled as outlined in the Site Preparation section. Once the loose surface soil
materials have been remediated, and the subgrade has passed the proofroll test, the
excavated soils can be evaluated for use as structural fill and can be placed in controlled
lifts as outlined in the Fill Compaction Requirements section.
Fill Material Types
Fill required to achieve design grade should be classified as structural fill and general fill.
Structural fill is material used below, or within 10 feet of structures or constructed
slopes. General fill is material used to achieve grade outside of these areas. Earthen
materials used for structural and general fill should meet the following material property
requirements:
Soil Type USCS Acceptable Parameters (for Structural
Classification Fill)
Low Plasticity CL, CL-ML Liquid Limit less than 50
Cohesive ML, SM, SC Plasticity index less than 25
GW GP GM GCE
Granular SW, SP, SM, SC Less than 50% passing No. 200 sieve
1. Structural and general 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 frozen
subgrade. A sample of each material type should be submitted to the Geotechnical
Engineer for evaluation prior to use on this site. Additional geotechnical consultation
should be provided prior to use of uniformly graded gravel on the site.
Fill Placement and Compaction Requirements
Structural and general fill should meet the following compaction requirements.
Item Structural Fill General Fill
Maximum Lift 8 inches or less in loose thickness when Same as
heavy, self-propelled compaction equipment
Thickness structural fill
is used
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Item Structural Fill General Fill
98% of max. below foundations and within
Minimum 1 foot of finished grade
Compaction 95% of max. above foundations, below 92% of max.
Requirements 1,2,3 floor slabs, and more than 1 foot below
finished grade
Low plasticity cohesive: -2% to +3% of As required to
Water Content achieve min.
optimum
Range I compaction
Granular: -3% to +3% of optimum
requirements
1. Maximum density and optimum water content as determined by the standard Proctor
test (ASTM D 698).
2. High plasticity cohesive fill should not be compacted to more than 100% of standard
Proctor maximum dry density.
3. If the granular material is a coarse sand or gravel, or of a uniform size, or has a low
fines content, compaction comparison to relative density may be more appropriate. In
this case, granular materials should be compacted to at least 70% relative density
(ASTM D 4253 and D 4254). Materials not amenable to density testing should be placed
and compacted to a stable condition observed by the Geotechnical Engineer or
representative.
Grading and Drainage
All grades must provide effective drainage away from the substation during and after
construction and should be maintained throughout the life of the structure. Water
retained next to equipment pads and structures can result in soil movements greater
than those discussed in this report. Greater movements can result in unacceptable
differential slab and/or foundation movements and cracked slabs.
Earthwork Construction Considerations
Shallow excavations for the proposed structure are anticipated to be accomplished 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 equipment pads. 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.
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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
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 equipment pad 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
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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 2,500 psf - foundations bearing upon
Pressure '° 2 improved existing soils or new structural fill
Required Bearing Stratum 3 Approved structural fill or native soils
Minimum Foundation Dimensions Columns: 30 inches
Continuous: 18 inches
0.30 (existing fill and native soils)
Sliding Resistance 4
0.35 (granular material)
Minimum Embedment below
Finished Grade 5 12 inches
Estimated Total Settlement from
Structural Loads 2 Less than about 1 inch
Estimated Differential Settlement 2, 6 Less than 1/2" 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. Unsuitable or soft soils should be overexcavated and replaced per the recommendations
presented in Earthwork.
4. 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 ,/2 the dead load.
5. 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.
6. Differential settlements are noted for equivalent-loaded foundations and bearing
elevation as measured over a span of 50 feet.
Facilities I Environmental I Geotechnical I Materials 10

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
The foundation bearing materials should be evaluated at the time of the foundation
excavation. This is an essential part of the construction process. A representative of the
geotechnical engineer should use a combination of hand auger borings and dynamic
cone penetrometer (DCP) testing to determine the suitability of the bearing materials for
the design bearing pressure. DCP testing should be performed to a depth of 3 to 5 feet
below the bottom of foundation excavation. Excessively soft, loose, or wet bearing soils
should be over excavated to a depth recommended by the geotechnical engineer. The
excavated soils should be replaced with structural fill or crushed stone (NCDOT ABC).
However, footings could bear directly on the soils after over excavation if approved by
the Geotechnical Engineer.
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.
Item Description
Soil Moist Unit Weight 100 pcf
Soil Effective Unit Weight' 40 pcf
Soil included within the prism extending up from
Soil weight included in uplift
resistance the top perimeter of the footing at an angle of 20
degrees from vertical to ground surface
1. Effective (or buoyant) unit weight should be used for soil above the foundation level and
below a water level. The high groundwater level should be used in uplift design as
applicable.
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.
Facilities I Environmental I Geotechnical I Materials 11

Geotechnical Engineering Report "'-'
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina 0 ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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.
I'
111I
F
DESIGN
FOOTING LEVEL
LEAN
CONCRETE
RECOMMENDED _ 1=1
EXCAVATION LEVEL '—I I I,III—ITI
LEAN CONCRETE BACKFILL
NOTE:EXCAVATIONS ARE SHOWN VERTICAL;HOWEVER,THE
SIDEWALLS SHOULD BE SLOPED AS NECESSARY FOR SAFETY
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 the Earthwork section.
X
Ii1i1 11E ' -1I1=L-III
ll L1'
r-L Titi
DESIGN
FOOTING LEVEL c
STRUCTURAL D -III
FILL _
RECOMMENDED e r
-I
EXCAVATION LEVEL
OVER-EXCAVATION/BACKFILL ZONE
NOTE:EXCAVATIONS ARE SHOWN VERTICAL;HOWEVER,THE
SIDEWALLS SHOULD BE SLOPED AS NECESSARY FOR SAFETY
Deep Foundations
Drilled Shaft Design Parameters
Soil design parameters are provided below in the Drilled Shaft Design Summary table
for the design of drilled shaft foundations. The values presented for allowable side
friction and end bearing include a factor of safety. The allowable skin friction has a factor
of safety of about 2, while the allowable end bearing has a safety factor of 3. The provided
Facilities I Environmental I Geotechnical Materials 12

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
skin friction values should be reduced by 2/3 for uplift loading. These values should be
considered approximate.
The design should consider reducing or neglecting the upper 3 feet of surficial
material to the potential effects of construction disturbance and creation of an annulus from
lateral movements. If the design pier length exceeds 30 feet, Terracon should be contacted to
provide additional comment with regard to end bearing support. It may be necessary to drill
an additional soil test boring to confirm conditions at greater depths. It should be noted that
subsurface conditions could vary if supports are moved from the location of our boring or if
significant grade changes occur at the site.
Drilled Shaft Design Summary
Axial Drilled Shaft Design remeters (SB-1)
Groundwater observed to be at 4.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(feet) (psf) 3 (psf) 4
0 to 45 2 SM 15 --
4 to 8 2 SC 100 4,000
8 to 12 3 CL 15 300
12 to 17 2 SC 155 9,000
17 to 27 2 SM 195 3,200
27 to 30 2 SM 215 4,500
1. Design capacities are dependent upon the method of installation and quality control
parameters. The values provided are estimates and should be verified when installation
protocol have been finalized.
2. See Subsurface Profile in Geotechnical Characterization for more details on
stratigraphy.
3. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift
loading. The effective weight of the shaft can be added to uplift load resistance to the
extent permitted by IBC.
4. Shafts should extend at least one diameter into the bearing stratum (or to a depth equal
to the bell diameter for belled shafts) for end bearing to be considered.
5. Parameters interpolated from SB-3 and SB-4.
Facilities I Environmental I Geotechnical I Materials 13

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (SB-2)
Groundwater observed to be at 4.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet)
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf) 3 (psf) 4
0to65 2 SM 25 --
6 to 8 2 SC 145 3,200
8 to 12 3 CL 25 425
12 to 17 4 CH 135 2,200
17 to 27 2 SC 240 4,250
27 to 30 3 CL 145 2,380
1. Design capacities are dependent upon the method of installation and quality control
parameters. The values provided are estimates and should be verified when installation
protocol have been finalized.
2. See Subsurface Profile in Geotechnical Characterization for more details on
stratigraphy.
3. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift
loading. The effective weight of the shaft can be added to uplift load resistance to the
extent permitted by IBC.
4. Shafts should extend at least one diameter into the bearing stratum (or to a depth equal
to the bell diameter for belled shafts) for end bearing to be considered.
5. Parameters interpolated from SB-3 and SB-4.
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (SB-3)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet) No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf) 3 (psf) 4
0to6 2 SM 15 --
6 to 8 2 SC 75 1,850
8 to 17 2 SC 165 3,725
17 to 27 2 SP 215 7,450
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Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (SB-3)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet)
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf (psf) 4
27 to 30 4 CH 125 2,000
1. Design capacities are dependent upon the method of installation and quality control
parameters. The values provided are estimates and should be verified when installation
protocol have been finalized.
2. See Subsurface Profile in Geotechnical Characterization for more details on
stratigraphy.
3. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift
loading. The effective weight of the shaft can be added to uplift load resistance to the
extent permitted by IBC.
4. Shafts should extend at least one diameter into the bearing stratum (or to a depth equal
to the bell diameter for belled shafts) for end bearing to be considered.
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (TB-1)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet)
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf) 3 (psf) 4
0 to 3 3 CL 60 --
3 to 6 2 SC 35 --
6 to 8 3 CL 135 2,250
8 to 16 2 SP 165 5,250
16 to 22 2 SP 200 3,725
22 to 27 4 CH 100 1,600
27 to 32 4 CH 170 2,800
32 to 37 2 SC 240 7,000
37 to 42 4 CH 160 2,600
42 to 45 4 CH 325 8,000
Facilities I Environmental I Geotechnical Materials 15

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (TB-1)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet)
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf) 3 (psf) 4
1. Design capacities are dependent upon the method of installation and quality control
parameters. The values provided are estimates and should be verified when installation
protocol have been finalized.
2. See Subsurface Profile in Geotechnical Characterization for more details on
stratigraphy.
3. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift
loading. The effective weight of the shaft can be added to uplift load resistance to the
extent permitted by IBC.
4. Shafts should extend at least one diameter into the bearing stratum (or to a depth equal
to the bell diameter for belled shafts) for end bearing to be considered.
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (TB-2)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(feet) (psf) 3 a
(psf)
0 to 5 3 CL 25 --
5 to 11 2 SC 130 4,500
11 to 18 2 SP 150 2,400
18 to 22 2 SC 200 5,300
22 to 27 4 CH 85 1,400
27 to 32 4 CH 375 6,000
32 to 37 4 CH 220 3,600
37 to 42 3 CL 50 850
42 to 45 2 SC 260 5,300
Facilities I Environmental I Geotechnical Materials 16

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Drilled Shaft Design Summary
Axial Drilled Shaft Design Parameters (TB-2)
Groundwater observed to be at 6.0 feet
Approximate Stratigraphy 2 Allowable Skin Allowable End
Depth Friction Bearing Pressure
(feet) No. Material (Factor of Safety = 2) (Factor of Safety = 3)
(psf L (psf
1. Design capacities are dependent upon the method of installation and quality control
parameters. The values provided are estimates and should be verified when installation
protocol have been finalized.
2. See Subsurface Profile in Geotechnical Characterization for more details on
stratigraphy.
3. Applicable for compressive loading only. Reduce to 2/3 of values shown for uplift
loading. The effective weight of the shaft can be added to uplift load resistance to the
extent permitted by IBC.
4. Shafts should extend at least one diameter into the bearing stratum (or to a depth equal
to the bell diameter for belled shafts) for end bearing to be considered.
Shafts should be adequately reinforced as designed by the Structural Engineer for both
tension and shear to sufficient depths. Buoyant unit weights of the soil and concrete
should be used in the calculations below the highest anticipated groundwater elevation.
Drilled shaft should have a minimum (center-to-center) spacing of three diameters.
Closer spacing may require a reduction in axial load capacity. Axial capacity reduction
can be determined by comparing the allowable axial capacity determined from the sum
of individual piles in a group versus the capacity calculated using the perimeter and base
of the pile group acting as a unit. The lesser of the two capacities should be used in
design.
MFAD Parameters
It is our understanding that the new transmission line structure will be supported on a
deep foundation system, such as drilled shaft. We understand that the lateral load
capacity for deep foundations (drilled shafts or direct embedment) will be analyzed using
the MFDA program developed by the Electric Power Research Institute (EPRI) at each
foundation location. The soil parameters used in the analyses include moist unit weight
(ym), undrained shear strength (Su), angle of internal friction (CO, and the deformation
modulus (Ep). It should be noted that the recommended soil strength parameters are not
factored. Therefore, appropriate safety factors should be applied to the foundation design.
Allowable soil/concrete bond strength for the shaft are zero. Additionally, lateral pile capacity
Facilities I Environmental I Geotechnical I Materials 17

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
analysis programs typically require input of moist unit weight above the groundwater table
and submerged or effective unit weight below the groundwater table. Based on the data
obtained in our exploration, and correlations provided in the MFAD 5.0 Used Guide, we
recommend the following values for the soils encountered at this site:
MFAD — Soil Parameters
SB-1
Groundwater observed to be at 4.0 feet
Average SPT Moist Unit Modulus of Friction
Depth AngleEffective
Material N60 Value Weight Deformation(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) o (ksf)
(deg)
0 to 42 SM 4 105 0.2 26 --
4 to 8 SC 16 115 0.8 30 --
8 to 12 CL 2 105 0.1 -- 0.3
12 to 17 SC 42 125 1.5 34 --
17 to 27 SM 17 115 0.8 30 --
27 to 30 SM 23 120 1 32 --
1. Energy Efficiency 87% for the CME 45C calibrated on 4/11/2022.
2. Parameters interpolated from SB-3 and SB-4.
MFAD — Soil Parameters
SB-2
Groundwater observed to be at 4.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Effective
Material N60 Value Weight Deformation Angle
(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) o (ksf)
(deg)
0 to 62 SM 4 105 0.2 26 --
6 to 8 SC 13 110 0.6 30 --
8 to 12 CL 3 105 0.1 -- 0.3
12 to 17 CH 14 110 0.8 -- 1.3
17 to 27 SC 22 120 1 32 --
27 to 30 CL 23 120 1.5 -- 3
Facilities I Environmental I Geotechnical Materials 18

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina 0 lerracon
May 17, 2023 I Terracon Project No. 70235048.Revl
MFAD - Soil Parameters
SB-2
Groundwater observed to be at 4.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Effective
p Material N60 Value Weight Deformation Angle
(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) o (ksf)
(deg)
1. Energy Efficiency 87% for the CME 45C calibrated on 4/11/2022.
2. Parameters interpolated from SB-3 and SB-4.
MFAD - Soil Parameters
SB-3
Groundwater observed to be at 6.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Effective
p Material N60 Value Weight Deformation Angle
(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) o (ksf)
(deg)
0 to 6 SM 4 105 0.2 26 --
6 to 8 SC 8 110 0.5 28 --
8 to 17 SC 17 115 0.8 30 --
17 to 27 SP 39 125 3 36 --
27 to 30 CH 13 110 0.8 -- 1.3
1. Energy Efficiency 87% for the CME 45C calibrated on 4/11/2022.
MFAD - Soil Parameters
TB-1
Groundwater observed to be at 6.0 feet
Average SPT Moist Unit Modulus of Friction
Depth AngleEffective
Material N60 Value Weight Deformation(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) o (ksf)
(deg)
0 to 3 CL 8 110 0.6 -- 0.9
3 to 6 SC 4 105 0.2 26 --
Facilities I Environmental I Geotechnical Materials 19

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina 0 lerracon
May 17, 2023 I Terracon Project No. 70235048.Revl
MFAD - Soil Parameters
TB-1
Groundwater observed to be at 6.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Effective
p Material N60 Value Weight Deformation Angle
(feet) Cohesion c'
(bpf) (yr.) (pcf) (Er) (ksi) 0 (ksf)
(deg)
6 to 8 CL 17 115 1 -- 2
8 to 16 SP 22 120 2 34 --
16 to 22 SP 16 115 1.5 32 --
22 to 27 CH 11 110 0.8 -- 1.3
27 to 32 CH 19 115 1 -- 2
32 to 37 SC 39 125 1.5 34 --
37 to 42 CH 19 115 1 -- 2
42 to 45 CH 61 125 2 -- 3.5
1. Energy Efficiency 87% for the CME 45C calibrated on 4/11/2022.
MFAD - Soil Parameters
TB-2
Groundwater observed to be at 6.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Effective
Material N60 Value Weight Deformation Angle
(feet) Cohesion c'
(bpf) (Ym) (pcf) (Er) (ksi) 0 (ksf)
(deg)
0 to 6 CL 3 105 0.1 -- 0.3
6 to 15 SC 19 115 0.8 30 --
15 to 18 SP 11 110 1 32 --
18 to 22 SC 25 120 1 32 --
22 to 27 CH 10 110 0.6 -- 0.9
27 to 32 CH 50 125 2 -- 3.5
32 to 37 CH 26 120 1.5 -- 3
37 to 42 CL 9 110 0.6 -- 0.9
42 to 45 SC 29 120 1 32 --
Facilities I Environmental I Geotechnical I Materials 20

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina rr ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
MFAD — Soil Parameters
TB-2
Groundwater observed to be at 6.0 feet
Average SPT Moist Unit Modulus of Friction
Depth Material N60 Value Weight Deformation Angle Effective(feet) Cohesion c'
(bpf) (Ym) (Pcf) (En) (ksi) (ksf)
(deg)
1. Energy Efficiency 87% for the CME 45C calibrated on 4/11/2022.
The design should consider reducing the upper 3 feet of surficial material to the potential
effects of construction disturbance and creation of an annulus from lateral movements.
When shafts are used in groups, the lateral capacities of the shafts in the second, third,
and subsequent rows of the group should be reduced as compared to the capacity of a
single, independent shaft. Guidance for applying p-multiplier factors to the p values in
the p-y curves for each row of pile foundations within a pile group are as follows:
P-Multiplier, Pm 3
Center to Center Pile Third and
Spacing 1,2 Front Row Second Row Subsequent
Rows
3B 0.8 0.4 0.3
4B 0.9 0.65 0.5
5B 1.0 0.85 0.7
6B 1.0 1.0 1.0
1. Spacing in the direction of loading. B = pile diameter
2. For the case of a single row of piles supporting a ❑ ❑ ❑ ❑
laterally loaded grade beam, group action for lateral Loadsl , ❑ ❑ ❑ ❑
resistance of piles would need be considered when
spacing is less than three pile diameters (measured ❑ ❑ ❑ ❑
center-to-center). t t t
3. See adjacent figure for definition of front, second Third& Second Front
Subsequent Row Row
and third rows. Rows
Spacing closer than 3D (where D is the diameter of the shaft) is not recommended
without additional geotechnical consultation due to potential for the installation of a new
shaft disturbing an adjacent installed shaft likely resulting in axial capacity reduction.
Facilities I Environmental I Geotechnical I Materials 21

Geotechnical Engineering Report "
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina 0 ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Drilled Shaft Lateral Loading
The following table lists input values for use in LPILE analyses. Such analysis should be
considered if lateral loads exceeds 10 kips. Modern versions of LPILE provide estimated
default values of kh and E50 based on strength and are recommended for the project.
Since deflection or a service limit criterion will most likely control lateral capacity design,
no safety/resistance factor is included with the parameters.
TB-1
Stratigraphy' L-Pile Soil S. 4)2 y' K (pci)
Depth Material Model (psf)2 (deg) (pcf)2 E50 Static Cyclic
0 to 3 CL Stiff Clay w/o 800 110 Use Default Value
Free Water
3 to 6 SC Sand (Reese) -- 29 105 Use Default Value
6 to 8 CL Stiff Clay w/ 1,700 52.6__
Free Water Use Default Value
8 to 16 SP Sand (Reese) -- 33 57.6 Use Default Value
16 to 22 SP Sand (Reese) -- 32 52.6 Use Default Value
22 to 27 CH Stiff Clay w/ 1,100 47.6
Free Water --- Use Default Value
27 to 32 CH Stiff Clay w/ 1,900 52.6
Free Water --- Use Default Value
32 to 37 SC Sand (Reese) -- 36 62.6 Use Default Value
37 to 42 CH Stiff Clay w/ 1,900 52.6
Free Water --- Use Default Value
42 to 45 CH Stiff Clay w/ 6,000 62.6
Free Water --- Use Default Value
1. See Subsurface Profile in Geotechnical Characterization for more details on
Stratigraphy.
2. Definition of Terms:
Su: Undrained shear strength
4 : Internal friction angle
y': Effective unit weight
Facilities I Environmental I Geotechnical I Materials 22

Geotechnical Engineering Report "
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina 0 ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
TB-2
Stratigraphy' L-Pile Soil S. 4)2 y' K (pci)
Depth Material Model (psf)2 (deg) (pcf)2 £50 Static Cyclic
0 to 56 CL Soft Clay 300 -- 105 Use Default Value
5 to 11 SC Sand (Reese) -- 33 52.6 Use Default Value
11 to 18 SP Sand (Reese) -- 30 47.6 Use Default Value
18 to 22 SC Sand (Reese) -- 33 57.6 Use Default Value
Stiff clay w/
22 to 27 CH -- 47.6 Use Default Value
free water 1,000
Stiff clay w/27 to 32 CH __free water 4,800 62.6 Use Default Value
Stiff clay w/
32 to 37 CH -- 57.6 Use Default Value
free water 2,400
Stiff clay w/
37 to 42 CL 900 -- 47.6 Use Default Value
free water
42 to 45 SC Sand (Reese) -- 33 57.6 Use Default Value
1. See Subsurface Profile in Geotechnical Characterization for more details on
Stratigraphy.
2. Definition of Terms:
Su: Undrained shear strength
(I): Internal friction angle
y': Effective unit weight
When shafts are used in groups, the lateral capacities of the shafts in the second, third,
and subsequent rows of the group should be reduced as compared to the capacity of a
single, independent shaft. Guidance for applying p-multiplier factors to the p values in
the p-y curves for each row of pile foundations within a pile group are as follows:
P-Multiplier, Pm 3
Center to Center Pile Third and
Spacing 1,2 Front Row Second Row Subsequent
Rows
3B 0.8 0.4 0.3
4B 0.9 0.65 0.5
5B 1.0 0.85 0.7
6B 1.0 1.0 1.0
Facilities I Environmental I Geotechnical Materials 23

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
P-Multiplier, Pm 3
Center to Center Pile Third and
Spacing 1,2 Front Row Second Row Subsequent
Rows
1. Spacing in the direction of loading. B = pile
diameter Lateral
Load Illar ❑ 1=1 � ❑
2. For the case of a single row of piles supporting a
laterally loaded grade beam, group action for ❑ ❑ ❑ Ll
lateral resistance of piles would need be t t t t
considered when spacing is less than three pile Third& Second Front
Subsequent Row Row
diameters (measured center-to-center). Rows
3. See adjacent figure for definition of front, second and third rows.
Spacing closer than 3D (where D is the diameter of the shaft) is not recommended
without additional geotechnical consultation due to potential for the installation of a new
shaft disturbing an adjacent installed shaft likely resulting in axial capacity reduction.
Drilled Shaft Construction Considerations
We anticipate groundwater to be encountered at a depth of approximately 4 to 6 feet below
existing grades. To prevent collapse of the sidewalls and/or to control groundwater seepage,
the use of temporary steel casing and/or slurry drilling procedures may be required for
construction of the drilled pier foundation. Significant seepage could occur in case of
excavations penetrating water-bearing sandy soil layers. The drilled pier contractor and
foundation design engineer should be informed of these risks.
A full-depth temporary steel casing may be required to stabilize the sides of the shaft
excavations in the overburden. If casing is removed during concrete placement, care
should be exercised to maintain concrete inside the casing at a sufficient level to resist
earth and hydrostatic pressures present on a casing exterior. Water or loose soil should
be removed from the bottom of the drilled shafts prior to placement of the concrete.
Care should be taken to not disturb the sides and bottom of the excavation during
construction. The bottom of the shaft excavation should be free of loose material before
concrete placement. Concrete should be placed as soon as possible after the foundation
excavation is completed, to reduce potential disturbance of the bearing surface.
Due to the relatively shallow depth to groundwater encountered in the boring, the drilled
pier should be constructed as "wet." "Wet" piers should be constructed by slurry
displacement techniques. In this process, the pier excavation is filled with approved
polymer-based slurry to counter-balance the hydraulic forces below the water level and
stabilize the wall of the pier. Concrete would then be placed using a tremie extending to
within 6 inches of the pier base of the slurry-filled excavation. The tremie remains
Facilities I Environmental I Geotechnical I Materials 24

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
inserted several feet into the fresh concrete as it displaces the slurry upward and until
placement is complete. The slurry should have a sand content no greater than 1 percent
at the time concrete placement commences.
While withdrawing casing, care should be exercised to maintain concrete inside the
casing at a sufficient level to resist earth and hydrostatic pressures acting on the casing
exterior. Arching of the concrete, loss of seal and other problems can occur during
casing removal and result in contamination of the drilled shaft. These conditions should
be considered during the design and construction phases. Placement of loose soil backfill
should not be permitted around the casing prior to removal.
The drilled shaft installation process should be performed under the direction of the
Geotechnical Engineer. The Geotechnical Engineer should document the shaft installation
process including soil/rock and groundwater conditions encountered, consistency with
expected conditions, and details of the installed shaft.
Gravel-Surfaced Drives and Parking
The site is expected to be suitable for support of the proposed access roadway when
subgrade preparation is performed as described in the earthwork section of this report.
As previously discussed, in-place compaction followed by proofrolling should be
performed along the roadway alignment.
Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the
construction phase. Fills are typically placed and compacted in a uniform manner.
However, as construction proceeds, the subgrade may be disturbed due to utility
excavations, construction traffic, desiccation, or rainfall/snow melt. As a result, the
aggregate-surfaced roadway or parking area subgrade may not be suitable for
construction and corrective action will be required. The subgrade should be carefully
evaluated at the time of construction for signs of disturbance or instability. We
recommend the subgrade be thoroughly proofrolled with a loaded tandem-axle dump
truck prior to final grading. All aggregate-surfaced roadway or parking subgrade areas
should be moisture conditioned and properly compacted to the recommendations in this
report immediately prior to placement of the aggregate surfacing.
Design Recommendations
Roadway thickness design is dependent upon:
■ The anticipated traffic conditions during the life of the pavement
Facilities I Environmental I Geotechnical I Materials 25

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
• Subgrade and paving material characteristics
• Climatic conditions of the region
Based on empirical data and our experience with similar soils, we selected a design CBR value
of 7.0 for the roadway subgrade. As previously noted, we expect the road to service
occasional maintenance vehicles and potentially emergency service vehicles. A traffic
loading of 2,500 18-kip equivalent single axle loads (ESALs) over an assumed design life of 20
years was assumed in our pavement design. Base course materials should conform to the
North Carolina Department of Transportation (NCDOT ABC).
In consideration of these factors, the DEP standard roadway section of 12 inches of
compacted crushed aggregate base course (NCDOT ABC) is suitable for this site. Base course
materials should conform to the North Carolina Department of Transportation (NCDOT ABC).
Aggregate-surfaced roadways 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 aggregate-surfaced roadways:
• Site grades should slope a minimum of 10 percent away from the roadways;
• The subgrade and the aggregate-surfaced roadways have a minimum 10 percent
slope to promote proper surface drainage;
• Consider appropriate edge drainage; and
• Install pavement drainage in surrounding areas anticipated for frequent wetting.
Ingress and Egress Pavement Sections
For areas subject to concentrated and repetitive loading conditions, i.e. ingress and
egress areas, we recommend using a Portland cement concrete pavement with a
thickness of at least 7 inches underlain by at least 4 inches of aggregate base course
(ABC). Edge restraints (i.e. concrete curbs or aggregate shoulders) should be planned
along curves and areas of maneuvering vehicles.
Concrete pavement sections should be checked for concentrated loading conditions. A
modulus of subgrade reaction of 150 pci can be used for the subgrade soils. The value
was empirically derived based upon our experience with the subgrade soils and our
expectation of the quality of the subgrade as prescribed by the Site Preparation
conditions as outlined in Earthwork. A modulus of rupture of 600 psi can be used for
the concrete (based on correlations with a minimum 28-day compressive strength of
4,000 psi).
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
Facilities I Environmental I Geotechnical I Materials 26

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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.
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.
Maintenance
Periodic maintenance extends the service life of the aggregate-surfaced roadways and
parking areas and should include re-grading and replacement of aggregate base course
in any deteriorated areas. Thicker aggregate base course sections could be used to
reduce the required maintenance and extend the service life of the aggregate-surfaced
roadways. Design alternatives which could reduce the risk of subgrade saturation and
improve long-term performance include installing surface drains next to any areas where
surface water could pond. Properly designed and constructed subsurface drainage will
reduce the time subgrade soils are saturated and can also improve subgrade strength
and performance.
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.
Facilities I Environmental I Geotechnical I Materials 27

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
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.
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 effect 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.
Facilities I Environmental I Geotechnical I Materials 28

Geotechnical Engineering Report
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Figures
Contents:
GeoModel
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
GeoModel Raleigh,NC
250 SB-1 SB-2 •
S$-3 S$-4 •
•
1 0.33 ----
0.33 1 ' i 0.25 0.6 TB-2245 ...4� • ���12/�/ 4 l�� 6� 6mNM
Z 6 TB-1 p
240 �i1 a //Z.a L12
love
3 1z 3235 © 1z / s®2 j/�s
230 • �d 8111115 3%/,8 2
r 17 .:
N 22500° 2 22
,61
0 220 �27 27 �S
30 ©%/30 10 30 22
d
w 215 4
210 //0i,/�32 i/37
4e re
205 2/. 37 a2
Ord
200 4 ©%as
OV
4
195 04ro 45
This is not a cross section.This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
Model Layer Layer Name General Description
I
1 Surface Gravel,Topsoil and Cultivated Topsoil
2 I Sand Silty/Clayey Sand and Poorly Graded Sand Soils;Loose to
Dense
3 Lean Clay Sandy Lean CLAY;Soft to Very Stiff
4 Fat Clay Sandy Fat CLAY;Stiff to Hard
LEGEND
®Aggregate Base Course VA Sandy Lean Clay Poorly-graded Sand with 0 Fat Clay
Silt
BE Silty Sand 0 Sandy Fat Clay .1 Poorly-graded Sand
E2 Clayey Sand Topsoil Poorly-graded Sand with
UJ Clay
o First Water Observation NOTES:
Layering shown on this figure has been developed by the geotechnical
engineer for purposes of modeling the subsurface conditions as
required for the subsequent geotechnical engineering for this project.
Numbers adjacent to soil column indicate depth below ground surface.
The groundwater levels shown are representative of the date and time of our
exploration.Significant changes are possible over time.
Water levels shown are as measured during and/or after drilling.In some cases,
boring advancement methods mask the presence/absence of groundwater.See
individual logs for details.

Geotechnical Engineering Report
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Attachments
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • Terracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Exploration and Testing Procedures
Field Exploration
Approximate Boring
Number of Borings Location
Depth (feet)
3 30 Substation
1 15 Substation Pavement
2 40 Transmission Line
Structures
Boring Layout and Elevations: Terracon personnel provided the boring layout using
handheld GPS equipment (estimated horizontal accuracy of about ±20 feet) and
referencing existing site features. Approximate ground surface elevations were
estimated using Google Earth. If elevations and a more precise boring layout are
desired, we recommend borings be surveyed.
We advanced the borings with a track-mounted rotary drill rig using continuous flight hollow
stem augers. 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/middle 12 inches of a 24-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. Soil samples were sealed and taken to our soil
laboratory for testing and classified by a geotechnical engineer. In addition, we observed
and recorded groundwater levels during and after drilling.
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:
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report --
Raeford Raeford South 115kV - Rebuild Substation I Raeford, North Carolina • ierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
■ Moisture Content
■ Dry Unit Weight
■ Atterberg Limits
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.
Chemical Property Testing
Laboratory chemical testing will be performed on select samples of near-surface soils at
2-foot from each location. We expect the results of this testing will assist the designers
of corrosion protection for various other project elements. The following tests will be
performed in general accordance with the corresponding standards:
■ pH Analysis (ASTM D4972)
■ Sulfate, Sulfide, & Chloride Content (ASTM C1580, D4327, and D512)
■ Oxidation-Reduction Potential (ASTM G200)
■ Electrical Resistivity Testing (ASTM G57)
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report 'erracon
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina •
May 17, 2023 I Terracon Project No. 70235048.Revl
Site Location and Exploration Plans
Contents:
Site Location Plan (2 pages)
Exploration Plan (2 pages)
Note: All attachments are one page unless noted above.
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report I �erraeon
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina
May 17, 2023 I Terracon Project No. 70235048.Revl
Site Location
_ . .
l.
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• enrettsvila t ,,' ;' '� .Lumberton•' � lizatietthtown' _5miles
L'bincli. , ., r. •.�..a r•,., . • ��; [
" r _,2.�??''.AiQoso Corprjt on.,EarestarGeographits I 1 _ rrn
DIAGRAM IS FOR GENERAL LOCATION ONLY,AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report Iiierracon
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina
May 17, 2023 I Terracon Project No. 70235048.Revl
Site Location
ovi►,ton Ave ,..tc, 1\ C'
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DIAGRAM IS FOR GENERAL LOCATION ONLY,AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Facilities I Environmental I Geotechnical I MaterialE

Geotechnical Engineering Report
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina liierracon
May 17, 2023 I Terracon Project No. 70235048.Revl
Exploration Plan
•
•,,,...-1- -
' .
... Legend
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,.- • - -1 I. -
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, ....--- , • •-,..
1, ''-"- ....--..-• .
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"me
DIAGRAM IS FOR GENERAL LOCATION ONLY,AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY GOOGLE EARTH MAPS
Facilities I Environmental I Geotechnical I Materials

Geotechnical Engineering Report IFierracon
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina
May 17, 2023 I Terracon Project No. 70235048.Revl
Exploration Plan
(D
r / Vr 1
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DIAGRAM IS FOR GENERAL LOCATION ONLY,AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY GOOGLE EARTH MAPS
Facilities I Environmental I Geotechnical I Materials

Exploration and Laboratory Results
Contents:
Boring Logs (SB-1 through SB-4 and TB-1 and TB-2)
Atterberg Limits
Grain Size Distribution (3 pages)
Corrosivity Test Results
Note: All attachments are one page unless noted above.

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-1 Raleigh,NC
erberg
o Location: See Exploration Plan Attimits
T N a .� 8 Limits
J a+ j p T ut ut
u Latitude: 34.9601°Longitude: -79.2117° _1 asd
') o. a=.+ 5 Z n -o v ° v
o v m y E v 2 LL-PL-PI
(.00 p V) v°
Depth(Ft.)
1 o u l n WELL GRADED GRAVEL,4"
SILTY SAND(SM),fine to coarse grained, reddish brown
2 CLAYEY SAND(SC),fine to medium grained, brown,medium dense
rj— 19.7 33-17-16
4-6-9-7
0.8N=15
.0
SANDY LEAN CLAY(CL), brown,soft
2-1-1-2
N=2
10-
12.0
// ' CLAYEY SAND(SC),fine to medium grained,gray and brown,dense
8-15-19
1�
X N=34
• 17.0
SILTY SAND(SM),fine to medium grained,gray to tan, medium dense
2
X
6-6-8=
N
20-
2-4-6
N=10
25—
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). 7 While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
HydroVac from 0 to 6 feet. Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-1 Raleigh,NC
o Location: See Exploration Plan Atterberg
T N a w 8 Limits
J a+ j p >. ut ut
rioLL—Iu Latitude: 34.9601°Longitude: -79.2117° _1 m d I— a;
v a '-' a`) n -ov my
o m aai m a, E v '' LL-PL-PI
it o
5 C7 0 �p O 0
Depth(Ft.)
SILTY SAND(SM),fine to medium grained,gray to tan, medium dense
(continued)
2
X
N=8-197
3o.a 30
Boring Terminated at 30 Feet
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
HydroVac from 0 to 6 feet. Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-2 Raleigh,NC
o Location: See Exploration Plan Atterberg
T N a w 8 Limits
J •a+ j o T ut ut
LL—IL.) Latitude: 34.9599°Longitude: -79.2115° _i as d F °;
v o. a=.+ 5Z n -ov my
o � v m y E v '' LL-PL-PI
it 0
5 C9 0 p O 0
Depth(Ft.)
1 o u l n 1 \WELL GRADED GRAVEL,4"
SILTY SAND(SM),fine to medium grained, brown
... .......'• i f; 7.7 NP
— U
2
5—
6.0 _
CLAYEY SAND(SC),fine to coarse grained, brown,medium dense —
5N12=7-
5
X .0 —
X .
SANDY LEAN CLAY(CL), gray and tan,soft
2-1-2-3
N=3
s X 10
X
/12.0 —
SANDY FAT CLAY(CH),gray and tan, stiff
•
— X N547
=11
• 15—
•
•
/�17.0 —
7CLAYEY SAND(SC),fine to coarse grained, light gray, medium dense
•
-7-8
/ 20— :x:
8 8-18
X�2
/ _
/J'
/ 11-9-9
N=18
25—
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
HydroVac from 0 to 6 feet. Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-2 Raleigh,NC
o Location: See Exploration Plan Atterberg
T N a w 8 Limits
J a+ j o >. vi ut
LL—Iu Latitude: 34.9599°Longitude: -79.2115° _1 m d I— a;
v a -c a`) n -ov my
a m m y E v '' LL-PL-PI
it o
Z (0 0 p O 0
Depth(Ft.)
/
,,,/// • CLAYEY SAND(SC),fine to coarse grained, light gray,medium dense
(continued)
2 —
27.0 _
SANDY LEAN CLAY(CL),tan and gray,very stiff
430.0 ' X 9-6-11
N=17
Boring Terminated at 30 Feet 30
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
HydroVac from 0 to 6 feet. Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-3 Raleigh,NC
o Location: See Exploration Plan Atterberg
. N a w a Limits
J a+ j T u
p t ut
LL—Iu Latitude: 34.9602°Longitude: -79.2112° m d I— °;—
v a -c " Z n -ov my
a m m y E v >i LL-PL-PI
it o
Z C7 O 8 rn 0
Depth(Ft.)
1 :`'I":``..I-.\TOPSOIL, 3"
SILTY SAND(SM),fine to coarse grained, brown and gray, very loose to 3-3-2-1
• loose — N=5 10.7 NP
— 4
_ 2-1-1-2
4 N=2
1-4-5-4
5_ N=9
6.0 _ 0 4
#f0.f CLAYEY SAND(SC),fine to coarse grained, reddish orange and brownish
// gray,loose to medium dense 2-2-4-4
N=6
r/0/ _ 8-7-7-7
N=14
10—
/0
.#9
2 /
..,4
X N=15
0 15—
///b 17.0 —
POORLY GRADED SAND WITH SILT(SP-SM),fine to coarse grained,gray
and brown, medium dense to dense
9-12-13
//�\ N=25
• 20-
•
X
1 -16-16
N=3225—
32
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-27-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-27-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-3 Raleigh,NC
o Location: See Exploration Plan Atterberg
T N a w a Limits
J a+ j p >. ut ut
rioLL—IL.) Latitude: 34.9602°Longitude: -79.2112° _1 m d I— a;
v 0. a=.+ 5Z n -ov my
a m m y E v '' LL-PL-PI
it o
Z C7 0 p rn 0
Depth(Ft.)
POORLY GRADED SAND WITH SILT(SP-SM),fine to coarse grained,gray
and brown,medium dense to dense(continued)
2 —
iie27.0 _
SANDY FAT CLAY(CH), light gray,stiff
•
4 /. .
— 7-5-5
X
•
/30.0 N=10
30
Boring Terminated at 30 Feet
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-27-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-27-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. SB-4 Raleigh,NC
v o Location: See Exploration Plan Atterberg
T N a w a Limits
J a+ j p T ut ut
LL-Iu Latitude: 34.9597°Longitude: -79.2112° _i m - F °;
v lac. a=.+ ,- n -o v m y
-csa v m y E Ts '' LL-PL-PI
Z C7 0 �p rn v°
Depth(Ft.)
1 ,a4, .10.6 TOPSOIL, 7"
POORLY GRADED SAND WITH SILT(SP-SM),fine grained, brown and tan, 2-3-2-1
very loose to loose N=5
_ 4
1-WOH-WOH-1 5.9 NP
2 N=WOH
4.0 _
//� CLAYEY SAND(SC),fine to coarse grained, brown and orange, loose
// 4 2-4-5-4
N=9
��/� 5- N=9
s6.0 _ 0 4
SANDY LEAN CLAY(CL),tan and orange,stiff
4 N=129
j —
3 6-5-6-7
j N=11
• 1 0-
12.0 _
POORLY GRADED SAND WITH SILT(SP-SM),fine to medium grained, browr
and gray, medium dense
2
X
6-7-13
N=20
. 15.0 15
Boring Terminated at 15 Feet
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p while drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
WOH=Weight of Hammer Boring Started
Abandonment Method 03-27-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-27-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. 1 B-1 Raleigh,NC
T
o Location: See Exploration Plan Atterberg
. N a w 8. Limits
J a+ j T u
o t ut
LL-Iu Latitude: 34.9637°Longitude: -79.2138° m d I— a;—
v a -c " Z n vv my
-csa it o
v m y E v >i LL-PL-PI
Depth(Ft.)
'•° TOPSOIL,Cultivated Topsoil- 12"
'•
(/•)a•I;•1.0 _
SANDY LEAN CLAY(CL),brown,medium stiff
1:1:
X 3-4-3 20.7 33 20 13
3 — N=7
ily ' 3.0 —
I : CLAYEY SAND(SC),fine grained, brown and gray, loose —
j X
1-2-2 24.0 25-15-10
2 • - N_4
5
6.0 _ 0
ri SANDY LEAN CLAY(CL),gray and tan,very stiff
3-4-12
— X N=16
j 8.0 _
POORLY GRADED SAND(SP),fine to medium grained,brown and tan,
medium dense
X 6-8-12
N=20
20
10—
— N X
7-9=187
VN 2
//�\ =2
2 15—
X 7-7-9
N=16
N=
V 6 -63
//�\ -71
2�
_
SANDY FAT CLAY(CH),gray and tan,medium stiff to stiff
4
3-3-5
X N=8
25-
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. 1 B-1 Raleigh,NC
T
o Location: See Exploration Plan Atterberg
T N a w 8 Limits
J •a+ j o T in u
LiLatitude: 34.9637°Longitude: -79.2138° _i as d F °;
v a -c a`) n -ov my
o m aai @ y E v '' LL-PL-PI
it o
Z (0 0 p O 0
Depth(Ft.)
V. SANDY FAT CLAY(CH),gray and tan,medium stiff to stiff(continued)
0/o
4
N=14
X 10-4-10
3�
032.°
-
CLAYEY SAND(SC),fine to coarse grained,gray and tan,medium dense
35- 12-15-12
X N27
/I.
0
37.0 _
SANDY FAT CLAY(CH),trace silt,gray and tan,stiff to hard
•
— 6-7-6
•
• 40-
X N=13
4 .
•
/ 15
N2
45.0 X 11-15-27
Boring Terminated at 45 Feet 4`�
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-28-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-28-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. 1 B-2 Raleigh,NC
T
o Location: See Exploration Plan Atterberg
T N a S. a Limits
J a+ j p T ut ut
LL—Iu Latitude: 34.9599°Longitude: -79.2227° _1 m d I— °;
c, (U v m y E v '' LL-PL-PI
it o
z C7 0 p V) o
Depth(Ft.)
•'•••" TOPSOIL,Cultivated Topsoil- 12"
I,•.a•i,•1.0
r SANDY LEAN CLAY(CL),brown and red,soft — ),(
1-2-2
N_4
3 j
j N=2
//�� — X
N=2
,%s.o 5
// CLAYEY SAND(SC),fine to medium grained, brown and red,medium dense
0 5-6-8
— X N=14
r, -
0,
i.,
10— X6-10-8N=18
11.0
POORLY GRADED SAND WITH CLAY(SP-SC),fine to medium grained,orange
• and pink,loose to medium dense _ X N71 0
12.0 NP
N=195-8-11
.;% 15—
X
X
5-4-5
VCLAYEY SAND(SC),fine to medium grained,tan and pink,medium dense
— x
12_11-9
2� N 20
i22.0 —
1...
SANDY FAT CLAY(CH),gray, pink and yellow,medium stiff to hard
1-2-5
X N=7
25—
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p while drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-27-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-27-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Boring Log No. 1 B-2 Raleigh,NC
T
v o Location: See Exploration Plan Atterberg
> a w a Limits
J a+ Ti.)j o T ut ut
LL—Iu Latitude: 34.9599°Longitude: -79.2227° _ as d F °;
v a -c a`) Z n vv my
-csa m @ y E v '' LL-PL-PI
it 0
Z C7 0 p V) o
Depth(Ft.)
• SANDY FAT CLAY(CH),gray, pink and yellow,medium stiff to hard
(continued)
/ —
/
// — 12- 5-21
/ N=136
/ X
/ 3�
/
/
032.0 _
FAT CLAY(CH),gray,very stiff
/ — 7-10-8
X N=18
35-
—
37.0
,"#.
SANDY LEAN CLAY(CL),gray and pink,medium stiff
/ _
4� x3-3-3
N=6
//
y/ 42.0 _
CLAYEY SAND(SC),fine to medium grained,gray and tan, medium dense
2
/
7-11-9
Y/./,45.0 X N 20
Boring Terminated at 45 Feet 45
See Exploration and Testing Procedures for a description of field and laboratory Water Level Observations Drill Rig
procedures used and additional data(If any). p While drilling CME 45 track
See Supporting Information for explanation of symbols and abbreviations. Hammer Type
Automatic
Driller
Notes Advancement Method M.Radford Bridger Drilling
Elevation Reference: Elevations were interpolated from a topographic site plan. Mud rotary Logged by
Samples obtained using a 2"O.D.split spoon sampler
Boring Started
Abandonment Method 03-27-2023
Boring backfilled with auger cuttings upon completion.
Boring Completed
03-27-2023
Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation � ferracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Atterberg Limit Results Raleigh,NC
ASTM D4318
60 /
/
/
/
50 // O�
// Ot
/
/
/ G*Z
40 //
/
x /
a, r
c /
- /
30 / —
:g /
/
ea / O\'
/
//
20 /
OI
/
// Pi or OH
// O
10 // O
a — / ' I` '//// ML or O L
i 10 16 20 30 40 50 60 70 80 90 100 110
Liquid Limit
Boring ID Depth(Ft) LL PL PI Fines USCS Description
• SB-1 4-6 33 17 16 27.4 SC CLAYEY SAND
m SB-2 2-4 NP NP NP 14.6 SM SILTY SAND
A SB-3 0-2 NP NP NP 13.6 SM SILTY SAND
* SB-4 2-4 NP NP NP 7.9 SP-SM POORLY GRADED SAND with SILT
O TB-1 1 -2.5 33 20 13 53.0 CL SANDY LEAN CLAY
O TB-1 3.5- 5 25 15 10 36.0 SC CLAYEY SAND
O TB-2 11 - 12.5 NP NP NP 10.6 SP-SM POORLY GRADED SAND with SILT
Laboratory tests are not valid if separated from original report. Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Raleigh,NC
Grain Size Distribution
ASTM D422 / ASTM C136
U.S.Sieve Opening in Inches I U.S. Sieve Numbers I Hydrometer
6 4 3 2 1.5 13/4 1/23/8 3 4 6 810 1416 20 30 40 50 60 100140200
I I I I J °
100ci:
95 P.
10
90 '�
85
20
80
75
30
70
65 •
40
60
°)55 roc)\ o
7-,
2 50 50 0
a
a) N
IL 45 cr
v 40 60
m
a 35 T
30 II 70
25 '
20 \41404444. 80
15i
10 90
5
p 100
100 10 1 0.1 0.01 0.001
Grain Size(mm)
Cobbles Gravel San i I Silt or Clay
Icoarse I fine coarse medium fine
Boring ID Depth les i %Sar 110 Fines %Silt %Clay USCS
• SB-1 4-6 0.0 0.7 72.0 27.4 SC
II SB-2 2-4 0.0 7.1 78.3 14.6 SM
A SB-3 0-2 0.0 0.3 86.0 13.6 SM
Description • ♦ Grain Size
• CLAYEY SAND Sieve %Finer SievIN Winer Sieve %Finer • m
I SILTY SAND 3/8" 100.0 1/2" 100.0 3/8" 100.0 D60 0.363 0.496 0.411
#4 99.34 3/8" 94.58 #4 99.69
A SILTY SAND #10 98.9 #4 92.85 #10 99.2 D30 0.102 0.238 0.251
#40 67.3 #10 90.7 #40 62.04
111- Remarks #60 42.87 #40 56.62 #60 29.65 Di0
#100 33.28 #60 30.93 #100 19.17
• #200 27.36 #100 21.01 #200 13.64 = Coefficients
#200 14.6
m
'MIN I • II A
♦
Cc
Cu
Laboratory tests are not valid if separated from original report. Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Raleigh,NC
Grain Size Distribution
ASTM D422 / ASTM C136
U.S.Sieve Opening in Inches I U.S. Sieve Numbers I Hydrometer
6 4 3 2 1.5 13/4 1/23/8 3 4 6 810 1416 20 30 40 50 60 100140200
I I I ; IAII I . I I I I I : 0
100 �I
95 •
` 1111
I 10
90
85 1111�
20
80
75
�� 30
70
65
40
60
.1 1111 -o
°i 55 n
co
() II o
50
't
2 50 o
a
a) N
S
45
c
v 40 60
a)
n)
a 35 T
30 70
25
20 80
15
10 •
90
5
0 100
100 10 1 0.1 0.01 0.001
Grain Size(mm)
Cobbles Gravel San i Silt or Clay
Icoarse I fine coarse medium fine
Boring ID Depth les ravel 0/0 Sand % Fines %Si it %Clay USCS
• SB-4 2-4 0.0 0.0 92.1 7.9 SP-SM
I TB-1 1 -2.5 0.0 0.0 47.0 53.0 CL
A TB-1 3.5 - 5 0.0 0.8 63.2 36.0 SC
Description • ♦ Grain Size
• POORLY GRADED SAND with SILT Sieve %Finer Sieval Mrner Sieve Va Finer • i
I SANDY LEAN CLAY #10 100.0 #10 100.0 3/8" 100.0 D60 0.425 0.098 0.169
#40 60.04 #40 94.13 #4 99.2
A CLAYEY SAND #60 27.85 #60 84.4 #10 98.81 D30 0.259
#100 14.6 #100 70.93 #40 90.25
Remarks #200 7.91 #200 53.0 #60 75.32 D10 0.093
#100 55.21
• #200 35.97
m --Milw ♦
A
Cc 1.70
Cu 4.56
Laboratory tests are not valid if separated from original report. Facilities I Environmental I Geotechnical I Materials

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Raleigh,NC
Grain Size Distribution
ASTM D422 / ASTM C136
U.S.Sieve Opening in Inches I U.S. Sieve Numbers I Hydrometer
6 4 3 2 1.5 13/4 1/23/8 3 4 6 810 1416 20 30 40 50 60 100140200
I I ; I J I I I ' I I I I I :
100
95
10
90
85
20
80
75 :1
30
70
65
40
60
-o
°)55
't
2 50 50 °
✓ N
S 45
S cr
40 60
m
• 35
30 70
25
20 80
15 •
•10 90
5
0 100
100 10 1 0.1 0.01 0.001
Grain Size(mm)
Cobbles Gravel San i Silt or Clay
Icoarse I fine coarse medium fine
Boring ID Depth les i %Sar liao Fines %Silt %Clay USCS
• TB-2 11 - 12.5 0.0 0.0 89.4 10.6 SP-SM
Description • Grain Size
• POORLY GRADED SAND with SILT Sieve %Finer Sieve %Finer Sieve %Finer •
#10 100.0 D60 0.318
#40 78.01
#60 45.14 D30 0.172
#100 24.6
Remarks ' #200 10.6 D10
• Coeff
Cc 1.27
Cu 4.36
Laboratory tests are not valid if separated from original report. Facilities I Environmental I Geotechnical I Materials

CHEMICAL LABORATORY TEST REPORT lirerracon
Project Number: 70235048
Service Date: 05/02/23 10400 State Highway 191
Report Date: 05/03/23 Midland,Texas 79707
432-684-9600
Client Project
Duke Energy Corporation Duke-Raeford South 115kV-Rebuild Substation
410 South Wilmington Street Oakdale Gin Road
Raleigh,NC 27601-1849 Raeford,NC
Sample Location TB-1
Sample Depth (ft.) 1-4
pH Analysis,ASTM-G51-18 5.7
Water Soluble Sulfate(SO4),ASTM C 1580 5
(mg/kg)
Sulfides,ASTM-D4658-15,(mg/kg) nil
Chlorides,ASTM D 512,(mg/kg) 88
RedOx,ASTM D-1498,(mV) +495
Total Salts,ASTM D1125-14,(mg/kg) 310
Resistivity,ASTM G187,(ohm-cm) 13,423
Analyzed By:
Zach Robertson
Engineering Technician III
The tests were performed in general accordance with applicable ASTM,AASHTO,or DOT test methods. This report is exclusively for the use of the client
indicated above and shall not be reproduced except in full without the written consent of our company. Test results transmitted herein are only applicable to
the actual samples tested at the location(s)referenced and are not necessarily indicative of the properties of other apparently similar or identical materials.

Supporting Information
Contents:
General Notes
Unified Soil Classification System
Note: All attachments are one page unless noted above.

Duke-Raeford South 115kV-Rebuild Substation Irerracon
Oakdale Gin Road I Raeford,NC
Terracon Project No.70235048 2401 Brentwood Rd Ste 107
Raleigh,NC
General Notes
Sampling Water Level field Tests
N Standard Penetration Test
Water Initially Resistance(Blows/Ft.)
XStandard Encountered
Penetration Water Level After a (HP) Hand Penetrometer
Test m Specified Period of Time
Water Level After (T) Torvane
V a Specified Period of Time
.,r,, Cave In (DCP) Dynamic Cone Penetrometer
Encountered
Water levels indicated on the soil boring logs are the UC Unconfined Compressive
Strength
levels measured in the borehole at the times indicated.
Groundwater level variations will occur over time. In (pID) Photo Ionization Detector
low permeability soils,accurate determination of
groundwater levels is not possible with short term
water level observations. (OVA) Organic Vapor Analyzer
Descriptive Soil Classification
Soil classification as noted on the soil boring logs is based Unified Soil Classification System.Where sufficient laboratory data exist to classify the soils
consistent with ASTM D2487"Classification of Soils for Engineering Purposes"this procedure is used.ASTM D2488"Description and Identification of
Soils(Visual-Manual Procedure)"is also used to classify the soils,particularly where insufficient laboratory data exist to classify the soils in accordance
with ASTM D2487. In addition to USCS classification,coarse grained soils are classified on the basis of their in-place relative density,and fine-grained
soils are classified on the basis of their consistency. See"Strength Terms"table below for details.The ASTM standards noted above are for reference
to methodology in general. In some cases,variations to methods are applied as a result of local practice or professional judgment.
And Elevation NotesIIIIII
Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and Longitude are
approximate. See Exploration and Testing Procedures in the report for the methods used to locate the exploration points for this project. Surface
elevation data annotated with+/-indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead,the surface
elevation was approximately determined from topographic maps of the area.
Strength Terms
Relative Density of Coarse-Grained Soils Consistency of Fine-Grained Soils
(More than 50%retained on No. 200 sieve.) (50%or more passing the No. 200 sieve.)
Density determined by Standard Penetration Resistance Consistency determined by laboratory shear strength testing,field visual-manual
procedures or standard penetration resistance
Standard Penetration or Unconfined Compressive Strength Standard Penetration or
N-Value
N-Value Consistency
(Blows/Ft.) Qu(tsf) (Blows/Ft.)
Very Loose 0- 3 Very Soft less than 0.25 0- 1
Loose 4-9 Soft 0.25 to 0.50 2-4
Medium Dense 10- 29 Medium Stiff 0.50 to 1.00 4-8
Dense 30- 50 Stiff 1.00 to 2.00 8- 15
Very Dense > 50 Very Stiff 2.00 to 4.00 15-30
Hard > 4.00 > 30
Relevance of Exploration and Laboratory Test Results
Exploration/field results and/or laboratory test data contained within this document are intended for application to the project as described in this
document. Use of such exploration/field results and/or laboratory test data should not be used independently of this document.
Facilities I Environmental I Geotechnical I Materials

Im
Geotechnical Engineering Report Irerracon
Raeford South 115kV - Rebuild Substation I Raeford, North Carolina
May 17, 2023 I Terracon Project No. 70235048.Revl
Unified Soil Classification System
Criteria for Assigning Group Symbols and Group Names Using Soil Classification
Laboratory Tests A Symbol Group Name B
Clean Gravels: Cu>_4 and 1<_Cc<_3 E GW Well-graded gravel F
Gravels:
More than 50% of Less than 50/0 fines Cu<4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F
coarse fraction Fines classify as ML or MH GM Silty gravel F,G,H
retained on No. 4 Gravels with Fines:
Coarse-Grained Soils: sieve More than 12%fines Fines classify as CL or CH GC Clayey gravel F,G,H
More than 50% retained
on No. 200 sieve Clean Sands: Cu>_6 and 1<_Cc<_3 E SW Well-graded sand I
Sands: Less than 5%fines° E I
50% or more of Cu<6 and/or [Cc<1 or Cc>3.0] SP Poorly graded sand
coarse fraction Fines classify as ML or MH SM Silty sand G,H,I
passes No. 4 sieve Sands with Fines:
More than 12%fines° Fines classify as CL or CH SC Clayey sand G,H,I
PI > 7 and plots above"A"line' CL Lean clay K,L•"
Silts and Clays: Inorganic:
Y PI < 4 or plots below"A"line i ML Silt K,L,"
Liquid limit less than
50 LL oven dried Organic clay K,L•M'N
Fine-Grained Soils: Organic: <0.75 OL
LL not dried Organic silt K,L,N,o
50% or more passes the
No. 200 sieve PI plots on or above"A"line CH Fat clay K,L'PI
Silts and Clays: Inorganic:
Y PI plots below"A"line MH Elastic silt K,L,PI
Liquid limit 50 or
more LL oven dried Organic clay K,L,"•P
Organic: <0.75 OH
LL not dried Organic silt K,L,"•Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve. "If fines are organic, add"with organic fines"to group name.
B If field sample contained cobbles or boulders, or both, add"with ' If soil contains >_ 15% gravel, add"with gravel"to group name.
cobbles or boulders, or both"to group name. ' If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
c Gravels with 5 to 12%fines require dual symbols: GW-GM well- K If soil contains 15 to 29% plus No. 200, add"with sand"or
graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM "with gravel,"whichever is predominant.
poorly graded gravel with silt, GP-GC poorly graded gravel with clay. L If soil contains >_ 30% plus No. 200 predominantly sand, add
° Sands with 5 to 12%fines require dual symbols: SW-SM well- "sandy"to group name.
graded sand with silt, SW-SC well-graded sand with clay, SP-SM "If soil contains >_ 30% plus No. 200, predominantly gravel, add
poorly graded sand with silt, SP-SC poorly graded sand with clay. "gravelly"to group name.
E Cu = Dso/Dio Cc = (D )2 "PI >_ 4 and plots on or above"A"line.
30 °PI < 4 or plots below"A"line.
D,o x Doo P PI plots on or above"A"line.
F If soil contains >_ 15% sand, add"with sand"to group name. Q PI plots below"A"line.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
60 I I I I i
For classification of fine-grained
soils and fine-grained fraction '
50 —of coarse-grained soils p0,��' �e
Equation of"A"-line sJ, yPv
P. Horizontal at P1=4 to LL=25.5.
w 40 — then PI=0.73(LL-20) �' `O�
o Equation of"U"-line J.o
z Vertical at LL=16 to P1=7, G
>- 30 — then PI=0.9(LL-8)
H ' &
cn 20 G
_I MH or OH
D_
10 /
CL-ML
4 -- ML or OL
1
0
0 10 16 20 30 40 50 60 70 80 90 100 110
LIQUID LIMIT(LL)
Facilities 1 Environmental 1 Geotechnical 1 Materials