SW6180602_Geotech Report_20180613

ECS Southeast, LLP
Geotechnical Engineering Report
Linden 230 kV, Greenfield HRS Substation

Linden, Harnett County, North Carolina

ECS Project Number 33:4260.Rev1

May 2, 2018

May 2, 2017
Mr. Jason Sesler, PE
Project Manager
Stantec
801 Jones Franklin Road, Suite 300
Raleigh, North Carolina 27606
ECS Project No. 33:4260.Rev1

Reference: Geotechnical Engineering Report
Linden 230 kV, Greenfield HRS Substation
Linden, Harnett County, North Carolina

Dear Mr. Sesler:

ECS Southeast (ECS) has completed the subsurface exploration and geotechnical engineering
analyses for the above-referenced project. Our services were performed in general accordance with
our Proposal No. 33:3379, dated February 27, 2018. This report presents our understanding of the
geotechnical aspects of the project along with, the results of the field exploration, and our design
and construction recommendations.

It has been our pleasure to be of service to Stantec during the design phase of this project. We
would appreciate the opportunity to remain involved during the continuation of the design phase,
and we would like to provide our services during construction phase operations as well to verify the
assumptions of subsurface conditions made for this report. Should you have any questions
concerning the information contained in this report, or if we can be of further assistance to you,
please contact us.

Respectfully submitted,

ECS Southeast, LLP

Annemarie Crumrine, E.I. Winslow Goins, PE
Assistant Project Manager Principal Engineer
[e-mail] [e-mail]

05/02/18

Linden 230 kV, Greenfield HRS Substation May 2, 2018
ECS Project No. 33:4260.Rev1 Page i

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................. 1
1.0 INTRODUCTION .................................................................................................................. 2
1.1 General ................................................................................................................................... 2
1.2 Scope of Services .................................................................................................................... 2
1.3 Authorization .......................................................................................................................... 3
2.0 PROJECT INFORMATION ..................................................................................................... 4
2.1 Project Location...................................................................................................................... 4
2.2 Current Site Conditions .......................................................................................................... 4
2.3 Proposed Construction ........................................................................................................... 4
3.0 FIELD EXPLORATION ........................................................................................................... 5
3.1 Field Exploration Program ...................................................................................................... 5
3.1.1 Soil Test Borings ............................................................................................................ 5
3.2 Regional/Site Geology ............................................................................................................ 5
3.3 Subsurface Characterization .................................................................................................. 7
3.4 Groundwater Observations .................................................................................................... 7
4.0 DESIGN RECOMMENDATIONS ............................................................................................. 8
4.1 Structural Design .................................................................................................................... 8
4.1.1 Foundations .................................................................................................................. 8
4.1.2 Seismic Design Considerations ..................................................................................... 9
4.2 Site Design Considerations ................................................................................................... 10
4.2.1 Access Road ................................................................................................................ 10
5.0 SITE CONSTRUCTION RECOMMENDATIONS ....................................................................... 11
5.1 Subgrade Preparation .......................................................................................................... 11
5.1.1 Stripping and Grubbing ............................................................................................... 11
5.1.2 Proofrolling ................................................................................................................. 11
5.2 Earthwork Operations .......................................................................................................... 12
5.2.1 Structural Fill Materials............................................................................................... 12
5.2.2 Compaction ................................................................................................................. 12
5.3 Foundation Observations ..................................................................................................... 14
5.4 General Construction Considerations .................................................................................. 14
6.0 CLOSING ........................................................................................................................... 16

APPENDICES
Appendix A – Drawings
 Site Location Diagram
 Exploration Location Diagram
Appendix B – Field Operations
 Reference Notes for Boring Logs
 SPT Boring Logs B-1 through B-7
 Soil Parameters
 Generalized Subsurface Profile
Appendix C – Supplemental Report Documents
 ASFE Document
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ECS Project No. 33:4260.Rev1 Page 1

EXECUTIVE SUMMARY

The following summarizes the main findings of the exploration, particularly those that may have a
cost impact on the planned development. Further, our principal foundation recommendations
are summarized. Information gleaned from the executive summary should not be utilized in lieu
of reading the entire geotechnical report.

 The geotechnical exploration performed for the planned substation and access road
included seven (7) standard penetration test (SPT) borings drilled to depths of 10 to 30
feet below existing grades.

 The borings generally encountered a surficial topsoil layer of approximately 6 inches.
Beneath the surficial materials, Coastal Plain soils were encountered that consisted of
Clayey SAND (SC), SAND with Gravel (SP), Clean SAND (SP), Gravel (GP), Lean CLAY (CL),
and Fat CLAY (CH).

 Groundwater was encountered at depths of approximately 3.0 to 8.0 feet below
prevailing grades in borings B-5 through B-7. Groundwater was not encountered in
borings B-1 through B-4 to the depths explored.

 Provided that axial loads do not exceed 50 kips and approximately 3 feet of fill is place on
site, the proposed structures can be supported by conventional shallow foundations with
a maximum allowable bearing pressure of 1,500 psf. Alternatively, proposed structures
can be supported by deep foundations consisting of drilled shafts. Deep foundations can
be designed using the provided soil parameters.

 Based on the provided design site grades, it is anticipated that grades will generally be
raised about 3 feet in the substation area and about 1 to 2 feet in access drive areas.

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1.0 INTRODUCTION
1.1 GENERAL

The purpose of this study was to provide geotechnical information for the construction of the
proposed substation expansion located off of Horseshoe Bend Road in Linden, Harnett County,
North Carolina.

The recommendations developed for this report are based on project information supplied by Mr.
Jason Sesler, P.E. of Stantec. This report contains the results of our subsurface explorations, site
characterization, engineering analyses, and recommendations for the design and construction of
the geotechnical aspects of the new structures for the substation.

1.2 SCOPE OF SERVICES

To obtain the necessary geotechnical information required for design of the new substation,
seven (7) standard penetration tests (SPT) borings to depths of 10 to 30 feet were conducted at
the locations selected by the client. These borings were spaced across the proposed construction
area.

This report discusses our exploratory and testing procedures, presents our findings and
evaluations and includes the following.

 Project description and site observations.
 Information on site conditions including surface drainage, geologic information, and special
site features.
 A discussion of the general subsurface conditions encountered at the site.
 Groundwater level at time of exploration.
 Estimated soil layer parameters to include, but not limited to the following:
1. Soil layer classification
2. Total soil unit weight
3. Soil layer friction angle, where applicable
4. Soil layer cohesion, where applicable
5. Soil layer strength reduction factor
6. Pressuremeter Modulus
 A discussion of undocumented fill, soft soils, or groundwater, if encountered, and its
potential impact on project construction.
 Foundation recommendations.
 Pavement design recommendations.
 Estimated undercut quantities/mucking (cy)
 Topsoil estimates (depth and square feet)
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ECS Project No. 33:4260.Rev1 Page 3

 Our recommendations regarding the geotechnical aspects of the proposed design and
construction, as outlined above.
 An Appendix presenting:
o Site location diagram,
o Exploration location diagram,
o Soil test borings logs, and
o Reference Notes for USCS and soil boring logs
1.3 AUTHORIZATION
Our services were provided in accordance with our Proposal No. 33:3379, dated February 27,
2018, as authorized by Stantec’s Subconsultant Agreement.
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ECS Project No. 33:4260.Rev1 Page 4

2.0 PROJECT INFORMATION
2.1 PROJECT LOCATION
The site is located off of Horseshoe Bend Road in Linden, Harnett County, North Carolina. Figure
2.1.1 below shows an aerial image of the site.

Figure 2.1.1 Site Location

2.2 CURRENT SITE CONDITIONS
At the time of our site visit and exploration, the site consisted of an undeveloped open field with
some wooded areas in the middle of the lot. Based on our site visit and the provided site survey,
the site was generally level with typical elevations ranging from about 113 to 115 feet.
2.3 PROPOSED CONSTRUCTION
ECS understands that the project consists of construction of a new substation and access road.
Based on the provided information, the road will be unpaved. The development area for the
substation is approximately 261 feet wide by 324 feet long. Project information regarding
structural loads was not available at the time of this report.
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3.0 FIELD EXPLORATION
3.1 FIELD EXPLORATION PROGRAM
The field exploration was planned with the objective of characterizing the project site in general
geotechnical and geological terms and to evaluate subsequent field data to assist in developing
geotechnical design and construction recommendations.
3.1.1 Soil Test Borings
The subsurface conditions were explored by drilling seven soil test borings within the proposed
construction footprint. A truck mounted drill rig was used to access the drilling locations. Borings
were generally advanced to depths of 10 to 30 feet below the current ground surface using mud
rotary drilling methods. The subsurface exploration was completed under the general supervision
of an ECS staff geotechnical engineer.

Boring locations were identified in the field by ECS personnel by using a hand held GPS unit,
existing site features, and the site plans provided by Stantec. The approximate as-drilled boring
locations are shown on the Boring Location Diagram in Appendix A.

Standard penetration tests (SPTs) were conducted in the borings at regular intervals in general
accordance with ASTM D 1586. Small representative samples were obtained during these tests
and were used to classify the soils encountered. The standard penetration resistances (N-values)
obtained provide a general indication of soil shear strength and compressibility. Individual boring
logs are included in Appendix B.
3.2 REGIONAL/SITE GEOLOGY
The site is located in the Coastal Plain Physiographic Province of North Carolina. The Coastal Plain
is composed of seven terraces, each representing a former level of the Atlantic Ocean. Soils in
this area generally consist of sedimentary materials transported from other areas by the ocean or
rivers. These deposits vary in thickness from a thin veneer along the western edge of the region
to more than 10,000 feet near the coast. The sedimentary deposits of the Coastal Plain rest upon
consolidated rocks similar to those underlying the Piedmont and Mountain Physiographic
Provinces. In general, shallow unconfined groundwater movement within the overlying soils is
largely controlled by topographic gradients. Recharge occurs primarily by infiltration along higher
elevations and typically discharges into streams or other surface water bodies. The elevation of
the shallow water table is transient and can vary greatly with seasonal fluctuations in
precipitation.

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Based on the U.S. Geological Survey1,2, the site of the proposed construction lies within the Cape
Fear Formation (Kc) geological unit. The Cape Fear Formation is characterized by Cretaceous
period yellowish gray to bluish gray and red to yellowish orange, sandstone and sandy mudstone
with some blocky clay, feldspar, and mica. An overview of the general site geology is illustrated in
Figure 3.2.1 below.

Figure 3.2.1
Geologic map for Figure 3.2.1 obtained from The North Carolina Dept. of Environment, Health, and Natural Resources, Division of Land
Resources, NC Geological Survey, in cooperation with the NC Center for Geographic Information and Analysis, 1998, Geology - North
Carolina (1:250,000), coverage data file geol250 and Google Earth.

1 The North Carolina Dept. of Environment, Health, and Natural Resources, Division of Land Resources, NC Geological
Survey, in cooperation with the NC Center for Geographic Information and Analysis, 1998, Geology - North Carolina
(1:250,000), coverage data file geol250. The data represents the digital equivalent of the official State Geology map
(1:500,000 scale), but was digitized from (1:250,000 scale) base maps.

2 Rhodes, Thomas S., and Conrad, Stephen G., 1985, Geologic Map of North Carolina: Department of Natural Resources
and Community Development, Division of Land Resources, and the NC Geological Survey, 1:500,000-scale, compiled by
Brown, Philip M., et al, and Parker, John M. III, and in association with the State Geologic Map Advisory Committee.
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3.3 SUBSURFACE CHARACTERIZATION
The subsurface conditions encountered were generally consistent with published geological
mapping. The following sections provide generalized characterizations of the soil encountered at
each boring during our subsurface exploration. For subsurface information at a specific location,
refer to the SPT Boring Logs and Soil Parameters in Appendix B of this report.

Table 3.3.1 SPT Borings Subsurface Stratigraphy
Approximate
Depth Range (ft)
Stratum Description Ranges of
N-Values(1) blows
per foot (bpf)
0-0.5
(Surface Cover)
N/A Borings performed contained an observed
approximately 6 inches of topsoil across the site.
Deeper topsoil or organic laden soils are most likely
present in wet, poorly drained areas and potentially
unexplored areas of the site.

N/A
0.5-3.5 I Firm Lean and Fat CLAY (CL, CH), moist 5 to 7
3.5-10.0 II Loose to Medium Dense, Clean and Clayey SAND (SP,
SC) and Soft to Firm, Sandy Fat and Fat CLAY (CH),
moist to wet
4 to 20
10.0-22.0 III Very Loose to Medium Dense, Clean, Clean with
Gravel, and Clayey SAND (SP, SC), wet
3 to 11
22.0-30.0 IV Loose to Medium Dense, Clean with Gravel and Clayey
SAND (SP, SC) and Gravel (GP) and Very Stiff, Sandy
Fat CLAY (CH), wet
9 to 23
Notes: (1) Standard Penetration Test Resistances

3.4 GROUNDWATER OBSERVATIONS
The apparent groundwater depths were observed in borings B-5 through B-7 to have ranged from
approximately 3.0 to 8.0 feet below ground surface. Groundwater depths were not encountered
in borings B-1 through B-4 to the depths explored. The water measurements are noted on the
boring logs found in Appendix B of this report.

The highest groundwater observations are normally encountered in the late winter and early
spring. Variations in the long-term water table may occur as a result of changes in precipitation,
evaporation, surface water runoff, construction activities, and other factors not immediately
apparent at the time of this exploration. If long term water levels are crucial to the development
of this site, it would be prudent to verify water levels with the use of perforated pipes or
piezometers.

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4.0 DESIGN RECOMMENDATIONS
4.1 STRUCTURAL DESIGN
The following section provides recommendations for foundation design of structures at the site.
4.1.1 Foundations
Shallow Foundations: It is recommended that axial loads be limited to 50 kips per footing to help
limit the potential for general bearing capacity failure and total settlement in excess of 1 inch.
Provided that the subgrades and structural fills are prepared as discussed herein, the axial loads
do not exceed 50 kips, and approximately 3 feet of approved structural fill is placed on site, the
proposed structures can be supported by conventional shallow foundations. The design of the
foundations shall utilize the following parameters:

Table 4.1.1.1 Foundation Design
Design Parameter Spread Footings
Net Allowable Bearing Pressure1 1,500 psf
Acceptable Bearing Soil Material Approved Structural
Fill
Minimum Width 30 inches
Minimum Footing Embedment Depth (below
finished grade)
12 inches
Estimated Total Settlement 1 inch
Estimated Differential Settlement Less than 0.5 inches

1. Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils
above the base of the foundation.

A majority of the soils at the foundation bearing elevation are anticipated to be suitable for
support of the proposed structures. It will be important to have the geotechnical engineer of
record observe the foundation subgrade prior to placing foundation concrete; to confirm the
bearing soils are what was anticipated. Where soft or unsuitable soils are observed at the footing
bearing elevations, the unsuitable soils should be undercut and replaced with approved structural
fill to the bearing elevation. The depth and lateral extent of the undercut should be determined in
the field during undercutting operation. An ECS representative must be on site during the
undercut and backfill of the areas in order to document the repairs were in accordance with our
recommendations.

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Deep Foundations: Alternatively, structures at the site can be supported on deep foundations
consisting of drilled shafts. Recommended soil parameters for each soil layer to be used in
designing deep foundations are included with the soil test boring logs in Appendix B. Soil
parameters include moist unit weight (pcf), effective friction angle, (φ’ in degrees), effective
cohesion (c’ in psf), pressuremeter modulus (ksi), and soil strength reduction factor. The provided
pressuremeter modulus values are based on correlations to SPT N-value presented in the Electric
Power Research Institute (EPRI) “Manual on Estimating Soil Properties for Foundation Design.”
4.1.2 Seismic Design Considerations
Seismic Site Classification: The International Building Code (IBC) 2009 requires site classification
for seismic design based on the upper 100 feet of a soil profile. Three methods are utilized in
classifying sites, namely the shear wave velocity (vs) method; the unconfined compressive
strength (su) method; and the Standard Penetration Resistance (N-value) method. The third
method (N-value) was used in classifying this site.

The results of the shear wave velocity profiles are contained in Appendix C. The seismic site class
definitions for the weighted average of shear wave velocity or SPT N-value in the upper 100 feet
of the soil profile are shown in the following table:

Table 4.1.2.1: Seismic Site Classification
Site
Class Soil Profile Name Shear Wave Velocity, Vs,
(ft./s)
N value (bpf)
A Hard Rock Vs > 5,000 fps N/A
B Rock 2,500 < Vs ≤ 5,000 fps N/A
C Very dense soil and soft rock 1,200 < Vs ≤ 2,500 fps >50
D Stiff Soil Profile 600 ≤ Vs ≤ 1,200 fps 15 to 50
E Soft Soil Profile Vs < 600 fps <15
The North Carolina Building Code (2009 International Building Code with North Carolina
Amendments) requires that a seismic site class be assigned for new structures. The seismic site
class for the site was determined by calculating and extrapolating a weighted average of the N-
values to a depth of 100 feet. The SPT data indicates that the existing natural, overburden soils at
the site have N-values ranging from 3 to 23 bpf. The method for determining the weighted
average value is presented in Section 1613.5.5 of the IBC 2009. The weighted average value for
the site is approximately 16.3 bpf. Based on the results of the SPT data and our evaluation of the
site, the site shall be assigned a seismic class “D”.

Ground Motion Parameters: In addition to the seismic site classification noted above, ECS has
determined the design spectral response acceleration parameters following the IBC 2009
methodology The Mapped Reponses were estimated from the free Java Ground Motion
Parameter Calculator available from the USGS website
(http://earthquake.usgs.gov/designmaps/us/application.php). The design responses for the short
(0.2 sec, SDS) and 1-second period (SD1) are noted in bold at the far right end of the following table.

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Table 4.1.2.2: Ground Motion Parameters (IBC 2009 Method)
Period
(sec)
Mapped Spectral
Response
Accelerations
(g)
Values of Site
Coefficient
for Site Class
Maximum Spectral
Response Acceleration
Adjusted for Site Class (g)
Design Spectral
Response
Acceleration
(g)
Reference Figures 1613.5.1
(1) & (2)
Tables 1613.5.3
(1) & (2)
Eqs. 16-37 &
16-38
Eqs. 16-39 &
16-40
0.2 SS 0.257 Fa 1.594 SMS=FaSs 0.410 SDS=2/3
SMS 0.273
1.0 S1 0.093 Fv 2.400 SM1=FvS1 0.224 SD1=2/3
SM1 0.148

The Site Class definition should not be confused with the Seismic Design Category designation,
which the Structural Engineer typically assesses.

4.2 SITE DESIGN CONSIDERATIONS
4.2.1 Access Road
Subgrade Characteristics: Based on the results of our borings and proposed final elevations, it
appears that the soils that will be exposed as access road subgrades consist mainly of Approved
Structural Fill. Recommendations provided are assuming approximately 1 to 2 feet of approved
structural fill will be placed in the access road areas.

Design Considerations: For the design and construction of roadways, the subgrades should be
prepared in strict accordance with the recommendations in Sections 6.1 and 6.2 of this report. An
important consideration with the design and construction of roadways is surface and subsurface
drainage. Where standing water develops, softening of the subgrade and other problems related
to the deterioration of the roadway can be expected. Furthermore, good drainage should
minimize the possibility of the subgrade materials becoming saturated during the normal service
period of the pavement.

Anticipated traffic conditions were not provided to ECS. However, based on our experience with
similar projects, an unpaved roadway section may consist of at least 12 inches of compacted
aggregate base course.

Aggregate base course materials should be placed and compacted in at least two lifts. Materials
should be compacted to at least 98 percent of their modified Proctor maximum dry density (ASTM
D 1557).

Saturation of the subgrade materials results in softening of the subgrade material and shortened
life span for the roadway. Therefore, we recommend that both the surface and subsurface
materials for the roadway be properly graded to enhance surface and subgrade drainage. By
quickly removing surface and subsurface water, softening of the subgrade can be reduced and the
performance of the roadway can be improved. Site preparation for the access road should be
similar to that for the substation area including stripping, proofrolling, and the placement of
compacted structural fill.
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5.0 SITE CONSTRUCTION RECOMMENDATIONS
5.1 SUBGRADE PREPARATION
5.1.1 Stripping and Grubbing
The subgrade preparation should consist of stripping all vegetation, rootmat, topsoil, and any
other soft or unsuitable materials from the 10-foot expanded construction area. ECS should be
called on to verify that topsoil and unsuitable surficial materials have been completely removed
prior to the placement of structural fill or construction for the substation.

Based on the anticipated substation area of 324 ft by 261 ft and topsoil depths of 6 inches in that
area, it is anticipated that topsoil quantities will be on the order of 1,600 cubic yards. It is
anticipated that the access roads will have approximately 30,000 square feet of surface area.
Topsoil depths in the access road borings were approximately 6 inches. It is anticipated that
topsoil quantities in the access road will be on the order of 600 cubic yards.

In the wooded portion of the site, it is anticipated that additional stripping and grubbing efforts
will be required below the topsoil to remove roots and stumps.
5.1.2 Proofrolling
After removing all unsuitable surface materials, cutting to the proposed grade, and prior to the
placement of any structural fill or other construction materials, the exposed subgrade should be
examined by the geotechnical engineer or authorized representative. The exposed subgrade
should be thoroughly proofrolled with previously approved construction equipment having a
minimum axle load of 10 tons (e.g. vibratory steel drum roller). The areas subject to proofrolling
should be traversed by the equipment in two perpendicular (orthogonal) directions with
overlapping passes of the vehicle under the observation of the geotechnical engineer or
authorized representative. This procedure is intended to assist in identifying any localized
yielding materials. In the event that unstable or “pumping” subgrade is identified by the
proofrolling, those areas should be marked for repair prior to the placement of any subsequent
structural fill or other construction materials. Methods of repair of unstable subgrade, such as
undercutting, moisture conditioning or chemical stabilization, should be discussed with the
geotechnical engineer to determine the appropriate procedure with regard to the existing
conditions causing the instability. Shallow test pits may be excavated to explore the shallow
subsurface materials in the area of the instability to help in determined the cause of the observed
unstable materials and to assist in the evaluation of the appropriate remedial action to stabilize
the subgrade. Provided that the anticipated approximately 3 feet of approved structural fill is
placed in the substation area and the anticipated approximately 1 to 2 feet of approved structural
fill is placed in the access road areas and proper placement and proofrolling is performed,
undercutting is not anticipated.

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5.2 EARTHWORK OPERATIONS
5.2.1 Structural Fill Materials
Product Submittals: Prior to placement of structural fill, representative bulk samples (about 50
pounds) of on-site and off-site borrow should be submitted to ECS for laboratory testing, which
will include Atterberg limits, natural moisture content, grain-size distribution, and moisture-
density relationships for compaction. Import materials should be tested prior to being hauled to
the site to determine if they meet project specifications.

Satisfactory Structural Fill Materials: Materials satisfactory for use as structural fill should consist
of inorganic soils classified as SM, SW, SP, GW, GP, GM, and GC, or a combination of these group
symbols, per ASTM D 2487. The materials should be free of organic matter, debris, and should
contain no particle sizes greater than 4 inches in the largest dimension. Open graded materials,
such as gravels (GW and GP), which contain void space in their mass should not be used in
structural fills unless properly encapsulated with filter fabric. Suitable structural fill material
should have the index properties shown in Table 5.2.1.1.

Table 5.2.1.1 Structural Fill Index Properties
Location LL PI Max % Passing #
200 Sieve
Proposed Construction Area 35 max 9 max 35

Unsatisfactory Materials: Materials that should not be used as engineered fill include topsoil,
organic materials (OH, OL), and clays and silts (CH, MH, CL, ML). Such materials removed during
grading operations should be either stockpiled for later use in landscape fills, or placed in
approved on or off-site disposal areas.

On-Site Borrow Suitability: The near surface clays encountered by the borings at the site will not
be suitable for re-use as structural fill. Clean and silty sands with fines contents less than 35
percent should be suitable for re-use as structural fill. However, moisture conditioning should be
anticipated for the soils to achieve the optimum moisture content for fill placement.
5.2.2 Compaction
Structural Fill Compaction: Structural fill within the expanded building, pavement, and
embankment limits should be placed in maximum 8-inch loose lifts, moisture conditioned as
necessary to within -3 and +3 % of the soil’s optimum moisture content, and be compacted with
suitable equipment to a dry density of at least 98% of the standard Proctor maximum dry density
(ASTM D698). Beyond these areas, compaction of at least 95% should be achieved. ECS should
be called on to document that proper fill compaction has been achieved.

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Fill Compaction Control: The expanded limits of the proposed construction areas should be well
defined, including the limits of the fill zones for the canopy and pavement areas, at the time of fill
placement. Grade controls should be maintained throughout the filling operations. All filling
operations should be observed on a full-time basis by a qualified representative of the
construction testing laboratory to determine that the minimum compaction requirements are
being achieved. Field density testing of fills will be performed at the frequencies shown in Table
5.2.2.1, but not less than 1 test per lift.

Table 5.2.2.1 Frequency of Compaction Tests in Fill Areas
Location Frequency of Tests
Substation Area 1 test per 2,500 sq. ft. per lift
Access Road Area 1 test per 200 linear feet

Compaction Equipment: Compaction equipment suitable to the soil type being compacted should
be used to compact the subgrades and fill materials. Sheepsfoot compaction equipment should
be suitable for the fine-grained soils (Clays and Silts). A vibratory steel drum roller should be used
for compaction of coarse-grained soils (Sands) as well as for sealing compacted surfaces.

Fill Placement Considerations: Fill materials should not be placed on frozen soils, on frost-heaved
soils, and/or on excessively wet soils. Borrow fill materials should not contain frozen materials at
the time of placement, and all frozen or frost-heaved soils should be removed prior to placement
of structural fill or other fill soils and aggregates. Excessively wet soils or aggregates should be
scarified, aerated, and moisture conditioned.

At the end of each work day, all fill areas should be graded to facilitate drainage of any
precipitation and the surface should be sealed by use of a smooth-drum roller to limit infiltration
of surface water. During placement and compaction of new fill at the beginning of each workday, the
Contractor may need to scarify existing subgrades to a depth on the order of 4 inches so that a weak
plane will not be formed between the new fill and the existing subgrade soils.

The grading contractor should have equipment on site during earthwork for both drying and
wetting fill soils. We do not anticipate significant problems in controlling moisture within the fill
during dry weather, but moisture control may be difficult during winter months or extended
periods of rain. The control of moisture content of higher plasticity soils is difficult when these
soils become wet. Further, such soils are easily degraded by construction traffic when the
moisture content is elevated.

Drying and compaction of wet soils is typically difficult during the cold, winter months.
Accordingly, earthwork should be performed during the warmer, drier times of the year, if
practical. Proper drainage should be maintained during the earthwork phases of construction to
prevent ponding of water which has a tendency to degrade subgrade soils.

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5.3 FOUNDATION OBSERVATIONS
Protection of Foundation Excavations: Exposure to the environment may weaken the soils at the
footing bearing level if the foundation excavations remain open for too long a time. Therefore,
foundation concrete should be placed the same day that excavations are made. If the bearing
soils are softened by surface water intrusion or exposure, the softened soils must be removed
from the foundation excavation bottom immediately prior to placement of concrete. If the
excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils
are exposed, a 2 to 3-inch thick “mud mat” of “lean” concrete should be placed on the bearing
soils before the placement of reinforcing steel.

Foundation Subgrade Observations: Most of the soils at the foundation bearing elevation are
anticipated to be suitable for support of the proposed structures provided the anticipated 3 feet
of fill is placed in the substation area and 1 to 2 feet of fill is placed in the access road areas. The
preparation of subgrades, for the construction areas, should be observed on a full-time basis by
ECS personnel. These observations should be performed by an experienced geotechnical
engineer or qualified person to ensure that unsuitable materials have been removed and that the
prepared subgrade meets project requirements for support of the proposed construction and/or
fills.

5.4 GENERAL CONSTRUCTION CONSIDERATIONS
Moisture Conditioning: During the cooler and wetter periods of the year, delays and additional
costs should be anticipated. At these times, reduction of soil moisture may need to be
accomplished by a combination of mechanical manipulation and the use of chemical additives,
such as lime or cement, in order to lower moisture contents to levels appropriate for compaction.
Alternatively, during the drier times of the year, such as the summer months, moisture may need
to be added to the soil to provide adequate moisture for successful compaction according to the
project requirements.

Subgrade Protection: Measures should also be taken to limit site disturbance, especially from
rubber-tired construction equipment, and to control and remove surface water from
development areas, including structural and pavement areas. It would be advisable to designate a
haul road and construction staging area to limit the areas of disturbance and to prevent
construction traffic from excessively degrading sensitive subgrade soils. Haul roads and
construction staging areas could be covered with excess depths of aggregate to protect those
subgrades. The aggregate can later be removed and used in pavement areas.

Surface Drainage: Surface drainage conditions should be properly maintained. Surface water
should be directed away from the construction area, and the work area should be sloped away
from the construction area at a gradient of at least 1 percent or greater to reduce the potential of
ponding water and the subsequent saturation of the surface soils. At the end of each work day,
the subgrade soils should be sealed by rolling the surface with a smooth drum roller to minimize
infiltration of surface water.

Linden 230 kV, Greenfield HRS Substation May 2, 2018
ECS Project No. 33:4260.Rev1 Page 15

Excavation Safety: Cuts or excavations associated with utility excavations may require forming or
bracing, slope flattening, or other physical measures to control sloughing and/or prevent slope
failures. Contractors should be familiar with applicable OSHA codes to ensure that adequate
protection of the excavations and trench walls is provided. Site safety shall be the sole
responsibility of the contractor.

Excavation Considerations: Based on the results of the borings, we expect that the fill and
natural Coastal Plain soils encountered on this site can be excavated with conventional earth
moving equipment such as loaders, bulldozers, rubber tired backhoes, etc.

The upper site soils are OSHA Type C soils for the purpose of temporary excavation support.
Excavations should be constructed in compliance with current OSHA standards for excavation and
trenching safety. Excavations should be observed by a “competent person,” as defined by OSHA,
who should evaluate the specific soil type and other conditions, which may control the excavation
side slopes or the need for shoring or bracing. Regardless, site safety shall be the sole
responsibility of the contractor and their subcontractors. Exposed earth slopes shall be protected
during periods of inclement weather.

Erosion Control: The surface soils may be erodible. Therefore, the contractor should provide and
maintain good site drainage during earthwork operations to maintain the integrity of the surface
soils. All erosion and sedimentation controls should be in accordance with sound engineering
practices and local requirements.
Linden 230 kV, Greenfield HRS Substation May 2, 2018
ECS Project No. 33:4260.Rev1 Page 16

6.0 CLOSING

ECS has prepared this report of findings, evaluations, and recommendations to guide
geotechnical-related design and construction aspects of the project.

The description of the proposed project is based on information provided to ECS by Stantec. If any
of this information is inaccurate, either due to our interpretation of the documents provided or
site or design changes that may occur later, ECS should be contacted immediately so that we can
review the report in light of the changes and provide additional or alternate recommendations as
may be required to reflect the proposed construction.

We recommend that ECS be allowed to review the project’s plans and specifications pertaining to
our work so that we may ascertain consistency of those plans/specifications with the intent of the
geotechnical report.

Field observations, monitoring, and quality assurance testing during earthwork and foundation
installation are an extension of and integral to the geotechnical design recommendation. We
recommend that the owner retain these quality assurance services and that ECS be allowed to
continue our involvement throughout these critical phases of construction to provide general
consultation as issues arise. ECS is not responsible for the conclusions, opinions, or
recommendations of others based on the data in this report.

APPENDIX A – Drawings

Site Location Diagram
Exploration Location Diagram

Linden 230 kV, Greenfield HRS
Substation
Linden, North Carolina
EXPLORATION
LOCATION DIAGRAM 4/24/20172 of 233:4260NTSWEGACCPROJECTNO.SHEETDATESCALEENGINEERDRAFTINGREFERENCEDENOTES APPROXIMATE LOCATION OF SOIL TEST BORINGB-1B-2B-3B-4B-5B-6B-7 NWSE NWSEStantecSheet: 6 of 17

APPENDIX B – Field Operations

Reference Notes for Boring Logs
Boring Logs B-1 through B-7
Soil Parameters
Subsurface Profiles

Reference Notes for Boring Logs (03-22-2017) © 2017 ECS Corporate Services, LLC. All Rights Reserved
COHESIVE SILTS & CLAYS
UNCONFINED
COMPRESSIVE
STRENGTH, QP
4
SPT5
(BPF)
CONSISTENCY7
(COHESIVE)
<0.25 <3 Very Soft
0.25 - <0.50 3 - 4 Soft
0.50 - <1.00 5 - 8 Firm
1.00 - <2.00 9 - 15 Stiff
2.00 - <4.00 16 - 30 Very Stiff
4.00 - 8.00 31 - 50 Hard
>8.00 >50 Very Hard

GRAVELS, SANDS & NON-COHESIVE SILTS
SPT5 DENSITY
<5 Very Loose
5 - 10 Loose
11 - 30 Medium Dense
31 - 50 Dense
>50 Very Dense

REFERENCE NOTES FOR BORING LOGS

1Classifications and symbols per ASTM D 2488-09 (Visual-Manual Procedure) unless noted otherwise.
2To be consistent with general practice, “POORLY GRADED” has been removed from GP, GP-GM, GP-GC, SP, SP-SM, SP-SC soil types on the boring logs.
3Non-ASTM designations are included in soil descriptions and symbols along with ASTM symbol [Ex: (SM-FILL)].
4Typically estimated via pocket penetrometer or Torvane shear test and expressed in tons per square foot (tsf).
5Standard Penetration Test (SPT) refers to the number of hammer blows (blow count) of a 140 lb. hammer falling 30 inches on a 2 inch OD split spoon sampler
required to drive the sampler 12 inches (ASTM D 1586). “N-value” is another term for “blow count” and is expressed in blows per foot (bpf).
6The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable
when augering, without adding fluids, in granular soils. In clay and cohesive silts, the determination of water levels may require several days for the
water level to stabilize. In such cases, additional methods of measurement are generally employed.
7Minor deviation from ASTM D 2488-09 Note 16.
8Percentages are estimated to the nearest 5% per ASTM D 2488-09.

RELATIVE
AMOUNT7
COARSE
GRAINED
(%)8
FINE
GRAINED
(%)8

Trace <5 <5
Dual Symbol
(ex: SW-SM)
10 10
With 15 - 20 15 - 25
Adjective
(ex: “Silty”)
>25 >30
WATER LEVELS6
WL Water Level (WS)(WD)
(WS) While Sampling
(WD) While Drilling
SHW Seasonal High WT
ACR After Casing Removal
SWT Stabilized Water Table
DCI Dry Cave-In
WCI Wet Cave-In
DRILLING SAMPLING SYMBOLS & ABBREVIATIONS
SS Split Spoon Sampler PM Pressuremeter Test
ST Shelby Tube Sampler RD Rock Bit Drilling
WS Wash Sample RC Rock Core, NX, BX, AX
BS Bulk Sample of Cuttings REC Rock Sample Recovery %
PA Power Auger (no sample) RQD Rock Quality Designation %
HSA Hollow Stem Auger

PARTICLE SIZE IDENTIFICATION
DESIGNATION PARTICLE SIZES
Boulders 12 inches (300 mm) or larger
Cobbles 3 inches to 12 inches (75 mm to 300 mm)
Gravel: Coarse ¾ inch to 3 inches (19 mm to 75 mm)
Fine 4.75 mm to 19 mm (No. 4 sieve to ¾ inch)
Sand: Coarse 2.00 mm to 4.75 mm (No. 10 to No. 4 sieve)
Medium 0.425 mm to 2.00 mm (No. 40 to No. 10 sieve)
Fine 0.074 mm to 0.425 mm (No. 200 to No. 40 sieve)
Silt & Clay (“Fines”) <0.074 mm (smaller than a No. 200 sieve)

MATERIAL1,2

ASPHALT

CONCRETE

GRAVEL

TOPSOIL

VOID

BRICK

AGGREGATE BASE COURSE

FILL3 MAN-PLACED SOILS

GW WELL-GRADED GRAVEL
gravel-sand mixtures, little or no fines

GP POORLY-GRADED GRAVEL
gravel-sand mixtures, little or no fines

GM SILTY GRAVEL
gravel-sand-silt mixtures

GC CLAYEY GRAVEL
gravel-sand-clay mixtures

SW WELL-GRADED SAND
gravelly sand, little or no fines

SP POORLY-GRADED SAND
gravelly sand, little or no fines

SM SILTY SAND
sand-silt mixtures

SC CLAYEY SAND
sand-clay mixtures

ML SILT
non-plastic to medium plasticity

MH ELASTIC SILT
high plasticity

CL LEAN CLAY
low to medium plasticity

CH FAT CLAY
high plasticity

OL ORGANIC SILT or CLAY
non-plastic to low plasticity

OH ORGANIC SILT or CLAY
high plasticity

PT PEAT
highly organic soils

0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
SS
SS
SS
SS
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) FAT CLAY, orange, moist, firm
(SP) FINE SAND, tan, moist, medium dense
(SP) FINE TO MEDIUM SAND, tan, wet, loose
END OF BORING @ 10'
2
3
4
4
9
11
5
7
9
3
3
5
7
20
16
8
CLIENT
Stantec
Job #:
33:4260
BORING #
B-1
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Auto
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-1Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 3CH125 0 827 1.1 0.503 8SP125 35 0 1.0 0.458 10SP115 30 0 0.6 0.45
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
SS
SS
SS
SS
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) FAT CLAY, orange, moist, firm
(SC) CLAYEY FINE SAND, tan, moist, medium
dense
(SP) FINE SAND, tan, moist, loose
(SP) MEDIUM TO COARSE SAND, orange,
wet, loose
END OF BORING @ 10'
2
3
3
4
8
8
3
4
4
4
5
5
6
16
8
10
CLIENT
Stantec
Job #:
33:4260
BORING #
B-2
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Auto
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-2Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 3CH125 0 735 1.0 0.503 5.5SC125 34 0 0.9 0.455.5 8SP115 30 0 0.6 0.458 10SP115 31 0 0.7 0.45
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
SS
SS
SS
SS
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) FAT CLAY, orange, moist, firm
(SP) FINE SAND, tan/gray, moist, medium
dense to loose
(SP) FINE TO MEDIUM SAND, gray/tan, wet,
medium dense
END OF BORING @ 10'
2
3
4
4
6
7
5
4
5
5
5
6
7
13
9
11
CLIENT
Stantec
Job #:
33:4260
BORING #
B-3
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Manual
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-3Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 3CH125 0 827 1.1 0.503 10SP120 32 0 0.7 0.45
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
SS
SS
SS
SS
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) FAT CLAY, tan, moist, firm
(CH) SANDY FAT CLAY, gray, moist, soft to
firm
(SP) FINE TO MEDIUM SAND, tan/gray, wet,
medium dense
END OF BORING @ 10'
1
2
3
3
2
2
3
3
3
3
5
7
5
4
6
12
CLIENT
Stantec
Job #:
33:4260
BORING #
B-4
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Manual
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-4Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 8CH125 0 551 0.8 0.508 10SP120 32 0 0.8 0.45
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
S-6
S-7
S-8
SS
SS
SS
SS
SS
SS
SS
SS
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CL) LEAN CLAY, tan/ orange, moist, firm
(SP) FINE SAND, tan, moist to wet, medium
dense to loose
(SP) FINE TO MEDIUM SAND, tan/gray, wet,
loose
(SP) COARSE SAND WITH GRAVEL, tan, wet,
medium dense
(SP) MEDIUM SAND WITH GRAVEL, gray,
wet, medium dense
(GP) GRAVEL, dark gray, wet, loose
END OF BORING @ 30'
2
3
4
3
5
7
2
3
4
3
3
4
4
5
4
3
5
6
10
9
7
5
5
4
7
12
7
7
9
11
16
9
CLIENT
Stantec
Job #:
33:4260
BORING #
B-5
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL 3.0 WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Auto
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-5Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 3.5CL125 0 827 1.1 0.503.5 5.5SP120 32 0 0.8 0.455.5 8SP110 30 0 0.5 0.458 17SP115 30 0 0.6 0.4517 22SP120 32 0 0.7 0.4522 27SP125 34 0 0.9 0.4527 30GP115 31 0 0.6 0.45
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Boring:B-5Shaft Diameter: 5 ft.Top Depth (ft)Bottom Depth(ft)Allowable End Bearing (ksf) Allowable Average Side Friction (ksf)0 3.5--3.5 5.5--5.5 8--8 176.50.3517 2212.00.5522 2720.00.6827 3016.00.78Allowable loads were calculated using a F.S. = 2.0 for end bearing, F.S. = 3.0 for side friction.
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
S-6
S-7
S-8
SS
SS
SS
SS
SS
SS
SS
SS
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) FAT CLAY, tan, moist, firm
(SP) FINE SAND, tan, wet, loose to medium
dense
(SP) FINE TO MEDIUM SAND, tan, wet, loose
(SP) MEDIUM TO COARSE SAND WITH
GRAVEL, gray, wet, very loose
(SP) FINE SAND, gray, wet, very loose
(CH) SANDY FAT CLAY, gray to dark green,
wet, very stiff
END OF BORING @ 30'
2
2
4
2
2
3
4
5
6
4
5
4
4
1
2
2
2
2
2
3
14
8
8
15
6
5
11
9
3
4
17
23
CLIENT
Stantec
Job #:
33:4260
BORING #
B-6
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL 8.0 WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Auto
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-6Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 3.5CH125 0 735 1.0 0.503.5 5.5SP110 29 0 0.4 0.455.5 8SP120 32 0 0.7 0.458 12SP115 31 0 0.6 0.4512 22SP105 28 0 0.3 0.4522 30CH135 0 2389 2.2 0.50
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Boring:B-6Shaft Diameter: 5 ft.Top Depth (ft)Bottom Depth(ft)Allowable End Bearing (ksf) Allowable Average Side Friction (ksf)0 3.5--3.5 5.5--5.5 8--5.5 128.50.2212 227.50.3822 3016.01.58Allowable loads were calculated using a F.S. = 2.0 for end bearing, F.S. = 3.0 for side friction.
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
S-6
S-7
S-8
SS
SS
SS
SS
SS
SS
SS
SS
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
18
Topsoil/Rootmat Depth [6"]
(CH) SANDY FAT CLAY, orange, moist, firm
(CH) FAT CLAY, orange, moist, firm
(SP) FINE TO MEDIUM SAND, tan, moist,
medium dense
(SC) CLAYEY FINE SAND, tan/orange, wet,
loose
(SP) FINE TO MEDIUM SAND, gray, wet, loose
(SC) CLAYEY FINE SAND, gray to green, wet,
medium dense
END OF BORING @ 30'
2
2
3
3
3
4
3
3
4
6
7
9
6
5
2
2
3
3
4
7
13
5
9
11
5
7
7
16
7
6
20
20
CLIENT
Stantec
Job #:
33:4260
BORING #
B-7
SHEET
PROJECT NAME
Linden 230kV 150509F01, Greenfield HRS
Substation - GEO
ARCHITECT-ENGINEER
Dennis D. Lowery
SITE LOCATION
Horseshoe Bend Rd, Linden, Harnett, NC
NORTHING EASTING STATION
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.
WL 3.0 WS WD BORING STARTED 04/03/18 CAVE IN DEPTH
WL(SHW)WL(ACR) BORING COMPLETED 04/03/18 HAMMER TYPE Auto
WL RIG Truck FOREMAN Mike Radford DRILLING METHOD Mud RotaryDRILLING METHOD Mud RotaryDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION
DESCRIPTION OF MATERIAL
WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+
20% 40% 60% 80% 100%
1 2 3 4 5+
ENGLISH UNITS
BOTTOM OF CASING LOSS OF CIRCULATION
CALIBRATED PENETROMETER TONS/FT2
PLASTIC
LIMIT %
WATER
CONTENT %
LIQUID
LIMIT %
ROCK QUALITY DESIGNATION & RECOVERY
RQD% REC.%
STANDARD PENETRATION
BLOWS/FT
1 OF 1
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Recommended Soil ParametersBoring:B-7Top Depth (ft)Bottom Depth(ft)USCS Soil ClassificationMoist Unit Weight (pcf)φ' (degrees)c' (psf)PressuremeterModulus (ksi)Soil Strength Reduction Factor0 8CH125 0 735 1.0 0.508 12SP125 34 0 0.9 0.4512 17SC110 30 0 0.5 0.4517 22SP110 29 0 0.5 0.4522 30SC125 35 0 1.1 0.45
Project: Linden 230 kV, Greenfield HRS SubstationLocation: Linden, North CarolinaProject #: 33:4260Boring:B-7Shaft Diameter: 5 ft.Top Depth (ft)Bottom Depth(ft)Allowable End Bearing (ksf) Allowable Average Side Friction (ksf)0 8--8 12180.3212 17100.4517 22110.4222 30320.90Allowable loads were calculated using a F.S. = 2.0 for end bearing, F.S. = 3.0 for side friction.
B-1720168END OF BORING@ 10'TopsoilCHSPB-2616810END OF BORING@ 10'TopsoilCHSCSPB-3713911END OF BORING@ 10'TopsoilCHSPB-454612END OF BORING@ 10'TopsoilCHSPB-571277911169TopsoilCLSPGP0612182430Depth in Feet0612182430Depth in Feet
Subsurface SoilProfileNOTES:1 SEE INDIVIDUAL BORING LOG AND GEOTECHNICAL REPORT FOR ADDITIONAL INFORMATION.2 PENETRATION TEST RESISTANCE IN BLOWS PER FOOT (ASTM D1586).3 HORIZONTAL DISTANCES ARE NOT TO SCALE.Linden 230kV 150509F01, GreenfieldStantecHorseshoe Bend Rd, Linden, Harnett, NCPROJECT NO.:4260 DATE:4/26/2018 VERTICAL SCALE:1"=
B-665119341723TopsoilCHSPCHB-757716762020TopsoilCHSPSCSPSC0612182430Depth in Feet0612182430Depth in Feet
Subsurface SoilProfileNOTES:1 SEE INDIVIDUAL BORING LOG AND GEOTECHNICAL REPORT FOR ADDITIONAL INFORMATION.2 PENETRATION TEST RESISTANCE IN BLOWS PER FOOT (ASTM D1586).3 HORIZONTAL DISTANCES ARE NOT TO SCALE.Linden 230kV 150509F01, GreenfieldStantecHorseshoe Bend Rd, Linden, Harnett, NCPROJECT NO.:4260 DATE:4/26/2018 VERTICAL SCALE:1"=

APPENDIX C – Supplemental Report Documents

ASFE Document

Important Information About Your
Geotechnical Engineering Report
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes
The following information is provided to help you manage your risks.
Geotechnical Services Are Performed for
Specifi c Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specifi c needs of
their clients. A geotechnical engineering study conducted for a civil engineer
may not fulfi ll the needs of a construction contractor or even another civil
engineer. Because each geotechnical engineering study is unique, each geo-
technical engineering report is unique, prepared solely for the client. No one
except you should rely on your geotechnical engineering report without fi rst
conferring with the geotechnical engineer who prepared it. And no one - not
even you - should apply the report for any purpose or project except the one
originally contemplated.
Read the Full Report
Serious problems have occurred because those relying on a geotechnical
engineering report did not read it all. Do not rely on an executive summary.
Do not read selected elements only.
A Geotechnical Engineering Report Is Based on
A Unique Set of Project-Specifi c Factors
Geotechnical engineers consider a number of unique, project-specifi c factors
when establishing the scope of a study. Typical factors include: the client’s
goals, objectives, and risk management preferences; the general nature of the
structure involved, its size, and confi guration; the location of the structure
on the site; and other planned or existing site improvements, such as access
roads, parking lots, and underground utilities. Unless the geotechnical engi-
neer who conducted the study specifi cally indicates otherwise, do not rely on
a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specifi c site explored, or
• completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those that affect:
• the function of the proposed structure, as when it’s changed from a
parking garage to an offi ce building, or from alight industrial plant
to a refrigerated warehouse,
• elevation, confi guration, location, orientation, or weight of the
proposed structure,
• composition of the design team, or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
changes - even minor ones - and request an assessment of their impact.
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider developments of which they
were not informed.
Subsurface Conditions Can Change
A geotechnical engineering report is based on conditions that existed at the
time the study was performed. Do not rely on a geotechnical engineering
report whose adequacy may have been affected by: the passage of time; by
man-made events, such as construction on or adjacent to the site; or by natu-
ral events, such as fl oods, earthquakes, or groundwater fl uctuations. Always
contact the geotechnical engineer before applying the report to determine if it
is still reliable. A minor amount of additional testing or analysis could prevent
major problems.
Most Geotechnical Findings Are Professional
Opinions
Site exploration identifi es subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnical engineers
review fi eld and laboratory data and then apply their professional judgment
to render an opinion about subsurface conditions throughout the site. Actual
subsurface conditions may differ-sometimes signifi cantly from those indi-
cated in your report. Retaining the geotechnical engineer who developed your
report to provide construction observation is the most effective method of
managing the risks associated with unanticipated conditions.
A Report’s Recommendations Are Not Final
Do not overrely on the construction recommendations included in your re-
port. Those recommendations are not fi nal, because geotechnical engineers
develop them principally from judgment and opinion. Geotechnical engineers
can fi nalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnical engi-
neer who developed your report cannot assume responsibility or liability for
the report’s recommendations if that engineer does not perform construction
observation.
A Geotechnical Engineering Report Is Subject to
Misinterpretation
Other design team members’ misinterpretation of geotechnical engineer-
ing reports has resulted in costly problems. Lower that risk by having your
geotechnical engineer confer with appropriate members of the design team
after submitting the report. Also retain your geotechnical engineer to review
pertinent elements of the design team’s plans and specifi cations. Contractors
can also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconstruction
conferences, and by providing construction observation.
Do Not Redraw the Engineer’s Logs
Geotechnical engineers prepare fi nal boring and testing logs based upon
their interpretation of fi eld logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating logs from the report can elevate risk.
Give Contractors a Complete Report and
Guidance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly problems, give con-
tractors the complete geotechnical engineering report, but preface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the report’s
accuracy is limited; encourage them to confer with the geotechnical engineer
who prepared the report (a modest fee may be required) and/or to conduct ad-
ditional study to obtain the specifi c types of information they need or prefer.
A prebid conference can also be valuable. Be sure contractors have suffi cient
time to perform additional study. Only then might you be in a position to give
contractors the best information available to you, while requiring them to at
least share some of the fi nancial responsibilities stemming from unantici-
pated conditions.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineering disciplines.
This lack of understanding has created unrealistic expectations that have led
to disappointments, claims, and disputes. To help reduce the risk of such
outcomes, geotechnical engineers commonly include a variety of explanatory
provisions in their reports. Sometimes labeled “limitations” many of these
provisions indicate where geotechnical engineers’ responsibilities begin
and end, to help others recognize their own responsibilities and risks. Read
these provisions closely. Ask questions. Your geotechnical engineer should
respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenviron-
mental study differ signifi cantly from those used to perform a geotechnical
study. For that reason, a geotechnical engineering report does not usually re-
late any geoenvironmental fi ndings, conclusions, or recommendations; e.g.,
about the likelihood of encountering underground storage tanks or regulated
contaminants. Unanticipated environmental problems have led to numerous
project failures. If you have not yet obtained your own geoenvironmental in-
formation, ask your geotechnical consultant for risk management guidance.
Do not rely on an environmental report prepared for someone else.
Obtain Professional Assistance To Deal with Mold
Diverse strategies can be applied during building design, construction, op-
eration, and maintenance to prevent signifi cant amounts of mold from grow-
ing on indoor surfaces. To be effective, all such strategies should be devised
for the express purpose of mold prevention, integrated into a comprehensive
plan, and executed with diligent oversight by a professional mold prevention
consultant. Because just a small amount of water or moisture can lead to
the development of severe mold infestations, a number of mold prevention
strategies focus on keeping building surfaces dry. While groundwater, wa-
ter infi ltration, and similar issues may have been addressed as part of the
geotechnical engineering study whose fi ndings are conveyed in-this report,
the geotechnical engineer in charge of this project is not a mold prevention
consultant; none of the services performed in connection with
the geotechnical engineer’s study were designed or conducted
for the purpose of mold prevention. Proper implementation of
the recommendations conveyed in this report will not of itself
be suffi cient to prevent mold from growing in or on the struc-
ture involved.
Rely on Your ASFE-Member Geotechnical
Engineer For Additional Assistance
Membership in ASFE/The Best People on Earth exposes geotechnical engi-
neers to a wide array of risk management techniques that can be of genuine
benefi t for everyone involved with a construction project. Confer with your
ASFE-member geotechnical engineer for more information.
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone:’ 301/565-2733 Facsimile: 301/589-2017
e-mail: [e-mail] www.asfe.org
Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s specifi c
written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes
of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other fi rm,
individual, or other entity that so uses this document without being anASFE member could be committing negligent or intentional (fraudulent) misrepresentation.
IIGER06045.0M
The Best People on Earth