HomeMy WebLinkAboutSW5180501_Geotech Report_20180523Preliminary Geotechnical
Engineering Report
Siler Solar, LLC
Siler Business Drive
Siler City, North Carolina
April 6, 2018
Project No. 70185047
Prepared for:
Cypress Creek Renewables, LLC
Sacramento, California
Prepared by:
Terracon Consultants, Inc.
Raleigh, North Carolina DRAFT
Terracon Consultants, Inc. 2401 Brentwood Road, Suite 107 Raleigh, North Carolina 27604
P [919] 873 2211 F [919] 873 9555 T erracon.com North Carolina Registered F -0869
April 6, 2018
Cypress Creek Renewables
770 L Street, Suite 950
Sacramento, California 95814
Attn: Mr. Jake Clay
Geotechnical Engineering Coordinator
Mobile: (313) 207-9207
Email: Jacob.clay@ccrenew.com
Re: Preliminary Geotechnical Engineering Report
Siler Solar, LLC
Siler Business Drive
Siler City, North Carolina
Terracon Project No. 70185047
Dear Mr. Clay,
Terracon Consultants, Inc. (Terracon) is pleased to submit this report detailing the completed preliminary
geotechnical engineering services for the above r eferenced project. This report summarizes the results of
our testing programs and provides geotechnical engineering recommendations relative to the proposed
development at the site. Our services have been performed in general accordance with our February 23,
2018 proposal and associated Statement of Work issued under the terms of our Master Services
Agreement.
We appreciate the opportunity to be of service to you on this project. If you have any questions concerning
this report, or if we may be of further service, please contact us.
Sincerely,
Terracon Consultants, Inc.
Thomas R. Bartlett, P.E. Andrew A. Nash, P.E.
Project Engineer Senior Engineer
Registered, NC 43116 DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable i
TABLE OF CONTENTS
PAGE
1.0 INTRODUCTION ............................................................................................................. 1
2.0 PROJECT UNDERSTANDING ....................................................................................... 1
2.1 Project & Site Description ..................................................................................... 1
2.2 Site Geologic Background..................................................................................... 2
3.0 SUBSURFACE CONDITIONS ........................................................................................ 3
3.1 Subsurface Materials ............................................................................................ 3
3.2 Groundwater ......................................................................................................... 3
4.0 GEOTECHNICAL RECOMMENDATIONS ...................................................................... 4
4.1 Geotechnical Considerations ................................................................................ 4
4.2 Earthwork ............................................................................................................. 5
4.2.1 Engineered Fill Property Requirements ..................................................... 6
4.2.2 Engineered Fill Compaction Requirements ............................................... 6
4.2.3 Excavations .............................................................................................. 7
4.2.4 General Earthwork Considerations ............................................................ 7
4.2.5 Preliminary Slopes .................................................................................... 7
4.3 Preliminary Recommendations for Racking System Pile Foundations .................. 8
4.3.1 Preliminary Axial Capacity Design Recommendations .............................. 8
4.3.2 Preliminary Lateral Capacity Design Recommendations ........................... 8
4.3.3 Preliminary Construction Considerations................................................... 9
4.4 Shallow Foundation Recommendations ................................................................ 9
4.4.1 Spread Footing Foundation Design ..........................................................10
4.4.2 Shallow Mat or Equipment Pad Foundations ............................................11
4.4.3 Shallow Foundation Construction .............................................................11
4.5 Seismic Parameters .............................................................................................12
4.6 Aggregate Surfaced Roadway .............................................................................12
4.7 Miscellaneous Other Design Considerations ........................................................13
5.0 GENERAL COMMENTS ................................................................................................14
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Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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TABLE OF CONTENTS
(continued)
APPENDIX A – LOCATION INFORMATION
Exhibit A-1 Site Location Plan
Exhibit A-2 Field Testing Location Plan
APPENDIX B – FIELD EXPLORATION
Exhibit B-1 Field Exploration Description
Exhibit B-2 In-Situ Soil Electrical Resistivity Results
Exhibit B-3 Soil Test Boring Summary
Boring Logs B-1, B-2, & B-3
APPENDIX C – LABORATORY TESTING
Exhibit C-1 Laboratory Testing Description
Exhibit C-2 Laboratory Testing Summary
Exhibit C-3 Atterberg Limits
Exhibit C-4 Report of Corrosive Potential Laboratory Testing
Exhibits C-5 and C-6 Moisture Density Relationship
Exhibits C-7 and C-8 California Bearing Ratio (CBR) Testing
Exhibit C-9 Thermal Resistivity Test Results
APPENDIX G– SUPPORTING DOCUMENTS
Exhibit G-1 General Notes
Exhibit G-2 Unified Soil Classification System (USCS)
Exhibit G-3 Drill Rig SPT Hammer Energy Calibration Report (6 pages)
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PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
SILER SOLAR, LLC
SILER BUSINESS DRIVE
SILER CITY, NORTH CAROLINA
Terracon Project No. 70185047
April 6, 2018
1.0 INTRODUCTION
Terracon Consultants, Inc. (Terracon) is pleased to submit this report detailing the completed
preliminary geotechnical engineering services performed for the above referenced project. Our
scope of work included performing a field exploration and laboratory testing program. The
purpose of this report is to summarize the results of our site characterization testing programs
and to provide preliminary recommendations for:
general geotechnical considerations for site development;
earthwork including site grading, excavations, & slopes;
design & construction of the PV panel racking system foundations
design & construction of shallow foundations for equipment pads & ancillary
structures;
seismic considerations;
design & construction of the proposed aggregate-surfaced roadway; and
miscellaneous other design considerations.
2.0 PROJECT UNDERSTANDING
2.1 Project & Site Description
A solar power facility is planned as outlined in the table below. Reference the attached Exhibit
Nos. A-1 and A-2 for further details regarding the site location. The site consists of two open
fields within surrounding wooded areas. There is a pond located to the southeast of the
proposed construction area. The site also contains various utilities and other improvements that
were previously installed in anticipation for development of the site as a business park. The
project site also contains two water mains that join the storage tanks to the north of the site.
Site Address Lat/Long Target
Capacity Array Acreage
Siler Solar, LLC Siler Business Dr Siler City, NC 35.740° -79.473° 4MW (AC) ±53
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Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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We understand that the PV solar panels will be mounted to a racking system that is likely to be
supported with driven W-section, pile foundations. Other various project components include the
design and construction of shallow foundations for lightly-loaded structures and equipment; an
electrical ground system; corrosion protection; and underground electric cable/conduit. We
expect that very little grading will be performed and that earthwork will be mainly limited to
subgrade preparation.
As part of the overall project development, a base course surfaced access road / storage area
may be constructed and will facilitate construction traffic and, after project completion,
occasional maintenance vehicles and potentially emergency service vehicles. Traffic loads over
the design life are expected to be less than 10,000 18-kip ESALs. The proposed unpaved
access roadway is expected to tie into the existing asphalt paved roadway.
If any of the information presented above is inconsistent with the proposed construction, or the
design changes, Terracon requests the opportunity to revise our recommendations.
2.2 Site Geologic Background
The project site is located in the Piedmont Physiographic Province, an area underlain by ancient
igneous and metamorphic rocks. The residual soils in this area are the product of in-place chemical
and physical weathering of rock. The typical residual soil profile consists of clayey soils near the
surface where soil weathering is more advanced, underlain by sandy silts / silty sands that
generally become harder / denser with depth to the top of parent bedrock. According to the 1998
Geologic Map of North Carolina, the bedrock under the project site is Cambrian Period / later
Proterozoic eon Metamudstone and Meta-Argillite.
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Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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3.0 SUBSURFACE CONDITIONS
3.1 Subsurface Materials
Based on the results of the borings, conditions below the ground surface (bgs) at the site can be
idealized as follows:
Description Approximate Depth bgs to
Bottom of Stratum Material Encountered Consistency/Density
Stratum 1 4 to 5 feet moderate to highly plastic
CLAY Medium Stiff to Very Stiff
Stratum 2A 6 to 8 feet elastic SILT Medium Stiff to Stiff
Stratum 2B 19 to 29 feet 1 sandy SILT Stiff to Very Stiff
Stratum 3 To Maximum Boring
Termination Depths of ±35 ft Partially Weathered Rock Very Hard Soil /
Soft to M. Hard Rock
1. Boring B-2 was terminated at a depth of 20 feet bgs in very stiff silty sand.
Detailed descriptions of the conditions encountered at the individual boring locations are indicated
on the attached boring logs. Stratification boundaries on the boring logs represent the approximate
location of changes in soil types; in-situ, the transition between materials may be gradual.
3.2 Groundwater
The recovered soil samples and the drill tooling were observed for the presence of free water
while drilling and the open boreholes were checked for the presence of groundwater
immediately after drilling. We did not encounter groundwater at these times and we have
reported the depth to dry cave-in of the open borehole immediately after drilling.
However, groundwater level fluctuations can occur due to seasonal and climatic changes in the
amount of precipitation, runoff, evaporation and other factors not evident at the time the boring
was performed. The possibility of varied groundwater levels relative to what was encountered in
our investigation should be considered when developing design and construction plans and
specifications for the project.
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Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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4.0 GEOTECHNICAL RECOMMENDATIONS
4.1 Geotechnical Considerations
Based on our experience, we expect that driven W -section or other steel pile foundations
embedded on the order of 6 to 10 feet below the surface will be sufficient for support of typical
solar panel racking systems.
We have provided preliminary geotechnical parameters for foundation evaluation based on the
results of our preliminary subsurface characterization. Preconstruction pile load testing should
be performed as part of the design process for the panel racking system foundation. We expect
the results of a preconstruction pile load testing study to result in economic optimization for the
foundation design.
Partially weathered rock, where encountered in our soil test borings, was generally below the
bearing elevations anticipated for production piles. However, rock or PWR may exist at more
shallow depths and higher elevations between the widely-spaced borings at the site. We expect
that occasional driving refusal could be encountered when installing production piles and, as with
every project in the Piedmont, a contingency plan for this should be in place. Rock and PWR, if
encountered in excavations, will require additional effort to penetrate. Groundwater is not
expected to be encountered in excavations.
We expect that some of the existing near-surface conditions will require remediation at the time
of construction in order to support shallow foundations and equipment pads, especially if the
subgrade is exposed to moisture.
Additionally, the near-surface soils are subject to degradation with exposure to moisture. To the
extent practical, earthwork and construction should be performed during summer and early fall
due to the improved drying conditions and shorter time periods of rainfall associated with these
seasons.
The results of our chemical testing indicate that the site soils are acidic which can be conducive
to corrosion. The project structural design should consider the potential effects of corrosion for
the steel piles over the design life of the project. We recommend that a qualified engineer
evaluate the corrosion potential for the project site and its other potential impacts on
development. The complete results of our field and laboratory testing are expected to assist the
corrosion engineer.
Additional testing should also be performed during the project earthwork phase. A qualified
geotechnical engineer should be retained at this time to observe and perform necessary tests
and observations during subgrade preparation; proof-rolling; placement and compaction of DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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controlled compacted fills; backfilling of excavations into the completed subgrade, and just prior
to construction of shallow foundations.
A more complete discussion of these ideas is provided in the following sections.
4.2 Earthwork
We have provided recommendations for site earthwork in this report. However, the designers of
the PV panel racking system foundations should ultimately stipulate earthwork specifications in
areas to support the PV panels. Overall, we expect relatively minor grading with final grades to
remain within 2 feet of existing grades.
Site preparation should begin by clearing and grubbing. The root systems of trees should be
completely removed. Vegetation and topsoil / rootmat should be stripped from areas to be
graded and areas within footprint of the proposed roadways and shallow-foundation-supported
structures. However, if desired, topsoil may remain in-place for areas where grades will remain
the same beneath the PV panels.
Areas along the roadway alignment and within the footprint of shallow foundations should be
generally evaluated for plasticity and compacted in-place. The existing near-surface site soils in
localized areas are highly plastic and subject to shrink-swell behavior with fluctuations in
moisture content. A vertical separation of 2 feet should be maintained between highly plastic
soils and the design subgrade elevation for shallow foundations and roadways. This can be
accomplished through a combination of overexcavation of the existing highly plastic soils and
replacement with low plasticity engineered fill or by raising grades with low to moderate
plasticity engineered fill. Even with the recommended mitigation of potentially expansive soils,
some movement and distress of roadways and shallow foundation supported project elements
could occur. Eliminating the risk of movement and distress may not be feasible, but this risk can
be reduced if earthwork is performed as described in this report. Where performed, in-place
compaction should be accomplished with a medium’ to heavy-weight sheep’s foot roller making
make at least 6 passes.
Prior to placing fill, or at the subgrade elevation in cut areas, we recommend proofrolling to
detect soft, unstable, or otherwise unsuitable soil. Proofrolling should be performed with a
loaded, tandem-axle dump truck or similar rubber-tired construction equipment with a minimum
gross weight of 20,000 lb. The proofrolling operations should be observed by a representative of a
qualified geotechnical engineer and. Areas exhibiting excessive deflection or rutting, or areas
where otherwise unsuitable material is encountered should be remediated as directed by a
qualified geotechnical engineer.
In-place compaction and proofrolling should be performed after a suitable period of dry weather
to avoid degrading an otherwise acceptable subgrade DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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4.2.1 Engineered Fill Property Requirements
Engineered fill should generally have a maximum particle diameter of ¾ inches. Engineered fill
should also meet the following material property requirements:
Table 2: Engineered Fill Materials
Fill Type 1 USCS Classification Acceptable Location for Placement1
Imported Low- to
Moderate- Plasticity
Soil 2,3
CL, ML, SC or SM All locations and elevations
Sand / Gravel with
less than 12% fines 3 GW/GP, SW/SP
Crushed stone base course (NCDOT ABC) may be
used for the access roadway or beneath shallow
foundations as a replacement material for
overexcavated soils.
Low to Moderate
Plasticity,
Near-Surface,
On-site soils
CL / CH, ML / MH, SM
&
LL<60 or PI <30
The low-to moderate-plasticity on-site soils generally
appear suitable for use as engineered fill when they
contain at least 12% fines (clay and/or silt) and are
compacted at an appropriate moisture content.
High Plasticity,
Near-Surface,
On-site soils
CH / MH
&
LL>60 and PI>30
As general fill within array areas and at least 2 feet
below the design subgrade elevation within the
footprint of shallow foundations and roadways.4
1. Controlled, compacted fill should consist of approved materials that are free of organic matter and
debris. A sample of each material type should be submitted to the geotechnical engineer for
evaluation.
2. Low- to moderate-plasticity cohesive soil or granular soil having at least 12% fines.
3. Placing clean granular soils above some of the subgrade soils at the site risks the development of
perched water conditions as surface water infiltrating the surface sand becomes trapped above the
less permeable materials.
4.2.2 Engineered Fill Compaction Requirements
Item Description
Fill Lift Thickness 9-inches or less in loose thickness (4” to 6” lifts when hand-
operated equipment is used)
Compaction Requirements 1 Minimum of 95% of the materials standard Proctor maximum
dry density (ASTM D698)
Moisture Content
Within the range of -3% to +3% of optimum moisture content
as determined by the standard Proctor test at the time of
placement and compaction
1. Engineered fill should be tested for moisture content and compac tion during placement. If in-place
density tests indicate the specified moisture or compaction limits have not been met, the area
represented by the tests should be reworked and retested as required until the specified moisture
and compaction requirements are achieved.
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Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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4.2.3 Excavations
Based on the widely-spaced borings, rock and partially weathered rock are below the
anticipated depth of excavation for the project. Therefore we expect that excavation can be
performed with conventional earthmoving equipment. Groundwater or perched groundwater,
which may be encountered in trench excavations, will require dewatering until backfilling
operations are complete.
All excavations that may be required should, at a minimum, comply with applicable local, state
and federal safety regulations, including the current OSHA Excavation and Trench Safety
Standards to provide stability and safe working conditions.
4.2.4 General Earthwork Considerations
The on-site soils are subject to degradation with exposure to moisture. To the extent practical,
earthwork should be performed during the summer and fall due to the shorter duration of
precipitation and increased drying potential associated with these seasons. This does not
necessarily preclude performing earthwork during other times of the year; however, increased
remedial measures due to wet and soft or otherwise unsuitable conditions should be expected if
earthwork is performed during other times of year.
A qualified geotechnical engineer should be retained during the earthwork phase of the project
to observe earthwork and to perform necessary tests and observations during subgrade
preparation; to monitor proof-rolling, placement and compaction of controlled compacted fills,
and backfilling of excavations to the completed subgrade.
4.2.5 Preliminary Slopes
For permanent slopes in unreinforced compacted fill areas, recommended maximum
configurations for on-site materials are as follows:
Maximum Slope
Material Horizontal:Vertical
Cohesive soils (on-site/imported clays and silts) ........................................ 2-1/2:1
Cohesionless soils (on-site or imported granular soils w/ >12% fines) .............. 3:1
The face of all slopes should be compacted to the minimum specification for fill embankments;
fill slopes should be overbuilt and trimmed to achieve compaction. If steeper slopes are required
for site development, stability analyses should be completed to design the grading plan.
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Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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4.3 Preliminary Recommendations for Racking System Pile Foundations
Based on our experience, we expect that driven W -section or other steel pile foundations
embedded on the order of 6 to 10 feet below the surface will be sufficient for support of typical
solar panel racking systems. We have provided preliminary geotechnical parameters for
foundation evaluation based on the results of our preliminary subsurface characterization.
Preconstruction pile load testing should be performed as part of the design process for the
panel racking system foundation. We expect the results of a preconstruction pile load testing
study to result in economic optimization for the foundation design.
4.3.1 Preliminary Axial Capacity Design Recommendations
The axial tensile (pull-out) capacity can be developed from skin friction while the axial
compressive capacity can be developed from skin friction and end bearing. The parameters in
following table can be used in preliminary analyses of the axial capacity of driven steel piles in
support of solar panel arrays. A safety factor of at least 1.5 should be applied to the ultimate
capacities listed in the table below for design of foundations using allowable stress design (ASD).
For load resistance factored design (LRFD), we recommend a resistance factor of 0.8.
Parameters for Analysis of Axial Capacity
Layer
(feet bgs)
Ultimate Unit Skin Friction
(psf)
Ultimate End Bearing Capacity
(lbs)
0 – 1.5 -- --
1.5 – 5 250 --
5 – 8 350 750
8 – 20 200 – 500 1 1,000
1. Increase linearly with depth.
The above indicated ultimate skin friction is appropriate for uplift and compressive loading. The
skin friction perimeter should be calculated using the “fully-plugged” assumption where the
perimeter equals twice the sum of the flange width and web depth. The upper 18 inches of frost-
susceptible soils should be neglected when calculating skin friction.
Piles should have a minimum center-to-center spacing of at least 3 times their largest cross-
sectional dimension to prevent reduction in the axial capacities due to group effects. If the piles
are designed using the above parameters, settlements are not anticipated to exceed 1 inch.
4.3.2 Preliminary Lateral Capacity Design Recommendations
We understand that the structural engineer may perform preliminary, p-y based analyses to
model the soil-structure interaction for driven pile foundations subjected to lateral load. We have
developed p-y model parameters based on the results of our subsurface characterization which
are presented in the table below.
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Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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Layer
Depth
(feet bgs)
p-y model
Effective
Unit
Weight,
γ’
(pcf)
Effective
Friction
Angle, Φ’
Modulus
Factor,
k
(pci)
Undrained
Cohesion,
c
(psf)
Strain
Factor,
ε50
0 – 1.5 Liquified Sand
(Rollins, 2005) 105 -- -- -- --
1.5 – 5 Stiff Clay
(Reese & Welch, 1975)
100 1,000 0.007
5 – 8 105 -- -- 2,000 0.005
8 – 20 Sand
(Reese, 1974) 110 32° 90 -- --
The above indicated effective unit weight, effective friction angle, modulus factor, undrained
cohesion and strain factor have no factor of safety. The strength of the upper 18 inches of frost
susceptible soil should be treated as indicated to account for potential strength loss due to soil
disturbance from construction activities, seasonal effects, freeze-thaw behavior, and other
factors.
Production piles should have a minimum center-to-center spacing of at least 5 times their
largest cross-sectional dimension in the direction of lateral loads, or the lateral capacities should
be reduced due to group effects. If piles will be spaced closer than 5 times their largest cross-
sectional dimension we should be notified to provide supplemental recommendations.
4.3.3 Preliminary Construction Considerations
Based on our experience, there is a general correlation between pile drive rate and the axial
capacity. Therefore, the recommend preconstruction pile load testing program results should be
evaluated in conjunction with test pile installation records to develop a base line for production
pile acceptance. For production piles, we recommend that the time rate of installation (seconds
per foot of embedment) be recorded as part of the overall quality control program. Automated
systems to simplify this task come standard on many new, solar pile driving rigs and several
aftermarket systems are available for temporary retrofit. Periodic proof testing should be
performed on production piles that do not meet the specified installation criteria.
4.4 Shallow Foundation Recommendations
In our opinion, the proposed ancillary structures and equipment pads can be supported on
shallow foundations following the completion of subgrade preparation as described in the
earthwork section of this report and additional subgrade evaluation at the time of construction.
We expect that some of the existing very loose and loose near -surface conditions will require
remediation in order to support shallow foundations and equipment pads. in-place compaction
with a sheep’s foot roller in these areas may reduce the amount of remedial effort required at DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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the time of shallow foundation construction. The following sections present our
recommendations for shallow foundation design and construction.
4.4.1 Spread Footing Foundation Design
We anticipate that column and wall loads f or ancillary structures will be less than 30 kips and 2
kips / linear foot, respectively. Ancillary structures of this size can be supported on shallow,
spread footing foundations or monolithic turndown slab foundations. Shallow foundation
excavations should be further evaluated at the time of construction.
Description Value
Foundation Subgrade Approved native soil or engineered fill extending
to approved native soil
Net allowable bearing pressure 1 2,000 psf
Minimum embedment below lowest adjacent
finished grade for frost protection and
protective embedment 2
18 inches
Minimum width for continuous wall footings 16 inches
Minimum width for isolated column footings 24 inches
Approximate total settlement 3 Up to 1 inch
Estimated differential settlement 3 Less than 3/4 inch over 40 feet
Coefficient of Lateral Sliding Resistance 0.25
1. The recommended net allowable bearing pressure is the pressure in excess of the minimum
surrounding overburden pressure at the footing base elevation.
2. For perimeter footings and footings beneath unheated areas.
3. The actual magnitude of settlement that will occur beneath the foundations will depend upon the site
earthwork phase, careful evaluation of foundation bearing conditions at the time of construction and
the structural loading conditions. The estimated total and differential settlements listed assume that the
foundation related earthwork and the foundation design are completed in accordance with our
recommendations.
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4.4.2 Shallow Mat or Equipment Pad Foundations
Equipment pads can be supported on shallow mat foundations. Equipment pads with maximum
plan dimensions of 10 feet x 10 feet can be designed using the parameters in the following
table.
Description Value
Foundation Subgrade Approved native soil or engineered fill extending
to approved native soil
Net allowable bearing pressure 1 500 psf
Max toe bearing pressure for transient loading
conditions 1,500 psf
Vertical Modulus of Subgrade Reaction (pci) 10
Minimum embedment below lowest adjacent
finished grade for frost protection and
protective embedment
18 inches
Approximate total settlement 2 Up to 1 inch
Coefficient of sliding friction 0.25
1. The recommended net allowable bearing pressure is the pressure in excess of the minimum
surrounding overburden pressure at the footing base elevation.
2. The foundation settlement will depend upon the variations within the subsurface soil profile, the
structural loading conditions, the embedment depth of the footing, the thickness of compacted fill,
and the quality of the earthwork operations.
4.4.3 Shallow Foundation Construction
The foundation bearing materials should be further evaluated at the time of the foundation
excavation. The representative of a qualified 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. Excessively soft, loose or wet bearing
soils should be overexcavated to a depth recommended by a qualified geotechnical engineer.
The footings could then bear directly on these soils at the lower level or the excavated soils
could be replaced with compacted engineered fill as described in this report. Washed, crushed
stone, should not be used as a replacement material beneath shallow foundations due to their
potential to store water. If shallow foundations are constructed during a period of wet weather,
we expect that some overexcavation and replacement will be required to address wet and
soft/loose near-surface conditions.
The base of all foundation excavations should be free of water and loose soil prior to placing
concrete. Concrete should be placed as soon as practical after excavating to reduce bearing DRAFT
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Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
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soil disturbance. Should the soils at bearing level become excessively disturbed or saturated,
the affected soil should be removed prior to placing concrete.
4.5 Seismic Parameters
Item Seismic Parameter
2009 International Building Code
Seismic Site Classification D 1
Design Spectral Response Acceleration Parameters Sds = 0.247g
Sd1 = 0.140g
1. The IBC seismic site classification is based on the subsurface profile depth of 100 feet. The scope
of work did not authorize exploration to a depth of 100 feet. The recommended seismic site
classification assumes that the very stiff silt or PWR encountered at boring termination depths
continue through a depth of 100 feet. This is a reasonable assumption based on the geologic
background of the project site. A geophysical exploration to develop the shear wave velocity profile to
a depth of 100 feet could be utilized to verify the seismic site class or as an attempt to justify a higher
seismic site class.
4.6 Aggregate Surfaced Roadway
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.
Roadway thickness design is dependent upon:
the anticipated traffic conditions during the life of the pavement;
subgrade and paving material characteristics; and
climatic conditions of the region.
We recommend that the roadway section consist of a 6- to 8-inch thick layer of compacted
crushed aggregate base course (NCDOT CABC). Base course materials should conform to the
North Carolina Department of Transportation (NCDOT) "Standard Specifications for Roads and
Structures.”
The performance of all roadways can be enhanced by minimizing excess moisture which can
reach the subgrade soils. We recommend constructing the subgrade and base course surface
with a minimum 1/4 inch per foot (2%) slope to promote proper drainage and site grading at a
minimum 2 percent grade away from the road. For unpaved roads, maintaining the p roper slope DRAFT
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Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable 13
over the life of the roadway with periodic re-grading and resurfacing, as needed, will enhance
long term performance.
4.7 Miscellaneous Other Design Considerations
The results of our chemical testing indicate that the site soils are acidic which can be conducive
to corrosion. The project structural design should consider the potential effects of corrosion for
the steel piles over the design life of the project. We recommend that a qualified engineer
evaluate the corrosion potential for the project site and its other potential impacts on
development. The complete results of our field and laboratory testing are expected to assist the
corrosion engineer.
Based on the results of our testing and guidelines published by the Portland Cement Associate,
the sulfate exposure class for concrete at the project is negligible. Therefore, Type I cement
should be suitable for use on the project.
Laboratory soil thermal resistivity testing has been performed on bulk samples of near-surface
site soils. The laboratory results indicate that a rho value of 144 to 201°C-cm/W is
representative of conditions measured on a sample at a near dry water content after preparation
by compacting to 85 percent of the maximum dry density as determined by the standard
Proctor.
Frost heave is a serviceability hazard that can impose a large uplift load on structures.
Production piles should be designed to resist adfreeze forces. Alternatively, adfreeze concerns
should be otherwise mitigated through the application of specially-formulated friction reducing
coatings for the near-surface portions of production piles.
DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable 14
5.0 GENERAL COMMENTS
Terracon should be retained to review the design plans and specifications so comments can be
made regarding interpretation and implementation of our geotechnical recommendations in the
design and specifications. Terracon also should be retained to provide observation and testing
services during grading, excavation, foundation construction and other earth-related
construction phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained
from the testing performed at the indicated locations and from other information discussed in
this report. This report does not reflect variations that may occur across the site, or due to the
modifying effects of weather. The nature and extent of such variations may not become evident
until during or after construction. If variations appear, we should be immediately notified so that
further evaluation and supplemental recommendations can be provided.
The scope of services for this project 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.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as outlined in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this
report in writing. DRAFT
APPENDIX A
LOCATION INFORMATION
DRAFT
2401 Brentwood Road, Suite 107 Raleigh, North Carolina 27604
PH. (919) 873-2211 FAX. (919) 873-9555 A-1
EXHIBITSITE LOCATION PLANProject Mngr.
Drawn By:
Checked By:
Approved By:
TRB
TRB
PCL
TRB
70185047
Project No.
Approx. Scale:
File Name:
Date:
Not Standard
N
70185047.A-1
SUBJECT SITE
MARCH 2018
SILER SOLAR, LLC
SILER BUSINESS DRIVE
SILER CITY, NORTH CAROLINADRAFT
2401 Brentwood Road, Suite 107 Raleigh, North Carolina 27604
PH. (919) 873-2211 FAX. (919) 873-9555 A-2
EXHIBITFIELD TESTING LOCATION PLANProject Mngr.
Drawn By:
Checked By:
Approved By:
TRB
TRB
PCL
TRB
70185047
Project No.
Approx. Scale:
File Name:
Date:
Not Standard
N
70185047.A-2
MARCH 2018
SILER SOLAR, LLC
SILER BUSINESS DRIVE
SILER CITY, NORTH CAROLINA
DIAGRAM IS FOR GENERAL LOCATION ONLY. LOCATIONS ARE APPROXIMATE. ELECTRICAL RESISTIVITY ARRAYS ARE NOT TO SCALE.
Existing Water Utility LinesDRAFT
APPENDIX B
FIELD EXPLORATION
DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable EXHIBIT: B-1
Field Testing Location Procedures
The field testing locations are indicated in Exhibit A-2. These locations were established in the field
by measuring from existing site features and estimating right angles. The actual test locations were
later mapped using hand-held GPS technology (accurate to about 15 feet). Ground surface
elevations were not obtained. The mapped test locations should be considered accurate only to
the degree implied by the means and methods used to define them.
In-situ Soil Electrical Resistivity Survey
An electrical resistivity survey was performed using the Wenner Four Point method (ASTM G57)
and a Model 6470-B Digital Ground Resistance Tester manufactured by AEMC Instruments.
Reference the attached Exhibit A-2 for further details regarding the testing locations and
orientation. For each array, four copper-clad electrodes were inserted approximately 8 inches into
the ground and one measurement was recorded at each A-spacing interval of 2, 5, 10, 25, and 50
feet. Soil electrical resistivity testing results are summarized in Exhibit B-2 of this report and may
assist with the design of electrical grounding components and corrosion protection.
Soil Test Boring Program
The soil test borings were advanced with 2-1/4 inch hollow stem augers using a rubber track-
mounted Acker Renegade rotary drill rig. Samples of the soil encountered in the borings were
obtained using the split barrel sampling procedure.
In the split-barrel sampling procedure, the number of blows required to advance a standard 2-inch
outer diameter split-barrel sampler from 6 to 18 inches of the typical total 18- or 24-inch
penetration by means of a 140-pound hammer with a free fall of 30 inches, is the standard
penetration resistance value (SPT-N). This value is used to estimate the in-situ relative density of
cohesionless soils and consistency of cohesive soils. Five soil samples were taken in the upper
10 feet bgs and at 5-foot intervals below thereafter. Bulk samples of near-surface materials
were obtained from auger cuttings at select locations.
The samples collected in the field were tagged for identification, sealed to reduce moisture loss as
appropriate, and taken to our laboratory for further examination, testing, and classification. A field
log of each boring was prepared by the drill crew. These logs included visual classifications of the
materials encountered during drilling as well as the driller’s interpretation of the subsurface
conditions between samples. Final boring logs included with this report represent the engineer's
interpretation of the field logs and include modifications based on laboratory observation and/or
testing of the samples.
An automatic SPT hammer was used to advance the split-barrel sampler in the borings
performed on this site. A greater efficiency is typically achieved with the automatic hammer DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable EXHIBIT: B-1
compared to the conventional safety hammer operated with a cathead and rope. Published
correlations between the SPT values and soil properties are based on the lower efficiency
cathead and rope method. This higher efficiency affects the standard penetration resistance
blow count (N) value by increasing the penetration per hammer blow over what would be
obtained using the cathead and rope method. The effect of the automatic hammer's efficiency
has been considered in the interpretation and analysis of the subsurface information for this
report. The attached supporting documents in Appendix G include the attached drill rig SPT
hammer energy calibration report.
DRAFT
Electrode Spacing
(feet)Array ER-1A Array ER-1B Array ER-2A Array ER-2B
2 25,625 25,325 13,075 13,175
5 35,025 35,525 14,600 14,700
10 47,475 42,650 12,500 12,725
25 46,550 44,775 9,825 10,300
50 37,075 35,250 12,825 13,325
Minimum 25,625 25,325 9,825 10,300
Date Tested 3/5/2018 3/5/2018 3/5/2018 3/5/2018
Personnel HBB HBB HBB HBB
Notes:Test Instrument:AEMC 6470 Digital Ground Resistance Tester
EXHIBIT: B-2
IN-SITU ELECTRICAL RESISTIVITY RESULTS
SILER SOLAR, LLC
Apparent Earth Resistance (Ω-cm)
(ASTM G57)
Reference Exhibit A-2 for details regarding test location and orientation.
1,000
10,000
100,000
10
100
1,000
0 10 20 30 40 50 Apparent Resistivity, Ω-cmApparent Resistivity, Ω-mElectrode Spacing, feet
Array ER-1A
Array ER-1B
Array ER-2A
Array ER-2B
DRAFT
-30
-25
-20
-15
-10
-5
0
-30
-25
-20
-15
-10
-5
0
NOTES:
Fat Clay Elastic Silt
with Sand Sandy Silt Weathered
Rock
Lean Clay
with Sand
Borehole
Number
Sampling
(See General Notes)
Explanation
Borehole
Lithology
Moisture
Content %w
B-1
B-32401 Brentwood Rd Ste 107
Raleigh, NC
PH. 919-873-2211 FAX. 919-873-9555
EXHIBIT
File Name: 70185047.B-3
Scale: 1in = 5ft
Project No.: 70185047
Drawn by: TRB
Date: 4/3/2018
Approved by: TRB
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. SMART FENCE 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/181-3-4-7
N=7
2-4-6-9
N=10
2-6-8-9
N=14
4-5-7-8
N=12
4-5-8-11
N=13
4-7-7
N=14
4-9-10
N=19
4-8-12
N=20
30-50/6"
50/5"
BT-33.9 Ft.
3079
41
43
30
14
14
12
19
18
10
9
B-1 PLLL%w
2-2-4-5
N=6
3-7-9-11
N=16
2-4-8-10
N=12
2-4-8-12
N=12
4-6-10-14
N=16
4-4-7
N=11
7-7-10
N=17
BT-20.0 Ft.
32
36
36
27
17
B-2%w
0-2-2-3
N=4
4-4-5-7
N=9
2-3-3-4
N=6
2-4-6-7
N=10
4-6-9-12
N=15
7-12-15
N=27
14-50/5"
BT-19.4 Ft.
2138
23
25
27
32
24
20
14
9
B-3 PLLL%w
Water Level Reading
Project Manager: TRB
SILER SOLAR, LLC
SILER BUSINESS DRIVE
SILER CITY, NORTH CAROLINA
SOIL TEST BORING RESULTSDepth below ground surface, feetSee General Notes in Appendix G for description of symbols and soil
classifications.
Soils between borings may differ
BT - Boring Termination
BT Borehole
Termination Depth
LL PL %P200 Liquid Limit, Plastic Limit, & Percent Fines DRAFT
98
41
43
30
14
14
12
19
18
10
9
79-30-49
1-3-4-7
N=7
2-4-6-9
N=10
2-6-8-9
N=14
4-5-7-8
N=12
4-5-8-11
N=13
4-7-7
N=14
4-9-10
N=19
4-8-12
N=20
30-50/6"
50/5"
5.0
7.0
29.0
33.9
FAT CLAY (CH), red-brown, moist, medium stiff to stiff
ELASTIC SILT (MH), with sand, red-orange, moist, stiff
SANDY SILT (ML), tan, moist to dry, stiff to very stiff
PARTIALLY WEATHERED ROCK, tan, dry, sandy silt texture
Boring Terminated at 33.9 FeetGRAPHIC LOGHammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18PERCENT FINESWATERCONTENT (%)LL-PL-PI
ATTERBERG
LIMITS
WATER LEVELOBSERVATIONSDEPTH (Ft.)5
10
15
20
25
30 SAMPLE TYPEFIELD TESTRESULTS Siler Business Drive
Siler City, North Carolina
SITE:
Page 1 of 1
Advancement Method:
Advanced 2-1/4 inch hollow stem augers.
Abandonment Method:
Borings backfilled upon completion.
Notes:
Project No.: 70185047
Drill Rig: Acker Renegade
Boring Started: 03-07-2018
BORING LOG NO. B-1
Cypress Creek Renewables, LLCCLIENT:
Sacramento, North Carolina
Driller: WTD
Boring Completed: 03-07-2018
PROJECT: Siler Solar, LLC
2401 Brentwood Rd Ste 107
Raleigh, NCDry cave-in @ 19.5 ft (after boring)Dry cave-in @ 19.5 ft (after boring)
WATER LEVEL OBSERVATIONS
Groundwater not encountered
DEPTH
LOCATION
Latitude: 35.7419° Longitude: -79.4758°DRAFT
32
36
36
27
17
2-2-4-5
N=6
3-7-9-11
N=16
2-4-8-10
N=12
2-4-8-12
N=12
4-6-10-14
N=16
4-4-7
N=11
7-7-10
N=17
4.0
8.0
20.0
FAT CLAY (CH), red-brown, moist, medium stiff to very stiff
ELASTIC SILT (MH), with sand, red-brown and black, moist, stiff
SANDY SILT (ML), red-brown and light bluish gray, moist to dry, stiff to very stiff
Boring Terminated at 20 FeetGRAPHIC LOGHammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18PERCENT FINESWATERCONTENT (%)LL-PL-PI
ATTERBERG
LIMITS
WATER LEVELOBSERVATIONSDEPTH (Ft.)5
10
15
20 SAMPLE TYPEFIELD TESTRESULTS Siler Business Drive
Siler City, North Carolina
SITE:
Page 1 of 1
Advancement Method:
Advanced 2-1/4 inch hollow stem augers.
Abandonment Method:
Borings backfilled upon completion.
Notes:
Project No.: 70185047
Drill Rig: Acker Renegade
Boring Started: 03-07-2018
BORING LOG NO. B-2
Cypress Creek Renewables, LLCCLIENT:
Sacramento, North Carolina
Driller: WTD
Boring Completed: 03-07-2018
PROJECT: Siler Solar, LLC
2401 Brentwood Rd Ste 107
Raleigh, NCDry cave-in @ 10.5 ft (after boring)Dry cave-in @ 10.5 ft (after boring)
WATER LEVEL OBSERVATIONS
Groundwater not encountered
DEPTH
LOCATION
Latitude: 35.7401° Longitude: -79.4746°DRAFT
85
23
25
27
32
24
20
14
9
38-21-17
0-2-2-3
N=4
4-4-5-7
N=9
2-3-3-4
N=6
2-4-6-7
N=10
4-6-9-12
N=15
7-12-15
N=27
14-50/5"
4.0
6.0
19.0
19.4
LEAN CLAY (CL), with sand, red-brown, moist, medium stiff to stiff
ELASTIC SILT (MH), with sand, orange and yellow, moist, medium stiff
SANDY SILT (ML), tan, moist to dry, stiff to very stiff
PARTIALLY WEATHERED ROCK, tan, dry, sandy silt texture
Boring Terminated at 19.4 FeetGRAPHIC LOGHammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18PERCENT FINESWATERCONTENT (%)LL-PL-PI
ATTERBERG
LIMITS
WATER LEVELOBSERVATIONSDEPTH (Ft.)5
10
15 SAMPLE TYPEFIELD TESTRESULTS Siler Business Drive
Siler City, North Carolina
SITE:
Page 1 of 1
Advancement Method:
Advanced 2-1/4 inch hollow stem augers.
Abandonment Method:
Borings backfilled upon completion.
Notes:
Project No.: 70185047
Drill Rig: Acker Renegade
Boring Started: 03-07-2018
BORING LOG NO. B-3
Cypress Creek Renewables, LLCCLIENT:
Sacramento, North Carolina
Driller: WTD
Boring Completed: 03-07-2018
PROJECT: Siler Solar, LLC
2401 Brentwood Rd Ste 107
Raleigh, NCDry cave-in @ 10 ft (after boring)Dry cave-in @ 10 ft (after boring)
WATER LEVEL OBSERVATIONS
Groundwater not encountered
DEPTH
LOCATION
Latitude: 35.7394° Longitude: -79.4716°DRAFT
APPENDIX C
LABORATORY TESTING
DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable EXHIBIT: C-1
LABORATORY TESTING DESCRIPTION
Laboratory testing has been performed as described below. Detailed results of laboratory
testing are included in the following Exhibits. Variations in soil composition may influence
laboratory testing results. Laboratory values should be evaluated based on the measured data in
conjunction with published values for the material. Our laboratory program included testing for:
index properties & classification
chemical properties
moisture-density relationship
thermal conductivity
California bearing ratio
Index Properties & Classification
The boring logs attached to this report include consistency evaluations, boring depths, sampling
intervals, and groundwater conditions. Also shown are estimated Unified Soil Classification
System (USCS) symbols. Descriptive classifications of the soils indicated on the boring logs are
in accordance with the enclosed General Notes and the USCS. A brief description of the USCS
is attached to this report. Soil classification was generally performed using visual-manual
procedures. Select samples were further classified using the results of Atterberg limits and grain
size testing performed in general accordance with ASTM D4318 and D1140, respectively.
Chemical Property Testing
Laboratory chemical testing was performed on select representative bulk samples of near
surface soils. We expect the results of this testing will assist the designers of corrosion
protection for driven piles and various other project elements. The following tests have been
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 G187)
Moisture Density Relationship
Standard Proctor compaction testing was performed in general accordance with ASTM D698 on
one select representative bulk sample of near surface soils. The moisture-density testing results
were used to remold the bulk soil samples for thermal conductivity and California Bearing Ratio
(CBR) testing.
DRAFT
Preliminary Geotechnical Engineering Report
Siler Solar, LLC ■ Siler City, North Carolina
April 6, 2018 ■ Terracon Project No. 70185047
Responsive ■ Resourceful ■ Reliable EXHIBIT: C-1
Thermal Conductivity Testing
Laboratory thermal conductivity testing was performed in general accordance with ASTM D5334
on select representative bulk samples of near surface soils. We expect the results of this testing
to assist the designers of buried electrical cable/conduit. The laboratory specimen was prepared
based on the results of the testing for compaction characteristics. One thermal dry out curve has
been provided for the sample remolded at a relative compaction of 85% of the standard Proctor
maximum dry density.
Laboratory CBR Testing
California Bearing Ratio (CBR) testing was performed in general accordance with ASTM D1883
on select representative bulk sample of near surface soils. The laboratory specimen was
prepared based on the results of the testing for compaction characteristics. The test specimens
were compacted to 85% of its maximum dry density at a moisture content within +/- 1% of the
optimum moisture content as determined by standard Proctor. The specimens were soaked for
96 hours prior to measurement of swell. DRAFT
wopt (γ'DRY)MAX
(%)LL PL PI #200 (mV)(Ω-cm)(%)(pcf)@ 0.1"@ 0.2"Wet Dry
B-1 1 -3 BS-1 CH 43 79 30 49 98 685 3.87 78 <1 70 33,000 33.4 83.7 2.7 2.5 86 201
B-3 1 -3 BS-2 CL 25 38 21 17 85 684 4.97 28 <1 75 27,000 15.8 109.1 4.7 5.1 58 144
B-1 0 -2 SS-1 41
B-1 2 -4 SS-2
B-1 4 -6 SS-3 30
B-1 6 -8 SS-4 14
B-1 8 -10 SS-5 14
B-1 13.5 -15 SS-6 12
B-1 18.5 -20 SS-7 19
B-1 23.5 -25 SS-8 18
B-1 28.5 -30 SS-9 10
B-1 33.5 -34 SS-10 9
B-2 0 -2 SS-1 32
B-2 2 -4 SS-2 36
B-2 4 -6 SS-3
B-2 6 -8 SS-4 36
B-2 8 -10 SS-5 27
B-2 13.5 -15 SS-6
B-2 18.5 -20 SS-7 17
B-3 0 -2 SS-1 23
B-3 2 -4 SS-2 27
B-3 4 -6 SS-3 32
B-3 6 -8 SS-4 24
B-3 8 -10 SS-5 20
B-3 13.5 -15 SS-6 14
B-3 18.5 -20 SS-7 9
Notes:
Reference Exhibit C-1 for a description of laboratory tests and procedures.
EXHIBIT: C-2
LABORATORY TESTING SUMMARY
SILER SOLAR, LLC
Sample
Depth
Chemical Properties
CBR Value
BoringSample
ID USCS
Atterberg
Limits pHNatural MoistureThermal
ResistivityCompaction
Min. Resis.(°C-cm/W)Grain Size(ppm)ChlorideSulfideSulfateEh
DRAFT
0
10
20
30
40
50
60
0 20 40 60 80 100CH or OHCL or OLML or OL
MH or OH"U" Line"A" Line
ATTERBERG LIMITS RESULTS
ASTM D4318
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
PROJECT NUMBER: 70185047PROJECT: Siler Solar, LLC
SITE: Siler Business Drive
Siler City, North Carolina
CLIENT: Cypress Creek Renewables, LLC
Sacramento, North Carolina
EXHIBIT: C-3
2401 Brentwood Rd Ste 107
Raleigh, NC
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18PL PIBoring ID Depth Description
CH
CL
Fines
79
38
30
21
49
17
98
85
LL USCS
B-1
B-3
1 - 3
1 - 3
FAT CLAY
LEAN CLAY with SAND
CL-ML
DRAFT
Sample ID
Description
Eh
pH
Sulfate Content
Sulfide Content
Chloride Content
Minimum Resistivity
2401 Brentwood Road Suite 107 Raleigh, North Carolina 27604
PH: (919) 873-2211 Fax: (919) 873-9555
Laboratory Soil Electrical Resistivity
684 mV
4.97
28 mg/kg
ADDITIONAL LABORATORY DATA
B-1, BS-1
Fat Clay
685 mV
B-3, BS-2
Lean Clay with Sand
% Moisture
75 mg/kg
27,000 Ω-cm
EXHIBIT
3.87
78 mg/kg
33,000 Ω-cm
70 mg/kg
<1 mg/kg <1 mg/kg
Date Sampled 3/1/2018 Project Manager:TRB REPORT OF CORROSIVE POTENTIAL LABORATORY TESTING
C-4
Date Reported 3/23/2018 Checked By:SHH
Sample Method Hand Excavation Tested By:SHH
SILER SOLAR, LLC .
Terracon Job No.70185047 Reviewed By:AAN SILER BUSINESS DRIVE
File Name 70185047.C-3 Approved By:TRB SILER CITY, NORTH CAROLINA
1,000
10,000
100,000
0 20 40 60 80 100 120Resistance Value (ohm•cm)B-1, BS-1
B-3, BS-2
DRAFT
75
80
85
90
95
100
105
110
115
120
125
130
135
0 5 10 15 20 25 30 35 40 45
Test Method
Remarks:
TEST RESULTS
PIPLLL
ATTERBERG LIMITS
79 30 49
PCF
%
Maximum Dry Density
Optimum Water Content
83.7
% Percent Fines
ASTM D698 Method A
33.4
97.8
DRY DENSITY, pcfWATER CONTENT, %
Z
A
V
f
o
r
G
s =
2
.
8
Z
A
V
f
o
r
G
s =
2
.
7
Z
A
V
f
o
r
G
s =
2
.
6
Source of Material
Description of Material
MOISTURE-DENSITY RELATIONSHIP
ASTM D698/D1557
B-1 @ 1 - 3 feet
FAT CLAY(CH)
PROJECT NUMBER: 70185047PROJECT: Siler Solar, LLC
SITE: Siler Business Drive
Siler City, North Carolina
CLIENT: Cypress Creek Renewables, LLC
Sacramento, North Carolina
EXHIBIT: C-5
2401 Brentwood Rd Ste 107
Raleigh, NC
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. COMPACTION - V2 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18DRAFT
75
80
85
90
95
100
105
110
115
120
125
130
135
0 5 10 15 20 25 30 35 40 45
Test Method
Remarks:
TEST RESULTS
PIPLLL
ATTERBERG LIMITS
38 21 17
PCF
%
Maximum Dry Density
Optimum Water Content
109.1
% Percent Fines
ASTM D698 Method B
15.8
85.0
DRY DENSITY, pcfWATER CONTENT, %
Z
A
V
f
o
r
G
s =
2
.
8
Z
A
V
f
o
r
G
s =
2
.
7
Z
A
V
f
o
r
G
s =
2
.
6
Source of Material
Description of Material
MOISTURE-DENSITY RELATIONSHIP
ASTM D698/D1557
B-3 @ 1 - 3 feet
LEAN CLAY with SAND(CL)
PROJECT NUMBER: 70185047PROJECT: Siler Solar, LLC
SITE: Siler Business Drive
Siler City, North Carolina
CLIENT: Cypress Creek Renewables, LLC
Sacramento, North Carolina
EXHIBIT: C-6
2401 Brentwood Rd Ste 107
Raleigh, NC
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. COMPACTION - V2 70185047 SILER SOLAR, LLC.GPJ TERRACON_DATATEMPLATE.GDT 3/4/18DRAFT
Project No.
Proctor Method:
Maximum Dry Density (pcf):
DENSITY DATA
MOISTURE DATA
Dry Density Before Soaking (pcf)78.1
49
Sample Location:
Depth:
Soaked
10
Soaking Condition
44.0
Before Compaction (%)
Average After Soaking (%)
After Compaction (%)
Compaction of Proctor (%)93.3
83.7
33.4
79
Surcharge Weight (lbs)
CBR Value at 0.200 inch
2.7
1-3'
Fat Clay
BS-1
B-1
Bulk Sample
ASTM D698 - Method A
Length of Soaking (hours)
Swell (%)
96
2.5
2.5
CBR TEST DATA
SAMPLE INFORMATION
Plasticity Index:
Optimum Moisture:
Liquid Limit:
Sample Number:
Boring Number:
Material Description:
Top 1" After Soaking (%)
33.5
33.3
41.0
CBR Value at 0.100 inch
REPORT FOR CALIFORNIA BEARING RATIO
Attn: Scott Lasalle
Siler Solar, LLC
Siler Business Drive
919-873-2211
Project
Test Methods:ASTM D1883
2401 Brentwood Road, Suite 107
Raleigh, NC 27604
Service Date: 03/13/18
03/26/18
#REF!
Report Date:
Siler City, NC
70185047
Sacramento, CA 95814
Client
770 L Street, Suite 950
Cypress Creek Renewables, LLC
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0.000 0.100 0.200 0.300 0.400 0.500Load (psi)Penetration (inch)
EXHIBIT: C-7DRAFT
Project No.
Proctor Method:
Maximum Dry Density (pcf):
DENSITY DATA
MOISTURE DATA
Dry Density Before Soaking (pcf)106.0
17
Sample Location:
Depth:
Soaked
10
Soaking Condition
22.9
Before Compaction (%)
Average After Soaking (%)
After Compaction (%)
Compaction of Proctor (%)97.1
109.1
15.8
38
Surcharge Weight (lbs)
CBR Value at 0.200 inch
4.7
1-3'
Lean Clay with Sand
BS-2
B-3
Bulk Sample
ASTM D698 - Method B
Length of Soaking (hours)
Swell (%)
96
1.4
5.1
CBR TEST DATA
SAMPLE INFORMATION
Plasticity Index:
Optimum Moisture:
Liquid Limit:
Sample Number:
Boring Number:
Material Description:
Top 1" After Soaking (%)
16.4
16.5
20.6
CBR Value at 0.100 inch
REPORT FOR CALIFORNIA BEARING RATIO
Attn: Scott Lasalle
Siler Solar, LLC
Siler Business Drive
919-873-2211
Project
Test Methods:ASTM D1883
2401 Brentwood Road, Suite 107
Raleigh, NC 27604
Service Date: 03/13/18
03/26/18
#REF!
Report Date:
Siler City, NC
70185047
Sacramento, CA 95814
Client
770 L Street, Suite 950
Cypress Creek Renewables, LLC
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
0.000 0.100 0.200 0.300 0.400 0.500Load (psi)Penetration (inch)
EXHIBIT: C-8DRAFT
Project Name:Siler Solar Thermal Resistivity Test Results
Project Number:70185047
Moisture
Content (%)
Thermal
Resistivity
(˚C-cm/watt)
Temperature
(°C)
Sample ID:B-1 1-3'0.0 201 23.2
Soil Type:Fat Clay 2.0 150 23.2
Standard/Modified Proctor:ASTM D 698-A 5.0 136 22.0
Max Dry Density, pcf:83.7 17.1 94 23.9
Optimum Moisture Content, %:33.4 22.8 87 23.6
Target % Compaction:85 35.4 86 20.6
Sample Dry Density, pcf:71
Sample % Compaction:85
0
50
100
150
200
250
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38ThermalResistivity,°C-cm/wattMoisture Content, %
Thermal Resistivity Dry-Out Curve
Run By: TKS Reviewed By: RBDate: 4/5/2018
EXHIBIT: C-9DRAFT
Project Name:Siler Solar Thermal Resistivity Test Results
Project Number:70185047
Moisture
Content (%)
Thermal
Resistivity
(˚C-cm/watt)
Temperature
(°C)
Sample ID:B-3 1-3'0.0 144 23.4
Soil Type:Lean Clay with Sand 4.4 90 24.9
Standard/Modified Proctor:ASTM D 698-B 5.3 85 22.1
Max Dry Density, pcf:109.1 8.6 68 24.0
Optimum Moisture Content, %:15.8 11.7 61 23.6
Target % Compaction:85 19.9 58 20.1
Sample Dry Density, pcf:92
Sample % Compaction:85
0
20
40
60
80
100
120
140
160
0 2 4 6 8 10 12 14 16 18 20 22ThermalResistivity,°C-cm/wattMoisture Content, %
Thermal Resistivity Dry-Out Curve
Date: 4/5/2018 Run By: TKS Reviewed By: RAB
EXHIBIT: C-10DRAFT
APPENDIX G
SUPPORTING DOCUMENTS DRAFT
Trace
With
Modifier
Water Level After
a Specified Period of Time
GRAIN SIZE TERMINOLOGYRELATIVE PROPORTIONS OF SAND AND GRAVEL
Trace
With
Modifier
Standard Penetration or
N-Value
Blows/Ft.
Descriptive Term
(Consistency)
Loose
Very Stiff
Standard Penetration or
N-Value
Blows/Ft.
Ring Sampler
Blows/Ft.
Ring Sampler
Blows/Ft.
Medium Dense
Dense
Very Dense
0 - 1 < 3
4 - 9 2 - 4 3 - 4
Medium-Stiff 5 - 9
30 - 50 WATER LEVELAuger
Shelby Tube
Ring Sampler
Grab Sample
8 - 15
Split Spoon
Macro Core
Rock Core
PLASTICITY DESCRIPTION
Term
< 15
15 - 29
> 30
Descriptive Term(s)
of other constituents
Water Initially
Encountered
Water Level After a
Specified Period of Time
Major Component
of SamplePercent of
Dry Weight
(More than 50% retained on No. 200 sieve.)
Density determined by Standard Penetration Resistance
Includes gravels, sands and silts.
Hard
Very Loose 0 - 3 0 - 6 Very Soft
7 - 18 Soft
10 - 29 19 - 58
59 - 98 Stiff
less than 500
500 to 1,000
1,000 to 2,000
2,000 to 4,000
4,000 to 8,000> 99
LOCATION AND ELEVATION NOTESSAMPLING FIELD TESTS(HP)
(T)
(b/f)
(PID)
(OVA)
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
Descriptive Term
(Density)
Non-plastic
Low
Medium
High
Boulders
Cobbles
Gravel
Sand
Silt or Clay
10 - 18
> 50 15 - 30 19 - 42
> 30 > 42
_
Hand Penetrometer
Torvane
Standard Penetration
Test (blows per foot)
Photo-Ionization Detector
Organic Vapor Analyzer
Water levels indicated on the soil boring
logs are the levels measured in the
borehole at the times indicated.
Groundwater level variations will occur
over time. In low permeability soils,
accurate determination of groundwater
levels is not possible with short term
water level observations.
CONSISTENCY OF FINE-GRAINED SOILS
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field
visual-manual procedures or standard penetration resistance
DESCRIPTIVE SOIL CLASSIFICATION
> 8,000
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. 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.
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
Plasticity Index
0
1 - 10
11 - 30
> 30
RELATIVE PROPORTIONS OF FINES
Descriptive Term(s)
of other constituents
Percent of
Dry Weight
< 5
5 - 12
> 12
No Recovery
RELATIVE DENSITY OF COARSE-GRAINED SOILS
Particle Size
Over 12 in. (300 mm)
12 in. to 3 in. (300mm to 75mm)
3 in. to #4 sieve (75mm to 4.75 mm)
#4 to #200 sieve (4.75mm to 0.075mm
Passing #200 sieve (0.075mm)STRENGTH TERMSUnconfined Compressive
Strength, Qu, psf
4 - 8
GENERAL NOTES
EXHIBIT G-1DRAFT
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name B
Coarse Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction retained
on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu 4 and 1 Cc 3 E GW Well-graded gravel F
Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F,G,H
Fines classify as CL or CH GC Clayey gravel F,G,H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu 6 and 1 Cc 3 E SW Well-graded sand I
Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G,H,I
Fines classify as CL or CH SC Clayey sand G,H,I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic: PI 7 and plots on or above “A” line J CL Lean clay K,L,M
PI 4 or plots below “A” line J ML Silt K,L,M
Organic: Liquid limit - oven dried 0.75 OL Organic clay K,L,M,N
Liquid limit - not dried Organic silt K,L,M,O
Silts and Clays:
Liquid limit 50 or more
Inorganic: PI plots on or above “A” line CH Fat clay K,L,M
PI plots below “A” line MH Elastic Silt K,L,M
Organic: Liquid limit - oven dried 0.75 OH Organic clay K,L,M,P
Liquid limit - not dried Organic silt K,L,M,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
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded
gravel with silt, GW -GC well-graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW -SM well-graded
sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
6010
2
30
DxD
)(D
F If soil contains 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name.
I If soil contains 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,”
whichever is predominant.
L If soil contains 30% plus No. 200 predominantly sand, add “sandy” to
group name.
M If soil contains 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI 4 and plots on or above “A” line.
O PI 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
EXHIBIT G-2DRAFT
DRILL RIG SPT HAMMER ENERGY
CALIBRATION REPORT
Drill Rig Model Acker Renegade Track ATV SN 019192-0
Terracon Drill Rig No. 660
January 24, 2017
Prepared by:
Terracon Consultants, Inc.
Raleigh, North Carolina
EXHIBIT: G-3DRAFT
EXHIBIT: G-3DRAFT
Drill Rig SPT Hammer Energy Calibration Report
Drill Rig Model Acker Renegade SN 019192-0
January 24, 2017
Responsive ■ Resourceful ■ Reliable 2
GENERAL INFORMATION
ITEM DESCRIPTION
Drill Rig Identification Acker Renegade SN 019192-0 (see photograph on cover page)
Terracon Rig No. 660
Drill Rig Owner Terracon Raleigh
Drill Rig Operator Willie Duggins
Testing Date November 22, 2016
Testing Location Yanceyville Road, Greensboro, Guilford County, North Carolina
Terracon Project Number 70165292
Boring Identification EB1-C (boring log attached)
Energy Measurement Depths 13.1 ft, 18.1 ft, 28.1 ft
Hammer Type Automatic - 140 lb - 30 in drop height
Boring Method Mud Rotary
Drill Rods
AWJ
1 3/4” outside diameter
3/16” wall thickness
SPT Calibration Testing Equipment
2 foot AWJ rod instrumented w/ 2 strain gauges and 2
accelerometers
Model SPT Analyzer™ SN 4102 (PDA)
SPT Standard Method Performed ASTM D1586-11, Standard Test Method for Standard
Penetration Test and Split-Barrel Sampling of Soils
ASTM D4633-10, Standard Method for Energy Measurement for
Dynamic Penetrometers
SPT Calibration Personnel James P. Smith
TEST RESULTS
Table 1: SPT Hammer Energy Calibration Testing Summary.
Boring
EB1-C
Start
Depth1
(ft)
Rod
Length2
(ft)
Rod
Sections3
Measured Blow Counts
(blows/6 inches) SPT
Nmeas
(bpf)
Soil Type4 2
ft
5
ft
10
ft
1st
Inc.
2nd
Inc.
3rd
Inc.
4th
Inc.
12.6 18.8 1 1 1 3 4 5 0 9 Tan Silt
17.6 23.8 1 0 2 3 4 5 0 9 Tan Silt
27.6 33.8 1 0 3 5 8 13 0 21 Tan Silt
1. Depth from existing ground surface to bottom of split spoon sampler.
2. Total rod length measured from instrumentation to bottom of split spoon sampler (split spoon sampler length is
1.8 ft).
3. Two foot section is instrumented and is located at top of drill rods .
4. Soil type provided by Terracon personnel.
EXHIBIT: G-3DRAFT
Drill Rig SPT Hammer Energy Calibration Report
Drill Rig Model Acker Renegade SN 019192-0
January 24, 2017
Responsive ■ Resourceful ■ Reliable 3
Table 2: Energy Measurement and Analysis Summary.
Boring
EB1-C
Start
Depth1
(ft)
SPT
Nm
(bpf)
No.
of
Blows2
EFV (kip-ft)3 ETR (%)3
Max. Min. Ave. Std.
Dev. Ave. Std.
Dev.
13.1 9 12 0.31 0.28 0.30 0.01 84.7 2.5
18.1 9 12 0.31 0.30 0.30 0.00 86.8 1.0
28.1 21 26 0.33 0.31 0.31 0.01 90.0 1.6
Average: 17 0.32 0.30 0.30 0.01 87.2 1.7
1. Depth from existing ground surface to bottom of sampler at the beginning of energy measurements
analyzed.
2. The number of blows at each energy measurement depth; analysis limited to measurements recorded during
the second and third 6-inch sampling intervals at each depth.
3. EFV = Measured Transferred Energy, ETR = Energy Transfer Ratio.
Table 3: Hammer Blow Rate Summary.
Boring
EB1-C
Start
Depth1
(ft)
SPT
Nmeas
(bpf)
No.
of
Blows2
BPM3
Max. Min. Ave. Std. Dev.
13.1 9 12 48.5 48.3 48.4 0.1
18.1 9 12 48.7 48.2 48.4 0.1
28.1 21 26 48.7 48.3 48.4 0.1
Average: 17 48.6 48.3 48.4 0.1
1. Boring ID and depth from existing ground surface to bottom of drill rods at the beginning of energy
measurements analyzed.
2. The number of blows at each energy measurement depth; analysis limited to measurements recorded
during the second and third 6-inch sampling intervals at each depth.
3. BPM = Blows per minute.
EXHIBIT: G-3DRAFT
Drill Rig SPT Hammer Energy Calibration Report
Drill Rig Model Acker Renegade SN 019192-0
January 24, 2017
Responsive ■ Resourceful ■ Reliable 4
CONCLUSIONS
3.1 Energy Transfer Ratio (ETR) and Hammer Efficiency Correction (CE)
Based on our testing and subsequent analysis, drill rig model Acker Renegade, (Serial Number
019192-0) has an ETR of 87.2% ± 1.7%. Based on this ETR, the hammer efficiency correction (CE)
is 1.45.
EXHIBIT: G-3DRAFT