20160742 Ver 1_More Info Received_20180213

Action History (UTC -05:00) Eastern Time (US & Canada)
Submit by Anonymous User 2/13/2018 8:01:29 AM (Supplemental Submital)
Accept by Montalvo, Sheri A 2/13/2018 8:24:08 AM (NON -DOT - Existing Project)
• The task was assigned to Montalvo, Sheri A 2/13/2018 8:01 AM

itial Review of Submittal
Staff Review:
ID#* Version*
20160742 1
Reviewer List:* Sue Homewood:eads\slhomewood
Select Reviewing Office:* Winston-Salem Regional Office - [phone]
Is the project located within a NC DCM Area of Environmental Concern (AEC)?*
r Yes r No r Unknown
Project Submittal Interim Form
submtted: 2/13/2018
Submittal Type: r New Project
r Pre -Application Submittal
r More Information Response
Project Contact Information:
Name: Eric Mularski
Vft is subrritting the information?
Email Address: [e-mail]
Project Information:
Existing ID #:* Existing Version:*
20160742 1
Project Name: Cedar Cliff Development Au)aliary Spillway
Upgrade Project
Is this a public transportation project?
r Yes
r No
Is the project located within a NC DCM Area of Environmental Concern (AEC)?*
r Yes r No r Unknown
County (ies)*
Jackson
Describe the attachments:
Cedar Cliff Rock Spoil Evaluation
Cedar Cliff - Status Update Presentation
Please upload all files that need to be submited.
Water Resources
ENVIRONMENTAL QUALITY

Rock Spoil Evaluation_Final_20180104_Reduced File Size.pdf 27.65MB
CCL_Agency Meeting_02.08.2018_Final-Draft.pdf 8.37MB
Only pdr files are accepted.
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Agency Briefing
January 18, 2018
Cedar Cliff Hydroelectric Development
Auxiliary Spillway Upgrade Project
Status Update and Permitting Process
Safety Briefing and
Housekeeping
Information
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Project Milestones
Engineering Design Updates
Rock Spoil Assessment
Turbidity Curtain and 404/401 Permit
Discussion
Cedar Cliff Site Visit –Optional / As Needed
Agency Briefing
January 18, 2018
Agenda Items
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Milestone and
Engineering Design
Updates
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FERC Issues Acceptance of Fusegate Alternative for Spillway
Remediation in May 2016
404/401 Permit Applications Submitted and Approved in March 2017
and December 2016, Respectively
Subsurface Drilling Program Initiated in August 2016
Engineering Design-Potential Failure Mode Analysis (PFMA) Meeting
with FERC in January 2017
Shook Cove Access Road Completed in June 2017
Phase 1 Physical Scale Model (1:19) Testing Completed in June 2017
Geological and Geotechnical Subsurface Investigation Report
Submitted to FERC in June 2017
30 Percent Design Package Submitted in November 2017
Rock Spoil Evaluation Report Completed in January 2017
FERC Acceptance of PFMA and Subsurface Investigation Reports in
January 2018
Cedar Cliff Auxiliary Spillway Upgrade
Project Milestones
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Cedar Cliff Dam –Temporary Bridge Crossing
o The 110 linear feet of temporary bridge crossing (culverts)
has been removed from design consideration at this phase in
our Cedar Cliff Spillway Upgrade Design
•Keep in the permit SAW-2015-02543 permit if needed at later
date
o Revised lower access road
•Raise above 100-year flood
•Ramp down to crossing of principal spillway channel
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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Bear Creek Powerhouse Tailrace Rock Vane
o Rock Vane creates back pressure conditions against hydro
turbine to minimize negative impact of turbine cavitation during
Cedar Cliff construction
o Rock Vane Construction and Design Criteria
•100-year flood with combined powerhouse and spillway operation
»Peak velocity –16.6 fps
»Water depth –12 feet
•Nominal Crest Elevation +/-2,328.5 feet msl
o Scheduled installation –Early April 2018
•Cedar Cliff Reservoir drawn down 10 feet to facilitate construction in
the dry
•Protective matts will be used to access available rock supply from
existing spillway
o Cedar Cliff Reservoir Drawdown in 2019–2020 for Auxiliary
Spillway Construction is 30 feet
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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New Cedar Cliff Principal Spillway Bridge
Located upstream of the existing Cedar Cliff Spillway
Bridge as an independent structure
Old spillway bridge will be maintained as walking bridge
that can support traffic as needed
Design criteria is based on PMF event
Realignment of upper access road at right abutment
and interface with access road across Cedar Cliff Dam
is required
Anticipate late 2018 construction
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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Auxiliary Spillway Channel
o High resolution LiDAR survey completed in March 2016
o Modified channel steps adopted
•Increased Hydraulic efficiency
•Reduced peak reservoir stage during PMF event
o Revised excavated material volume from hillside –
283,200 cyd
o Inner Channel Wall
•Left Abutment of Main Dam
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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1951 Access Road
o Shook Cove Access Road Extension
o 1951 Access Road Adjustment
»Hillside cut adjusted to 2H:1V
»Approximately 57,000 cyd of excavated material –upper
bound
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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Reservoir Spoil
o Spoil Area Modification –Post January 2017 PFMA
•Spoil Area Pulled Back from Upstream Toe of Dam and Plant
Intake
•Right Edge Pulled to the East and Toward Old East Fork
TuckasegeeThalweg
o 404/401 Original 2016 Application
•Reservoir spoil footprint -9.6 Acre
•Top of spoil Elevation 2,230 feet msl
•Available Bulk Storage Volume –316,600 cyd
o 30 Percent Design Package Submittal
•Reservoir spoil footprint -8.1 Acre
•Top of spoil Elevation 2,250 feet msl
•Available Bulk Storage Volume –341,900 cyd
»Includes additional rock cut in bottom of auxiliary spillway channel
Cedar Cliff Auxiliary Spillway Upgrade
Engineering Design Updates
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Rock spoil assessment initiated following internal review of subsurface
report and presence of pyrite material in rock core samples. The Cedar Cliff
site is underlain by rocks of the Tallulah Falls Formation (TFFm).
Background –
o Acid-producing potential of certain metasedimentary rocks of the Blue Ridge
Province has been known since the late 1960’s.
o The major acid-producing rocks are graphitic schists of the Anakeesta Formation
(AFm) located west of the Cedar Cliff Project.
•Rock with greater than 1% by volume of pyrite is considered to be
potentially acid-producing.
•The reaction rate of pyrite is related to surface area of the mineral; the finer
the pyrite the greater the surface area to volume.
•The pyrite in the AFm is very-fine grained and is generally not visible in
hand samples.
o There are no known instances of acid-drainage related to the Tallulah Falls
Formation (TFFm) that underlie the Cedar Cliff Project.
o Pyrite was identified in hand samples and rock core at Cedar Cliff dam and
petrographic analysis indicate that pyrite is present and greater than 1% by volume
of the rock in certain (TFFm) lithologies (garnet mica schist, mica schist, and
schistose biotite gneiss). ~26% of the excavated rock comprise three of these
lithologies.
Cedar Cliff Auxiliary Spillway Upgrade
Rock Spoil Assessment
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The evaluation study was initiated to characterize the pyritic rocks at the site and to evaluate potential
impact of the placement of pyritic rock into Cedar Cliff Lake. The evaluation addressed the following:
Literature Review
o Conditions and mechanisms leading to acid-production from sulfidic rock
o Underwater (subaqueous) disposal of pyrite-bearing rock
Field Investigations
o Locations for sampling the rock formations
o Rock sampling techniques
Petrographic Analysis and Evaluation
o Petrographic data showing the pyrite crystal (grain) size differences between potential acid -producing and
non-acid-producing rocks
o Petrographic data for Cedar Cliff site rocks (Tallulah Falls Formation) exposed to atmospheric conditions for
65 years on the downstream face of the dam and in the auxiliary spillway
o Petrographic data for Cedar Cliff site rocks (Tallulah Falls Formation) located subaqueously for 65 years on
the upstream faces of Cedar Cliff and Bear Creek Dams
Conclusions
o Literature Review
o Petrographic analysis and acid-production potential
o Disposal of rock spoil in Cedar Cliff Lake
Cedar Cliff Auxiliary Spillway Upgrade
Rock Spoil Assessment
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Rock Spoil Assessment
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Rock Spoil Assessment
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Rock Spoil Assessment
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Literature Review
o Permanent subaqueous storage is currently the most effective measure that can
be taken to inhibit acid-generation from sulfidic materials.
o Placing sulfides into a low-oxygen environment, such as a subaqueous
environment, is more geochemically stable than storage in fills exposed to
atmospheric oxygen-rich conditions.
Petrographic Analysis and Evaluation
o The pyrite crystal/grain size in the TFFm rock is orders of magnitude greater than
that of the known acid-producing AFm rock.
o Petrographic data for Cedar Cliff site rocks (Tallulah Falls Formation), located
subaqueously for 65 years on the upstream faces of Cedar Cliff and Bear Creek
Dams, indicates minimum to no oxidation/alteration of the coarse-grained pyrite.
Disposal in Cedar Cliff Lake
o Is the most suitable and effective disposal option based on the literature review,
lack of acid-production associate with the TFFm in the region, and the
petrographic analyses of the samples from the upstream shells of the Dams.
Cedar Cliff Auxiliary Spillway Upgrade
Rock Spoil Assessment –Conclusions
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Special Conditions –Section 20, Turbidity Barriers
o Section 20 –“Permittee shall install floating turbidity barriers with
weighted skirts that extend to within 1 foot of the bottom around
all work areas that are in, or adjacent to surface waters.”
o Site Characteristics
•Reservoir Depth During Normal Operation –130 feet to 140 feet
•Reservoir Depth During Construction Drawdown –100 feet to 110 feet
•Proposed top of spoil bench at elevation +/-2,260 feet msl
»Post construction water depth at spoil bench –70 feet
Practical Curtain Depth
o 3-foot to 5-foot curtain size
•Past approval, practice, and successful operation for sediment
management for Duke Energy –Nantahala Projects.
Reservoir Velocity due to Plant Operation –Construction
o Velocity less than 0.2 foot per second
Cedar Cliff Auxiliary Spillway Upgrade
Turbidity Curtain –404/401 Permit
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Comments and Questions

Cedar Cliff Rock Spoil
Evaluation
East Fork Hydroelectric Project and Cedar Cliff
Development (FERC No. 2698)

Tuckasegee, North Carolina

January 4, 2018

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | ii
Contents
Page
Report Verification .......................................................................................................................................... i
1 Introduction .......................................................................................................................................... 1
2 Acid-Production of Sulfidic Rocks ....................................................................................................... 2
3 Water Disposal of Potential Acid-Producing Rocks ............................................................................ 4
4 Field and Office Investigations ............................................................................................................ 5
4.1 Field Investigations .................................................................................................................... 5
4.1.1 Rock Hand Samples from Bear Creek and Cedar Cliff Dams ..................................... 5
4.1.2 Rock Core Samples from Cedar Cliff Auxiliary Spillway .............................................. 6
4.1.3 Anakeesta Formation Hand Samples .......................................................................... 7
4.1.4 Nantahala Formation Hand Samples ........................................................................... 7
4.2 Petrographic Evaluation and Results ........................................................................................ 8
4.2.1 Previous Petrographic Analysis of Rock Core from the Cedar Cliff
Subsurface Investigation .............................................................................................. 8
4.2.2 Petrographic Analysis of Hand Samples from Bear Creek and Cedar Cliff
Dams ............................................................................................................................ 9
4.2.3 Petrographic Analysis of Cedar Cliff Auxiliary Spillway Core Sample ....................... 11
4.2.4 Petrographic Analysis of Anakeesta Formation Hand Samples ................................ 12
4.2.5 Petrographic Analysis of Nantahala Slate Hand Samples ......................................... 12
4.2.6 Comparison of Pyrite Crystal Size between Anakeesta Formation and
Tallulah Falls Formation Rocks .................................................................................. 13
4.2.7 Comparison of Pyrite Crystal Size between Nantahala Formation and
Tallulah Falls Formation Rocks .................................................................................. 13
5 Conclusions of the Rock Spoil Evaluation ......................................................................................... 13
5.1 Literature Review .................................................................................................................... 13
5.2 Petrographic Analysis and Acid-Production Potential ............................................................. 14
5.3 Disposal of Rock Spoil in Cedar Cliff Lake .............................................................................. 14
6 Recommendations ............................................................................................................................ 15
7 References ........................................................................................................................................ 15

Tables
Table 1. Sampling Summary ....................................................................................................................... 20
Table 2. Petrographic Analysis and Weathering Profile Summary – BC, CDS, CUS, and CAS
Samples ......................................................................................................................................... 21

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | iii
Figures
Figure 1a. Rock Spoil Repository – Plan and Sections B, D, and E. .......................................................... 24
Figure 1b. Rock Spoil Repository – Section A. ........................................................................................... 25
Figure 1c. Rock Spoil Repository – Section C. .......................................................................................... 26
Figure 2. East wall of the Auxiliary Spillway near the north end of the Fuseplug. ...................................... 27
Figure 3. Rock Spoil Sample Locations ...................................................................................................... 28
Figure 4. Location of the upstream CUS samples. ..................................................................................... 29
Figure 5. Cedar Cliff Dam IDF Alternative Location of Cedar Cliff Auxiliary Spillway Rock Core
Samples ......................................................................................................................................... 30
Figure 6. Outcrop of typically inundated Biotite Gneiss in the vicinity of Bear Creek Dam. Very
little weathering was observed. ...................................................................................................... 31
Figure 7. Area of CAS sampling in the Auxiliary Spillway below the Fusegate. ......................................... 32
Figure 8. Hilti DD 500 diamond core drill setup on sample location CAS-1. .............................................. 33
Figure 9. Road cut in the Anakeesta Formation on NC Highway 28 northwest of Oak Grove, North
Carolina. ......................................................................................................................................... 34
Figure 10. Road cut in the Nantahala Formation metasiltstones on Winding Stairs Gap Road,
outside of Nantahala, North Carolina. ............................................................................................ 35
Figure 11. Stratigraphic Sequences 1 and 2 underlying the Cedar Cliff Auxiliary Spillway. ....................... 36

Appendices
Appendix A. Acid-Base Accounting Test Procedure
Appendix B. Bear Creek Dam and Cedar Cliff Dam, BC, CDS, and CUS Petrographic Analysis
Reports
Appendix C. Cedar Cliff Spillway, CAS Petrographic Analysis Reports
Appendix D. Anakeesta Formation Petrographic Analysis Reports
Appendix E. Nantahala Formation Petrographic Analysis Reports
Appendix F. Crystal Size Comparison of Anakeesta Formation and Tallulah Falls Formation
Lithologies – Photomicrographs and HDR (2017) Petrographic Analysis Reports
Appendix G Crystal Size Comparison of Nantahala Formation and Tallulah Falls Formation
Lithologies – Photomicrographs and HDR (2017) Petrographic Analysis Reports

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 1
1 Introduction
A geotechnical and geologic subsurface investigation was performed at the Cedar
Cliff Development (Site) in late 2016 to support the Cedar Cliff Inflow Design Flood
(IDF) and Spillway Upgrade Project. The Spillway Upgrade Project includes
deepening and widening the existing Auxiliary Spillway channel and a new Fusegate.
The present plan specifies spoiling the rock (approximately 283,200 cubic yards)
from the Auxiliary Spillway and Fusegate structure rock excavations into Cedar Cliff
Lake upstream of the dam (Figures 1a, 1b, and 1c).
Pyrite (FeS2) was identified in rock exposures at the site and in the rock core from
boreholes drilled for the subsurface investigation (HDR 2017). On some of the rock
faces on the east wall in the Auxiliary Spillway, pyrite in the rock has oxidized to form
soluble iron sulfate minerals 1, indicated by white to yellow to reddish-yellow
staining/crusts on the weathered rock surfaces (Figure 2). Pyrite oxidation and major
weathering was not noted in the rock core from boreholes drilled at Cedar Cliff (1,750
feet of rock core). Subsequent petrographic analyses of metasedimentary rocks of
the Tallulah Falls Formation (TFFm) collected from the rock core found that the
garnet mica schist, mica schist, and schistose biotite gneiss lithologies contain
greater than 1 percent pyrite by volume (2 percent to 7 percent pyrite; in HDR 2017).
Approximately 26 percent of the total estimated excavated material (73,600 cubic
yards) will be made up of these three rock lithologies based on the boreholes drilled
during the geological/ geotechnical site investigation for the Auxiliary Spillway
upgrades (HDR 2017).
Rocks with greater than 1 percent pyrite and/or pyrrhotite (Fe(1-x)S, x = 0 to 0.2) by
volume or pyritic sulfur in excess of 0.5 weight percent are considered to be
potentially acid-producing (Byerly 1990, 1996). Pyrite can react in the presence of
atmospheric oxygen and water to form ferrous sulfate and sulfuric acid (2FeS2 + 7O2
+ 2H2O -> 2FeSO4 + 2H2SO4). Although some acid-drainage is produced by natural
weathering (Huckabee et al. 1975), construction activities can expose large volumes
of rock containing sulfide (S2-) minerals to oxidizing conditions. Subsequent leaching
of the oxidation products by rainfall/groundwater result in the formation of acid-
drainage characterized by low pH values, high concentrations of sulfate (SO42-), and
mobilization of metals such as iron, aluminum, and manganese.
Key acid-producing rocks in the Blue Ridge are the graphitic mica schists of the
Anakeesta Formation (AFm) of the Great Smoky Group (Huckabee et al. 1975;
Bacon and Mass 1979; Mathews and Morgan 1982; Schaeffer and Clawson 1996).
The nearest outcrops of AFm are located approximately 23 miles west-northwest of
the Site (Figure 3). The Nantahala Formation (NFm), located approximately 35 miles
west of the Site, is a known pyritic, non-acid producing metasedimentary rock in the

1 Typically melanterite (FeSO4*7H2O) and jarosite (KFe3(OH)6(SO4)2) with limonite (H2Fe2O4(H2O)x).

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East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 2
region (Figure 3). There are no known instances of acid-drainage related to the
metasedimentary rocks of the TFFm in the region surrounding the Site.
A rock spoil evaluation was initiated to further characterize the pyritic rocks at the
Site, specifically with regard to pyrite crystal size and mineral abundance, and to
evaluate the potential impact of the placement of pyritic rock spoil into Cedar Cliff
Lake. This report discusses the following topics:
• Literature Review
o The conditions and mechanisms leading to acid-production from sulfidic rocks.
o Underwater (subaqueous) disposal of pyrite-bearing rock.
• Field Investigations
o Locations for sampling the rock formations.
o Rock sampling techniques.
• Petrographic Analysis and Evaluation
o Petrographic data from regional rock samples (AFm and NFm) showing the
pyrite/pyrrhotite crystal/grain size differences between potential acid-producing
rocks and non-acid-producing rocks.
o Petrographic data for TFFm rocks that have been exposed to atmospheric
conditions for 65 years on the downstream face of Cedar Cliff Dam and in the
Cedar Cliff Auxiliary Spillway,
o Petrographic data for TFFm rocks that have been located subaqueously for 65
years on the upstream face of Cedar Cliff Dam and Bear Creek Dam.
• Conclusions
o Literature review.
o Petrographic analysis and acid-production potential.
o Disposal of the excavated rock spoil in Cedar Cliff Lake.
• Recommendations
2 Acid-Production of Sulfidic Rocks
Rocks and soils containing pyritic sulfur in excess of 0.5 weight percent or greater
than 1 percent pyrite/pyrrhotite by volume and with no minerals capable of producing
alkalinity are prone to produce acid-drainage (Byerly 1990, 1996). Acidity (H+)
produced during the weathering of pyrite is generated by the following chemical
reactions (Barnes and Romberger 1968; Stumm and Morgan 1981; the chemical
reactions are similar for pyrrhotite2):

2 For pyrrhotite: EQ1: Fe(1-x)S + (2-0.5x)O2 + xH2O = (1-x)Fe2+ + SO42- + 2xH+, EQS 2 and 3 are the same
as for pyrite (Janzen et al. 2000).

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East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 3
EQ1: 2FeS2 (s) + 7O2 + 2H2O = 2Fe2+ + 4SO42- + 4H+ [2FeSO4 + 2H2SO4]
EQ2: Fe2+ + 1/4O2 + H+ = Fe3+ + 1/2H2O
EQ3: Fe3+ + 3H2O = Fe(OH)3 (s) + 3H+
EQ4: FeS2 (s) +14Fe3+ + 8H2O = 15Fe2+ + 2SO42- + 16H+
The sulfide oxidation reaction in EQ1 generally occurs at shallow depths above the
water table (Nicholson et al. 1988). The reactions in EQ1 through EQ3 produce the
initial acidity in micro-environments surrounding the surfaces of the sulfide mineral
particles (Byerly 1996). If excessive amounts of Fe3+ are produced during the EQ2
reaction, the Fe3+ increases the rate of FeS2 oxidation and results in the
development of high rates of acidity as shown by EQ4 (Byerly 1996). The rate of
oxidizing Fe2+ to Fe3+ is slow under ambient conditions (EQ2; Singer and Stumm,
1970); however, the presence of certain iron bacteria (primarily Thiobacillus
ferrooxidans) catalyze the oxidation reaction increasing acid-production (Kleinmann
et al. 1981). This bacterial-mediated catalysis may accelerate the rate as much as
500,000 times (Sobek et al. 1978), resulting in an increase of Fe3+, therefore, driving
the reaction in EQ4 (Byerly 1996). Thiobacillus ferrooxidans are present in
environments containing sulfidic rocks, atmospheric oxygen, and acidic conditions
(effective in the pH range of 2.8 to 3.2; Byerly 1996). In subaqueous disposal, the
EQ2 reaction is slowed down and the EQ4 reaction is not possible due to the
absence of aerobic iron bacteria to catalyze oxidation of Fe2+ to Fe3+ (Morin 1993).
Acid-producing potential is secondarily influenced by the presence of alkalinity-
producing material, either naturally occurring within the rock spoils or artificially
introduced to the spoils, which provides a buffering effect.
In addition to the factors discussed above, an important factor for the generation of
acid-drainage is the morphology and grain size of the iron sulfide minerals present in
the rock. Pugh et al. (1984) found that the relative oxidation rates for different
morphological forms of iron sulfide are: marcasite > framboidal pyrite3 > massive
(crystalline) pyrite. The morphological form affects the mineral surface area, in
particular, framboidal pyrite. The oxidation reaction rate of iron sulfide minerals is
related to the surface area of the mineral (Pugh et al. 1984). The morphological form
affects the mineral surface area, in particular, framboidal pyrite. Surface area is
inversely proportional to particle size; therefore, particle (crystal) size is an important
consideration, whereby it affects the area that is directly exposed to weathering and
oxidation. Coarse particles expose less surface area per volume compared to finer
particles, thus inhibiting the oxidation of a comparatively larger portion of the particle.

3 Framboidal pyrite is spherical and consists of micron-sized crystals indicating a higher surface area per
volume compared to other iron sulfides including massive (crystalline) pyrite. Mechanisms for
development of framboidal pyrite operate up to temperatures of 200oC (Pugh et al. 1981).

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East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

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3 Water Disposal of Potential Acid-Producing Rocks
In the mining industry, placement of sulfide-bearing tailings and waste rock
(exhibiting finer-grained pyrite than observed in the TFFm pyrite-bearing lithologies)
in submerged environments (water covered/subaqueous) is recognized as a
common technique for the effective control of acid-generation (Halbert el al. 1982;
Ferguson and Erickson 1988; Hammack and Watzlaf 1990; Rescan 1990a, 1990b,
1996, Sengupta 1993; Morin 1993; Lapakko 1994; Payant and Yanful 1997; Yanful
and Sims 1997; Trembley and Hogan 2001; Lapakko et al. 2013). Sulfides such as
pyrite/pyrrhotite originally form in reducing (oxygen-poor) environments and are,
therefore, unstable in the presence of oxygen. Reintroducing iron sulfides into a low-
oxygen or oxygen-free environment is more geochemically stable than storage in fills
exposed to atmospheric, oxygen-rich conditions. The Mine Environment Neutral
Drainage (MEND) Program research has demonstrated that the oxidation of sulfide
minerals is inhibited by water cover, as the water impedes the diffusion of oxygen
and acts as a barrier to the submerged sulfides; as such, subaqueous disposal is the
widely preferred prevention technology for both unoxidized sulfide-containing waste
rock and for oxidized waste rock (Tremblay and Hogan 2001).
Subaqueous environments contain dissolved oxygen in varying concentrations
depending on the depth of water and other limnological considerations Dissolved
oxygen concentrations in natural waters is approximately 25,000 times lower than
the concentration of oxygen in the atmosphere4, thus substantially diminishing the
rate of sulfide oxidation (Rescan 1996). Once the low concentration of dissolved
oxygen is consumed, it is slowly replaced by molecular diffusion and aeration
through small-scale turbulence; the diffusion rate of oxygen in water is nearly 10,000
times slower than similar transfers in the atmosphere (Rescan 1996). In addition, the
water cover prevents the action of aerobic, acidophyllic bacteria in facilitating the
acid-production steps, which requires atmospheric oxygen to drive the biotic-aided
acid-producing reaction (Waksman and Joffe 1921; Pugh et al. 1984; reaction
discussed in Section 2). A continuous layer of water needs to be maintained to avoid
the exposure of the material to atmospheric (aerobic) conditions (Sengupta 1993).
Sedimentation that will occur in the reservoir will additionally provide a reducing
barrier over time (Tremblay and Hogan 2001). Although the complete submergence
of sulfide-bearing materials may not completely halt the oxidation of sulfide and
resultant acid generation, the reaction rate in aquatic environments is significantly
inhibited through the mechanisms described above, thus resulting in negligible
environmental or water quality impact (Sengupta 1993). Permanent subaqueous
storage is currently the most effective measure that can be taken to inhibit acid-
production from sulfidic waste (Rescon 1996, Tremblay and Hogan 2001).

4 Percent oxygen in the atmosphere is 20.95 percent or 209,500 parts per million. Dissolved oxygen in
water is up to about ten molecules per million molecules of water; 10 ppm (USGS 2017).

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East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

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4 Field and Office Investigations
4.1 Field Investigations
HDR Engineering, Inc. of the Carolinas (HDR) completed multiple site
reconnaissance and rock sampling events to support the rock spoil investigation.
Sampling events have occurred at Cedar Cliff (both at the Dam and within the
Auxiliary Spillway), Bear Creek Dam, and offsite. Figures 3, 4, and 5 show the
approximate sample locations, and sampling details are summarized in Table 1. The
investigations evaluate two of the most important factors for producing acid-drainage:
1) morphology and grain size of the pyrite in the TFFm rocks compared to AFm rocks
which are known to produce acid-drainage, and 2) the effect of 65 years of
submergence on the oxidation/weathering of TFFm rocks used in the construction of
the rock shells for Bear Creek and Cedar Cliff Dams based on the
observation/description of the samples and direct microscopic/petrographic
observations and analyses of thin-sections prepared from the samples. In addition,
the pyrite crystal size of the TFFm pyrite-bearing lithologies are compared to the
pyrite/pyrrhotite crystal size of the AFm graphic mica schists and the pyrite crystal
size of NFm metasiltstones that have undergone Acid-Base Accounting Testing
(Schaeffer and Clawson 1996, see Appendix A for a summary of the Acid-Base
Accounting Test Procedure) that indicate potential acid production according to the
test, although acid-drainage is not associated with rocks of the NFm.
4.1.1 Rock Hand Samples from Bear Creek and Cedar Cliff Dams
On March 13, 2017, HDR and Duke Energy collected samples of various site
lithologies from the downstream face of the Cedar Cliff Dam (CDS-series samples,
locations shown in Figure 3). This phase of analysis supported the characterization
and investigation of weathering and oxidation profiles of selected lithologies that
have been exposed to sustained atmospheric oxidizing conditions since construction
of the Cedar Cliff Dam in 1952. A selection of three samples from this event (one
biotite gneiss sample and two garnet mica schist samples) were sent for thin-section
preparation and were petrographically analyzed (Table 1). The results of the
petrographic analyses are presented in Section 4.2.2 and the petrographic reports
are presented in Appendix B.
On March 21, 2017, HDR and Duke Energy collected samples from the upstream
face of the Bear Creek Dam (BC-series samples; see Figure 3 for approximate
locations; located 1.75 miles east of Cedar Cliff Dam). Samples were collected from
below the full pond elevation of Bear Creek Reservoir (sample interval was near the
drawdown elevation of 2,534 feet on the day of sampling; full pond elevation is 2,560
feet). This typically submerged area was made accessible through a scheduled
drawdown of the lake. The upstream face of the dam was accessed by boat, with the
sample team disembarking the boat and ascending the dam’s rock face when a
potential sample was identified. Approximate sample locations were marked using
survey monuments and piles as landmarks. Two samples from this sampling event

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(both schistose biotite gneiss) were sent for thin-section preparation and were
petrographically analyzed (Table 1). This phase of analysis supported the
characterization and investigation of weathering/oxidation profiles of selected
lithologies that have been exposed to minimally fluctuating water levels and
consistent subaqueous oxidizing conditions since the construction of the Bear Creek
Dam in 1953. It was noted during site reconnaissance and during the sampling event
that the dominant Bear Creek site lithology is biotite gneiss, with very little mica
schist, garnet mica schist, or schistose biotite gneiss observed in TFFm
outcrops/rock cuts around the Bear Creek site. The results of the petrographic
analyses are presented in Section 4.2.2 and the petrographic reports are presented
in Appendix B.
Additionally, HDR and Duke Energy performed reconnaissance by boat of the Bear
Creek Reservoir to observe the oxidation of typically inundated TFFm outcrops
underlying and surrounding the Bear Creek reservoir. A representative, typically
inundated outcrop near the Bear Creek site is shown in Figure 6. HDR geologists
noted at this outcrop, and at the majority of other typically inundated outcrops at full
pond, that the rock faces were relatively fresh and observed very little indication of
weathering/oxidation (such as iron staining, sulfide staining, or dulled mica surfaces).
Samples were not collected at these outcrops.
On August 10, 2017, HDR and Duke Energy collected nine samples of rock from the
upstream rock shell of Cedar Cliff Dam (CUS-series samples). The sampling was
performed by divers with Mainstream Diving at depths of approximately 10 feet, 30
feet, and 50 feet below that day’s pond elevation of 2,325 feet (Cedar Cliff Lake full
pond elevation is 2,330 feet). The locations of the upstream CUS samples were
collected using Survey Stations CC-7, CC-8, and CC-9 for lateral control of the dive
locations (Figure 4). The approximate depths of the samples were determined by the
diver’s oxygen supply hose and length of rope attached to a wire basket for bringing
the samples to the surface. From a selection of samples collected by the diver at
each sample location, an HDR senior engineering geologist selected one sample
based on its lithology (with preference given to garnet mica schist, mica schist, and
schistose biotite gneiss). The samples, six garnet mica schist samples, one mica
schist sample, and two biotite gneiss samples were sent for thin-section preparation
and were petrographically analyzed (Table 1). The results of the petrographic
analyses are presented in Section 4.2.2, and the petrographic reports are presented
in Appendix B.
4.1.2 Rock Core Samples from Cedar Cliff Auxiliary Spillway
From July 27 to August 3, 2017, HDR and Duke Energy investigated a section of the
Auxiliary Spillway channel downstream of the existing fuseplug (Figure 5).
Vegetation and debris were cleared and the channel floor was cleaned and prepared
for drilling (Figure 7). A Hilti DD 500 diamond core drill was used to collect 3.75-inch
diameter (single-wall core barrel) samples of garnet mica schist (one sample), biotite
gneiss (one sample), and schistose biotite gneiss (two samples) from this area
(CAS-series samples; Figures 5 and 8; Table 1). The total depth of these drill holes

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ranged from 1.0 foot to 1.7 feet below the rock surface. Overburden removed from
the prepared surface ranged from less than one inch thick to about 24 inches thick.
Termination depth was determined in the field based on the sample lithologies
encountered and the degree of weathering observed. HDR geologists were onsite
during drilling operations to establish drilling extents, location of the drill holes for the
three target lithologies, and the number of drill holes and sample quantities.
The results of the petrographic analyses are presented in Section 4.2.3, and the
petrographic reports are presented in Appendix C.
4.1.3 Anakeesta Formation Hand Samples
On March 20, 2017, and July 26, 2017, HDR collected samples of graphitic mica
schist from AFm outcrops and roadcuts at ten locations approximately 23 miles
offsite (Figure 3 and Figure 9). Due to the extent of weathering and the
characteristic structure of the graphitic mica schist, only three samples from two
locations along NC Highway 28 in Macon County, North Carolina (Figure 3) with
sufficient structural integrity were sent for thin-section preparation and were
petrographically analyzed (AK-L series; Table 1). During thin-section preparation
these samples were impregnated and coated with epoxy to maintain structural
integrity during the thin-section preparation process. This phase of the analysis
supported the comparison (size and morphology of pyrite/pyrrhotite crystals)
between the known acid-producing rocks of the AFm and the TFFm pyritic rocks
found at Cedar Cliff, which are not known to produce acid-drainage. The results of
the petrographic analyses are presented in Section 4.2.4, and the petrographic
reports are presented in Appendix D.
4.1.4 Nantahala Formation Hand Samples
On July 26, 2017, HDR collected samples of NFm metasiltstones (sometimes
referred to as slate) at roadcuts at four locations on Winding Stairs Gap Road,
Macon County, North Carolina approximately 32 miles offsite (Figure 3 and Figure
10). Samples from three locations were sent for thin-section processing and were
petrographically analyzed (NF-series; Table 1). This analysis supported the
comparison (percent by volume, size, and morphology of pyrite) between rocks with
greater than 1 percent pyrite by volume of the NFm, which are not known to produce
acid-drainage in the Blue Ridge, with the TFFm pyritic rocks found at Cedar Cliff,
which are also not known to produce acid-drainage. Despite previous acid-base
accounting testing (test described in Appendix A) indicating that the NFm has the
potential for acid-drainage, the production of acid-drainage has not been noted in
association with NFm rocks primarily due to the larger grain size of the contained
massive (crystalline) pyrite developed during regional amphibolite facies
metamorphism of the rocks (Schaeffer and Clawson 1996). The results of the
petrographic analyses are presented in Section 4.2.5, and the petrographic reports
are presented in Appendix E.

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4.2 Petrographic Evaluation and Results
4.2.1 Previous Petrographic Analysis of Rock Core from the Cedar Cliff
Subsurface Investigation
Petrographic analyses of metasedimentary rocks of the TFFm from the Site found
that the garnet mica schist, mica schist, and schistose biotite gneiss lithologies
contain greater than 1 percent pyrite by volume (2 percent to 7 percent pyrite; in
HDR 2017; in Section 4.2.2 and Petrographic Analyses Reports in Appendix H of
that report). Petrographic reports for rock core sample thin-sections utilized in this
report are included in Appendices F and G. The descriptions of these three rock
lithologies follow:
• Garnet Mica Schist and Mica Schist: Mica schist is typically dark gray to
grayish black, moderately hard, fine- to medium-grained, and very thinly foliated.
The mica schist is similar to the garnet mica schist with the exception of less
garnet (trace amounts compared to 2 percent to 5 percent) and less pyrite (<1
percent to 4 percent). Mica schist and garnet mica schist were occasionally noted
to have crenulated fabric. In thin-section, the garnet mica schist has a
lepidoblastic texture with schistosity defined by subparallel muscovite, biotite,
and quartz-feldspar rich layers. The primary minerals are muscovite, biotite with
pleochroic inclusions of zircon, quartz, plagioclase, alkali feldspar, garnet, 2
percent to 5 percent and up to 10 mm in diameter that is poikiloblastic with many
inclusions of fine-grained biotite, quartz, and minor feldspar, and pyrite (0.05 mm
to 0.5 mm), sometimes fractured and bounded by more or less regular crystal
faces, 2 percent to 6 percent crystalline pyrite in equant (0.02 mm to 1.5 mm)
and elongate crystals (0.2 mm to 1.75 mm), and trace amounts of zircon, apatite,
sphene, and kyanite. Sillimanite is present in varying amounts in the garnet mica
schist from none to trace amounts to up to 10 percent.
• Schistose Biotite Gneiss: Schistose biotite gneiss is intermediary between
biotite gneiss and mica schist end members. It is typically medium gray to dark
gray, moderately hard to hard, fine- to medium-grained, and very thinly foliated.
Schistose biotite gneiss is often interlayered with either biotite gneiss or mica
schist. In thin-section, the schistose biotite gneiss has a granoblastic to
lepidoblastic texture with poorly to well-developed schistosity defined by parallel
bands of biotite/muscovite and feldspar, quartz, and myrmekite5. Feldspar and
quartz are dominant, comprising 60 percent to 75 percent of the rock, with biotite
and muscovite comprising about 25 percent of the rock. Pyrite (in one thin-
section) comprised about 7 percent of the rock and occurs as equant to elongate
grains from 0.2 mm to 1.5 mm in length. Apatite, zircon, sphene, and kyanite
occur in trace amounts.
The pyrite in all three lithologies described above are of the massive (crystalline)
morphology and have undergone kyanite-sillimanite grade amphibolite

5 Myrmekite – Worm-like intergrowth of quartz in plagioclase.

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metamorphism (500oC to 600oC) during regional metamorphism (Turner 1981, Butler
1991). These three lithologies comprise approximately 26 percent of the lithologies
encountered in the boreholes near the Auxiliary Spillway (HDR 2017).
The dominant metasedimentary rock at the Site is biotite gneiss (metagraywacke)
and it comprises approximately 44 percent of the rock encountered in boreholes near
the Auxiliary Spillway (HDR 2017). Its description follows:
• Biotite Gneiss: Biotite gneiss is typically a medium dark gray to grayish black,
moderately hard to very hard, fine- to medium-grained, and primarily weakly
foliated with thinly spaced (<1 foot) banding. Feldspar augen were occasionally
observed. In thin-section, the biotite gneiss has a granoblastic texture with
banding defined by elongate quartz crystals, plagioclase, and alkali feldspar and
early formed subparallel biotite. The dominant constituents are quartz,
plagioclase, alkali feldspar, and biotite with minor muscovite, pyrite (<1 percent),
and myrmekite and trace amounts of apatite, zircon, sphene, and rutile.
The bedrock along the Auxiliary Spillway channel can be divided into two sequences
based on borehole data and observations of the rock in the spillway: Rock Sequence
1, in which the dominant lithologies (approximately 61 percent of the sequence) are
the pyrite-bearing garnet mica schist, mica schist, and schistose biotite gneiss, is
located along the northern portions of the Auxiliary Spillway (Figure 2) including the
left abutment rock mass and the Fusegate Structure foundation. Rock Sequence 2,
in which the dominate lithologies (approximately 78 percent of the sequence) are
minor pyrite bearing (<1 percent) biotite gneiss and non-pyrite-bearing granite, is
located along the southern portion of the Auxiliary Spillway. The three pyrite-bearing
lithologies comprise approximately 14 percent of Sequence 2. The approximate
spatial distribution of these two sequences in relation to the Auxiliary Spillway is
shown in Figure 11.
4.2.2 Petrographic Analysis of Hand Samples from Bear Creek and
Cedar Cliff Dams
The samples collected from the Bear Creek upstream rock shell (two samples), the
Cedar Cliff downstream rock shell (three samples) and the Cedar Cliff upstream rock
shell (nine samples; as discussed in Section 4.1.1 and summarized in Table 1) were
petrographically examined and analyzed. Two to four thin-sections for the
petrographic work were made from the samples starting at the surface of the
samples and extending into the interior portion of the samples in order to describe
the extent of weathering and mineral alteration (in particular any weathering/
alteration of pyrite). The full petrographic reports for the samples are in Appendix B
and contain the following:
• Page 1 – pictures of the collected hand sample, the sample after cutting with
the locations of the thin-sections and the approximate locations of the
included photomicrographs, two pictures with the thin-sections overlaid on the
cut sample, and the hand sample description (samples CUS-9-30 and CUS-
9-50 do not show the location of the thin-sections as they could not be

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reliably located on the cut rock slabs returned by the laboratory that made the
thin-sections),
• Page 2 – microscopic description of the thin-sections, and
• Pages 3 to a maximum of Page 6 – photomicrographs of the thin-sections at
the locations shown on Page 1.
The results and interpretations of the petrographic analyses are summarized in
Table 2.
The two samples of schistose biotite gneiss from the Bear Creek Dam upstream rock
shell, collected approximately 25 feet below full pond level, have a depth of minor
surface staining of up to 10 mm, but generally less than 1 mm into the samples. No
mineral alteration was observed, including alteration of pyrite within 0.2 mm of the
sample surface, in the thin-sections. Oxidation products of pyrite (discussed in
Section 1) have not developed in the rock during the 65 years of submergence in
the lake.
The three samples from the Cedar Cliff Dam downstream rock shell include one
sample of biotite gneiss (CDS-5) and two samples of garnet mica schist (CDS-2 and
CDS-7). The biotite gneiss has minor mineral alteration throughout the two thin-
sections and is associated with the biotite-rich layers. The pyrite (~2%) in the biotite
gneiss thin-sections is altered to limonite. The garnet mica schist samples exhibit
mineral alteration throughout all thin-sections with biotite altering to limonite and iron
oxide with the majority of pyrite altered to limonite and some pyrite crystals having
limonite rims. The samples have been exposed to atmospheric oxidizing conditions
on the downstream rock shell of Cedar Cliff Dam for 65 years. It is likely that all three
samples were already weathered to some degree before placement in the rock shell.
The nine samples from the Cedar Cliff upstream shell include samples of biotite
gneiss (two samples), mica schist (one sample), and garnet mica schist (six
samples). The biotite gneiss sample, CUS-7-10 collected approximately 15 feet
below full pond (2,330 feet), exhibits minimal alteration of biotite to limonite near the
sample surface with no weathering/mineral alteration noted at distances greater than
2 mm from the sample surface in the thin-sections. The other biotite gneiss sample,
CUS-7-30 collected approximately 35 feet below full pond (2,330 feet) exhibits no
mineral alteration/weathering in any of the three thin-sections. One of the six garnet
mica schist samples, CUS-8-10 collected approximately 15 feet below full pond
(2,330 feet), exhibits mineral alteration throughout the two thin-sections with biotite
altering to limonite and iron oxide with the majority of pyrite altered to limonite. A few
pyrite crystals have limonite rims. The remaining garnet mica schist samples and the
mica schist sample, collected from 15 feet to 55 feet below full pond (2,330 feet)
show no mineral alteration/weathering or oxidation of pyrite in any of the eighteen
thin-sections.
With the exception of sample CUS-8-10, the samples collected on the upstream shell
below full pond have minimal surface staining with no mineral alteration due to
weathering or oxidation of pyrite in the samples after 65 years of submergence in

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Cedar Cliff Lake. Sample CUS-8-10 is almost identical in both appearance and
mineral alteration to samples CDS-2 and CDS-7 from the downstream shell of Cedar
Cliff Dam. It is likely this sample was already weathered when placed in the
upstream shell as none of the other CUS garnet mica schist/mica schist samples,
including CUS-9-10 at the same submerged depth as CUS-8-10, exhibit
weathering/alteration or oxidation of pyrite. The rock shell is largely comprised of
rock generated during the blasting/construction of the Auxiliary Spillway. Review of
construction photos for the Auxiliary Spillway and Dam, in conjunction with the
natural topography of the site, suggest some portion of the rock shell would have
been derived from previously weathered rock.
4.2.3 Petrographic Analysis of Cedar Cliff Auxiliary Spillway Core
Sample
The samples collected from the Cedar Cliff Auxiliary Spillway floor (four samples) as
discussed in Section 4.1.2 and summarized in Table 1 were petrographically
examined and analyzed. The petrographic report format is the same as described in
Section 4.2.2, and the full petrographic reports are included in Appendix C.
The four core samples collected below the Fuseplug in the Auxiliary Spillway channel
include biotite gneiss (one sample), garnet mica schist (one sample), and schistose
biotite gneiss (two samples). Three of the four samples are unstained and
unweathered at the top core surface while one of the samples exhibits minor staining
less than 0.5 mm into the sample interior from the top of the core. No mineral
alteration/weathering including oxidation of pyrite was observed in any of the thin-
sections from the samples after 65 years of exposure since Auxiliary Spillway
excavation (Table 2).
It was anticipated that the rock in the Auxiliary Spillway channel would exhibit, at a
minimum, surficial staining/weathering having been subjected to sustained oxidizing
conditions (air, water, and vegetation) since the construction of the Auxiliary Spillway
65 years ago and would provide a high-end estimate of the weathering/oxidation
profile that can be expected from these lithologies. The staining/weathering
encountered in the recovered cores was less than expected. However, the lack of
weathering is consistent with observations of the left abutment rock mass and in the
deeper cuts of the Auxiliary Spillway to the south where minimal staining/weathering
was noted in the rock walls and in the floor for all lithologies.
It is possible the thin overburden provided a primarily reducing environment. Soil
chemistry consists of complex redox (reducing-oxidation) reactions, and soil may be
a reducing or oxidizing environment based on parameters such as aeration,
precipitation, microbial communities, pore space, and rates of organic
decomposition. Water conditions within the Auxiliary Spillway are based solely on
very minor leakage from the upstream fuseplug foundation and precipitation. The
Auxiliary Spillway channel has never been used in the history of the Project.

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4.2.4 Petrographic Analysis of Anakeesta Formation Hand Samples
The sampled AFm rocks are graphitic mica schists, light gray to medium bluish gray,
very fine- to medium-grained, very thinly foliated with kink folds, and moderately to
slightly weathered. Extensive weathering products present on the samples’ exteriors
ranged from grayish brown to pale yellowish brown and were also observed to a
lesser extent in the samples’ interiors with the weathering products generally parallel
to the foliation defined by muscovite in alternating layers of finer and coarser grain
sizes.
In thin-section (five total; petrographic reports with photomicrographs are in
Appendix D), the graphitic mica schist consists of alternating granoblastic and
lepidoblastic textured bands. The granoblastic bands consist primarily of quartz with
minor plagioclase (some primary, but the majority in the form of later porphyroblasts
up to 7 mm in length), muscovite, kyanite (as porphyroblasts up to 10 mm in length),
trace biotite, trace pyrite/pyrrhotite as equant to tabular crystals (up to 0.2 mm in
length parallel with the bands. The lepidoblastic bands consist of muscovite that
defines the primary foliation, quartz, and graphite layers and lenses that contain very
fine-grained disseminated pyrite/pyrrhotite that account for the largest percentage of
pyrite/pyrrhotite in the schist, and have trace equant to elongate pyrite/pyrrhotite
(<0.02 mm) aligned with the foliation. Trace amounts of rutile, zircon, and apatite are
present in the lepidoblastic bands. Both the granoblastic and lepidoblastic bands
contain trace ilmenite in tabular and skeletal crystals parallel to the foliation defined
by the muscovite. Limonite and melanterite (both oxidation products of
pyrite/pyrrhotite) occur in both bands along grain boundaries and in thin veins with
the latter being prevalent in the lepidoblastic bands. Jarosite (oxidation product of
pyrite/pyrrhotite) was present in one sample (AK-L-8B) as small equant well-formed
crystals. The bands/foliation are tightly folded and kinked.
The graphitic mica schist has undergone amphibolite grade metamorphism
(580oC±35oC, Mohr and Newton 1983) and the pyrite/pyrrhotite including the finely
disseminated grains associated with the graphite (light colored pinhead size material
within the graphite layers/lenses under reflected light, see photomicrographs in
Appendix D) is of the massive (crystalline) morphology. This very fine-grain
pyrite/pyrrhotite with corresponding large surface area per volume of material
exposed to weathering/oxidation is responsible for the known acid-drainage
associated with the Anakeesta Formation as discussed in Section 1.
4.2.5 Petrographic Analysis of Nantahala Slate Hand Samples
The sampled NFm rocks are metasiltstones, medium gray with light gray layers, very
fine- to fine-grained with slightly coarser layers consisting primarily of quartz, thinly
laminated with very slight weathering on the outside of one sample and extending 2
mm to 3 mm into the interior of two of the samples.
In thin-section (three total; petrographic reports are in Appendix E), the
metasiltstone has a lepidoblastic texture with a very fine-grained groundmass
consisting primarily of quartz, muscovite, and minor graphite interlayered with slightly

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coarser quartz-rich bands with minor biotite and garnet porphyroblasts, and from 4
percent to 7 percent pyrite, in equant to tabular crystals up to 0.5 mm. The pyrite
crystals are non-oxidized. Fractures and anastomosing fractures, both parallel and at
angle to the banding in the metasiltstone have iron oxide staining (hematite).
The metasiltstones have undergone amphibolite grade metamorphism (580oC±35oC,
Mohr and Newton 1983) and the pyrite is of the massive (crystalline) morphology.
Acid-Base Accounting tests of three NFm metasiltstones gave results suggesting
they are potentially acid-producing (Schaeffer and Clawson 1996) although there are
no known instances of acid-production associated with NFm rocks. The pyrite in the
metasiltstones is coarser, with less surface area per volume than in the known acid-
producing graphitic mica schists of the AFm.
4.2.6 Comparison of Pyrite Crystal Size between Anakeesta Formation
and Tallulah Falls Formation Rocks
Photomicrographs for six, side-by-side comparisons of pyrite/pyrrhotite crystal size in
the AFm and pyrite crystal size in TFFm rocks are included in Appendix F. Crystal
size comparisons are provided in different polarization states. The comparisons
show the significant difference in the crystal size between the rocks of the two
formations viewed at the same scale. Differences in crystal size is most easily
visualized in the reflected light state. The majority of pyrite/phyrrhotite, which occurs
in the graphite-rich layers in the AFm known acid-producing graphitic mica schists, is
on the order of magnitudes finer than the relatively coarse pyrite crystal size of the
TFFm rocks.
4.2.7 Comparison of Pyrite Crystal Size between Nantahala Formation
and Tallulah Falls Formation Rocks
Photomicrographs for three, side-by-side comparisons of pyrite grain size in NFm
and TFFm rocks, photomicrographs are included in Appendix G. The pyrite crystal
size comparison shows that pyrite crystals in the NFm metasiltstones are finer than
those in the TFFm rocks, but are still orders of magnitude larger than those of the
known acid-producing AFm graphic mica schists.
5 Conclusions of the Rock Spoil Evaluation
5.1 Literature Review
The following are the conclusions based on the literature review:
• Permanent subaqueous storage is currently the most effective measure that can
be taken to inhibit acid-generation from sulfidic material.
• Placing sulfides into a low-oxygen or oxygen-free environment, such as a
subaqueous environment, is more geochemically stable than storage in fills
exposed to atmospheric, oxygen-rich conditions.

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5.2 Petrographic Analysis and Acid-Production Potential
The following are the conclusions based on the petrographic analyses:
• The petrographic analyses of the AFm, NFm, and TFFm pyritic rocks, as
documented by the grain size comparison, show the orders of magnitude
differences in the very fine-grain size of pyrite/pyrrhotite in the known acid-
producing AFm graphitic mica schists compared to the coarser-grained pyrite in
both the NFm metasiltstones and the TFFm garnet mica schists, mica schists,
and schistose biotite gneisses that have no known instances or history of acid-
production in the region.
• The petrographic analyses of the rock samples from the downstream shell of
Cedar Cliff Dam (CDS-samples) and from the Auxiliary Spillway (CAS-samples)
that have been exposed to atmospheric oxidizing conditions for at least 65 year
are inconclusive concerning a rate of weathering. It is likely that the relatively
advanced pyrite alteration noted in the CDS-samples, in particular the garnet
mica schist samples, is a result of a much longer period of weathering that
occurred when the rocks were in-situ, well before the construction of the Auxiliary
Spillway and Dam. The similarity of the weathering of these samples to sample
CUS-8-10, which has been submerged below Cedar Cliff Lake for 65 years,
strongly suggests that the CDS garnet mica schist samples and CUS-8-10 garnet
mica schist sample were weathered before placement in the Cedar Cliff Dam
upstream and downstream rock shells and have undergone minimal weathering,
if any, in the 65 years since construction. The lack of any significant weathering
and oxidation of pyrite in the other ten samples (BC-samples and the other CUS-
samples) that have been continuously submerged additionally supports the
conclusion of varied pre-existing weathering of the rocks prior to placement in the
rock shells. The lack of significant staining/crusts in the Auxiliary Spillway floor
core samples (although possibly related to reducing conditions in the thin
soil/rock covering) and the lack of significant staining/crusts on rock surfaces in
the cut slopes and floors of the deeper spillway sections south of the Fuseplug,
support this conclusion as well. The petrographic analyses of the nine samples
from the Cedar Cliff Dam upstream rock shell collected at depths of
approximately 15 feet, 35 feet, and 55 feet below full pond elevation (2,330) feet
have minimal surface staining and no mineral alteration due to weathering or
oxidation of pyrite in the samples after 65 years of submergence in Cedar Cliff
Lake, with the exception of sample CUS-8-10 as previously discussed
5.3 Disposal of Rock Spoil in Cedar Cliff Lake
Subaqueous disposal of the rock spoil in the lake from the widening of the Auxiliary
Spillway is the most suitable and effective disposal option based on the literature
review, the lack of acid-production associated with the TFFm in the region, and the
petrographic analyses of the samples from the Bear Creek and Cedar Cliff upstream
rock shells (no oxidation of pyrite after 65 years of submergence). Cedar Cliff Dam
provides a stable infrastructure already in place for the subaqueous disposal, and

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January 4, 2018 | 15
has established operation/maintenance costs and regularly scheduled safety
inspections. Subaqueous disposal requires maintaining a consistent submergence
such that atmospheric oxygen does not periodically flux into the spoil pile. The
location of the proposed submerged spoil area and the associated placement depth
anticipated for the rock spoil will maximize the height of the water cover overlying the
rock spoil. The proposed submerged spoil area will provide a minimum of seventy
feet of cover at maximum drawdown elevation of 2,300 feet (full pond Elevation
2,330 feet), thus preventing agitation by wave action and sequestering the material
to the lower layer of the reservoir (Figures 1a, 1b, and 1c). Restricting the material
to this region, where dissolved oxygen is typically limited or non-existent will inhibit
the exposure of the rock spoil to atmospheric oxygen, thereby reducing the potential
for oxidation reactions. Although the complete submergence of pyrite-bearing
materials may not completely halt the oxidation of sulfide and resultant acid-
generation, the reaction rate in deep aquatic environments is greatly reduced,
resulting in negligible impact (Sengupta 1993).
6 Recommendations
The results of this rock spoil evaluation demonstrate a low potential for acid-
production due to the coarse grain pyrite-bearing rocks in the TFFm, based on the
petrographic analysis of samples that have been continuously submerged since the
reservoir was filled, and is consistent with the site’s 65 year history of non-acid-
production. The subaqueous disposal of the rock spoil will create a low to oxygen-
free environment with 70 feet to 100 feet of water cover over the life of the facility
further minimizing the risk of acid-production. Subaqueous disposal is the most
suitable and effective solution for disposing of the pyrite-bearing rocks of the TFFm.
The following recommendations are made in conjunction with the subaqueous
disposal of the rock spoil:
• The excavation blasting plan should be designed to minimize the amount of fines
generated.
• The excavation work and placement of the rock spoil in the lake should be
sequenced such that the rock excavated from Rock Sequence 1, which contains
the highest percentages of the lithologies with the higher percent of pyrite, is
placed as deep as possible in the disposal area.
7 References
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Barnes, H. L. and S. B. Romberger. 1968. Chemical aspects of acid mine drainage:
Journal of Water Pollution Control Federation, Vol. 40, No. 3, Part 1, p. 371-
384.

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East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 16
Butler, J. R. 1991. Metamorphism, p. 127-141, in, Horton, J. W. Jr. and V. A. Zullo,
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Charleston, WV, April 23-26, 1990.
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Hydroelectric Project and Cedar Cliff Development (FERC No. 2698),
Tuckasegee, North Carolina, June 5, 2017: Report for Duke Energy of the
Carolinas, LLC.
Huckabee, J. W., C. P. Goodyear, and R. D. Jones. 1975. Acid rocks in the Great
Smokies: unanticipated impact on aquatic biota of road construction in regions
of sulfide mineralization: Transactions of the American Fishery Society, No. 4,
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Lapakko, K.A. 1994. Subaqueous disposal of mine waste: laboratory investigation. Paper
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Drainage, Pittsburgh, Pa. April 24-29, 1994.
Lapakko, K., L. Leopold, D. Antonson, S. Theriault, and E. Mehleiss. 2013. Subaqueous
disposal of sulfide waste rock: Six-year laboratory batch experiment: Minnesota

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 17
Department of Natural Resources, Division of Land and Minerals, Saint Paul,
MN 55155-4045, 75p.
Mathews, R. C., Jr. and E. L. Morgan. 1982. Toxicity of Anakeesta Formation leachates
to shovel-nose salamander, Great Smoky Mountains National Park: Journal of
Environmental Quality, Vol. 11, p. 102-106.
Mohr, D. W. and R. C. Newton. 1983. Kyanite-staurolite metamorphism in sulfidic schists
of the Anakeesta Formation, Great Smoky Mountains, North Carolina:
American Journal of Science, Vol. 283, p. 97-134.
Moses, C. O. and J. S. Herman. 1991. Pyrite oxidation at circumneutral pH: Geochimica
et Cosmochimica Acta, Vol. 5, p. 471-482.
Morin, K. A. 1993. Rates of sulfide oxidation in submerged environments: Implications for
subaqueous disposal: Proceedings of the 17th Annual British Columbia Mine
Reclamation Symposium, Port Hardy, BC, The Technical and Research
Committee on Reclamation, p. 235-247.
Nicholson, R. V., R. W. Gillham, J. A. Cherry, and E. J. Reardon. 1988. Reduction of acid
generation in mine tailings through the use of moisture-retaining cover layers
as oxygen barriers: Canadian Geotechnical Journal, Download from
www.nrcreaserchpress.com by UNIV OF NC – CHARLOTTE on 06/07/17. 8p.
Payant, S.C. and E.K. Yanful. 1997. Evaluation of techniques for preventing acidic rock
drainage – Final Report. Mine Environment Neutral Drainage Project 2.35.2b.
Pugh, C.E., L.R. Hossner, and J.B. Dixon. 1981. Pyrite and marcasite surface area as
influenced by morphology and particle diameter: Soil Science Society of
America Journal. Volume 45 No. 5, pp. 979-982.
Pugh, C.E., L.R. Hossner, and J.B. Dixon. 1984. Oxidation rate of iron sulfides and
affected by surface area, morphology, oxygen concentration, and autotrophic
bacteria: Soil Science. Vol. 137 No. 5, pp. 309-314.
Rescan Environmental Services, Ltd. 1990a. Geochemical assessment of subaqueous
tailings disposal in Butte Lake, British Columbia, MEND Project 2.11.1b:
Prepared for and Funded by British Columbia Ministry of Energy, Mines, and
Petroleum Resources, CANMET, Environmental Canada, Hudson Bay Mining
and Smelting Company, Ltd., The Canada/British Columbia Mineral
Development Agreement, Vancouver, British Columbia.
Rescan Environmental Services, Ltd. 1990b. Geochemical assessment of subaqueous
tailings disposal in Mandy Lake, Flin Flon Area, Manitoba, MEND Project
2.11.1b-c: Prepared for and Funded by British Columbia Ministry of Energy,
Mines, and Petroleum Resources, CANMET, Environmental Canada, Hudson
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tailings disposal in Anderson Lake, Manitoba, 1993-1995 Study Program –
Final Report, MEND Project 2.11.3abc: Prepared for and Sponsored by
Hudson Bay Mining and Smelting Company Limited, Natural Water Research
Institute, Manitoba Energy and Mines, Canada Centre for Mineral and Energy

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 18
Technology (CANMET), through the Canada/Manitoba Mineral Development
Agreement.
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producing rocks and water quality monitoring along a transmission line in the
Blue Ridge Province, southwestern North Carolina: Environmental and
Engineering Geoscience, Volume II, pp. 35-48.
Sengupta, M. 1993 Environmental Impacts of Mining, Monitoring, Restoration, and
Control: CRC Press, Boca Raton, Florida, 494p.
Singer, P. C. and W. Stumm. 1970. Acid mine drainage: the rate determining step:
Science, Vol. 167, 20 February, p. 1121-1123.
Sobek, A. A., W. A. Schuller, J. R. Freeman, and R. M. Smith. 1978. Field and
Laboratory Methods Applicable to Overburdens and Mine Soils: U. S.
Environmental Protection Agency, Publication No. EPA-600/2-78-054,
Washington, DC, 204p.
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New York, NY, 780p.
Tremblay, G. A. and C. M. Hogan, Editors. 2001. MEND Manual, Volume 4 – Prevention
and Control, MEND 5.4.3d: Sponsored by Natural Resources Canada,
Northern Ontario Development Agreement (NODA-MEND Ontario), Quebec
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the 4th International Conference on Acid Rock Drainage.
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2nd Edition: Hemisphere Publishing Corporation, Washington, New York,
London, 524p.
U. S. Environmental Protection Agency. 1994. Acid Mine Drainage Prediction: Technical
Document, EPA530-R-94-026, NTIS PB94-201829, USEPA, Office of Solid
Waste, Special Waste Branch, Washington, DC, 48p.
U. S. Geological Survey. 2017. Water properties (Dissolved oxygen):
https://water.usgs.gov/edu/dissolvedoxygen.html
Waksman, S. A. and J. S. Joffe. 1921. Microorganisms concerned in the oxidation of
sulfur in the soil – II. Thiobacillus thiooxidans, a new sulfur-oxidizing organism
isolated from the soil: Journal of Bacteriology, Vol. VII, No. 2, p. 239-256.
Yanful, E. K. and P. Sims. 1997. Review of Water Cover Sites and Research Projects –
MEND Project 2.18.1: Sponsored by Brunswick Mining and Smelting
Corporation, the Ontario Ministry of Environment and Mining, the Ontario
Ministry of Northern Development and Mines, and the Canada Centre for
Mineral and Energy Technology (CANMET) through the CANADA/Northern
Ontario Development Agreement (NODA).

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Tables

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Table 1. Sampling Summary
Sample ID Site Sample Date Sample Location Approximate Sample
Coordinates
Lithology # of
Thin-
Sections
Sample Purpose Notes
AK-L7-B Offsite 3/20/2017 Anakeesta Location 7 35°18'44.47", -83°30'21.01" Graphitic Schist 2 Crystal Size Comparison Anakeesta Formation
AK-L8-A Offsite 3/20/2017 Anakeesta Location 8 35°18'48.28", -83°30'16.44" Graphitic Schist 2 Crystal Size Comparison Anakeesta Formation
AK-L8-B Offsite 3/20/2017 Anakeesta Location 8 35°18'48.28", -83°30'16.44" Graphitic Schist 1 Crystal Size Comparison Anakeesta Formation
B-10I-T1 Cedar Cliff 9/6/2017 Boring B-10I, 27.1 - 27.5 linear feet below ground surface 35°15'12.56", -83°05'50.52" Garnet Mica Schist 1 Crystal Size Comparison HDR (2017)
B-11I-T4 Cedar Cliff 9/15/2016 Boring B-11I, 151.15-151.5 linear feet below ground surface 35°15'11.30", -83°05'50.53" Gneissic Biotite Schist 1 Crystal Size Comparison HDR (2017)
B-14I-T1 Cedar Cliff 11/30/2016 Boring B-14I, 58.25 - 58.55 linear feet below ground surface 35°15'07.14", -83°05'51.55" Schistose Biotite Gneiss 1 Crystal Size Comparison HDR (2017)
B-4-T1A Cedar Cliff 12/1/2016 Boring B-4, 31.2 - 31.55 feet below ground surface 35°15'11.55", -83°05'53.36" Garnet Mica Schist 2 Crystal Size Comparison HDR (2017)
B-9I-T2 Cedar Cliff 9/7/2016 Boring B-9I, 90.2 - 90.7 linear feet below ground surface 35°15'13.73", -83°05'51.06" Sillimanite Garnet Mica
Schist
1 Crystal Size Comparison HDR (2017)
BC-1 Bear Creek 3/21/2017 Upstream of Bear Creek Dam, ~25 ft below full pond elevation 35°14'30.60", -83°4'20.75" Schistose Biotite Gneiss 3 Petrographic Analysis and Weathering Profile Collected from boat during
pond drawdown.
BC-7 Bear Creek 3/21/2017 Upstream of Bear Creek Dam, ~25 ft below full pond elevation 35°14'27.59", -83°4'19.23" Schistose Biotite Gneiss 3 Petrographic Analysis and Weathering Profile Collected from boat during
pond drawdown.
CAS-1 Cedar Cliff 7/31/2017 Auxiliary Spillway of Cedar Cliff 35° 15'12.55", -83°5' 52.45" Biotite Gneiss 2 Petrographic Analysis and Weathering Profile
CAS-2 Cedar Cliff 8/1/2017 Auxiliary Spillway of Cedar Cliff 35°15' 12.08", -83°5'52.35" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile
CAS-3 Cedar Cliff 8/2/2017 Auxiliary Spillway of Cedar Cliff 35° 15'12.39", -83°5'52.53" Schistose Biotite Gneiss 2 Petrographic Analysis and Weathering Profile
CAS-4 Cedar Cliff 8/3/2017 Auxiliary Spillway of Cedar Cliff 35° 15'12.17", -83°5'52.40" Schistose Biotite Gneiss 3 Petrographic Analysis and Weathering Profile
CDS-2 Cedar Cliff 3/13/2017 Downstream of Cedar Cliff Dam 35°15'10.13", -83° 5'57.88" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile
CDS-5 Cedar Cliff 3/13/2017 Downstream of Cedar Cliff Dam 35°15'10.13", -83° 5'57.88" Biotite Gneiss 2 Petrographic Analysis and Weathering Profile
CDS-7 Cedar Cliff 3/13/2017 Downstream of Cedar Cliff Dam 35°15'10.13", -83° 5'57.88" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile
CUS-7-10 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam; ~15 ft below full pond elev. 35°15' 12.25", -83°5' 58.07" Biotite Gneiss 3 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-7-30 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~35 ft below full pond elev. 35°15' 12.25", -83°5' 58.07" Biotite Gneiss 3 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-7-50 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~55 ft below full pond elev. 35°15' 12.25", -83°5' 58.07" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-8-10 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam; ~15 ft below full pond elev. 35°15' 12.13", -83°5' 56.88" Mica Schist 2 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-8-30 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~35 ft below full pond elev. 35°15' 12.13", -83°5' 56.88" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-8-50 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~55 ft below full pond elev. 35°15' 12.13", -83°5' 56.88" Garnet Mica Schist 2 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-9-10 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam; ~15 ft below full pond elev. 35°15' 11.91", -83°5' 55.71" Garnet Mica Schist 3 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-9-30 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~35 ft below full pond elev. 35°15' 11.91", -83°5' 55.71" Garnet Mica Schist 2 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
CUS-9-50 Cedar Cliff 8/10/2017 Upstream Slope of Cedar Cliff Dam, ~55 ft below full pond elev. 35°15' 11.91", -83°5' 55.71" Garnet Mica Schist 4 Petrographic Analysis and Weathering Profile Samples collected by Divers.
Full Pond = 2,330 feet.
NF-2-1 Offsite 7/26/2017 Nantahala Location 2 35°16'40.18", -83°39'42.08" Metasiltstone 1 Crystal Size Comparison Nantahala Formation
NF-3-3 Offsite 7/26/2017 Nantahala Location 3 35°16'40.55", -83°39'51.57 Metasiltstone 1 Crystal Size Comparison Nantahala Formation
NF-4-1 Offsite 7/26/2017 Nantahala Location 4 35°16'41.46", -83°39'58.33 Metasiltstone 1 Crystal Size Comparison Nantahala Formation
Notes:
1. Offsite sample locations are approximate; Bear Creek upstream and Cedar Cliff downstream sample locations are approximate.
2. CAS-series locations were supplied by Duke Energy of the Carolinas, LLC on September 8, 2017.
3. B-4, B-9I, B-10I, B-11I, and B-14I sample locations were surveyed by Alliance Land Surveying on January 25, 2017.

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Table 2. Petrographic Analysis and Weathering Profile Summary – BC, CDS, CUS, and CAS Samples
Sample
ID Lithology
Thin-Section Photo-
micrograph ID
Depth of Surface
Weathering /
Staining Rind
Pyrite Percentage and
Size Condition of Pyrite In Interior of Sample Observations Oxidizing Conditions Interpretation
BC-1 Schistose Biotite Gneiss <1 mm
No mineral alteration/weathering noted in
any of the three thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Bear Creek Lake.
BC-1, Thin-Section 1
~3% in equant crystals
0.05 to 1.5 mm
Unaltered 6 mm from sample surface.
BC-1, Thin-Section 2 No pyrite in photomicrograph. No mineral alteration
or weathering present
BC-1, Thin-Section 3 Unaltered <0.2 mm from sample surface
BC-7 Schistose Biotite Gneiss ~1 cm Fe-staining and mineral discoloration
extends into sample interior with the
effects restricted to around and along
biotite grains within 1 cm of the sample
surface.
Prolonged Submergence
Fe-staining at surface an up to 1 cm into the sample
due to alteration of biotite, possibly before placement
on the upstream rock shell of the dam. No alteration
or oxidation of pyrite in the sample after 65 years of
submergence in Bear Creek Lake.
BC-7, Thin-Section 1

~2% in schistose layers in
equant crystals 0.05 to
1.5 mm
Unaltered 33 mm form sample surface
BC-7, Thin-Section 2 Unaltered 2-3 mm from sample surface
BC-7, Thin-Section 3 Unaltered 5 mm from sample surface
CDS-2 Garnet Mica Schist Both the surface
and the interior of
the sample exhibits
moderate
weathering effects
and mineral
alteration.

Mineral alteration present throughout all
three thin-sections with biotite altering to
limonite and iron oxide with the majority of
pyrite altered to limonite. A few pyrite
crystals have limonite rims.
Atmospheric oxidizing
conditions and
precipitation
The sample has been exposed to oxidizing conditions
on the downstream rock shell of Cedar Cliff Dam for
65 years. It is likely that the sample was already
weathered before placement in the rock shell.
CDS-2, Thin-Section 1 ~4% limonite replacing
pyrite; ~1% pyrite in
equant crystals 0.2 to
0.75 mm.
Limonite pseudomorphs after pyrite
CDS-2, Thin-Section 2 Limonite pseudomorphs after pyrite
CDS-2, Thin-Section 3
Limonite pseudomorphs after pyrite
CDS-5 Biotite Gneiss ~5 mm with minor
mineral alteration
and iron staining in
the interior of the
sample
~2% limonite replacing
pyrite with trace amounts
in equant crystals 0.2 to
0.5 mm.
Minor mineral alteration is present
throughout the two thin-sections
associated with the biotite-rich layers. The
minor pyrite in the sample (~2%) is altered
to limonite.
Atmospheric oxidizing
conditions and
precipitation
The sample has been exposed to oxidizing conditions
on the downstream rock shell of Cedar Cliff Dam for
65 years. It is likely that the sample was already
weathered before placement in the rock shell.
CDS-5, Thin-Section 1 Limonite pseudomorphs after pyrite
CDS-5, Thin-Section 2 Limonite pseudomorphs after pyrite
CDS-7 Garnet Mica Schist Both the surface
and the interior of
the sample exhibits
moderate
weathering effects
and mineral
alteration.

Mineral alteration present throughout all
three thin-sections with biotite altering to
limonite and iron oxide with the majority of
pyrite altered to limonite. A few pyrite
crystals have limonite rims.
Atmospheric oxidizing
conditions and
precipitation
The sample has been exposed to oxidizing conditions
on the downstream rock shell of Cedar Cliff Dam for
65 years. It is likely that the sample was already
weathered before placement in the rock shell.
CDS-7, Thin-Section 1 ~4% limonite replacing
pyrite; <1% pyrite in
equant crystals 0.05 to
0.4 mm.
Limonite pseudomorphs after pyrite
CDS-7, Thin-Section 2 Limonite pseudomorphs after pyrite
CDS-7, Thin-Section 3
Limonite pseudomorphs after pyrite
CUS-7-10 Biotite Gneiss <0.5 mm Minor alteration of biotite to limonite near
the sample surface. No mineral
alteration/weathering noted at distance
greater than 2 mm from the sample
surface in the three thin-sections.
Prolonged Submergence
Minimal surface staining with minor near surface
alteration of biotite to limonite. No effects due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-7-10a <1% in equant to
elongate crystals to 0.05
mm
Unaltered 4 mm from sample surface
CUS-7-10b Unaltered 35 mm from sample surface
CUS-7-10c Unaltered 28 mm from sample surface
CUS-7-30 Biotite Gneiss ~1 mm
No mineral alteration/weathering noted in
any of the three thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-7-30a

<1% in equant to
elongate crystals to 0.05
mm
Unaltered 23 mm from sample surface
CUS-7-30b Unaltered 38 mm from sample surface
CUS-7-30c Unaltered 9 mm from sample surface
CUS-7-50 Garnet Mica Schist <0.5 mm
No mineral alteration/weathering noted in
any of the three thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-7-50a
4% in equant to elongate
crystals to 0.5 mm
Unaltered 12 mm from sample surface
CUS-7-50b Unaltered 30 mm from sample surface
CUS-7-50c Unaltered 70 mm from sample surface
CUS-8-10 Mica Schist Both the surface
and the interior of
the Sample exhibits
moderate
weathering effects
and mineral
alteration.
~5% in equant to
elongate crystals to 0.5
mm, completely to
partially altered to
limonite.

Mineral alteration present throughout all
two thin-sections with biotite altering to
limonite and iron oxide with the majority of
pyrite altered to limonite. A few pyrite
crystals have limonite rims.
Prolonged Submergence
Sample is almost identical to samples CDS-2 and
CDS-7 from the downstream shell of Cedar Cliff Dam.
None of the other CUS garnet mica schist/mica schist
samples exhibit weathering/alteration. It is likely the
sample was already weathered when place in the
upstream shell.
CUS-8-10a Altered, completely to partially replaced by limonite
CUS-8-10b
Altered, completely to partially replaced by limonite
CUS-8-30 Garnet Mica Schist <0.5 mm
No mineral alteration/weathering noted in
any of the three thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-8-30a
7% in equant to elongate
crystals to 0.75 mm
Unaltered 11 mm from sample surface
CUS-8-30b Unaltered 20 mm from sample surface
CUS-8-30c Unaltered 19 mm from sample surface
CUS-8-50 Garnet Mica Schist <0.2 mm No mineral alteration/weathering noted in
either of the two thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-8-50a 5% in equant to elongate
crystals to 0.5 mm
Unaltered 2 mm from sample surface
CUS-8-50b Unaltered 30 mm from sample surface
CUS-9-10 Garnet Mica Schist <1 mm No mineral alteration/weathering noted in
any of the three thin-sections. Prolonged Submergence CUS-9-10a Unaltered 3 mm from sample surface

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Sample
ID Lithology
Thin-Section Photo-
micrograph ID
Depth of Surface
Weathering /
Staining Rind
Pyrite Percentage and
Size Condition of Pyrite In Interior of Sample Observations Oxidizing Conditions Interpretation
CUS-9-10b 7% in equant to elongate
crystals to 1.5 mm
Unaltered 46 mm from sample surface Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake. CUS-9-10c Unaltered 30 mm from sample surface
CUS-9-30 Garnet Mica Schist <1 mm No mineral alteration/weathering noted in
either of the two thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-9-30a 5% in equant to elongate
crystals to 0.5 mm
Unaltered pyrite throughout the thin-section
CUS-9-30b Unaltered pyrite throughout the thin-section
CUS-9-50 Garnet Mica Schist <1 mm
No mineral alteration/weathering noted in
either of the two thin-sections. Prolonged Submergence
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of submergence in Cedar Cliff Lake.
CUS-9-50a

5% in equant crystals
0.05 to 0.4 mm and
elongate crystals to 0.5 to
1.5 mm
Unaltered pyrite throughout the thin-section
CUS-9-50b Unaltered pyrite throughout the thin-section
CUS-9-50c Unaltered pyrite throughout the thin-section
CUS-9-50d Unaltered pyrite throughout the thin-section
CAS-1 Biotite Gneiss
Sample
unweathered from
top of core to the
interior

No mineral alteration/weathering noted in
either of the two thin-sections.
Atmospheric oxidizing
conditions and
precipitation. Possible
that the minimal soil cover
produced a reducing
environment.
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of exposure after Auxiliary Spillway
excavation.
CAS-1_TS--1 <1% in equant to
elongate crystals 0.05 to
0.2 mm
Unaltered 6 mm from top of core sample surface
CAS-1_TS-2
Unaltered 102 mm from top of core sample surface
CAS-2 Garnet Mica Schist
No mineral alteration/weathering noted in
any of the three thin-sections.
Atmospheric oxidizing
conditions and
precipitation. Possible
that the minimal soil cover
produced a reducing
environment.
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of exposure after Auxiliary Spillway
excavation.
CAS-2_TS--1 Sample
unweathered from
top of core to the
interior
~3% in equant 0.05 to 1
mm to elongate crystals
0.5 to 4 mm
Unaltered 4 mm from top of core sample surface
CAS-2_TS-2 Unaltered 80 mm from top of core sample surface
CAS-2_TS-3 Unaltered 123 mm from top of core sample surface
CAS-3 Schistose Biotite Gneiss <0.5 mm
<1% in equant 0.02 to
0.05 to elongate crystals
0.05 to 1.5 mm

No mineral alteration/weathering noted in
any of the three thin-sections.
Atmospheric oxidizing
conditions and
precipitation. Possible
that the minimal soil cover
produced a reducing
environment.
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of exposure after Auxiliary Spillway
excavation.
CAS-3_TS-1 Unaltered 3 mm from top of core sample surface
CAS-3_TS-2
Unaltered 60 mm from top of core sample surface
CAS-4 Schistose Biotite Gneiss
No mineral alteration/weathering noted in
any of the three thin-sections.
Atmospheric oxidizing
conditions and
precipitation. Possible
that the minimal soil cover
produced a reducing
environment.
Minimal surface staining with no alteration due to
weathering or oxidation of pyrite in the sample after
65 years of exposure after Auxiliary Spillway
excavation.
CAS-4_TS--1 Sample
unweathered from
top of core to the
interior
~3% in equant 0.05 to 1
mm to elongate crystals
0.5 to 4 mm
Unaltered 2 mm from top of core sample surface
CAS-4_TS-2 Unaltered 84 mm from top of core sample surface
CAS-4_TS-3 Unaltered 113 mm from top of core sample surface
Notes:
1. BC-samples from Bear Creek Dam upstream rock shell; CDS-Samples from Cedar Cliff Dam downstream rock shell; CUS-Samples from Cedar Cliff Dam upstream rock shell; CAS-Samples from Cedar Cliff Auxiliary Spillway channel floor; See Figures 3, 4, and 5 for locations and Table 1 for sample
summary.
2. Location of thin-sections from samples CUS-9-30 and CUS-9-50 could not be determined from the returned prepared samples.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 23

Figures

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 24

Figure 1a. Rock Spoil Repository – Plan and Sections B, D, and E.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 25

Figure 1b. Rock Spoil Repository – Section A.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 26

Figure 1c. Rock Spoil Repository – Section C.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 27
Figure 2. East wall of the Auxiliary Spillway near the north end of the Fuseplug.
White to yellow to reddish staining/crusts of soluble iron sulfate minerals due to the oxidation of pyrite in rocks of the Tallulah Falls
Formation. Rock Sequence 1 discussed in Section 4.2.1.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 28

Figure 3. Rock Spoil Sample Locations

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 29

Figure 4. Location of the upstream CUS samples.
Collected by divers using Survey Stations CC-7, CC-8, and CC-9 for control of dive locations.
Approximate depths of samples controlled by diver’s oxygen supply hose and length of rope
attached to a wire basket for bringing the samples to the surface. Pond at elevation 2,325 feet (full
pond = 2,330 feet) during sampling on August 10, 2017. Last digits in the sampling number is feet
below elevation 2,325 feet.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 30

Figure 5. Cedar Cliff Dam IDF Alternative Location of Cedar Cliff Auxiliary Spillway Rock Core Samples

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 31
Figure 6. Outcrop of typically inundated Biotite Gneiss in the vicinity of Bear Creek Dam. Very little weathering was observed.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 32
Figure 7. Area of CAS sampling in the Auxiliary Spillway below the Fusegate.
The pipes mark the location of Samples CAS-2 and CAS-2B (backup). Samples CAS-1, CAS-3 and CAS-4 are located between the CAS-2
samples and the fuseplug (see Figure 5 for location).

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 33
Figure 8. Hilti DD 500 diamond core drill setup on sample location CAS-1.
Note thickness of overburden removed to access the rock surface.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 34

Figure 9. Road cut in the Anakeesta Formation on NC Highway 28 northwest of Oak Grove, North Carolina.
White to yellow staining/crusts of soluble iron sulfate minerals are due to the oxidation of pyrite/pyrrhotite in the graphitic mica schists
of the Anakeesta Formation.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 35

Figure 10. Road cut in the Nantahala Formation metasiltstones on Winding Stairs Gap Road, outside of Nantahala, North Carolina.
Note the lack of extensive pyrite oxidation products compared to the Anakeesta Formation as shown in Figure 9.

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

January 4, 2018 | 36
Figure 11. Stratigraphic Sequences 1 and 2 underlying the Cedar Cliff Auxiliary Spillway.
Percentages of major rock types in Sequences 1 and 2 of the stratigraphic sequence based on
Borehole Lithologies. Actual percentages of the lithologies may vary due to the 3-Dimensional
variation in the continuity and thicknesses of the lithologies and the complex structure (folding).
From HDR (2017).

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

Appendices

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

A
Appendix A. Acid-Base
Accounting Test
Procedure

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)
Appendix A

Page 1 of 1

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

B
Appendix B. Bear Creek
Dam and Cedar Cliff
Dam, BC, CDS, and CUS
Petrographic Analysis
Reports

Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: BC-1 (three thin sections from one sample: BC-1A, BC-1B, and BC-1C)
Sample Location:
Photo 3: BC-1 with three thin sections overlayed on
their respective locations.
Photo 4: Close view of location of three thin sections
from BC-1.
Schistose Biotite Gneiss - hard to very hard; fine to coarse grained; very thin, weakly defined foliation with alternating
zones of increased schistosity and gneissicity; light gray (N7) to dark gray (N3); migmatitic zones up to 2cm thick,
migmatitic zones are primarily medium to coarse grained quartz and feldspar; trace pyrite primarily parallel to weak
foliation; few feldspar augen; very slightly weathered to fresh, outside sample margins are Fe-stained, micas are very
slightly dulled to fresh. Weathered margins do not generally extend more than 1mm into sample interior. Sample interior
is fresh, with no readily apparent mineral alteration or staining.
Hand Sample Description:
Photo 2: BC-1 after thin section processing.
Location of the three thin sections (BC-1A, BC-1B,
and BC-1C) are shown.
Photo 1: BC-1 hand sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
Approximately 25 feet below normal pond elevation (2560 ft msl) on Bear Creek Lake. Sample is
from upstream rockfill for the Bear Creek dam.
BC-1: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Bear Creek Dam
Page 1 of 6
B-2
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Gneissic Layers
replacing biotite in places.
Schistose Layers
replacing biotite in places.
Chloritoid - Trace, poikiloblastic with inclusions of plagioclase.
Prepared By:Date:
M. F. Schaeffer, LG May 8, 2017
Reviewed By: Date
S.K. Townsend May 11, 2017
Sphene - Trace
Rock Type: Schistose Biotite Gneiss
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Biotite - ~45%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Muscovite - 30%, medium to coarse grain size; sillimanite replacing muscovite in places.
Pyrite - ~3%, Equant (0.05 to 1.5 mm).
Apatite - Trace
Zircon - Trace
Apatite - Trace
Zircon - Trace.
Sphene - 1%.
Quartz - Trace, undulatory extinction, sutured grain contacts.
Plagioclase (Oligoclase) - 20%, anhedral.
Plagioclase (Oligoclase) - 45%, anhedral, some poikiloblastic with muscovite inclusions.
Quartz - ~35%, undulatory extinction, sutured and embayed grain contacts.
Biotite - ~15%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Muscovite - 3%, fine grain size; sillimanite replacing muscovite in places.
Pyrite - <1%, Equant (0.05 to 0.2 mm).
Microscopic Description (Three Thin-Sections: BC-1A; BC-1B; BC-1C):
Granoblastic (xenoblastic) texture with poorly developed gneissicity (banding) defined by early subparallel biotite with later
overprinting biotite and muscovite with coarse quartz and plagioclase alternating with lepidoblastic (schistose), biotite-rich
layers with finer grained quartz and plagioclase. No mineral alteration due to weathering or oxidation within the rock
mass.
Mineral Percentages: Percentages are from Thin-Section BC-1A; Mineral Percentages separated into Gneissic and
Schistose Layers
BC-1: Petrographic Analysis
Page 2 of 6
B-3
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-1, Thin Section 1: Photomicrographs
Sample: BC-1A-1 (Section 1, Position 1; 6 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Sample: BC-1A-1 (Section 1, Position 1; 6 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Sample: BC-1A-1 (Section 1, Position 1; 6 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Page 3 of 6
B-4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-1, Thin Section 1: Photomicrographs
Sample: BC-1A-2 (Section 1, Position 2; <1 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
G = Garnet
Sample: BC-1A-2 (Section 1, Position 2; <1 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
G = Garnet
Sample: BC-1A-2 (Section 1, Position 2; <1 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
G = Garnet
Page 4 of 6
B-5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-1, Thin Section 2: Photomicrographs
Sample: BC-1B-1 (Section 2, Position 1)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Ap = Apatite
Sample: BC-1B-1 (Section 2, Position 1)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Ap = Apatite
Page 5 of 6
B-6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-1, Thin Section 3: Photomicrographs
Sample: BC-1C-1 (Section 3, Position 1)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Ap = Apatite
Py = Pyrite (<0.2 mm from sample surface)
Sample: BC-1C-1 (Section 3, Position 1)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Ap = Apatite
Py = Pyrite (<0.2 mm from sample surface)
Sample: BC-1C-1 (Section 3, Position 1)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Ap = Apatite
Py = Pyrite (<0.2 mm from sample surface)
Page 6 of 6
B-7
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: BC-7 (three thin sections from one sample: BC-7A, BC-7B, BC-7C)
Sample Location:
Photo 3: BC-7 with three thin sections overlayed on
their respective locations.
Photo 4: Close view of location of three thin sections
from BC-7.
Schistose Biotite Gneiss - hard to very hard; fine to very coarse grained, primarily fine to medium grained; very thin,
weakly defined foliation with alternating zones of increased schistosity and gneissicity (both gradational and sharp
contacts between these end-members); very light gray (N8) to dark gray (N3); migmatitic zones up to 2cm thick,
migmatitic zones primarily medium to coarse grained quartz and feldspar; few feldspar augen, pyrite not readily observed
in hand sample; slightly weathered to fresh, outside margins are Fe-stained, micas on sample surface are very slightly
dulled to fresh. Weathered margins extend into sample interior, although weathering effects are primarily restricted to
outer 1cm of sample. Fe-staining and mineral discoloration in sample interior is primarily restricted to around and parallel
Hand Sample Description:
Photo 2: BC-7 after thin section processing.
Location of the three thin sections (BC-7A, BC-7B,
and BC-7C) are shown.
Photo 1: BC-7 hand sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
Approximately 25 feet below normal pond elevation (2560 ft msl) on Bear Creek Lake. Sample is
from upstream rockfill for the Bear Creek dam.
BC-7: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Bear Creek Dam
Page 1 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Gneissic Layers
Schistose Layers
Myrmekite - Trace
Chloritoid - Trace
Prepared By:Date:
M. F. Schaeffer, LG May 8, 2017
Reviewed By: Date
S.K. Townsend May 11, 2017
Quartz - ~18%, undulatory extinction, sutured grain contacts
Plagioclase (Oligoclase) - 25%, anhedral.
Alkali Feldspar - ~5%, fine to medium grain size, anhedral.
Sphene - Trace
Rock Type: Schistose Biotite Gneiss
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Biotite - ~25%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon.
Muscovite - 25%, medium to coarse grain size.
Pyrite - ~2%, Equant (0.05 to 1.5 mm).
Apatite - Trace
Zircon - Trace
Zircon - Trace
Sphene - Trace
Plagioclase (Oligoclase) - 45%, coarse grain size, anhedral
Quartz - ~5%, undulatory extinction, sutured and embayed grain contacts
Biotite - ~5%, green to greenish brown, fine to medium grain size
Muscovite - Trace
Apatite - Trace
Alkali Feldspar - 45%, coarse grain size, anhedral
Microscopic Description (Three Thin-Sections: BC-7A; BC-7B; BC-7C):
Granoblastic (xenoblastic) texture with poorly developed gneissicity (banding) defined by early subparallel biotite with later
overprinting biotite and muscovite with coarse quartz and plagioclase alternating with lepidoblastic (schistose), biotite-rich
layers with finer grained quartz and plagioclase. No mineral alteration due to weathering or oxidation within the rock
mass.
Mineral Percentages: Percentages are from Thin-Section BC-7B; Mineral Percentages separated into Gneissic and
Schistose Layers
BC-7: Petrographic Analysis
outer 1cm of sample. Fe-staining and mineral discoloration in sample interior is primarily restricted to around and parallel
to biotite-rich layers.
Page 2 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-7, Thin Section 1: Photomicrographs
Sample: BC-7A-1 (Section 1, Position 1; 33 nn fron
sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
My = Myrmekite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7A-1 (Section 1, Position 1; 33 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
My = Myrmekite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7A-1 (Section 1, Position 1; 33 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
My = Myrmekite
Q = Quartz
B = Biotite
Py = Pyrite
Page 3 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-7, Thin Section 1: Photomicrographs
Sample: BC-7A-2 (Section 1, Position 2; 2 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7A-2 (Section 1, Position 2; 2 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7A-2 (Section 1, Position 2, 2 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Page 4 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-7, Thin Section 2: Photomicrographs
Sample: BC-7B-1 (Section 2, Position 1; 2-3 mm
from sample surace)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7B-1 (Section 2, Position 1; 2-3 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7B-1 (Section 2, Position 1; 2-3 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Page 5 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
BC-7, Thin Section 3: Photomicrographs
Sample: BC-7C-1 (Section 3, Position 1; 5 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7C-1 (Section 3, Position 1; 5 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Sample: BC-7C-1 (Section 3, Position 1; 5 mm
from sample surface)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
M = Muscovite
Q = Quartz
B = Biotite
Py = Pyrite
Page 6 of 6
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CDS-2 (three thin sections from one sample: CDS-2A, CDS-2B, CDS-2C)
CDS-2: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CDS-2 with three thin sections overlayed
on their location.
Photo 4: Close view of location of three thin sections
from CDS-2.
Garnet Mica Schist - hard; fine to medium grained; very thinly foliated; medium light gray (N6) to dark gray (N3); pyrite not
readily visible, likely altered to limonite; moderately weathered, both the margins and interior of the hand sample exhibit
weathering effects such as Fe-staining and mineral alteration (biotite and garnet crystals are either zoned with or entirely
replaced by limonite and oxides), oxides present along grain boundaries, most feldspar crystals are slightly discolored.
Hand Sample Description:
Sample Location:
Photo 2: CDS-2 after thin section processing.
Location of the three thin sections (CDS-2A, CDS-
2B, and CDS-2C) are shown.
Photo 1: CDS-2 hand sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
Sample from the downstream rockfill face of Cedar Cliff Dam
Page 1 of 5
B-14
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Muscovite - 25%, coarse grain size.
Quartz - ~20%, Undulatory extinction.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in bioitite.
Sphene - Trace.
Sillimanite - ~2%, primarily in a fiber mass replacing biotite and muscovite in places.
Prepared By:Date:
M. F. Schaeffer, LG May 8, 2017
Reviewed By: Date
S.K. Townsend May 11, 2017
Alkali Feldspar - Trace.
Garnet - ~3%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor feldspar, larger
grains fractured, bounded by more or less regular faces.
Pyrite - ~1%, Equant (0.2 to 0.75 mm) to elongate grains (0.5 to 1.0 mm length) subparallel to schistosity. Most pyrite
replaced by limonite with remaining pyrite having limonite rims.
Plagioclase (Oligoclase) - 15%, anhedral.
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Rock Type: Garnet Mica Schist
Limonite - ~4%, Pseudomorphs after pyrite with some limonite associated with biotite alteration.
Microscopic Description (Three Thin-Sections: CDS-2A; CDS-2B; CDS-2C):
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers. Mineral
alteration throughout section with biotite altering to limonite and iron oxide and pseudomorphs of limonite after pyrite.
Limonite and iron oxides along grain boundaries.
Mineral Percentages: Percentages are from Thin-Section CDS-2B
CDS-2: Petrographic Analysis
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Page 2 of 5
B-15
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-2, Thin Section 1: Photomicrographs
Sample: CDS-2A-1 (Section 1, Position 1; 2-3 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
S = Sillimanite
L = Limonite (pseudomorph after pyrite).
Sample: CDS-2A-1 (Section 1, Position 1; 2-3 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
S = Sillimanite
L = Limonite (pseudomorph after pyrite).
Sample: CDS-2A-1 (Section 1, Position 1: 2-3 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
S = Sillimanite
L = Limonite (pseudomorph after pyrite).
Page 3 of 5
B-16
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-2, Thin Section 2: Photomicrographs
Sample: CDS-2B-1 (Section 2, Position 1; 35 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-2B-1 (Section 2, Position 1; 35 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-2B-1 (Section 2, Position 1; 35 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
L
L
Page 4 of 5
B-17
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-2, Thin Section 3: Photomicrographs
Sample: CDS-2C-1 (Section 3, Position 1; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-2C-1 (Section 3, Position 1; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-2C-1 (Section 3, Position 1; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Page 5 of 6
B-18
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CDS-5 (two thin sections from one sample: CDS-5A and CDS-5B)
Photo 3: CDS-5A and CDS-5B with thin sections
overlayed on their respective locations.
Photo 4: Close view of locations of two thin sections
from CDS-5.
Biotite Gneiss - hard to very hard, fine to medium grained, with some grain size segregation parallel to foliation/banding;
thinly foliated/banded, very light gray (N8) to medium dark gray (N4); trace garnet in biotite-rich layers, pyrite is not readily
visible in hand sample; very slightly weathered, Fe and oxide staining on surface, slightly dulled micas where present on
surface. Fe-staining, slight mineral discoloration, and mineral alteration is present throughout the interior of sample but is
primarily concentrated in biotite-rich layers, some feldspars exhibit discoloration.
Hand Sample Description:
Sample Location:
Photo 2: CDS-5 after thin section processing.
Location of the two thin sections (CDS-5A and CDS-
5B) are shown.
Photo 1: CDS-5 hand sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
Sample from the downstream rockfill face of Cedar Cliff Dam
CDS-5: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Page 1 of 5
B-19
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Quartz - ~28%, Undulatory extinction.
Muscovite - Trace.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Prepared By:Date:
M. F. Schaeffer, LG
May 8, 2017
Reviewed By: Date
S.K. Townsend May 11, 2017
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke).
Rock Type: Biotite Gneiss
Microscopic Description (Two Thin-Sections: CDS-5A; CDS-5B):
Granoblastic (xenoblastic) texture with poorly developed gneissicity (banding) defined by early subparallel biotite with later
overprinting biotite and muscovite.
Mineral Percentages: Percentages are from Thin-Section CDS-5A
Limonite - ~2%, Pseudomorphs after pyrite with some limonite associated with biotite alteration.
Pyrite - Trace, Equant (0.05 to 0.2 mm) to elongate grains (0.2 to 0.5 mm length) subparallel to schistosity. Most pyrite
replaced by limonite with remaining pyrite having limonite rims.
Plagioclase (Oligoclase) - 40%, anhedral.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Garnet - <1%, up to 1 mm, larger grains fractured, bounded by more or less regular faces.
CDS-5: Petrographic Analysis
Page 2 of 5
B-20
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-5, Thin Section 1: Photomicrographs
Sample: CDS-5A-1 (Section 1, Position 1; 5 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-5A-1 (Section 1, Position 1; 5 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-5A-1 (Section 1, Position 1;
5 mm from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite).
Page 3 of 5
B-21
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-5, Thin Section 1: Photomicrographs
Sample: CDS-5A-2 (Section 1, Position 2 ; 28 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-5A-2 (Section 1, Position 2; 28 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-5A-2 (Section 1, Position 2; 28 mm
form sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
L = Limonite (pseudomorph after pyrite)
Page 4 of 5
B-22
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-5, Thin Section 2: Photomicrographs
Sample: CDS-5B-1 (Section 2, Position 1; 20 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
L = Limonite (pseudomorph after pyrite)
Lp = Limonite altering from Pyrite
Sample: CDS-5B-1 (Section 2, Position 1; 20 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
L = Limonite (pseudomorph after pyrite)
Lp = Limonite altering from Pyrite
Sample: CDS-5B-1 (Section 2, Position 1; 20
mm from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
L = Limonite (pseudomorph after pyrite)
Lp = Limonite altering from Pyrite
Page 5 of 5
B-23
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CDS-7 (three thin sections from one sample: CDS-7A, CDS-7B, CDS-7C)
Sample Location:
Photo 2: CDS-7 after thin section processing.
Location of the three thin sections (CDS-7A, CDS-
7B, and CDS-7C) are shown.
Photo 1: CDS-7 hand sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
Sample from the downstream rockfill face of Cedar Cliff Dam
CDS-7: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CDS-7A, CDS-7B, and CDS-7C with thin
sections overlayed on their respective locations.
Photo 4: Close view of locations of three thin
sections from CDS-7.
Garnet Mica Schist - hard; fine to medium grained; very thinly foliated; medium light gray (N6) to medium dark gray (N4)
with dark yellowish orange (10YR 6/6) oxides; pyrite is not readily visible in hand sample, likely altered to limonite;
moderately weathered throughout exterior and interior of sample, interior staining and mineral alteration is parallel to
foliation.
Hand Sample Description:
Page 1 of 6
B-24
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Muscovite - 25%, coarse grain size.
Quartz - ~15%, Undulatory extinction.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Sillimanite - ~2%, primarily in a fiber mass replacing biotite and muscovite.
Prepared By:Date:
M. F. Schaeffer, LG May 8, 2017
Reviewed By: Date
S.K. Townsend May 11, 2017
CDS-7: Petrographic Analysis
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Rock Type: Garnet Mica Schist
Pyrite - <1%, Equant (0.05 to 0.4 mm) to elongate grains (0.5 to 1.0 mm length) subparallel to schistosity. Most pyrite
replaced by limonite with remaining pyrite having limonite rims.
Microscopic Description (Three Thin-Sections: CDS-7A; CDS-7B; CDS-7C):
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers. Mineral
alteration throughout section with biotite altering to limonite and iron oxide and pseudomorphs of limonite after pyrite.
Limonite and iron oxides along grain boundaries.
Mineral Percentages: Percentages are from Thin-Section CDS-7B
Plagioclase (Oligoclase) - 15%, anhedral.
Biotite - ~35%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Limonite - ~4%, Pseudomorphs after pyrite with some limonite associated with biotite alteration.
Alkali Feldspar - Trace.
Garnet - ~4%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor feldspar, larger
grains fractured, bounded by more or less regular faces.
Page 2 of 6
B-25
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-7, Thin Section 1: Photomicrographs
Sample: CDS-7A-1 (Section 1, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-7A-1 (Section 1, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-7A-1 (Section 1, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Page 3 of 6
B-26
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-7, Thin Section 2: Photomicrographs
Sample: CDS-7B-1 (Section 2, Position 1; 18 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Lp = Limonite altering from Pyrite
Sample: CDS-7B-1 (Section 2, Position 1; 18 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Lp = Limonite altering from Pyrite
Sample: CDS-7B-1 (Section 2, Position 1; 18 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Lp = Limonite altering from Pyrite
Page 4 of 6
B-27
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-7, Thin Section 3: Photomicrographs
Sample: CDS-7C-1 (Section 3, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-7C-1 (Section 3, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Sample: CDS-7C-1 (Section 3, Position 1; 7 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
L = Limonite (pseudomorph after pyrite)
Page 5 of 6
B-28
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CDS-7, Thin Section 3: Photomicrographs
Sample: CDS-7C-2 (Section 3, Position 2; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Lp = Limonite altering from Pyrite
Sample: CDS-7C-2 (Section 3, Position 2; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Lp = Limonite altering from Pyrite
Sample: CDS-7C-2 (Section 3, Position 2; 20 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Lp = Limonite altering from Pyrite
Page 6 of 6
B-29
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-7-10 (three thin-sections from one sample: CUS-7-10a, CUS-7-10b, CUS-7-10c)
Sample Location:
Photo 3: CUS-7-10 with three thin sections
overlayed on their approximate respective locations.
Photo 4: Close view of three thin sections from CUS-
7-10 with the locations of the photomicrographs.
Hand Sample Description:
Biotite Gneiss, Dark gray (N3), hard to very hard fine- to medium-grained with light gray (N7) quartz-feldspar rich layers,
thinly layered. Inside of sample, very slight weathering to fresh. Outside of sample stained dark gray (N3) with moderate
reddish orange (10 R6/6) splotches/staining. The staining extends less than 0.5 mm into the interior of the sample.
Photo 2: CUS-7-10 after thin section processing.
Location of the three thin sections (CUS-7-10a, CUS-
7-10b and CUS-7-10c) are shown.
Photo 1: CUS-7-10 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 15 feet (2315 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#7.
CUS-7-10: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Page 1 of 5
B-30
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Apatite - Trace
Prepared By:Date:
M. F. Schaeffer, LG Oct. 2, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Limonite - Trace, from biotite weathering.
Pyrite - <1%, in equant to elongate crystals to 0.05 mm.
Rock Type: Biotite Gneiss
Alkali Feldspar - 20% (microcline).
Quartz - 30%, Undulatory extinction.
Plagioclase - 30%.
Muscovite - Trace.
Biotite - 20%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Microscopic Description (Three Thin-Sections: CUS-7-10a, CUS-7-10b, CUS-7-10c):
Mineral Percentages: Percentages are from Thin-Section CUS-7-10a).
Granoblastic texture with poorly developed foliation defined by overprinting biotite and muscovite. No alteration or
weathering of minerals except minor development of limonite within 3 mm of the sample surface (Section CUS-7-10a).
CUS-7-10: Petrographic Analysis
Page 2 of 5
B-31
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-10a: Photomicrographs
Sample: CUS-7-10a (Position 1; 4 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
L = Limonite
Zr = Zircon
Sample: CUS-7-10a (Position 1; 4 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
L = Limonite
Zr = Zircon
Sample: CUS-7-10a (Position 1; 4 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
L = Limonite
Zr = Zircon
Page 3 of 5
B-32
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-10b: Photomicrographs
Sample: CUS-7-10b (Position 1; 35 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CUS-7-10b (Position 1; 35 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CUS-7-10b (Position 1; 35 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Page 4 of 5
B-33
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-10c: Photomicrographs
Sample: CUS-7-10c (Position 1; 28 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CUS-7-10c (Position 1; 28 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CUS-7-10c (Position 1; 28 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
Page 5 of 5
B-34
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-7-30 (three thin-sections from one sample: CUS-7-30a, CUS-7-30b, CUS-7-30c)
Sample Location:
Photo 2: CUS-7-30 after thin section processing.
Location of the three thin sections (CUS-7-30a, CUS-
7-30b and CUS-7-30c) are shown.
Photo 1: CUS-7-30 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 35 feet (2295 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#7.
CUS-7-30: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CUS-7-30 with three thin sections
overlayed on their approximate respective locations.
Photo 4: Close view of three thin sections from CUS-
7-30 with the locations of the photomicrographs.
Hand Sample Description:
Biotite Gneiss. Dark gray (N3), hard to very hard, fine- to medium-grained with light gray (N7) quartz-feldspar rich layers,
thinly layered. Inside of sample, very slight weathering to fresh. Outside of sample stained dark gray (N3) with moderate
reddish brown (10 R 6/6) splotches/staining. Staining extends ~1 mm into the interior of the sample.
Page 1 of 5
B-35
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Apatite - Trace
Pyrite - <1%, in equant to elongate crystals to 0.05 mm.
Prepared By:Date:
M. F. Schaeffer, LG Oct. 2, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Microscopic Description (Three Thin-Sections: CUS-7-30a, CUS-7-30b, CUS-7-30c):
Mineral Percentages: Percentages are from Thin-Section CUS-7-30b;
CUS-7-30: Petrographic Analysis
Granoblastic texture with poorly developed foliation defined by overprinting biotite and muscovite.
Rock Type: Biotite Gneiss
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Alkali Feldspar - 15% (microcline).
Quartz - 30%, Undulatory extinction.
Plagioclase - 25%.
Muscovite - 10%.
Biotite - 20%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Page 2 of 5
B-36
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-30a: Photomicrographs
Sample: CUS-7-30a (Position 1; 23 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30a (Position 1; 23 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30a (Position 1; 23 mm
from sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 3 of 5
B-37
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-30b: Photomicrographs
Sample: CUS-7-30b (Position 1; 38 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30b (Position 1; 38 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30b (Position 1; 38 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 4 of 5
B-38
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-30c: Photomicrographs
Sample: CUS-7-30c (Position 1; 9 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30c (Position 1; 9 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-30c (Position 1; 9 mm from
sample surface)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 5 of 5
B-39
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-7-50 (three thin-sections from one sample: CUS-7-50a, CUS-7-50b, CUS-7-50c)
Sample Location:
Photo 3: CUS-7-50 with three thin sections
overlayed on their approximate respective locations.
Photo 4: Close view of three thin sections from CUS-
7-50 with the locations of the photomicrographs.
Hand Sample Description:
Garnet Mica Schist with interlayers of Migmatite. Garnet mica schist is very light gray (N8) to dark gray (N3), hard, coarse-
grained, with well developed schistosity/foliation, and contains garnets up to 5 mm in diameter. The migmatite is white
(N9) to very light gray (N8), very coarse-grained quartz and feldspar with trace muscovite. Interior of sample is fresh.
The outside of the sample is stained moderate orange pink (10 R 7/4) to pale brown (5 YR 5/2). The staining extends
less than 0.5 mm into the interior of the sample.
Photo 2: CUS-7-50 after thin section processing.
Location of the three thin sections (CUS-7-50a, CUS-
7-50b and CUS-7-50c) are shown.
Photo 1: CUS-7-50 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 55 feet (2275 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#7.
CUS-7-50: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Page 1 of 5
B-40
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Garnet Mica Schist
replacing biotite in places.
Sillimanite - 5%, sheeves, fine needles, and fiber masses dispersed with quartz, replacing muscovite.
Garnet - 15%, up to 5 mm in diameter, poikiloblastic with many inclusions of fine-grained biotite, quartz, plagioclase, and
minor pyrite. Larger grains fractured, bounded by more or less regular crystal faces. (% based on entire thin-section.)
Sphene - Trace.
Apatite - Trace
Pyrite - 4%, in equant to elongate crystals to 0.5 mm. Unaltered.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Migmatite
Pyrite - Trace.
Prepared By:Date:
M. F. Schaeffer, LG Oct. 3, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock and development of
migmatite.
Alkali Feldspar - 5% (microcline).
Quartz - 5%, Undulatory extinction.
Plagioclase - 30%.
Muscovite - 15%.
Biotite - 20%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Rock Type: Garnet Mica Schist with Interlayers of Migmatite.
Quartz - Very coarse-grained, undulatory extinction, with sutured and embayed contacts with surrounding crystals.
Plagioclase - Coarse-grained.
Biotite - Trace
Microscopic Description (Three Thin-Sections: CUS-7-50a, CUS-7-50b, CUS-7-50c):
Mineral Percentages: Percentages for garner mica schist are from Thin-Section CUS-7-50b; Composition of the
migmatite from Thin-Section CUS-7-50c.
CUS-7-50: Petrographic Analysis
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers. Garnet
porphyroblasts.
Page 2 of 5
B-41
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-50a: Photomicrographs
Sample: CUS-7-50a (Position 1; 12 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Py = Pyrite
Sample: CUS-7-50a (Position 1; 12 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Py = Pyrite
Sample: CUS-7-50a (Position 1; 12 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Py = Pyrite
Page 3 of 5
B-42
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-50b: Photomicrographs
Sample: CUS-7-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CUS-7-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CUS-7-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
Page 4 of 5
B-43
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-7-50c: Photomicrographs
Sample: CUS-7-50c (Position 1; 70 mm from
sample surface)
Lithology: Garent Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-50c (Position 1; 70 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-7-50c (Position 1; 70 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 5 of 5
B-44
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-8-10 (two thin-sections from one sample: CUS-8-10a, CUS-8-10b);
Sample Location:
Photo 3: CUS-8-10 with two thin sections overlayed
on their approximate respective locations.
Photo 4: Close view of two thin sections from CUS-8-
10 with the locations of the photomicrographs.
Mica Schist. Moderately hard to hard, medium- to coarse-grained, interior of sample light brownish gray (5YR 6/1) to light
olive gray (5Y 6/1) with outside of sample light brown (5YR 6/4). Pyrite is not visible in hand sample, moderately
weathered throughout interior of the sample, interior iron staining and mineral alteration along foliation.
Hand Sample Description:
Photo 2: CUS-8-10 after thin section processing.
Location of the two thin sections (CUS-8-10a and
CUS-8-10b) are shown.
Photo 1: CUS-8-10 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 15 feet (2315 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#8.
CUS-8-10: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Page 1 of 4
B-45
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Garnet -Trace
Sphene - Trace.
Apatite - Trace
Pyrite - ~5%, in equant to elongate crystals to 0.5 mm. Completely to partially altered to limonite.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Garnet -Trace
Prepared By:Date:
M. F. Schaeffer, LG
Oct. 3, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Limonite - Pseudomorphs after pyrite with some associated with biotite alteration
Rock Type: Mica Schist
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - Trace.
Quartz - 10%, Undulatory extinction, fractured.
Plagioclase - 30%, fractured.
Muscovite - 25%, medium- to coarse-grained.
Biotite - 30%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon.
Microscopic Description (Two Thin-Sections: CUS-8-10a, CUS-8-10b):
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and fractured quartz-feldspar layers,
folded. Mineral alteration throughout the section with biotite altering to limonite and iron oxide and psuedomorphs of
limonite after pyrite.
Mineral Percentages: Percentages for garner mica schist are from Thin-Section CUS-8-10a;
CUS-8-10: Petrographic Analysis
Page 2 of 4
B-46
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-10a: Photomicrographs
Sample: CUS-8-10a (Position 1; 11 mm from
sample surface)
Lithology: Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Sample: CUS-8-10a (Position 1; 11 mm
from sample surface)
Lithology: Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Sample: CUS-8-10a (Position 1; 11 mm
from sample surface)
Lithology: Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q=Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Page 3 of 4
B-47
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-10b: Photomicrographs
Sample: CUS-8-10b (Position 1; 28 mm from
sample surface)
Lithology: Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Sample: CUS-8-10b (Position 1; 28 mm from
sample surface)
Lithology: Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Sample: CUS-8-10b (Position 1; 28 mm from
sample surface)
Lithology: Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q =Quartz
B = Biotite
M = Muscovite
Py-L = Pyrite with Limonite Rim
Py = Pyrite
Page 4 of 4
B-48
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-8-30 (three thin-sections from one sample: CUS-8-30a, CUS-8-30b, CUS-8-30c)
Sample Location:
Photo 2: CUS-8-30 after thin section processing.
Location of the three thin sections (CUS-8-30a, CUS-
8-30b and CUS-8-30c) are shown.
Photo 1: CUS-8-30 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 35 feet (2295 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#8.
CUS-8-30: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CUS-8-30 with three thin sections
overlayed on their approximate respective locations.
Photo 4: Close view of three thin sections from CUS-
8-30 with the locations of the photomicrographs.
Hand Sample Description:
Garnet Mica Schist with interlayered MIgmatite. Very light gray (N8) to dark gray (N3), hard, coarse-grained, with well
developed schistosity/foliation, and contains garnets up to 5 mm in diameter. Interior of sample is fresh. The outside of
the sample is stained moderate orange pink (10R 7/4) to pale brown (5YR 5/2). The staining extends less than 0.5 mm
into the interior of the sample.
Page 1 of 5
B-49
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite and muscovite in places.
Sillimanite - 3%, sheeves, fine needles, and fiber masses dispersed with quartz, replacing biotite and muscovite.
Garnet - 10%, up to 5 mm in diameter, poikiloblastic with many inclusions of fine-grained biotite, quartz, plagioclase, and
minor pyrite. Larger grains fractured, bounded by more or less regular crystal faces. (% based on entire thin-section.)
Sphene - Trace.
Apatite - Trace
Pyrite - 7%, in equant to elongate crystals to 0.75 mm. Unaltered.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Prepared By:Date:
M. F. Schaeffer, LG
Oct. 3, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Microscopic Description (Three Thin-Sections: CUS-8-30a, CUS-8-30b, CUS-8-30c):
Mineral Percentages: Percentages for garnet mica schist are from Thin-Section CUS-8-30b;
CUS-8-30: Petrographic Analysis
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers. Garnet
porphyroblasts..
Rock Type: Garnet Mica Schist with interyayered Migmatite.
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock and development of
migmatite.
Alkali Feldspar - Trace.
Quartz - 10%, Undulatory extinction, sutured and embayed grain boundaries.
Plagioclase - 30%.
Muscovite - 15%.
Biotite - 25%, pale brown to brown, coarse grain size has pleochroic inclusions of zircon; sillimanite
Page 2 of 5
B-50
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-30a: Photomicrographs
Sample: CUS-8-30a (Position 1; 11mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
Sample: CUS-8-30a (Position 1; 11 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
Sample: CUS-8-30a (Position 1; 11 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
Py = Pyrite
Page 3 of 5
B-51
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-30b: Photomicrographs
Sample: CUS-8-30b (Position 1; 20 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-8-30b (Position 1; 20 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-8-30b (Position 1; 20 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 4 of 5
B-52
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-30c: Photomicrographs
Sample: CUS-8-30c (Position 1; 19 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Zr = Zircon
Sample: CUS-8-30c (Position 1; 19 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Zr = Zircon
Sample: CUS-8-30c (Position 1; 19 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
p = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Zr = Zircon
Page 5 of 5
B-53
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-8-50 (two thin-sections from one sample: CUS-8-50a, CUS-8-50b);
Sample Location:
Photo 2: CUS-8-50 after thin section processing.
Location of the two thin sections (CUS-8-50a and
CUS-8-50b) are shown.
Photo 1: CUS-8-50 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 55 feet (2275 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#8.
CUS-8-50: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CUS-8-50 with two thin sections overlayed
on their approximate respective locations.
Photo 4: Close view of two thin sections from CUS-8-
50 with the locations of the photomicrographs.
Garnet Mica Schist. Very light gray (N8) to dark gray (N3), hard, coarse-grained, with well developed schistosity/foliation,
and contains garnets to 5 mm in diameter. Interior of sample is fresh. The outside of the sample is stained moderate
orange pink (10R 7/4) to pale brown (5YR 5/2) in places. The staining extends less than 0.2 mm into the interior of the
sample. The schist is cut by pegmatite, very light gray (N8), hard to very hard, coarse-grained, consisting of quartz,
feldspar, and minor muscovite.
Hand Sample Description:
Page 1 of 4
B-54
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Muscovite - 25%.
Sillimanite - Trace, sheeves, fine needles, and fiber masses dispersed with quartz, replacing muscovite.
Garnet - 5%, up to 5 mm in diameter, poikiloblastic with many inclusions of fine-grained biotite, quartz, plagioclase, and
minor pyrite. Larger grains fractured, bounded by more or less regular crystal faces. (% based on entire thin-section.)
Sphene - Trace.
Apatite - Trace
Pyrite - 5%, in equant to elongate crystals to 0.5 mm. Unaltered.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Prepared By:Date:
M. F. Schaeffer, LG Oct. 3, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Microscopic Description (Two Thin-Sections: CUS-8-50a, CUS-8-50b):
Mineral Percentages: Percentages for garnet mica schist are from Thin-Section CUS-8-50a;
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers, with garnet
porphyroblasts.
CUS-8-50: Petrographic Analysis
Main Rock Type: Garnet Mica Schist
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - Trace.
Quartz - 10%, Undulatory extinction, sutured and embayed grain boundaries.
Plagioclase - 30%.
Biotite - 25%, pale brown to brown, coarse grain size has pleochroic inclusions of zircon.
Page 2 of 4
B-55
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-50a: Photomicrographs
Sample: CUS-8-50a (Position 1; 2 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-8-50a (Position 1; 2 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-8-50a (Position 1; 2 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q=Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Page 3 of 4
B-56
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-8-50b: Photomicrographs
Sample: CUS-8-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-8-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-8-50b (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q =Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Page 4 of 4
B-57
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-9-10 (three thin-sections from one sample: CUS-9-10a, CUS-9-10b, CUS-9-10c)
Sample Location:
Photo 2: CUS-9-10 after thin section processing.
Location of the three thin sections (CUS-9-10a, CUS-
9-10b and CUS-9-10c) are shown.
Photo 1: CUS-9-10 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 15 feet (2315 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#9.
CUS-9-10: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CUS-9-10 with three thin sections
overlayed on their approximate respective locations.
Photo 4: Close view of three thin sections from CUS-
9-10 with the locations of the photomicrographs.
Hand Sample Description:
Garnet Mica Schist. Very light gray (N8) to dark gray (N3), hard, coarse-grained, with well developed schistosity/foliation,
and contains garnets to 4 mm in diameter. Interior of sample is fresh. The outside of the sample is stained moderate
orange pink (10R 7/4) to pale brown (5YR 5/2). The staining extends less than 1 mm into the interior of the sample. With
lenses and pods of medium- to coarse-grained quartz and feldspar.
Page 1 of 5
B-58
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Garnet - 3%, up to 4 mm in diameter, poikiloblastic with many inclusions of fine-grained biotite, quartz, plagioclase, and
minor pyrite. Larger grains fractured, bounded by more or less regular crystal faces. (% based on entire thin-section.)
Sphene - Trace.
Apatite - Trace
Pyrite - 7%, in equant to elongate crystals to 1.5 mm. Unaltered.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Prepared By:Date:
M. F. Schaeffer, LG Oct. 3, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Microscopic Description (Three Thin-Sections: CUS-9-10a, CUS-9-10b, CUS-9-10c):
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers. Garnet
porphyroblasts..
Mineral Percentages: Percentages for garnet mica schist are from Thin-Section CUS-9-10a;
CUS-9-10: Petrographic Analysis
Rock Type: Garnet Mica Schist
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - Trace.
Quartz - 10%, Undulatory extinction, sutured and embayed grain boundaries.
Plagioclase - 20%.
Muscovite - 30%.
Biotite - 30%, pale brown to brown, coarse grain size has pleochroic inclusions of zircon; sillimanite
Page 2 of 5
B-59
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-10a: Photomicrographs
Sample: CUS-9-10a (Position 1; 3 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-10a (Position 1; 3 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-10a (Position 1; 3 mm
from sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Page 3 of 5
B-60
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-10b: Photomicrographs
Sample: CUS-9-10b (Position 1; 46 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M =Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-10b (Position 1; 46 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-10b (Position 1; 46 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Page 4 of 5
B-61
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-10c: Photomicrographs
Sample: CUS-9-10c (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-9-10c (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CUS-9-10c (Position 1; 30 mm from
sample surface)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 5 of 5
B-62
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-9-30 (two thin-sections from one sample: CUS-9-30a, CUS-9-30b);
Sample Location:
CUS-9-30: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam

Hand Sample Description:
Garnet Mica Schist. Very light gray (N8) to dark gray (N3), hard, coarse-grained, with well developed schistosity/foliation,
and contains garnets to 5 mm in diameter. Interior of sample is fresh. The outside of the sample is stained moderate
orange pink (10 R 7/4) to pale brown (5 YR 5/2) in places. The staining extends less than 1 mm into the interior of the
sample. The schist is cut by pegmatite, very light gray (N8), hard to very hard, coarse-grained, quartz, feldspar, and
minor muscovite.
Photo 2: CUS-9-30; Location of Thin-Sections could
not be determined from the cut sample. Surficial
weathering less than 1 mm into sample.
Photo 1: CUS-8-50 sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
Approximately 35 feet (2295 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey Monument
#9.
Page 1 of 4
B-63
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Muscovite - 10%.
Garnet - 10%, up to 5 mm in diameter, poikiloblastic with many inclusions of fine-grained biotite, quartz, plagioclase, and
minor pyrite. Larger grains fractured, bounded by more or less regular crystal faces. (% based on entire thin-section.)
Sphene - Trace.
Apatite - Trace
Pyrite - 5%, in equant to elongate crystals to 0.5 mm. Unaltered.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sillimanite - Trace, replacing muscovite.
Prepared By:Date:
M. F. Schaeffer, LG
Oct. 4, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Main Rock Type: Garnet Mica Schist
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - Trace.
Quartz - 20%, Undulatory extinction, sutured and embayed grain boundaries.
Plagioclase - 30%.
Biotite - 25%, pale brown to brown, coarse grain size has pleochroic inclusions of zircon.
Microscopic Description (Four Thin-Sections: CUS-9-50a, CUS-9-50b, CUS-9-50c, CUS-9-50d :
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers, with garnet
porphyroblasts. Granoblastic lenses and pods of quartz, plagioclase and minor biotite.
Mineral Percentages: Percentages for garnet mica schist are from Thin-Section CUS-9-30b;
CUS-9-30: Petrographic Analysis
Page 2 of 4
B-64
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-30a: Photomicrographs
Sample: CUS-9-30a (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-30a (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-30a (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q=Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Page 3 of 4
B-65
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-30b: Photomicrographs
Sample: CUS-9-30b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-30b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-30b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q =Quartz
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Page 4 of 4
B-66
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CUS-9-50 (four thin sections: CUS-9-50a, CUS-9-50b, CUS-9-50c, CUS-9-50d)
Sample Location:
Photo 2: CUS-9-50: Location of Thin-Sections could
not be determined from the cut sample. Surficial
weathering less than 1 mm into sample.
Photo 1: CUS-9-50 hand sample prior to thin
section processing. Approximate location of rock
saw cuts are shown.
Approximately 55 feet (2275 ft) below Cedar Cliff full pond level (2330 ft) at Dam Survey
Monument #9.
CUS-9-50: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Dam
Photo 3: CUS-9-50: Location of Thin-Sections
could not be determined from the cut sample.
Surficial weathering less than 1 mm into sample.

Hand Sample Description:
Garnet Mica Schist. Very light gray (N8) to dark gray (N3), hard, coarse-grained, with well developed schistosity/foliation,
and contains garnets to 5 mm in diameter. Interior of sample is fresh. The outside of the sample is stained moderate
orange pink (10R 7/4) to grayish brown (5YR 3/2) in places. The staining extends less than 1 mm into the interior of the
sample. The schist contains pods and lenses of very light gray (N8), hard to very hard, coarse-grained, quartz, feldspar,
and minor muscovite.
Page 1 of 6
B-67
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Muscovite - 25%, coarse grain size.
Quartz - ~10%, Undulatory extinction. (In schistose portion of section.)
Pyrite - 5%, Equant (0.05 to 0.4 mm) to elongate grains (0.5 to 1.5 mm length) subparallel to schistosity.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Sillimanite - ~2%, primarily in a fiber mass replacing biotite and muscovite.
Prepared By:Date:
M. F. Schaeffer, LG Oct. 4, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
CUS-9-50: Petrographic Analysis
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Rock Type: Garnet Mica Schist
Microscopic Description (Four Thin-Sections: CUS-9-50a, CUS-9-50b, CUS-9-50c, CUS-9-50d):
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers.
Mineral Percentages: Percentages are from Thin-Section CUS-9-50d
Plagioclase (Oligoclase) - 15%, anhedral.
Biotite - 35%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Alkali Feldspar - Trace.
Garnet - ~7%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor feldspar, larger
grains fractured, bounded by more or less regular faces.
Page 2 of 6
B-68
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-50a: Photomicrographs
Sample: CUS-9-50a Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Py = Pyrite
Zr = Zircon
Sample: CUS-9-50a Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
P = Pyrite
Zr = Zircon
Sample: CUS-9-50a (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Py = Pyrite
Zr = Zircon
Page 3 of 6
B-69
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-50b: Photomicrographs
Sample: CUS-9-50b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-50b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Sample: CUS-9-50b (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
M = Muscovite
Py = Pyrite
G = Garnet
Page 4 of 6
B-70
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-50c: Photomicrographs
Sample: CUS-9-50c (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-50c (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Sample: CUS-9-50c (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
Py = Pyrite
Page 5 of 6
B-71
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CUS-9-50d: Photomicrographs
Sample: CUS-9-50d (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Sample: CUS-9-50d (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Sample: CUS-9-50d (Position 1)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
Q = Quartz
B = Biotite
M = Muscovite
G = Garnet
Py = Pyrite
Page 6 of 6
B-72

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

C
Appendix C. Cedar Cliff
Spillway, CAS
Petrographic Analysis
Reports

Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CAS-1 (two thin-sections from one sample: CAS-1_TS-1, CAS-1_TS-2)
Sample Location:
Photo 3: CAS-1 with two thin sections overlayed on
their approximate respective locations.
Core Sample Description:
Biotite Gneiss - hard to very hard; medium- to coarse-grained; very thin weakly defined foliation; light gray (N7) to dark
gray (N3); cut by very coarse-grained quartz vein with minor biotite; trace pyrite. Top of core has minor staining that does
not extend into the sample interior. Sample interior is fresh, with no readily apparent mineral alteration or staining.
Photo 4: Close view of location of two thin sections
from CAS-1 with the locations of the
photomicrographs.
Photo 2: CAS-1 after thin section processing.
Location of the two thin sections (CAS-1_TS-1 and
CAS-1_TS-2) are shown.
Photo 1: CAS-1 core sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
CAS-1: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Auxiliary Spillway
Approximately 30 feet below the toe of the Cedar Cliff Fuseplug.
Page 1 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Prepared By:Date:
M. F. Schaeffer, LG Sept. 7, 2017
Reviewed By: Date
S.K. Townsend Sept. 23, 2017
Apatite - Trace
Zircon - Trace.
Sphene - 1%.
Rock Type: Biotite Gneiss
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Plagioclase (Oligoclase) - 40%, anhedral.
Quartz - 40%, undulatory extinction, sutured and embayed grain contacts.
Biotite - ~15%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Muscovite - <1%, fine grain size.
Pyrite - <1%, Equant to elongate (0.05 to 0.2 mm).
Microscopic Description (Two Thin-Sections: CAS-1_TS-1; CAS-1_TS-2):
Granoblastic (xenoblastic) texture with poorly developed gneissicity (banding) defined by early subparallel biotite with later
overprinting biotite and muscovite with quartz and plagioclase alternating with lepidoblastic (schistose). No mineral
alteration due to weathering or oxidation within the rock mass.
Mineral Percentages: Percentages are from Thin-Section CAS-1_TS-1
CAS-1: Petrographic Analysis
Page 2 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-1_TS-1: Photomicrographs
Sample: CAS-1_TS-1 (Position 1; 6 mm from top
of sample)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CSA-1_TS-1 (Position 1; 6 mm
from top of sample)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CAS-1_TS-1 (Position 1; 6 mm
from top of sample)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Py = Pyrite
Page 3 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-1_TS-2: Photomicrographs
Sample: CAS-1_TS-2 (Position 1; 102 mm from
top of sample)
Lithology: Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Fe-St = Iron Staining
Sample: CAS-1_TS-2 (Position 1; 102 mm from
top of sample)
Lithology: Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Fe-St = Iron Staining
Sample: CAS-1_TS-2 (Position 1; 102 mm from
top of sample)
Lithology: Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
B = Biotite
Q = Quartz
Fe-St = Iron Staining
Page 4 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CAS-2 (three thin-sections from one sample: CAS-2_TS-1, CAS-2_TS-2, CAS-2_TS-3)
Sample Location:
Photo 2: CAS-2 after thin section processing.
Location of the three thin sections (CSA-2_TS-1,
CAS-2_TS-2, and CAS-2_TS-3) are shown.
Photo 1: CAS-2 core sample prior to thin section
processing. Approximate location of rock saw cuts
are shown.
CAS-2: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Auxiliary Spillway
Approximately 75 feet from the toe of the Cedar Cliff Fuseplug.
Photo 3: CSA-2 with three thin sections overlayed
on their respective locations.
Photo 4: Close view of location of three thin sections
from CAS-2 with the locations of the
photomicrographs.
Garnet Mica Schist - Very light gray (N8) and dark gray (N3), moderately hard to hard, medium- to coarse-grained with
garnets up to 5 mm in diameter and medium-grained quartz-feldspar layers and lenses.
Core Sample Description:
Page 1 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Prepared By:Date:
M. F. Schaeffer, LG Sept. 14, 2017
Reviewed By: Date
S.K. Townsend Sept. 23, 2017
Microscopic Description (Three Thin-Sections: CAS-2-TS-1, CAS-2_TS-2, CAS-2_TS-3):
Lepidoblastic texture with schistosity defined by subparallel muscovite and biotite, and minor quartz/feldspar-rich layers.
Mineral Percentages: Percentages are from Thin-Section CAS-2_TS-2
CAS-2: Petrographic Analysis
Alkali Feldspar - ~2015 (microcline).
Quartz - 15%, Undulatory extinction.
Biotite - 25%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Muscovite - 40%, medium to coarse grain size; sillimanite replacing muscovite in places.
Sillimanite - sheeves and fine needles/fibers replacing muscovite.
Rock Type: Garnet Mica Schist
Origin: Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Garnet - ~2%, up to 4 mm, poikiloblastic with inclusions of fine-grained biotite and quartz, larger grains fractured.
Pyrite - 3%, Equant (0.05 to 1 mm) to elongate grains (0.5 mm to 4 mm) subparallel to schistosity.
Zircon - ~1%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Apatite - Trace
Page 2 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-2_TS-1: Photomicrographs
Sample: CAS-2_TS-1 (Position 1; 4 mm from top
of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Zr = Zircon
Sample: CAS-2_TS-1 (Position 1; 4 mm
from top of sample)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Zr = Zircon
Sample: CAS-2_TS-1 (Position 1; 4 mm
from top of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Zr = Zircon
Page 3 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-2_TS-2: Photomicrographs
Sample: CAS-2_TS-2 (Position 1; 80 mm from top
of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CAS-2_TS-2 (Position 1; 80 mm from top
of sample)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CAS-2_TS2 (Position 1; 80 mm from top
of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 4 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-2_TS-3: Photomicrographs
Sample: CAS-2_TS-3 (Position 1; 123 mm from
top of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CAS-2_TS-3 (Position 1; 123 mm from
top of sample)
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Sample: CAS-2_TS-3 (Position 1; 123 mm from
top of sample)
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Ap = Apatite
Q = Quartz
Py = Pyrite
Page 5 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CAS-3 (two thin-sections from one sample: CAS-3_TS-1, CAS-3_TS-2)
Sample Location:
Photo 3: CAS-3 with two thin sections overlayed on
their approximate respective locations.
Photo 4: Close view of location of two thin sections
from CAS-3 with the locations of the
photomicrographs.
Schistose Biotite Gneiss - hard to very hard; medium- to coarse-grained; very thin weakly defined foliation; light gray (N7)
to dark gray (N3); cut by ~1 inch thick mica schist, hard, coarse-grained, medium gray (N5), trace pyrite and small
garnets. Top of core has minor staining that does not extend into the sample interior (<0.5 mm). Sample interior is fresh,
with no readily apparent mineral alteration or staining.
Core Sample Description:
Photo 2: CAS-3 after thin section processing.
Location of the two thin sections (CAS-3_TS-1 and
CAS-3_TS-2) are shown.
Photo 1: CAS-3 core sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
CAS-3: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Auxiliary Spillway
Approximately 40 feet below toe of the Cedar Cliff Fuseplug.
Page 1 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Prepared By:Date:
M. F. Schaeffer, LG Sept. 7, 2017
Reviewed By: Date
S.K. Townsend Sept. 23, 2017
Primarily granoblastic texture with poorly developed schistosity (banding) defined by early subparallel biotite with later
overprinting biotite and minor muscovite with quartz and alkali feldspar in CAS_TS-1, with primarily lepidoblastic
(schistose) texture (muscovite-rich) in CAS-3_TS-2. No mineral alteration due to weathering or oxidation within the rock
mass.
Mineral Percentages: Percentages are from Thin-Section CAS-3_TS1 and CAS-3_TS-2
CAS-3: Petrographic Analysis
Microscopic Description (Two Thin-Sections: CAS-3_TS-1; CAS-3_TS-2):
Alkali Feldspar (microcline) - 20%.
Alkali Feldspar (microcline) - 30%.
Quartz - ~40%, undulatory extinction, sutured and embayed grain contacts.
Biotite - 25%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon.
Pyrite - <1%, Equant (0.02 to 0.05 mm) to elongate (0.05 to 1.5 mm).
Apatite - <1%.
Muscovite - 4%, fine to medium grain size.
Mineral Percentages from Thin-Section CAS-3_TS-1
Mineral Percentages from Thin-Section CAS-3_TS-2
Rock Type: Schistose Biotite Gneiss.
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (graywacke)
Biotite - 25%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon.
Pyrite - <1%, Equant (0.02 to 0.05 mm) to elongate (0.05 to 1.5 mm).
Apatite - <1%.
Zircon - Trace.
Muscovite - 20%, fine grain size.
Sphene - Trace.
Zircon - Trace.
Sphene - Trace.
Garnet - Trace, anhedral.
Quartz - ~35%, undulatory extinction, sutured and embayed grain contacts.
Page 2 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-3_TS-1: Photomicrographs
Sample: CAS-3_TS-1 (Position 1; 3 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Zr = Zircon
Sample: CSA-3_TS-1 (Position 1; 3 mm
from top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Zr = Zircon
Sample: CAS-3_TS-1 (Position 1; 3 mm
from top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Zr = Zircon
Page 3 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-3_TS-2: Photomicrographs
Sample: CAS-3_TS-2 (Position 1; 60 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Sample: CAS-3_TS-2 (Position 1; 60 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Sample: CAS-3_TS-2 (Position 1; 60 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Page 4 of 4
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
Site:
Project Location:Jackson County, North Carolina
Sample ID: CAS-4 (three thin-sections from one sample: CAS-4_TS-1, CAS-4_TS-2, CAS-4_TS-3)
Sample Location:
Photo 3: CAS-4 with three thin sections overlayed
on their approximate respective locations.
Schistose Biotite Gneiss - hard to very hard; medium- to coarse-grained; very thin weakly defined foliation; light gray (N7)
to dark gray (N3), with garnets to 2 mm; with thin mica schist layers, hard, coarse-grained, medium gray (N5), trace pyrite
and garnets. Top of core has minor staining that does not extend into the sample interior. Sample interior is fresh, with
no readily apparent mineral alteration or staining.
Core Sample Description:
Photo 4: Close view of location of three thin sections
from CAS-4 with the locations of the
photomicrographs.
Photo 2: CAS-4 after thin section processing.
Location of the three thin sections (CAS-4_TS-1,
CAS-4_TS2 and CAS-4_TS3) are shown.
Photo 1: CAS-4 core sample prior to thin section
processing. Approximate location of rock saw cuts
and thin-section locations are shown.
CAS-4: Sample Information and Hand Sample Description
East Fork Hydroelectric Project - Cedar Cliff Auxiliary Spillway
Approximately 60 feet from the toe of the Cedar Cliff Fuseplug.
Page 1 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
replacing biotite in places.
Prepared By:Date:
M. F. Schaeffer, LG Sept. 25, 2017
Reviewed By: Date
S.K. Townsend Oct. 7, 2017
Rock Type: Schistose Biotite Gneiss
Origin: Upper amphibolite grade metamorphism (regional) of an arenaceous/argillaceous sedimentary rock.
Pyrite - 4%, Equant (0.05 to 1 mm) to elongate grains (0.5 mm to 4 mm).
Zircon - ~1%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Apatite - Trace
Alkali Feldspar - 20% (microcline).
Quartz - 30%, Undulatory extinction.
Biotite - 35%, green to greenish brown, coarse grain size has minor pleochroic inclusions of zircon; sillimanite
Muscovite - 5%, medium to coarse grain size.
Garnet - ~4%, up to 4 mm, poikiloblastic with inclusions of fine-grained biotite and quartz, larger grains fractured.
Microscopic Description (Three Thin-Sections: CAS-4_TS-1, CAS-4_TS-2, CAS-4_TS-3):
Mineral Percentages: Percentages are from Thin-Section CAS-4_TS-2;
CAS-4: Petrographic Analysis
Granoblastic texture with poorly developed schistosity defined by overprinting biotite and muscovite.
Page 2 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-4_TS-1: Photomicrographs
Sample: CAS-4_TS-1 (Position 1; 2 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CAS-4_TS-1 (Position 1; 2 mm
from top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized
Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CAS-4_TS-1 (Position 1; 2 mm
from top of sample)
Lithology: Schisose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Page 3 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-4_TS-2: Photomicrographs
Sample: CAS-4_TS-2 (Position 1; 84 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CAS-4_TS-2 (Position 1; 84 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
Sample: CAS-4_TS2 (Position 1; 84 mm from top
of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Page 4 of 5
Project: Cedar Cliff IDF and Spillway Upgrades
Subject: Rock Spoil Evaluation
Job #: 10060948 066B
CAS-4_TS-3: Photomicrographs
Sample: CAS-4_TS-3 (Position 1; 113 mm from
top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CAS-4_TS-3 (Position 1; 113 mm from
top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Sample: CAS-4_TS-3 (Position 1; 113 mm from
top of sample)
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
Q = Quartz
Py = Pyrite
G = Garnet
Page 5 of 5

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

D
Appendix D. Anakeesta
Formation Petrographic
Analysis Reports

Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 1 of 3
PETROGRAPHIC DESCRIPTION
Location:NC Hwy 28 near intersection with Brush Creek Road, Macon County, NC
Sample #:AK-L7-B (Hand Sample)
Hand Sample Description:
Graphitic Mica Schist - moderately hard to hard, between light gray
(N7) and medium bluish gray (5B 5/1), very fine to medium grained,
very thinly foliated with kink folds. Moderately to very slightly
weathered; weathering products extensively observed on sample
exterior (grayish brown, 5Y 8/4, to pale yellowish orange, 10YR 8/6)
and also observed in sample interior to a lesser extent. Interior
weathering products are parallel to foliation, some minor pitting
observed in sample interior.
Microscopic Description (two thin-sections):
Granoblastic textured bands consisting primarily of quartz with minor plagioclase (some primary, but most in the
form of porphyroblasts up to 5 mm in length), muscovite, minor biotite, equant to tabular pyrite/pyrrhotite (up to
0.2 mm), trace kyanite (as porphyroblasts up to 6 mm in length) and trace garnet intercalated and folded with
lepidoblastic textured bands consisting primarily of muscovite, quartz, and graphite layers and lenses containing
very fine-grained disseminated pyrite/pyrrhotite. Limonite and melanterite occurs throughout both the
granoblastic and lepidoblastic layers along grain boundaries and in thin veins parallel to foliation. The
layers/foliation are tightly folded and kinked.
NOTE: Reasonable estimates of the mineral percentages was not possible because of interlayered granoblastic
bands and lepidoblastic bands, very large porphyroblasts of plagioclase and kyanite, and very fine-grained
minerals that are difficult to identify.
Granoblastic Layer Mineralogy:
Quartz - Undulatory extinction, sutured and embayed grain contacts.
Plagioclase (Oligoclase) - Occurs primarily as porphyroblasts, up to 5 mm in length, with inclusions
of quartz and muscovite and in trace amounts as a primary mineral in the granoblastic groundmass.
Muscovite - Fine-grain interstitial to quartz and plagioclase grains.
Pyrite/Pyrrhotite - In equant to tabular crystals aligned with the foliation.
Kyanite - Occurs as porphyroblasts up to 5 mm in length.
Ilmenite - Tabular crystals and skeleton crystals parallel to foliation, trace.
Petrographic description continues on next page.
D-2
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 2 of 3
PETROGRAPHIC DESCRIPTION, continued
Lepidoblastic Layer Mineralogy:
Muscovite - Primary constituent of schistose layers, folded and kinked.
Quartz - Undulatory extinction, sutured and embayed grain contacts
Plagioclase (Oligoclase) - Trace.
Graphite - Layers and lenses parallel to foliation with finely disseminated pyrite/pyrrhotite.
Pyrite/Pyrrhotite - In equant to tabular crystals aligned with the foliation.
Biotite - Pale brown, porphyroblastic. Trace amounts.
Ilmenite - Tabular crystals and skeleton crystals parallel to foliation, trace.
Garnet - Small euhedral garnets, minor amounts with additional growth rims.
Zircon - Trace.
Apatite - Trace.
Secondary Minerals - Oxidation Products of Pyrite/Pyrrhotite
Limonite - Reddish brown in plane polarized light; orangeish-brown to brown in plane reflected light. Trace.
Melanterite - Occurs as fibrous aggregates and along grain boundaries in both the granoblastic
and lepidoblastic layers. Pale yellow to white in plane reflected light. Trace.
Rock Type:
Graphitic Mica Schist
Origin:
Amphibolite grade metamorphism (regional) of a pelitic sedimentary rock deposited in a reducing
environment with the sulfur and carbon of syngenetic origin.
Prepared By:Date:
M. F. Schaeffer, LG June 23, 2017
Reviewed By:Date:
S.K. Townsend June 28, 2017
D-3
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 3 of 3
PHOTOMICROGRAPHS
Sample:AK-L7-B-1
Lithology:Graphitic Mica Schist
Polarization State:Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
Sample:AK-L7-B-1
Lithology:Graphitic Mica Schist
Polarization State:Cross Polarized Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
Sample:AK-L7-B-1
Lithology:Graphitic Mica Schist
Polarization State:Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
D-4
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No. : 10060948 066B
Page 1 of 4
PETROGRAPHIC DESCRIPTION
Location:NC Hwy 28 near intersection with Brush Creek Road, Macon County, NC
Sample #:AK-L8-A (Hand Sample)
Hand Sample Description:
Graphitic Mica Schist - moderately hard to hard, between light gray
(N7) and medium bluish gray (5B 5/1), very fine to medium grained,
very thinly foliated with kink folds. Moderately to very slightly
weathered; weathering products extensively observed on sample
exterior (Grayish Brown, 5Y 8/4, to Pale Yellowish Orange, 10YR
8/6), and also observed in sample interior to a lesser extent. Interior
weathering products are parallel to foliation, some minor pitting
observed in sample interior.
Microscopic Description (two thin-sections):
Granoblastic textured bands consisting primarily of quartz with minor plagioclase (some primary, but most in the
form of porphyroblasts up to 7 mm in length), muscovite, minor biotite, equant to tabular pyrite/pyrrhotite (up to
0.2 mm), trace kyanite (as prophyroblasts up to 6 mm in length) and trace garnet intercalated and folded with
lepidoblastic textured bands consisting primarily of muscovite, quartz, and graphite layers and lenses containing
very fine-grained desiminated pyrite/pyrrhotite. Minor limonite occurs in both the granoblastic and lepidoblastic
layers along grain boundaries and in thin veins parallel to foliation. The bands/foliation are tightly folded and
kinked.
NOTE: Reasonable estimates of the mineral percentages was not possible because of interlayered granoblastic
bands and lepidoblastic bands, very large porphyroblasts of plagioclase and kyanite, and very fine-grained
minerals that are difficult to identify.
Granoblastic Layer Mineralogy:
Quartz - Undulatory extinction, sutured and embayed grain contacts.
Plagioclase (Oligoclase) - Occurs primarily as porphyroblasts, up to 7 mm in length, with inclusions of quartz,
garnet, and muscovite and in trace amounts as a primary mineral in the granoblastic groundmass.
Muscovite - Fine-grain interstitial to quartz and plagioclase grains.
Kyanite - Occurs as porphyroblasts up to 6 mm in length.
Pyrite/Pyrrhotite - In equant to tabular crystals aligned with the foliation.
Ilmenite - Tabular crystals and skeleton crystals parallel to foliation, trace.
Biotite - Pale brown, porphyroblastic. Trace amounts.
Garnet - Small euhedral garnets, minor amounts with additional growth rims.
Petrographic description continues on next page.
D-5
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 2 of 4
PETROGRAPHIC DESCRIPTION, continued
Lepidoblastic Layer Mineralogy:
Muscovite - Primary constituent of lepidoblastic layers, folded and kinked.
Quartz - Undulatory extinction, sutured and embayed grain contacts
Plagioclase (Oligoclase) - Trace.
Graphite - Layers and lenses parallel to foliation with finely disseminated pyrite/pyrrhotite.
Pyrite/Pyrrhotite - in equant to tabular crystals aligned within the foliation.
Ilmenite - Tabular crystals and skeleton cystals parallel to foliation.
Garnet - Small euhedral garnets, minor amounts with additional growth rims.
Zircon - Trace.
Apatite - Trace.
Secondary Minerals - Oxidation Products of Pyrite/Pyrrhotite
Limonite - Reddish brown in plane polarized light; orangeish-brown to brown in plane reflected
light.
Rock Type:
Graphitic Mica Schist
Origin:
Amphibolite grade metamorphism (regional) of a pelitic sedimentary rock deposited in a reducing
environment with the sulfur and carbon of syngenetic origin.
Prepared By:Date:
M. F. Schaeffer, LG June 23, 2017
Reviewed By: Date:
S. K. Townsend June 28, 2017
D-6
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 3 of 4
PHOTOMICROGRAPHS

Sample:AK-L8-A1-1
Lithology:Graphitic Mica Schist
Polarization State:Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite w/ Disseminated
Pyrite/Pyrrhotite
G = Garnet
Ky = Kyanite
Sample:AK-L8-A1-1
Lithology:Graphitic Mica Schist
Polarization State:Cross Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite w/ Disseminated
Pyrite/Pyrrhotite
G = Garnet
Ky = Kyanite
Sample:AK-L8-A1-1
Lithology:Graphitic Mica Schist
Polarization State:Plane Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite w/ Disseminated
Pyrite/Pyrrhotite
G = Garnet
Ky = Kyanite
D-7
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 4 of 4
PHOTOMICROGRAPHS
Sample:AK-L8-A1-2
Lithology:Graphitic Mica Schist
Polarization State:Plane Polarized Light
Mineral Identification Key:
P = Plagioclase (porphyroblast
with quartz inclusions)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
Ky = Kyanite (porphyroblast)
Sample:AK-L8-A1-2
Lithology:Graphitic Mica Schist
Polarization State:Cross Polarized Light
Mineral Identification Key:
P = Plagioclase (porphyoblast
with quartz inclusions)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
Ky = Kyanite (porphyroblast)
Sample:AK-L8-A1-2
Lithology:Graphitic Mica Schist
Polarization State:Plane Reflected Light
Mineral Identification Key:
P = Plagioclase (porphyoblast
with quartz inclusions)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
Ky = Kyanite (porphyroblast)
D-8
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No. : 10060948 066B
Page 1 of 4
PETROGRAPHIC DESCRIPTION
Location:NC Hwy 28 near intersection with Brush Creek Road, Macon County, NC
Sample #:AK-L8-B (Hand Sample)
Hand Sample Description:
Graphitic Mica Schist - moderately hard to hard, between medium
gray (N5) and medium bluish gray (5B 5/1), very fine to medium
grained, very thinly foliated with kink folds. Moderately to very
slightly weathered; weathering products extensively observed on
sample exterior (Grayish Brown, 5Y 8/4, to Pale Yellowish Orange,
10YR 8/6), and also observed in sample interior to a lesser extent.
Interior weathering products are parallel to foliation, some minor
pitting observed in sample interior.
Microscopic Description (one thin-section):
Granoblastic textured bands consisting primarily of quartz with minor plagioclase (some primary, but most in the
form of porphyroblasts up to 6 mm in length), muscovite, minor biotite, equant to tabular pyrite/pyrrhotite (up to
0.2 mm), trace kyanite (as prophyroblasts up to 10 mm in length) and trace garnet intercalated and folded with
lepidoblastic textured bands, consisting primarily of muscovite, quartz, and graphite layers and lenses containing
very fine-grained disseminated pyrite/pyrrhotite. Limonite and melanterite occurs throughout both the
granoblastic and lepidoblastic layers along grain boundaries and in thin veins parallel to foliation. The
melanterite also occurs in fibrous aggregates primarily in the coarser granoblastic layers. The layers/schist
foliation are tightly folded and kinked.
NOTE: Reasonable estimates of the mineral percentages was not possible because of interlayered granoblastic
bands and lepidoblastic bands, very large porphyroblasts of plagioclase and kyanite, and very fine-grained
minerals that are difficult to identify.
Granoblastic Layer Mineralogy:
Quartz - Undulatory extinction, sutured and embayed grain contacts.
Plagioclase (Oligoclase) - Occurs primarily as porphyroblasts, up to 6 mm in length, with inclusions of quartz
and muscovite and in trace amounts as a primary mineral in the gneissic groundmass.
Kyanite - Occurs as porphyroblasts up to 10 mm in length.
Muscovite - Fine-grain interstitial to quartz and plagioclase grains.
Pyrite/Pyrrhotite - In equant to tabular crystals aligned with the foliation.
Ilmenite - Tabular crystals and skeleton crystals parallel to foliation, trace.
Biotite - Pale brown, porphyroblastic. Trace amounts.
Garnet - Small euhedral garnets, minor amounts with additional growth rims.
Petrographic description continues on next page.
D-9
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 2 of 4
PETROGRAPHIC DESCRIPTION, continued
Lepidoblastic Layer Mineralogy:
Muscovite - Primary constituent of schistose layers, folded and kinked.
Quartz - Undulatory extinction, sutured and embayed grain contacts
Plagioclase (Oligoclase) - Trace.
Graphite - Layers and lenses parallel to foliation with finely disseminated pyrite/pyrrhotite.
Ilmenite - Tabular crystals and skeleton crystals parallel to foliation.
Pyrite/Pyrrhotite - In equant to tabular crystals aligned within the foliation.
Garnet - Small euhedral garnets, minor amounts with additional growth rims.
Rutile - Trace.
Zircon - Trace.
Apatite - Trace.
Secondary Minerals - Oxidation Products of Pyrite/Pyrrhotite
Limonite - Reddish brown in plane polarized light; orangeish-brown to brown in plane reflected
light.
Melanterite - Occurs as fibrous aggregates and along grain boundaries in both the granoblastic
and lepidoblastic layers. Pale yellow to white in plane reflected light.
Jarosite - In small equant, small, well-formed grains, pale yellow in plane polarized light.
Rock Type:
Graphitic Mica Schist
Origin:
Amphibolite grade metamorphism (regional) of a pelitic sedimentary rock deposited in a reducing
environment with the sulfur and carbon of syngenetic origin.
Prepared By:Date:
M. F. Schaeffer, LG June 23, 2017
Reviewed By:Date:
S.K. Townsend June 28, 2017
D-10
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 3 of 4
PHOTOMICROGRAPHS

Sample:AK-L8-B-1 (Lepidoblastic
Layer)
Lithology:Graphitic Mica Schist
Polarization State:Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Py = Pyrite/Pyrrhotite
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
Il = Ilmenite
Me = Melanterite
Sample:AK-L8-B-1 (Lepidoblastic
Layer)
Lithology:Graphitic Mica Schist
Polarization State:Cross Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Py = Pyrite/Pyrrhotite
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
Il = Ilmenite
Me = Melanterite
Sample:AK-L8-B-1 (Lepidoblastic
Layer)
Lithology:Graphitic Mica Schist
Polarization State:Plane Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Py = Pyrite/Pyrrhotite
Gr = Graphite w/ disseminated
Pyrite/Pyrrhotite
Il = Ilmenite
Me = Melanterite
D-11
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Page 4 of 4
PHOTOMICROGRAPHS
Sample:AK-L8-B-2 (Granoblastic Layer)
Lithology:Graphitic Mica Schist
Polarization State:Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
L = Limonite
Sample:AK-L8-B-2 (Granoblastic Layer)
Lithology:Graphitic Mica Schist
Polarization State:Cross Polarized Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
L = Limonite
Sample:AK-L8-B-2 (Granoblastic Layer)
Lithology:Graphitic Mica Schist
Polarization State:Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
(porphyroblast)
M = Muscovite
Q = Quartz
Gr = Graphite w/ disseminated
pyrite/pyrrhotite
L = Limonite
D-12

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

E
Appendix E. Nantahala
Formation Petrographic
Analysis Reports

Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Location:Winding Stairs Gap Road, Macon County, NC
Sample #:NF-2-1 (Hand Sample)
Hand Sample Description:
Microscopic Description (one thin-section):
Quartz - Undulatory extinction, coarser grained than groundmass quartz, in layers and random crystals.
Hematite - Red, translucent.
Prepared By:Date:
M. F. Schaeffer, LG
Sept. 5, 2017
Reviewed By:Date:
S.K. Townsend Sept. 23, 2017
Pyrite - Equant to tabular crystals, 0.01 to 0.15 mm, randomly oriented. Unweathered.
Biotite - Pale brown, porphyroblastic.
Garnet - Subhedral to euhedral, fractured crystals up to 0.5 mm.
PETROGRAPHIC DESCRIPTION
Lepidoblastic texture with a very fine-grained groundmass consisting primarily of quartz, muscovite and minor
graphite with scattered larger quartz and pyrite crystals, porphyroblasts of biotite, and minor garnet. Fractures
and anastomosing fractures, both parallel and at an angle with the layering, with Fe-oxides (hematite) and Fe-
staining occur through the thin-section.
NOTE: Reasonable estimates of the mineral percentages were not possible because of the very-fine-grained
groundmass and porphyroblasts of biotite and garnet.
Groundmass - Very fine-grained quartz and muscovite with minor, trace graphite.
Mineralogy:
Metasiltstone - hard, medium gray (N6) with light gray (N7)
laminations, very fine- to fine-grained with slightly coarser layers
consisting primarily of quartz, thinly laminated, very slightly
weathered on the outside of the sample, pale brown (5YR 5/2) to
grayish orange pink (5YR 7/2) to grayish yellow (5Y 8/4) due to iron
staining.
Page 1 of 2
E-2
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B

PHOTOMICROGRAPHS
Sample: NF-2-1
Lithology: Metasiltstone
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to iron-oxides
Q = Quartz
M = Muscovite
Py = Pyrite
Gm = Groundmass consisting primarily of
Quartz-Muscovite with minor graphite.
Sample: NF-2-1
Lithology: Metasiltstone
Polarization State: Cross Polarized Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to
Iron Oxides
Q = Quartz
M = Muscovite
Py = Pyrite
Gm = Groundmass consisting
primarily of Quartz-Muscovite
Sample: NF-2-1
Lithology: Metasiltstone
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to
Iron Oxides
Q = Quartz
M = Muscovite
Py = Pyrite
Gm = Groundmass consisting
primarily of Quartz-Muscovite
Page 2 of 2
E-3
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Location:Winding Stairs Gap Road, Macon County, NC
Sample #:NF-3-3 (Hand Sample)
Hand Sample Description:
Microscopic Description (one thin-section):
Quartz - Undulatory extinction, coarser-grained than groundmass quartz, in layers and random crystals.
Limonite - Reddish brown in plane polarized light, orangish brown to yellow in reflected light.
Prepared By:Date:
M. F. Schaeffer, LG
Sept. 5, 2017
Reviewed By:Date:
S.K. Townsend Sept. 23, 2017
Pyrite - Equant to tabular crystals, 0.03 to 0.25 mm, randomly oriented. Unaltered.
Biotite - Pale brown, porphyroblastic.
Hematite - Red, translucent.
PETROGRAPHIC DESCRIPTION
Lepidoblastic texture with a very fine-grained groundmass consisting primarily of quartz, muscovite and minor
graphite with scattered larger quartz and pyrite crystals with porhyroblasts of biotite. The coarser quartz-rich
layers have weathered iron-oxides (hematite) and limonite.
NOTE: Reasonable estimates of the mineral percentages were not possible because of the very-fine-grained
groundmass and porphyroblasts of biotite and garnet.
Groundmass - Very fine-grained quartz and muscovite with minor, trace graphite.
Mineralogy:
Metasiltstone - hard, medium gray (N6) with pale yellowish brown
(10YR 6/2) layers, fine-grained with slightly coarser layers
consisting primarily of quartz and biotite, thinly laminated, slightly
weathered on the outside of the sample, pale brown (5YR 5/2) to
grayish brown (5YR 3/2). Weathering extends about 3 to 5 mm into
the interior of the hand sample.
Page 1 of 2
E-4
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B

PHOTOMICROGRAPHS
Sample: NF-3-3
Lithology: Metasiltstone
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to iron-oxides
M = Muscovite
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting
primarily of Quartz-Muscovite
with minor graphite.
Sample: NF-3-3
Lithology: Metasiltstone
Polarization State: Cross Polarized Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to iron-oxides
M = Muscovite
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting primarily of
Quartz-Muscovite with minor graphite.
Sample: NF-3-3
Lithology: Metasiltstone
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
Bw = Biotite altering to iron-oxides
M = Muscovite
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting primarily
of Quartz-Muscovite with minor graphite.
Page 2 of 2
E-5
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
Location:Winding Stairs Gap Road, Macon County, NC
Sample #:NF-4-1 (Hand Sample)
Hand Sample Description:
Microscopic Description (one thin-section):
Biotite - Pale brown, trace.
Hematite - Red, translucent.
Limonite - Reddish brown in plane polarized light, orangish brown to yellow in reflected light.
Prepared By:Date:
M. F. Schaeffer, LG Sept. 5, 2017
Reviewed By:Date:
S.K. Townsend Sept. 23, 2017
Lepidoblastic texture with a very fine-grained groundmass consisting primarily of quartz, muscovite and minor
graphite with larger quartz grains and trace biotite. Rock has an anastomosing shear fabric basically paralled
to the layering and the foliation defined by the fine-grained muscovite-quartz is folded in places. Pyrite
crystallized post shear fabric. The disrupted coarser quartz-rich layers have minor Fe-oxides (hematite) and
limonite.
PETROGRAPHIC DESCRIPTION
Metasiltstone - hard, interlayered medium dark gray (N4), very fine-
grained layers with very light gray ((N8) to light gray (N7) fine- to
medium-grained layers (quartz-rich), thickly laminated, slightly
weathered on the outside of the sample and along layers within the
sample to moderate yellowish brown (10YR 5/4) to dark reddish
brown (19R 3/4) into the interior of the hand sample.
Pyrite - Equant to tabular crystals, 0.03 to 0.25 mm, randomly oriented to parallel to shear fabric.
Mineralogy:
Quartz - Undulatory extinction, coarser-grained than groundmass quartz, in layers, generally oriented parallel
to the shear fabric.
Groundmass - Very fine-grained quartz and muscovite with minor, trace graphite.
NOTE: Reasonable estimates of the mineral percentages were not possible because of the very-fine-grained
groundmass and porphyroblasts of biotite and garnet.
Page 1 of 2
E-6
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Rock Spoil Investigation
Job No.: 10060948 066B
PHOTOMICROGRAPHS
Sample: NF-4-1
Lithology: Metasiltstone
Polarization State: Plane Polarized Light
Mineral Identification Key:
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting primarily of
Quartz-Muscovite with minor graphite.
Sample: NF-4-1
Lithology: Metasiltstone
Polarization State: Cross Polarized Light
Mineral Identification Key:
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting primarily of
Quartz-Muscovite with minor graphite.
Sample: NF-4-1
Lithology: Metasiltstone
Polarization State: Plane Reflected Light
Mineral Identification Key:
Q = Quartz
Py = Pyrite
Gm = Groundmass consisting primarily of
Quartz-Muscovite with minor graphite.
Page 2 of 2
E-7

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

F
Appendix F. Crystal Size
Comparison of Anakeesta
Formation and Tallulah
Falls Formation
Lithologies –
Photomicrographs and
HDR (2017) Petrographic
Analysis Reports

Page 1 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-2) versus Garnet Mica Schist (B-4-T1A-1)
Plane Polarized Light Comparison
Sample ID: AK-L7-B1-2
Sample Location: NC Highway 28, South of sample Location 8, Macon County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-4-T1A-1
Sample Location: Left Abutment of Cedar Cliff Dam, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Py = Pyrite
F-2
Page 2 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-2) versus Garnet Mica Schist (B-4-T1A-1)
Crossed Polarized Light Comparison
Sample ID: AK-L7-B1-2
Sample Location: NC Highway 28, South of sample Location 8, Macon County, NC
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-4-T1A-1
Sample Location: Left Abutment of Cedar Cliff Dam, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Py = Pyrite
F-3
Page 3 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-2) versus Garnet Mica Schist (B-4-T1A-1)
Reflected Light Comparison
Sample ID: AK-L7-B1-2
Sample Location: NC Highway 28, South of sample Location 8, Macon County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-4-T1A-1
Sample Location: Left Abutment of Cedar Cliff Dam, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Py = Pyrite
F-4
Page 4 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B2) versus Sillimanite Garnet Mica Schist (B-9I-T2-2)
Plane Polarized Light Comparison
Sample ID: AK-L8-B2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-9I-T2-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
F-5
Page 5 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B2) versus Sillimanite Garnet Mica Schist (B-9I-T2-2)
Crossed Polarized Light Comparison
Sample ID: AK-L8-B2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-9I-T2-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
F-6
Page 6 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B2) versus Sillimanite Garnet Mica Schist (B-9I-T2-2)
Reflected Light Comparison
Sample ID: AK-L8-B2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-9I-T2-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
G = Garnet
F-7
Page 7 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B-1) versus Biotite Gneiss (B-10I-T1-1)
Plane Polarized Light Comparison
Sample ID: AK-L8-B-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-10I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Z = Zircon
F-8
Page 8 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B-1) versus Biotite Gneiss (B-10I-T1-1)
Crossed Polarized Light Comparison
Sample ID: AK-L8-B-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-10I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Z = Zircon
F-9
Page 9 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-B-1) versus Biotite Gneiss (B-10I-T1-1)
Reflected Light Comparison
Sample ID: AK-L8-B-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-10I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Garnet Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Z = Zircon
F-10
Page 10 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-2) versus Gneissic Biotite Schist (B-11I-T4-1)
Plane Polarized Light Comparison
Sample ID: AK-L8-A2-2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Py = Pyrite
F-11
Page 11 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-2) versus Gneissic Biotite Schist (B-11I-T4-1)
Crossed Polarized Light Comparison
Sample ID: AK-L8-A2-2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Py = Pyrite
F-12
Page 12 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-2) versus Gneissic Biotite Schist (B-11I-T4-1)
Reflected Light Comparison
Sample ID: AK-L8-A2-2
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
G = Garnet
Py = Pyrite
F-13
Page 13 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-1) versus Gneissic Biotite Schist (B-11I-T4-2)
Plane Polarized Light Comparison
Sample ID: AK-L8-A2-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
Q = Quartz
Py = Pyrite
Ap = Apatite
F-14
Page 14 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-1) versus Gneissic Biotite Schist (B-11I-T4-2)
Crossed Polarized Light Comparison
Sample ID: AK-L8-A2-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
B = Biotite
Q = Quartz
Py = Pyrite
Ap = Apatite
F-15
Page 15 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L8-A2-1) versus Gneissic Biotite Schist (B-11I-T4-2)
Reflected Light Comparison
Sample ID: AK-L8-A2-1
Sample Location: NC Highway 28, South of intersection with Brush Creek Road, Macon
County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
G = Garnet
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Py = Pyrite
Sample ID: B-11I-T4-2
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Gneissic Biotite Schist
Polarization State: Reflected Light
Mineral Identification Key:
B = Biotite
Q = Quartz
Py = Pyrite
Ap = Apatite
F-16
Page 16 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-1) versus Schistose Biotite Gneiss (B-14-T1-1)
Plane Polarized Light Comparison
Sample ID: AK-L7-B1-1
Sample Location: NC Highway 28, South of Sample Location 8, Macon County, NC
Lithology: Graphitic Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-14I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
F-17
Page 17 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-1) versus Schistose Biotite Gneiss (B-14I-T1-1)
Crossed Polarized Light Comparison
Sample ID: AK-L7-B1-1
Sample Location: NC Highway 28, South of Sample Location 8, Macon County,
Lithology: Graphitic Mica Schist
Polarization State: Crossed Polarized Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-14I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Schistose Biotite Gneiss
Polarization State: Crossed Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
F-18
Page 18 of 18
Crystal Size Comparison: Graphitic Mica Schist (AK-L7-B1-1) versus Schistose Biotite Gneiss (B-14I-T1-1)
Reflected Light Comparison
Sample ID: AK-L7-B1-1
Sample Location: NC Highway 28, South of Sample Location 8, Macon County, NC
Lithology: Graphitic Mica Schist
Polarization State: Reflected Light
Mineral Identification Key:
M = Muscovite
Q = Quartz
Gr = Graphite with very fine-grained pyrite/phyrrhotite
Sample ID: B-14I-T1-1
Sample Location: East of Cedar Cliff Auxiliary Spillway, Jackson County, NC
Lithology: Schistose Biotite Gneiss
Polarization State: Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
P = Plagioclase
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
F-19
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:B-4-T1 Depth:
Rock Core Description:
Microscopic Description (two thin-sections):
Muscovite - ~30%, coarse grain size.
Quartz - ~15%, Undulatory extinction.
Apatite - Trace.
Zircon - ~0.5%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Garnet Mica Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 27, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - ~10% (Microcline).
31.2' to 31.55'
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar
layers.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Garnet Mica Schist: Very Light Gray (N8) and Dark
Gray (N3), Moderately Hard, Medium Grained, Very
Thinly Banded and Foliated. Medium to Coarse
Grained Garnets.
PETROGRAPHIC DESCRIPTION
Garnet - ~2%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz,
minor feldspar, minor pyrite. Larger grains fractured, bounded by more or less regular faces.
Plagioclase (Oligoclase) - 10%, anhedral.
Pyrite - ~2%, Equant (0.05 to 0.75 mm) to elongate grains (0.5 to 1.5 mm length) subparallel to
schistosity.
Page 1 of 2
F-20
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
PHOTOMICROGRAPHS
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Cross Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Page 2 of 2
F-21
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Muscovite - ~20%, coarse grain size.
Quartz - ~20%, Undulatory extinction.
Pyrite - ~6%, Equant (0.05 to 1.0 mm) to elongate grains (0.5 to 1.5 mm length) subparallel to schistosity.
Apatite - Trace.
Zircon - ~>0.5%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Rock Type:
Sillimanite Garnet Mica Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 28, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
PETROGRAPHIC DESCRIPTION
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
B-9I-T2 90.2' to 90.7'
Garnet Mica Schist: Light Gray
(N7) to Medium Gray (N5), Hard,
Fine to Medium Grained, Very
Thinly Foliated. Medium Grained
Garnets.
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers.
Biotite - ~25%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Plagioclase (Oligoclase) - 5%, anhedral.
Alkali Feldspar - ~10% (Microcline?).
Garnet - ~3%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor
feldspar, minor pyrite. Larger grains fractured, bounded by more or less regular faces.
Sillimanite - ~10%, sheeves and fine needles dispersed with quartz, replacing muscovite.
Page 1 of 2
F-22
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
PHOTOMICROGRAPHS
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Cross Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Page 2 of 2
F-23
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Quartz - ~25%, Undulatory extinction.
Apatite - Trace.
Zircon - ~0.1%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Garnet Mica Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 28, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
PETROGRAPHIC DESCRIPTION
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
B-10I-T1 27.1' to 27.5'
Lepidoblastic texture with schistosity defined by subparallel biotite and quartz-feldspar layers.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Garnet Mica Schist: Grayish
Black (N2), Fine to Coarse
Grained, Very Thinly Foliated
(50°). Trace Pyrite. Minor Fe-
Staining Primarily Restricted to
Schistose Layers. With coarser
grained quartz-feldspar-rich
lenses.
Plagioclase (Oligoclase) - Trace.
Alkali Feldspar - ~25% (Microcline or Orthoclase?).
Garnet - ~3%, up to 6 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor
feldspar, minor pyrite. Larger grains fractured, bounded by more or less regular faces.
Pyrite - ~6%, Equant (0.2 to 0.75 mm) to elongate grains (0.5 to 1.75 mm length) subparallel to schistosity.
Muscovite - ~10%, coarse grain size. Late stage growth indicated by poikiloblastic structure with inclusions
of pyrite, zircon, and apatite.
F-24
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Quartz - ~25%, Undulatory extinction with sutured grain contacts.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Gneissic Biotite Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 28, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
PETROGRAPHIC DESCRIPTION
Pyrite - ~4%, Equant (0.1 to 1.0 mm) to elongate grains (0.3 to 1.0 mm length) subparallel to schistosity.
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
B-11I-T4 151.15' to 151.5'
Mica Schist: Dark Gray (N3),
Moderately Hard, Fine to Medium
Grained, Very Thinly Foliated.
Granoblastic texture with a weak schistosity defined by subparallel biotite and quartz-feldspar layers.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Muscovite - ~20%, coarse grain size. Late stage growth indicated by poikiloblastic structure with inclusions of
biotite, quartz, and apatite and growth across schistosity defined by biotite.
Plagioclase (Oligoclase) - ~5%, anhedral.
Alkali Feldspar - ~15% (Microcline or Orthoclase?).
F-25
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Quartz - ~15%, undulatory extinction, sutured grain contacts.
Muscovite - 5%, coarse grain size.
Apatite - Trace.
Zircon - Trace.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Schistose Biotite Gneiss
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 29, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
B-14I-T1 58.25' to 58.55'
Schistose Biotite Gneiss: Medium
Dark Gray (N4) to Dark Gray
(N3), Hard, Fine to Medium
Grained, Very Thinly Foliated.
Lepidoblastic with schistosity defined by bands of biotite/muscovite and separated by quartz-feldspar layers
with the grains showing an overall elongation along the foliation defined by the schistosity.
PETROGRAPHIC DESCRIPTION
Upper amphibolite grade metamorphism (regional) of an arenaceous sedimentary rock (greywacke).
Plagioclase (Oligoclase) - 30%, anhedral.
Biotite - ~20%, brown to reddish brown.
Alkali Feldspar - ~20% (Microcline), anhedral.
Myrmekite - ~2%, quartz intergrown with plagioclase.
Pyrite - ~7%, Equant (0.05 to 1.0 mm) to elongate grains (0.3 to 1.5 mm length) subparallel to the
schistosity defined by biotite.
Page 1 of 2
F-26
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
PHOTOMICROGRAPHS
Sample: B-14I-T1
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Sample: B-14I-T1
Lithology: Schistose Biotite Gneiss
Polarization State: Cross Polarized Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Sample: B-14I-T1
Lithology: Schistose Biotite Gneiss
Polarization State: Plane Reflected Light
Mineral Identification Key:
P = Plagioclase
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
S = Sphene
Page 2 of 2
F-27

Cedar Cliff Rock Spoil Evaluation
East Fork Hydroelectric Project and Cedar Cliff Development (FERC No. 2698)

G
Appendix G. Crystal Size
Comparison of Nantahala
Formation and Tallulah
Falls Formation
Lithologies –
Photomicrographs and
HDR (2017) Petrographic
Analysis Reports

Page 1 of 3
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Page 3 of 3
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:B-4-T1 Depth:
Rock Core Description:
Microscopic Description (two thin-sections):
Muscovite - ~30%, coarse grain size.
Quartz - ~15%, Undulatory extinction.
Apatite - Trace.
Zircon - ~0.5%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Garnet Mica Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG March 27, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
Alkali Feldspar - ~10% (Microcline).
31.2' to 31.55'
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar
layers.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Garnet Mica Schist: Very Light Gray (N8) and Dark
Gray (N3), Moderately Hard, Medium Grained, Very
Thinly Banded and Foliated. Medium to Coarse
Grained Garnets.
PETROGRAPHIC DESCRIPTION
Garnet - ~2%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz,
minor feldspar, minor pyrite. Larger grains fractured, bounded by more or less regular faces.
Plagioclase (Oligoclase) - 10%, anhedral.
Pyrite - ~2%, Equant (0.05 to 0.75 mm) to elongate grains (0.5 to 1.5 mm length) subparallel to
schistosity.
Page 1 of 2
G-11
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
PHOTOMICROGRAPHS
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Cross Polarized Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Sample: B-4-T1A
Lithology: Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
P = Plagioclase
Page 2 of 2
G-12
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Muscovite - ~20%, coarse grain size.
Quartz - ~20%, Undulatory extinction.
Pyrite - ~6%, Equant (0.05 to 1.0 mm) to elongate grains (0.5 to 1.5 mm length) subparallel to schistosity.
Apatite - Trace.
Zircon - ~>0.5%, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Rock Type:
Sillimanite Garnet Mica Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 28, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
PETROGRAPHIC DESCRIPTION
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
B-9I-T2 90.2' to 90.7'
Garnet Mica Schist: Light Gray
(N7) to Medium Gray (N5), Hard,
Fine to Medium Grained, Very
Thinly Foliated. Medium Grained
Garnets.
Lepidoblastic texture with schistosity defined by subparallel muscovite, biotite, and quartz-feldspar layers.
Biotite - ~25%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Plagioclase (Oligoclase) - 5%, anhedral.
Alkali Feldspar - ~10% (Microcline?).
Garnet - ~3%, up to 4 mm, poikiloblastic with many inclusions of fine-grained biotite and quartz, minor
feldspar, minor pyrite. Larger grains fractured, bounded by more or less regular faces.
Sillimanite - ~10%, sheeves and fine needles dispersed with quartz, replacing muscovite.
Page 1 of 2
G-13
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
PHOTOMICROGRAPHS
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Plane Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Cross Polarized Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Sample: B-9I-T2
Lithology: Sillimanite Garnet Mica Schist
Polarization State: Plane Reflected Light
Mineral Identification Key:
A = Alkali Feldspar
B = Biotite
M = Muscovite
Q = Quartz
Py = Pyrite
Si = Sillimanite
Page 2 of 2
G-14
Site: East Fork Hydroelectric Project - Cedar Cliff
Project: Subsurface Investigation
Job No.: 10020225 063
Location:Jackson County, North Carolina
Sample #:Depth:
Rock Core Description:
Microscopic Description (one thin-section):
Quartz - ~25%, Undulatory extinction with sutured grain contacts.
Apatite - Trace.
Zircon - Trace, occurs primarily as inclusions surrounded by pleochroic haloes in biotite.
Sphene - Trace.
Kyanite - Trace.
Rock Type:
Gneissic Biotite Schist
Origin:
Prepared By:Date:
M. F. Schaeffer, LG
March 28, 2017
Reviewed By: Date
S.K. Townsend April 5, 2017
PETROGRAPHIC DESCRIPTION
Pyrite - ~4%, Equant (0.1 to 1.0 mm) to elongate grains (0.3 to 1.0 mm length) subparallel to schistosity.
Upper amphibolite grade metamorphism (regional) of an argillaceous sedimentary rock.
B-11I-T4 151.15' to 151.5'
Mica Schist: Dark Gray (N3),
Moderately Hard, Fine to Medium
Grained, Very Thinly Foliated.
Granoblastic texture with a weak schistosity defined by subparallel biotite and quartz-feldspar layers.
Biotite - ~30%, brown to reddish brown, coarse grain size has pleochroic inclusions of zircon.
Muscovite - ~20%, coarse grain size. Late stage growth indicated by poikiloblastic structure with inclusions of
biotite, quartz, and apatite and growth across schistosity defined by biotite.
Plagioclase (Oligoclase) - ~5%, anhedral.
Alkali Feldspar - ~15% (Microcline or Orthoclase?).
G-15