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Ver - Keowee-Toxaway-2503-PAD-Vol-II-110315 - 3/11/2015
KEOWEE- TOXAWAY RELICENSING FERC PROJECT NO. 2503 Pre - Application Document VOLUME II OF VIII SECTION 6.1 IDuke Energy,, Prepared For: Duke Energy Carolinas, LLC Charlotte, North Carolina March 2011 © Duke Energy Carolinas, LLC For copies of this Pre - Application Document, contact: Ms. Jennifer Huff Duke Energy Carolinas, LLC EC12Y, PO Box 1006 Charlotte, North Carolina 28201 -1006 Phone: 980 - 373 -4392 E -Mail: ktrelicensing&duke- energy.com Table of Contents VOL UME II OF VIII ACRONYMS, ABBREVIATIONS, AND DEFINITIONS ............................... VI 6.0 DESCRIPTION OF EXISTING ENVIRONMENTAL RESOURCES AND POTENTIAL RESOURCE IMPACTS ................. ..............................I 6.1 Geology and Soils ........................................................................... ..............................1 6.1.1 Jocassee Development Geology ......................................... ..............................8 6.1.2 Keowee Development Geology ......................................... .............................12 6.1.3 Seismicity .......................................................................... .............................13 6.1.4 Economic Minerals ............................................................ .............................18 6.1.5 Soils ................................................................................... .............................18 6.1.5.1 Lake Jocassee ...................................................... .............................19 6.1.5.2 Lake Keowee ....................................................... .............................23 6.1.5.3 Reservoir Shoreline Conditions .......................... .............................23 VOL UME I OF VIII CROSS - REFERENCE INDEX ACRONYMS AND ABBREVIATIONS EXECUTIVE SUMMARY 1.0 INTRODUCTION AND BACKGROUND 2.0 PURPOSE OF THE PRE- APPLICATION DOCUMENT 2.1 Search for Available, Relevant Information 2.2 Consultation Process 3.0 PROCESS PLAN, SCHEDULE, AND PROTOCOLS 3.1 Overall Process Plan and Schedule 3.2 Scoping Meeting and Site Visit 3.3 ILP Participation 3.4 Proposed Communication Protocol 3.5 Relicensing Teams 3.6 Consultation Guidelines 4.0 PROJECT LOCATION, FACILITIES, AND OPERATIONS 4.1 Applicant Contact Information 4.2 Project Location and Lands: North and South Carolina 4.3 Project Facilities: North and South Carolina 4.4 Summary of Project Generation and Flows 4.5 Current Operations 4.6 Proposed Operations 4.7 Proposed New Facilities 4.8 Other Project Information Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Table of Contents (continued) 5.0 GENERAL DESCRIPTION OF RIVER BASIN 5.1 Keowee River Watershed 5.2 Project Geography 5.3 Tributary Information 5.4 Land Use and Water Use VOL UME III OF VIII 6.2 Water Resources VOL UME IV OF VIII 6.3 Fish and Aquatic Resources VOL UME V OF VIII 6.4 Wildlife and Botanical Resources 6.5 Recreation, Land Use and Shoreline Management 6.6 Aesthetic Resources 6.7 Cultural Resources 6.8 Socioeconomic Resources 6.9 Tribal Resources and Interests VOL UME VI OF VIII 7.0 PRELIMINARY ISSUES AND STUDIES LIST 7.1 Summary of Existing Data 7.2 Project Effects 7.3 Proposed Studies 8.0 COMPREHENSIVE PLANS RELEVANT TO THE PROJECT 8.1 Qualifying Comprehensive Plans Deemed Relevant 8.2 Qualifying Comprehensive Plans Deemed Not Relevant 9.0 SUMMARY OF CONTACTS 10.0 LITERATURE CITED APPENDICES APPENDIX A - CONTACT AND DISTRIBUTION LIST APPENDIX B - EXISTING LICENSE ARTICLES APPENDIX C - CEII MAPS AND DRAWINGS (Located in Volume VII) APPENDIX D - DRAFT STUDY PLANS Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Table of Contents (continued) APPENDIX E - CONSULTATION RECORDS (Located in Volume VIII) APPENDIX F - FISHERY RESOURCES MOU AND 10 -YEAR WORK PLANS APPENDIX G - 1968 AGREEMENT BETWEEN DUKE, USACE, AND SEPA APPENDIX H - PLAN DEVELOPMENT PROCESS DESCRIPTIONS VOL UME VII OF VIII [CONTAINS CEII MATERIAL - NOT RELEASED TO THE PUBLIC] APPENDIX C - CEII MAPS AND FIGURES VOL UME VIII OF VIII APPENDIX E - CONSULTATION RECORDS E1 PAD QUESTIONNAIRES - STAKEHOLDER TEAM INVITATIONS E2 DUKE ENERGY - GENERAL COMMUNICATIONS E3 FEDERAL AGENCIES E4 STATE AGENCIES E5 LOCAL GOVERNMENTS E6 NON - GOVERNMENTAL ORGANIZATIONS E7 STAKEHOLDER TEAM E8 JOINT RESOURCE COMMITTEE E9 AQUATIC RESOURCE COMMITTEE E10 CULTURAL RESOURCES RESOURCE COMMITTEE Ell RECREATION RESOURCE COMMITTEE E12 SHORELINE MANAGEMENT PLAN RESOURCE COMMITTEE E13 WATER QUALITY RESOURCE COMMITTEE E14 WATER QUANTITY AND OPERATIONS RESOURCE COMMITTEE E15 WILDLIFE - BOTANICAL RESOURCE COMMITTEE E16 USACE SEPA PROJECT DELIVERY TEAM Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Figure 6.1 -1 Figure 6.1 -2 Figure 6.1 -3 Figure 6.1.3 -1 Figure 6.1.5 -1 Figure 6.1.5 -2 Figure 6.1.5 -3 Figure 6.1.5.3 -1 Figure 6.1.5.3 -2 Figure 6.1.5.3 -3 Figure 6.1.5.3 -4 Figure 6.1.5.3 -5 List of Geologic features map (Sheet 1 of 3) .................................... ..............................9 Geologic features map (Sheet 2 of 3) ................................... .............................10 Geologic features map (Sheet 3 of 3) ................................... .............................11 Seismic hazard and major earthquake location map ............ .............................15 Soils map (Sheet 1 of 3) ....................................................... .............................20 Soilsmap (Sheet 2 of 3) ....................................................... .............................21 Soils map (Sheet 3 of 3) ....................................................... .............................22 Wind Rose of ONS 1 O level Winds (1986 -2009) and Summary Wind Direction Frequency Plot ..................................................... .............................29 Spring and Summer 10m Wind Direction Frequency (ONS; 1986- 2009)........31 Autumn and Winter 10m Wind Direction Frequency (ONS; 1986- 2009)........32 ONS IOm Wind Speed Frequency Distribution ( 1986- 2009 ) ...........................33 Average Hourly Wind Speed versus Wind Direction Distribution ................... 34 II -iv Pre- Application Document Keowee - Toxaway Project (FERC No. 2503) List of Tables Table 6.1.5.3 -1 Seasonal and Total Wind Direction Frequency with Hourly Average Wind Speed(mph) ......................................................................... .............................30 Table 6.1.5.3 -2 Wind Speed Class Frequency: ONS lOm level (1986 -2009) ..........................33 II -v Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) ACRONYMS, ABBREVIATIONS, AND DEFINITIONS A ampere AAII Access Area Improvement Initiative Abutment The valley wall that supports the end of a dam or embankment ac acres AC Alternating current ac -ft acre -foot, the amount of water needed to cover one acre to a depth of one foot (325,853 gallons) ADA Americans with Disabilities Act AMSL above mean sea level APE Area of Potential Effect BIA Bureau of Indian Affairs BMP Best Management Practices BOD Biological Oxygen Demand BOR Bureau of Outdoor Recreation °C Degrees Centigrade CEII Critical Energy Infrastructure Information CFR Code of Federal Regulations cf cubic foot / cubic feet cfs cubic feet per second CHEOPS Computerized Hydro Electric Operations Planning Software Clark Hill Project Original name of the J. Strom Thurmond Project cm centimeters Creel Survey A survey conducted to determine the type and size of sport fish caught during a given period and the associated angler satisfaction CRRC Cultural Resources Resource Committee CWA Clean Water Act D Day II -vi Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations dbh diameter at breast height DC Direct Current DEM Digital Elevation Model Distribution System The substations, transformers, and lines that convey electricity from high -power transmission lines to the consumer DO Dissolved Oxygen DTA Devine Tarbell & Associates, Inc. Duke or Duke Energy The Licensee for the Project, Duke Energy Carolinas, LLC, including all predecessor licensees EBCI Eastern Band of Cherokee Indians EFH Essential Fish Habitat as designated by the regulations guide for Council Species (National Marine Fisheries Service) and the Magnuson Stevens Fishery Conservation Act EIS Environmental Impact Statement EPA U.S. Environmental Protection Agency Epilimnion The epilimnion is the freely circulating surface water of a lentic (standing water) ecosystem. ESA Endangered Species Act ESRI Environmental Systems Research Institute Eutrophic Describing a lake or reservoir with an abundant supply of nutrients stimulating excessive algae growth. The decomposition of this organic matter depletes the dissolved oxygen content. Existing License The license document as issued to Duke for the Keowee- Toxaway Hydroelectric Project (FERC Project No. 2503) with an effective date of September 1, 1966, and including all license amendments that have occurred since that time. The Existing License is effectively a contract between Duke and the FERC that provides requirements relative to Duke's operation of the Project through the license expiration date of August 31, 2016, unless extended by an annual license(s). OF Degrees Fahrenheit II -vii Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations FEMA Federal Emergency Management Agency FERC Federal Energy Regulatory Commission FERC Project Boundary The area surrounding hydro project facilities and features GPD as delineated in Exhibit G or originally Exhibit K of the gpm FERC license. FOLKS Friends of Lake Keowee Society Forebay The reservoir area immediately upstream from the hydro project powerhouse, from which water is drawn into a Governor tunnel or penstock for delivery to the powerhouse. FPA Federal Power Act FPC Federal Power Commission, the predecessor to the FERC full pond see definition for Normal Full Pond Elevation ft foot / feet FW Freshwater g gram GA EPD Georgia Environmental Protection Division GIS Geographic Information System GPD gallons per day gpm gallons per minute GPS Global Positioning System Generator A machine powered by a turbine that produces electric current Governor Device that adjusts the water flow through the turbine to control speed and maintain system frequency GSU Generator Step -Up - descriptive of an electrical power transformer GWS Greenville Water System ha Hectare Head Hydraulic head is the vertical distance between the water surface elevation of a reservoir and the water surface elevation at the tailrace of a hydro station HEC- ResSim Hydrologic Engineering Center Reservoir Simulation hp Horsepower II -viii Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations HP Historic Properties HPMP Historic Properties Management Plan hr Hour HUC Hydrologic Unit Code Hydrograph Characteristics of flow volume, velocity, and other hydrologic characteristics of a stream over a period of time, or a graph showing these characteristics Hypolimnion The layer of water in a thermally stratified lake that remains cold year round Hz Hertz (cycles per second) ILP Integrated Licensing Process IMZ Impact Minimization Zone in. Inch Installed Capacity The total generating capacity of the generating units in a hydroelectric plant JD jurisdictional determination JPSS Jocassee Pumped Storage Station Kg Kilograms Km Kilometers KT Keowee - Toxaway kV kilovolts: 1,000 volts kVA kilovolt amperes kW kilowatts: 1,000 watts kWh kilowatt -hour: 1,000 watt -hours L Liter LA /FLA (Final) License Application LED light- emitting diode Limnetic Zone The region of a reservoir or lake beyond the shore region (littoral zone) in open water LIP Low Inflow Protocol Littoral Zone Region of a lake or reservoir along the shore M Meter II -ix Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations Ma million years ago Macroinvertebrates Large or exceptionally prominent animals that lack a spinal column (e.g., mayflies, grasshoppers) Mandatory Conditioning Authority Authority of certain federal resource agencies under Sections 4(e) and 18 of the FPA and state water quality agencies under Section 401 of the CWA MEI Morphoedaphic Index (total dissolved solids per mean depth) Mesotrophic A reservoir or lake with an abundant supply of nutrients and a high rate of formation of organic matter by photosynthesis µ micro µgChla /L Micrograms of Chlorophyll a per Liter µg /L Micrograms per liter µtmho /cm Micromohls per centimeter, a measurement of conductivity meq /L Milliequivalents per liter, a measurement of concentration as one thousandth of gram equivalent weight of solute per liter of solution MEI Morphoedaphic Index Meq /L milli - equivalent per liter MGD Million gallons per day MGM Million gallons per month mg /L Milligrams per liter Mg/M3 milligram per cubic meter mi Mile min Minute misc. Miscellaneous mL milliliter mm millimeters mph miles per hour ms millisecond m/s meters per second II -x Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations MMI Modified Mercalli Intensity MOA Memorandum of Agreement MOU Memorandum of Understanding M/R Monitor /report MSD Marine Sanitation Device mVA megavolt- ampere MW Megawatt MWh Megawatt-hours m/yr meters per year N/A Not Applicable NAD North American Datum NAWMP North American Waterfowl Management Plan NC North Carolina NCDENR North Carolina Department of Environment and Natural Resources NCDPR North Carolina Department of Environment and Natural Resources, Division of Parks and Recreation NCDWQ North Carolina Department of Environment and Natural Resources, Division of Water Quality NCDWR North Carolina Department of Environment and Natural Resources, Division of Water Resources NCNHP North Carolina Natural Heritage Program NCWRC North Carolina Wildlife Resource Commission ND No data available NDZ No discharge zone NEPA National Environmental Policy Act New License The license document that will be issued to Duke by the FERC to replace the Existing License and will provide requirements relative to Duke's operation of the Project through the term of the New License, including any extension periods for the New License as may be granted by the FERC through annual licenses. NGO Non- Governmental Organization II -xi Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations NHD National Hydrography Dataset NHPA National Historic Preservation Act NMFS National Marine Fisheries Service NOAA National Oceanic & Atmospheric Administration NOI Notice of Intent Normal Full Pond Elevation Also referred to simply as "full pond," this is the level of a reservoir that corresponds to the point at which water would first begin to spill from the reservoir dam(s) if Duke took no action. This level corresponds to the lowest point along the top of the floodgates. To avoid confusion among the many reservoirs Duke operates, Duke has adopted the practice of referring to the Full Pond elevation for all of its reservoirs as equal to 100.0 -ft relative or local datum. NPDES National Pollution Discharge Elimination System NPS National Park Service NRC NRCS Nuclear Regulatory Commission Natural Resources Conservation Service NRHP National Register of Historic Places NRI Nationwide Rivers Inventory NTU Nephelometric turbidity units NWI National Wetland Inventory O &M Operation and Maintenance ONS Oconee Nuclear Station OPCWA Oconee - Pickens Clean Water Action Ops Operations ORW Outstanding Resource Waters PA Programmatic Agreement PAB Palustrine (freshwater) Aquatic Bed PAD Pre - Application Document PBL Project Boundary Line PDT Project Delivery Team — a group of USACE, SEPA, and Duke staff evaluating the effects of modifying the 1968 Agreement between the three parties II -xii Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations Peaking Operation of generating facilities to meet maximum instantaneous electrical demands PEM Palustrine (freshwater) emergent wetland Penstock An inclined pressurized pipe through which water flows from a forebay or tunnel to the hydro powerhouse turbine PFO Palustrine (freshwater) forested wetland pH The inverse log of the hydrogen ion concentration (measure of acidity /alkalinity) PM &E Protection, Mitigation, and Enhancement measures PMF Probable Maximum Flood Power Factor (pf) The ratio of actual power to apparent power. Power factor is the cosine of the phase angle difference between the current and voltage of a given phase. Unity power factor exists when the voltage and current are in phase. Profundal zone The region of a reservoir or lake below the limnetic zone characterized by limited light and inhabited by animals that are attached or move along the bottom of the lake or reservoir. These animals are called the benthos. Project Keowee - Toxaway Hydroelectric Project Protective Relay A device whose function is to detect defective lines or apparatus, or other power system conditions of an abnormal or dangerous. PSS Palustrine (freshwater) scrub /shrub wetland QAPP Quality Assurance Project Plan QA /QC Quality Assurance /Quality Control Reactive power The product of magnetizing current and voltage and is expressed in terms of kilovolt -amps reactance RC Resource Committee Relative Depth The ratio of the maximum depth of a water body compared to its surface area Relicensing The process of acquiring a new license for a hydroelectric project that has an existing license from FERC Riparian Relating to the bank of a natural course of water rm Cumulative distance from the Savannah Harbor II -xiii Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations RM Cumulative distance along a tributary from its confluence with a river RMP Recreation Management Plan RMS Recreation Management System rpm revolutions per minute RTE Rare, Threatened, and Endangered species ROS Recreation Opportunity Spectrum RUN Recreation Use and Needs RV recreational vehicle SC South Carolina SCDHEC South Carolina Department of Health and Environmental Control SCDNR South Carolina Department of Natural Resources SCORP State Comprehensive Outdoor Recreation Plan SCPRT South Carolina Department of Parks, Recreation and Tourism SDI Scoping Document 1 SD2 Scoping Document 2 SEPA Southeastern Power Administration SERC SERC Reliability Corporation (formerly called Southeast Electric Reliability Council) SHPO State Historic Preservation Office Sluiceway An artificial channel for conducting water, with a valve or floodgate to regulate the flow. SMG Shoreline Management Guidelines SMP Shoreline Management Plan SOW Scope of Work Spillway A structure or passage for releasing water from a reservoir to control high reservoir levels. sq ft square feet sq mi square mile II -xiv Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations Stakeholder(s) Federal and state resource agencies, federally recognized tribes, NGOs, and other interested parties. Study Area The geographic area covered by a specific study. Typically includes the reservoir and any area within the zone of operational influence. Tailrace Channel through which water is released from the hydro powerhouse turbines Tailwater The area immediately downstream of a hydro station without a tailrace TBD To be determined TCP Traditional Cultural Properties TDS Total Dissolved Solids THPO Tribal Historic Preservation Office Three - winding Transformer A transformer with a primary, secondary and tertiary winding , which may be used to connect generation with two different voltage transmission circuits, or with both distribution and transmission circuits, without the use of additional transformers. TKN total kjeldahl nitrogen TMDL Total Maximum Daily Load TN Total nitrogen TOC Total organic carbon TPGT Trout -put, grow, and take Trashrack A mechanism, found on a dam or intake structure, which clears the water of debris before the water passes through the structure TRC Total residual chlorine TSS total suspended solids Turbine A machine in a hydro station that converts the energy from a stream of water into the mechanical energy of rotation. This energy is then used to turn an electrical generator or other device. Also called a "water wheel" or "runner ". UIF Unimpaired inflow U.S. United States II -xv Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Acronyms and Abbreviations USACE U.S. Army Corps of Engineers USC United States Code is the codification by subject matter of the general and permanent laws of the U.S. USCS Unified Soil Classification System USDA U.S. Department of Agriculture USDC U.S. Department of Commerce USDOE U.S. Department of Energy USDOI U.S. Department of Interior USEPA U.S. Environmental Protection Agency USFS U.S. Forest Service USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey V Volts VSM Video segment manager W Watts WAAS Wide area augmentation system Wetland Lands intermediate between aquatic and terrestrial ecosystems where water is at, near, or above the land surface long enough to be capable of supporting water tolerant vegetation. WROS Water Recreation Opportunity Spectrum WS Water Supply WTP Water Treatment Plant WWTP Wastewater Treatment Plant Zooplankton Microscopic floating or drifting animal organisms within a waterbody (e.g., copepods and rotifers) II -xvi Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 DESCRIPTION OF EXISTING ENVIRONMENTAL RESOURCES AND POTENTIAL RESOURCE IMPACTS 6.1 Geology and Soils The Keowee - Toxaway Project (Project) lies within the Savannah River Basin in North Carolina and South Carolina on the east side of the Blue Ridge Mountains. Lake Jocassee drains approximately 148 square miles (sq mi) of the watershed while Lake Keowee drains a total of 439 sq mi. The drainage basin varies in elevation from approximately 3,700 feet (ft) above mean sea level (AMSL) along the Eastern Continental Divide in the Blue Ridge Mountains to about 700 ft AMSL at the Keowee Development. The Project extends across two physiographic provinces of the southeastern United States (U.S.), the Blue Ridge and Piedmont provinces. Piedm on t Province The Piedmont province is bounded on the west by the Blue Ridge front. The front is a prominent topographic feature and varies from about 1,200 to 2,500 ft AMSL in the upper drainages of the Keowee - Toxaway system. Elevations range from 220 to 600 ft AMSL in the eastern portion of the Piedmont and gradually rise to the west to about 1,500 ft AMSL at the foot of the Blue Ridge front. Gently rolling, well- rounded hills and long low ridges are underlain by saprolite and crystalline rocks characterize the Piedmont province. Local relief ranges up to about 200 ft. Mountainous remnants of erosion resistant rock stand above the rolling surfaces. A majority of the Project structures are within the Piedmont physiographic province. The vegetation of the Piedmont shows the impact of man's activities on the land. Several centuries of logging, farming, grazing, and increasing urbanization have converted a once forested landscape into patches of pine and deciduous forest mixed with fields in varying kinds of cultivation and in varying stages of abandonment. II -1 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Blue Ridge Province The Blue Ridge front rises abruptly above the Piedmont to mark the division between the Piedmont and Blue Ridge physiographic provinces. The Blue Ridge province is a highly dissected mountain plateau bounded by two mountain chains. The Blue Ridge Mountains are on the east and range from 3,000 to 4,000 ft AMSL in elevation with a few peaks reaching almost 6,000 ft AMSL. The Unaka and Great Smoky Mountains are along the western border and elevations range from 3,000 to 6,000 ft AMSL. Between these two boundary mountain chains are a number of cross ridges and broad intermontaine valley floors that give the area its rugged character. The crest of the eastern Blue Ridge Mountains marks the Eastern Continental Divide. The mountains are characterized by strong relief and slopes ranging from moderately steep to very steep. No Project structures are located in the Blue Ridge province. In the headwaters of the Keowee - Toxaway system within the Blue Ridge province, mature deciduous forests cover the valleys and hill slopes. Within the deciduous forests, on dry open ridges and on open steep south- and southwest - facing slopes, pine forests are common at lower elevations. Regional Geology The rocks of the southern crystalline Appalachians are in basically parallel geologic terranes orientated in a southwest to northeast direction. From northwest to southeast the geologic terranes crossing the Keowee - Toxaway River Basin are the Blue Ridge and Inner Piedmont terranes. The Blue Ridge terrane is within a mountainous zone that extends from southern Pennsylvania to central Alabama and varies in width from less than 15 miles to about 62 miles. Its greatest width is in the Tennessee /Carolinas/North Georgia segment. It is a complex crystalline terrane consisting of Precambrian gneissic basement core structurally overlain by a vast thickness of metasedimentary and metavolcanic rocks of Precambrian to lower Paleozoic age (Hatcher 1978a, 1978b). Numerous igneous bodies of mafic to felsic composition intrude into the basement core and the overlying metasedimentary and metavolcanic sequence. The structure of the Blue Ridge II -2 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects terrane is controlled by major thrust faults and associated complex pholyphase folding and later brittle faulting (Hatcher 1978a; Clendenin and Garihan 2007a). The southern Blue Ridge is divided into three belts: 1) a western belt of imbricate thrust sheets involving upper Precambrian and lower Paleozoic rock and some basement rocks, 2) a central belt containing most of the basement rocks exposed in the Blue Ridge terrane along with higher grade upper Precambrian and possible lower Paleozoic metasedimentary rocks, and 3) an eastern belt of high grade upper Precambrian -early Paleozoic metasedimentary and metavolcanic rocks (Hatcher 1978a, 1978b). The eastern belt is presently referred as the Tallulah Falls thrust sheet (Nelson et al. 1998). The principal rock units of the Tallulah Falls thrust sheet are the Tallulah Falls Formation and the Toxaway Gneiss (Hatcher 1977) which underlies the upper portion of Lake Jocassee northwest of the Rosman fault. The Tallulah Falls Formation consists of metagraywacke, pelitic schist, mafic volcanic rocks, and quartzite resting on 1,000 to 1,200 million years ago (Ma) Grenville basement on the Toxaway Domes (Hatcher 1977). The formation consists of four members: 1) the quartzite- schist member, 2) the lower graywacke- schist - amphibolite member, 3) the garnet - aluminous schist member, and 4) the upper graywacke- schist member (Hatcher 1977). The lower member contains quartzite with interlayered schist. The lower graywacke- schist - amphibolite member contains metagraywacke (quartz - biotite- plagioclase- muscovite gneiss), amphibolite, muscovite schist, and biotite schist. Layers of granitic gneiss and pegmatites also occur in the member. Overlying this member is the garnet - aluminous schist member. It consists of muscovite - garnet - kyanite schist with interlayered amphibolite, muscovite schist, metagraywacke, granitic gneiss, and pegmatites. It is generally easily recognizable by abundant garnet and kyanite. The upper graywacke- schist member contains metagraywacke, muscovite schist, muscovite - biotite schist, and minor amounts of amphibolite, granitic gneiss, and pegmatites. In some areas surrounding the domes, the lower members are not present suggesting either non - deposition or faulting out of the lower members (Hatcher 1977; Schaeffer 2007; Clendenin and Garihan 2007a). Recent mapping ( Clendenin and Garihan 2007a) of the Tallulah Falls Formation does not distinguish the members described by Hatcher (1977), however, they describe similar lithologic sequences. II -3 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects The Toxaway Gneiss, part of the Precambrian basement of the eastern Blue Ridge terrane, is exposed in the core of the Toxaway Dome. It is typically a medium- to coarse - grained banded biotite - plagioclase - microcline -quartz gneiss with some massive and augen varieties present, which do not appear to be significantly different in composition. The Toxaway Gneiss has a Rb /Sr whole -rock isochron age of 1203 +54 Ma (Fullagar et al. 1979). Metamorphism ranges from almost nonexistent along the western edge of the Blue Ridge terrane to granulite facies in the central Blue Ridge terrane near the North Carolina- Georgia border (Hatcher et al. 1979). East of this area, the Tallulah Falls Formation rocks were progressively metamorphosed to the kyanite zone of the almandine amphibolite facies of regional metamorphism (Hatcher 1977). These metamorphic assemblages were formed during a single regional event, likely during the Taconic orogeny about 480 -440 Ma (Butler 1972). A major retrograde overprint occurred on the southeast side of the Tallulah Falls formation in the rocks of the Brevard zone (Hatcher 1977). The basement rocks of the Blue Ridge terrane were subjected to granulite facies metamorphism about 1000 Ma (Fullagar and Odom 1973; Hatcher and Butler 1979). Crystalline thrust sheets dominate the Blue Ridge terrane of the southern Appalachians with ages ranging from pre- Taconic ( >480 Ma) to Alleghanian ( -250 Ma) in age (Hatcher 1978a; Hatcher and Odom 1980). The earliest thrusts were complexly deformed by the later deformation and were overprinted by the main metamorphic event. The vicinity of the Project has been subjected to four or possibly five episodes of folding. The first is recorded as isolated transposed fold fragments in a dominant foliation related to the second fold event. The second fold event consists of map scale isoclinal, recumbent folds with the prominent foliation axial planar to the folds. The third fold event consists of open to tight upright folds with variable development of foliation (Hatcher 1977; Schaeffer 1987). The northeast outcrop pattern of the Blue Ridge terrane northwest of the Brevard zone is the result of the interference between the second and third fold events. The Inner Piedmont terrane is located southeast of the Blue Ridge terrane and is separated from it along the Brevard zone. The Inner Piedmont terrane extends from Alabama to near the Virginia /North Carolina state line. Within South Carolina and North Carolina, it has a width of II -4 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects approximately 59 miles (95 km), but narrows both to the northeast and southwest. The Inner Piedmont terrane is a fault- bounded composite stack of thrust sheets containing a variety of gneisses, schists, amphibolites, sparse ultramafic bodies, and intrusive granitoids. The general structure of the thrust sheets is characterized by irregular foliation of low dip and folds transverse to the northeast regional geologic trend. The stratified rocks of the belt consist of thinly layered mica schist and biotite gneiss which are interlayered with lesser amounts of amphibolite, calc- silicate rocks, hornblende gneiss, and quartzite. Protoliths of these rocks were largely sedimentary and in part volcanic. Large and small masses of granite and granodiorite are present in the belt and form concordant to semi - concordant bodies in the country rock. Some of these granitoid bodies are gneissic and are probably older than the poorly foliated to nonfoliated granitoid facies. Small bodies of ultramafic rock are present along the eastern and western sides of the terrane. The rocks of the central core of the Inner Piedmont are in the sillimanite zone of amphibolite metamorphism. The flanks are primarily in the staurolite - kyanite zone of regional metamorphism. Along the northwestern edge of the terrane, the rocks are at lower grade of regional metamorphism. Rocks of the Jocassee thrust sheet (Brevard zone along its northwestern boundary), Walhalla nappe, and Six Mile thrust sheet (from northwest to southeast of the Blue Ridge terrane) of the Inner Piedmont terrane underlie the major Project structures. The Jocassee thrust sheet is southeast of the Blue Ridge terrane and separated from it by the Brevard zone. The sheet is comprised of the Henderson Gneiss, part of a large, regional igneous body that is granodioritic to granitic in composition and is coarse - grained biotite augen gneiss characterized by large microcline crystals (augen) up to 3.0 cm in a fine- grained biotite quartzo- feldspathic matrix (Lemmon 1981; Clendenin and Garihan 2007a). It is variably mylonitic with shearing expressed as thinly layered, schistose, fine -grain biotite- muscovite - quartz - feldspar gneiss with locally interlayered muscovite schist (Hatcher and Butler 1979; Clendenin and Garihan 2007a). In the Brevard zone, the Henderson Gneiss is a fine- grained leucocratic gneiss ( Clendenin and Garihan 2007a). Interlayered within the Henderson Gneiss are muscovite - quartz- feldspar gneiss, quartz - feldspar gneiss, aplite, pegmatite, quartz veins, and minor biotite amphibole gneiss. Rocks of the Walhalla nappe (Chauga River Formation) overlay the Henderson Gneiss in the Jocassee thrust sheet and the contact between the two rock units is the II -5 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Eastatoee fault (Garihan and Clendenin 2007). The fault is recognized by the abrupt change in lithology across the sharp contact and the marked grain size reduction in the underlying Henderson Gneiss (Garihan and Clendenin 2007). The Walhalla nappe is comprised of phyllonite, the Table Rock gneiss, the Poor Mountain Formation, the Chauga River Formation, and a biotite - porphyroclastic feldspar gneiss (Clendenin and Garihan 2007a). The phyllonite is a resistant, fine- to medium - grained schistose muscovite - quartz phyllonite which forms discontinuous zones up to several feet wide and up to 65 ft long. The phyllonite occurs within the formations of the Walhalla nappe and along the contacts of the formation (Clendenin and Garihan 2007a). The Table Rock gneiss is a metamorphosed suite of intrusive granitoid rocks (Clendenin and Garihan 2007a). It is generally a well - foliated biotite quartzo - feldspathic gneiss or a biotite granitoid. Migmatitic biotite - quartz - feldspar gneiss, fine- grained muscovite- biotite- quartz- feldspar gneiss, poorly to well - foliated biotite and muscovite granitoid gneisses, migmatitic biotite schist, aplite, pegmatites, and quartz veins are associated with the Table Rock gneiss unit (Clendenin and Garihan 2007a). The Poor Mountain Formation was described originally by Hatcher (1969, 1970) and recently re- evaluated by Clendenin and Garihan (2007a). Several mafic rock types make up the formation; fine- grained, thinly layered amphibolite, epidote amphibolite, biotite amphibolite, porphyroclastic plagioclase amphibolite, fine- grained porphyroclastic amphibolite with prismatic hornblende idioblasts, fine- to medium - grained hornblende gneiss, fine- grained porphyroclastic plagioclase hornblende gneiss, and ultramafic schist (Clendenin and Garihan 2007a). Felsic rocks interlayered with the mafic rocks include migmatitic biotite gneiss, garnet - mucovite - biotite schist, garnet -mica gneiss, quartz - feldspar gneiss, fine- grained biotite quartz - feldspar gneiss, fine- grained schistose muscovite - quartz - feldspar gneiss, biotite granitoid gneiss, pegmatite, and minor muscovite phyllite (Clendenin and Garihan 2007a). The Chauga River Formation was originally described by Hatcher (1969) and recently re evaluated by Clendenin and Garihan (2007a). The formation consists of schist, metagraywacke ( biotite gneiss), and mica gneisses. A fine - grain, button mica schist with mm -size garnets and II -6 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects locally magmatic garnet- muscovite biotite metagraywacke are common lithologies. The formation also includes schistose, fine- grained muscovite - quartz - feldspar gneiss with localized areas of muscovite schist and fine -grain biotite - quartz - feldspar gneiss and a fine - grained biotite gneiss (Clendenin and Garihan 2007a). Rocks of the Chauga River Formation have been multi - deformed by a series of ductile to brittle deformation events (Clendenin and Garihan 2007b). Biotite - porphyroclastic feldspar gneiss is present in several locations in the Walhalla nappe. The gneiss contains irregularly shaped feldspar porphyroblasts in a fine - grained biotite schist matrix. The gneiss is either above or below the Poor Mountain Formation amphibolites or the Chauga River Formation schists (Clendenin and Garihan 2007a). The Six Mile thrust sheet is southeast of the Walhalla nappe and has been thrust over the Walhalla nappe by the Seneca fault (Griffin 1971; 1974; Garihan 2005; Clendenin and Garihan 2007a). The Seneca fault is a knife -edge sharp, subhorizontal fault with marked grain size reduction in the footwall. The Six Mile thrust sheet is comprised of rocks of the Tallulah Falls Formation and other lithologies that have not been given formation status (Garihan 2005). The Tallulah Falls Formation has been divided into two mappable units, a porphyroclastic feldspar gneiss and a non - porphyroclastic mica amphibole gneiss and schist. The porphyroclastic feldspar gneiss is a fine - grain, schistose garnet - sillimanite- muscovite - biotite porphyroclastic plagioclase quartz gneiss. Lesser amounts of fine -grain muscovite - biotite gneiss, schistose sillimanite- muscovite gneiss, medium - grained muscovite -quartz schist, medium -grain migmatitic sillimanite - biotite schist, coarse -grain biotite gneiss, and minor granoblastic calc- silicate rocks and amphibolite are present. The mica amphibole gneiss unit contains coarse -grain biotite schist and medium - grain, poorly layered, biotite - hornblende gneiss with minor medium - grained migmatitic sillimanite- garnet- muscovite - biotite schist, medium -grain garnet— muscovite - biotite schist, medium- to coarse -grain sillimanite- muscovite schist, medium -grain graphite- garnet -mica quartzite, medium -grain amphibolite, and fine -grain hornblende gneiss (Garihan 2005). The other major lithology in the Six Mile thrust sheet is a biotite -garnet quartzite (Garihan 2005). Along the northwestern edge of the Jocassee thrust sheet, the primary structure is the Brevard zone, which extends from Alabama into North Carolina to near the Virginia state line. The Brevard zone, 0.6 to 1.2 miles (1 to 2 km) wide, is a linear belt of mylonitic rocks (Clendenin II -7 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects and Garihan 2008; Nelson et al. 1998). The northwestern portion of the Brevard zone, southeast of the Blue Ridge terrane, is a narrow belt of the Chauga River Formation low grade metasedimentary and metavolcanic rocks referred to as the Brevard fold belt (Clendenin and Garihan 2008). The Rosman fault occurs along the northwest limb of the Brevard fold belt and it separates the rocks of the Jocassee thrust sheet from the Tallulah Falls Formation rocks. The Rosman fault is a distinctive tectonic m6lange that consists of clasts of mylonite and slices of exotic carbonate rocks that chemically resemble platform -type carbonates of the Knox Group (Hatcher et al. 1973; Horton 1974; Hatcher 1978a; Clendenin and Garihan 2008). Southeast of the Brevard fold belt is the Brevard imbricate thrust stack consisting of thrust sheets comprised of Chauga River Formation rocks that had been previously thrust over the and Henderson Gneiss (Clendenin and Garihan 2007a, 2008). The Brevard zone has a lengthy and complex history of deformation including multiple ductile events involving both prograde and retrograde metamorphic processes followed by multiple brittle events (Clendenin and Garihan 2008). The latest faulting (Mesozoic or younger) to affect the rocks of the area are northeast- and northwest- trending brittle faults with a complex history of deformation ( Garihan et al. 1990; Clendenin and Garihan 2007a). 6.1.1 Jocassee Development Geology The Jocassee Development is located on the western edge of the Piedmont physiographic province with the reservoir extending into the Blue Ridge hysiographic province. The terrain at this boundary between these two provinces, near elevation 1,200 ft AMSL, slopes to the southeast. The major Project structures and the majority of the reservoir are underlain by rocks of the Henderson Gneiss within the Jocassee thrust sheet of the Inner Piedmont terrane. The upper reaches of the reservoir on the Whitewater River, Thompson River, and Horsepasture River arms are underlain by rocks of the Tallulah Falls Formation and Toxaway Gneiss within the Blue Ridge terrane. The Brevard zone passes through the upper reaches of the Whitewater River, Thompson River, and Horsepasture River arms of the reservoir, approximately 3.5 miles northwest of the Jocassee Dam and Powerhouse. Figures 6.1 -1 through 6.1 -3 show the geological features of the Project area. II -8 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1 -1 Geologic features map (Sheet 1 of 3) KeAVrrd - 7dxaWay GO�ciy�ii �xtSt9r5Qt10r1 Iel! "47rfrtl etrll glri �;iIrat,�rljay allu,,nunl Bkm Riaw Rarks Nartt,ead of tl m Rosman Fault TF Tallulah Fats FormaWn TAg Toxava Gnalss Imw Pledlnant Racks Sauhtast of IN Rosman F&uk Jocas"o 7hrim SPoeet Hgn Henderson Gneiss waltIMIA N ippe f,I,r '?YIIan n e 7FN ?ablaRorkeneiss b Green to Gnel55 Pwalq Pcyr Mrkurltun Fwrratiop h AmphlballtaHomb"e Grie.55 r'UmWcor Mr wrftain Forme6 cr Ultrarnsfic Schist CR(m trial ge Rlvor Forman I turf611r- PprpFlyC6tl�56C F'41d5pd E3195 ♦` ouaralfg � Six fiUI s Thrust Shsat 'M i a metMica Schist bm Mca Sci-rst- BuiJtB C n6iss it l gTehtc Psnphibde Groin h ,nmpbibd. xnb eGnr ss / 9 g xh' iJ' 9 lot " /J h ,1 I 9 In lq I} !T ConMts & Faults _ }y — – aplra),mi2ta zct= '74mLlIt! - _t,Upue-dipfaut UP apfrpbmate a aYft retl thrust fault 1, 'A �r -A applinmatethmsttault ....... ouncealed mntad h +- mnmaled oblique -sfp fault , 4' . WhCe8ft!d er•,Crbumedthrudt fault -- -_ - - -4ti wire mnlcd tflrust FauA. - sft-ar iSln9 I ull ri t.. I.II nl ry —'� r1•:2r rddeS 'I. 901mdary cl4 =urretsd ACCess �e.n.. raghwn Ge WM1ly�l .. h93tilr FdaBd IIL 'i �,f]fl4 1iA00 1 f Feet. ti ILI ob h t r7Ac` �nt•e r 9 9 4�r h I Keowee Dain YI - I f JIM Little River Dam b Koowow- Toxaway Ralicettsiltg FERC Project No. 2505 Geologic IFeatEJI'eS Map Sheet 9 d S Raa 5ourwc GwbY[s - C C'4ndonn, Jr r.J M GarAran, rnd A Gea67Y- $haaf�r, 19Bt i 9"dedi2aiaf -m pr a.aec aYmeelln4naisrE6F ?t_5hedcvlielleflMorldW RDpaien 8 9v epaneCodrtliateS IamrL+fi93.Idartela�elTeel II -9 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) b.1-2 ueoiogtc tea �., ' { 6.0 Description of Environmental Resources and Project Effects tures map (meet L of s) U Httn �`- � Ph'Isi:c,ly Af Hun x. # #• a 5 { _ prlalc Ir- IF TRg FUs 6 1 PIAS (c i IL TRg �HSIn rh 4 ✓' r I J -I- V I I ! 1 ^ 4N•- r f" — �. {ayes'' 'h ,� ` per,'• f° ban �L F1 it I v ban LaIpM 'See SheetIforGeO icEx fanationLe ends r I �S a Keowee-Toxaway Rekensing 3., — LWeOlkles FERC Project No. 2503 LAIR = urrik�.dAL-cess Geologic Features Map �.a" �wS�mMsv MwirFbad 5AU 17 OW Sheet , of 3 Feet f'ya Sour. �'w,7hg� . C W S;'♦.ndw ,Jr &J k,. Owffi , qW JDG7 Geology Schaefer, 1967 Shaded Rslef- hAepMrP a Ninecamh,spe�€S SbadedRehef 4ttorld 'ICY F4atedaan �C Pleas .nrtlr io S'jslem,f l:$3, InDerralmal dal II -10 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects vigure oa -s ciemogic features map (meet s of s) TF i P TF CRtm TXQ � 47 fi 1 t p a ccyra 1rtix V r a4 iF TF ! 16t I_ "- i - Lah Ioc.allsee TF _ Jocassee barn 7 N ■ a den.— X.`L.� l 7 5C. L*IWW 'See Sheet I for Geot lr Explanation Legends � P 9 iCec'~w ®e- Toxaway RQlicertsing �rd:ePn+aes FERC Pro *t No. 2503 — - 3 �'ov' Propo[Bomdary Lake = Ljmwaancess Geologic Features Map V — 49py-W cay.i; — Mmor%ad L = 0;910 12,900 Sheet 3 of GdaSwrmwCwa4 • CWC. drr n. J,gJMGyfian,gMWCq- kgP'Srh— Or.19M C1 Shaded Yal- h'�PA'YRSI1o7a. Nione.cnRtM e�E51fi-Shadishrai Id -2D PFafa�an SC SIad� Plane Cmorealaafins r'>•°1�B3.InRrralrar,alllaai II -11 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects The major Project structures are underlain by Henderson Gneiss. The Henderson Gneiss is a coarse- to very coarse - grained augen gneiss with microcline augen up to 1.0 inch. Its composition ranges from quartz monzonitic to granodioritic. Interlayered within the gneiss are hornblende - biotite gneiss and fine to medium - grained augen gneiss. Pegmatites are present parallel to the dominant foliation. The foliation (defined by biotite and the augen) strikes northeast and dips southeast and in the site vicinity varies from a direction of N10E to N70E with dips from 8 to 36SE. Four joint sets (N10 E to N30E; N40W to N50W; N45E to N60E; N10W to N20W) occur at the site and all except the N45E to N60E have near vertical dips. Spacing between joints ranges from about 1 ft to greater than 10 ft. The foundation of Jocassee Dam was excavated to "sound" rock in the core area. The rock foundation was treated with dental concrete and consolidation grouting. Sound rock was defined as rock that could not be excavated with a small backhoe. The foundations for the shells in the left abutment were excavated to firm soil or partially weathered rock exhibiting a Standard Penetration Resistance value of at least 20 blows per foot. The dam in the upper abutment area was founded on residual soil over weathered rock. The right abutment includes a thicker zone of residual soil than the left abutment. The powerhouse was excavated into competent or sound rock. The spillway foundation was also excavated to competent rock. 6.1.2 Keowee Development Geology Most elements of the Keowee Development are located within the Walhalla nappe. The complex contains primarily hornblende gneiss, amphibolite, and granitic gneiss in a complexly interlayered sequence. The rock units have been deformed into recumbent, isoclinal folds (fold limbs have the same dip, which approaches horizontal), whose axes plunge to the northeast and whose axial planes dip down to the southeast. Foliation generally parallels the compositional layering and is related to a tectonic event of recumbent, isoclinal folding (Schaeffer 1987). Four major joint sets (i.e., rock fractures without lateral movement in the plane of the fracture) have been measured in the area: 1) N78E; 85NW, 2) N50E; 84NW, 3) N5W; 87SW, and 4) N38W; 87SW (Schaeffer 1991). II -12 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Elements within the Walhalla nappe include the Keowee Dam, the Oconee Nuclear Station (ONS) Intake Dike, and the four Saddle Dikes designated A through D (see Section 4.3, Figure 4.3 -3 for a facilities map [located in Volume I of this PAD]). The Keowee Dam is located on the flank of a fold between a synform to the west and an antiform to the east. The dam spans alternating layers of granitic gneiss and hornblende gneiss /amphibolite. The ONS Intake Dike is situated on the nose of the synform, about 2,000 ft south of the west end of the Keowee Dam, and extends partly into the flank of the next fold westward. The ONS Intake Dike is underlain predominantly by granitic gneiss. Saddle Dike A spans several rock units at the downwarp of a synform. Saddle Dike B is located in a unit of granitic gneiss. Saddle Dikes C and D overlie hornblende gneiss and/or amphibolite. The Little River Dam is located in the Six Mile thrust sheet, approximately 0.5 miles southeast of the Seneca fault. Rocks of the thrust sheet are predominantly biotite gneiss and mica schist that grade into each other; amphibolites and hornblende gneiss are distinctly subordinate rock types. The Little River Dam is located on the lower limb of an isoclinal antiform and rock in the area is interlayered mica schist and biotite gneiss (Schaeffer 1987). Keowee Dam is located about 1.8 miles northwest of the Seneca fault and is founded on hornblende gneiss, amphibolite, and granitic gneiss. The rock foundation under the high central portion of the dam was pressure grouted during construction. Other portions of the dam are founded on residual soils. A generalized soil profile begins with an upper horizon of between 2 and 6 ft of residual red - brown, slightly clayey sand silt. Underlying this first horizon are tan, tan -gray, and reddish tan, slightly clayey silty fine sands which reflect a lesser degree of weathering. The second horizon, in general, has an average thickness of 15 ft. In some areas, there is a third horizon composed of gray or tan, slightly silty fine to coarse sand. As depth increases, the weathering influence is reduced until very soft but coherent partially weathered rock is encountered. 6.1.3 Seismicity The Project is within an area of relatively low seismicity in the Piedmont and Blue Ridge seismotectonic provinces (Figure 6.1.3 -1). Within a 50 -mile radius of the Jocassee and Keowee I1 -13 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Developments, 32 earthquakes of mb >3 have occurred. The U.S. Geological Survey (USGS) Seismic Hazard Maps indicates a PGA (horizontal) in the Keowee - Toxaway area of 0.149 to 0.16g with a recurrence interval of 2,475 years (2 percent probability of exceedance in 50 years; Figure 6.1.3 -1 [USGS 2008]). The South Carolina Seismic Network owns and operates two stations (CCK and JVW) around Lake Jocassee and Duke owns and operates three stations, one in Jocassee (BG3) and two in Keowee (SMT and MMC) (University of South Carolina [Department of Geologic Sciences 2010]). The Project spans the Piedmont and Blue Ridge seismotectonic provinces. Earthquakes in these provinces have not been associated with mapped surface faults such as the Brevard fault zone and the Seneca fault in the Project area. The Brevard Fault Zone is a northeast trending fault system that is located approximately 8 miles northwest of the Keowee Development and crosses Lake Jocassee approximately 3.5 miles upstream of the dam. The fault extends northeast 375 miles from Montgomery, Alabama crossing the Project area — placing most of Lake Jocassee into the Blue Ridge region to the northwest and Lake Keowee into the Piedmont Region to the southeast. The fault then continues to Mount Airy, North Carolina and possibly into Virginia. The contrast of rocks present along the zone suggests that it is an area of slip - strike faulting with past right- lateral movement. Historical earthquakes in the Piedmont province have occurred primarily in central Virginia and South Carolina (Bollinger et al. 1991). Recent instrumental data define a cluster of activity in central Virginia; however, the Piedmont of South Carolina has been less active according to these data. Network monitoring of these regions has shown that seismicity occurs at shallow depths in the upper crust, from near surface to about 9 miles. The average depth is approximately 5 miles, and 90 percent of the earthquakes occur at depths of 7 miles or less. II -14 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Nigure o.i.i -i Seismic hazard and mayor earthquake vocation map �Swt�hlsurl C' . TN • 4: • 1561,ltagnwde 5.2 # Mitchell W4v , N G 925:'6lagrri4de 5,2 5s F�erllr • � ■ YVII #tafir,ea, 1JC. * i + i9b1. M8 nikutle 5 1 ., • T�nn¢ssee • ; � • � • • • ■ �* .y _ *'- ;, Skyland.iJiC No th Carolma / • tq1£, Mega tuda 5.2 1-.. i • •J i # ■ r• Ala ma # • e vnx "D.m ,k Union Cnun4y SC., •' � � � f� 1g.13..Magnitude 5.+� ��.� * •tie+}+,vee dam ,. - Sine a. SC — • Di%tance Fresm Joransir Liam 1-111*1, Me nMde38 +. ' A - n,a€ Tai Ear[Frqual[# IAG7+1 #ltifa AAfleti # i .kkyl,r, ri, NC 44 nn.t"I, -11 Ct r.rtty, F C 79 • undan Cc,,. sc 71 - Georg 1, •, f- i SauthfCar Ilya a.,.. Johnson Cl ,'T'N 91 Wilkesboro, PitC 129 _ * � C- harlesl on, &C 220' t 2 • 01 stance from Keowreie Cram 4 � � • ` To Ear[1t kaaka Wcmtlon 14 H 1& '�, # 0 >a� Skytan+d, NC: 53 P.?lit.,;�holl CounLy, NC &a ~� � �. � • Llri rr.3 ro ca, SC Be J olrr�szsn C t , Thi li]] , • '. soplelirs re prese nt peak horizo nta l accele ration with prohatrility of exrxecrance irr 56 years. 4Source: USGS, wvllkesboro. NC 135 +T, r 1:11 :'esrlhquake, sgs gov:research;haznraps} Cc6arie-ston 'SC 212 't '� �oints represent earthquake renters vidti magntlude ol3 or grrater. S�slaGe: NCEER Earlhquake ;Catalog. Seneca, SC' .,earn 1627 - 2009 and Wg+nia Tech Earthquake Catalog? _._ -` -- " "I ay.nln ;rnn�' �] dkek— Ne K�Bowee- �{?Xa3Wc7 .B�IC t?IlSlr1 : NonhCar+cdine. T_a1� Lrgsnrl FER+C Project X14. 243 FWcem ;, -iey Gerihqu a Location Bmwde nevvlty � =r 4Q-w � 1_ I. rim �T. - iNRfiNRil�[ Imhl "ReFff lu) � .ter �' F,n`.• Seismic Hazard and Major Au :,a n, I.lelaen[r +;M9.11 Earthquake LUCatlOru Map ': QaVtil jlna ;,u..- Whhrr Yl - �ibn4 rA lfi. {_iE07�la. a ,r +.Yrinc,l 3G 54 go 120 Sumca ESRI u5a B3 Cab s.r.r Daft as r d tmm u+t�.•;s, srny.x�,rcr�,,.k..u� 4,re.r6mw leap sekrnl. r. ntrxc,. FAi1es a.,.sr� t =corns k r.eWa iae gin -.044. vArarr Erdrryaaa Cem dry � flrWIX+dL _, .ERfa �. l -. P+ryedion ,`�Y.' �Pene Coosdmaee Srseern. rte Iria+nrtmal feet II -15 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Network monitoring shows that hypocentral locations in the Piedmont as a whole are spatially diffuse, both vertically and horizontally. This is interpreted to indicate that multiple structures are responsible for the seismicity rather than several singular predominant structures (such as the case in the Brevard fault zone), and that the earthquakes are relatively shallow in the Piedmont. The region is notable for the occurrence of reservoir- induced seismicity limited to parts of South Carolina and Georgia. The largest seismic event in the Piedmont province was the August 31, 1861, Wilkesboro, North Carolina earthquake, with an epicentral Modified Mercalli Intensity (MMI) of VII (Figure 6.1.3 -1). It was felt over most of the middle Atlantic region and in areas as far away as Cincinnati, Ohio; Washington, D.C.; Columbus, Georgia; and Charleston, South Carolina. The felt area was reported as 784,000 km2 (Stover and Coffman 1993). Magnitude (Mb) was estimated at 5.1. The only other significant earthquake in the Piedmont region is the January 1, 1913, Union County, South Carolina event (Figure 6.1.3 -1), which was felt in parts of North and South Carolina. The event had an epicentral MMI of VII with an estimated mb 5.0 (Stover and Coffman 1993). The earthquake was felt over an elliptical area of 43,000 square miles in parts of North and South Carolina and as far away as Georgia and Virginia (Visvanathan 1980). Historical seismicity in the Blue Ridge province (and Valley and Ridge provinces) shows a general northeasterly trend, paralleling and generally lying within the Paleozoic thrust and fold belts from Alabama to west - central Virginia. The largest earthquake known in this region was the May 31, 1897, Giles County, Virginia event (MMI = VIII; Mb = 5.8). Reliable hypocentral locations are available for the two most active regions in the Blue Ridge and Valley and Ridge provinces: Giles County, Virginia seismic zone and eastern Tennessee- western North Carolina seismic zone. The earthquakes in the Giles County area define a 24.86 m (40 km) long, steeply dipping, northeast- trending seismogenic zone that includes the probable epicenter of the 1897 earthquake. The orientation of the Giles County seismic zone differs from the trend of surface geological structure. In addition, the earthquakes occur at depths ranging from 3 to 16 miles, entirely beneath the Paleozoic sedimentary cover rocks. Results from earthquake monitoring obtained in a zone extending from eastern Tennessee and western North Carolina through northwest Georgia and into northeast Alabama show significant similarities to those of the Giles II -16 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects County seismic zone. Most hypocenters are located beneath the Paleozoic cover rocks and crystalline thrust sheets, at depths between 2 and 18 miles, with a concentration in the range of 5 to 9 miles. Epicenters located by modern seismic networks show a spatial pattern similar to that exhibited by the earlier, pre- network data set. The most apparent difference between the two data sets is that the Blue Ridge region of western North Carolina has become less active, with a corresponding increase in activity in eastern Tennessee. The May 31, 1897, Giles County, Virginia earthquake epicenter was near Pearisburg, Virginia. Damage and effects from the earthquake included cracked and damaged brick chimneys, sliding of unstable rock, loud noises, and mud - filled springs. The epicentral MMI was estimated at VII - VIII, based on newspaper reports and eyewitness accounts. The earthquake was felt as far away as Indianapolis, Indiana, 330 miles from the epicenter. The felt area was about 266,409 m2 (690,000 km2) (Stover and Coffman 1993). Microearthquakes continue in the epicentral zone up to the present. Two other significant earthquakes have occurred in the Blue Ridge province: the 1916 Skyland, North Carolina earthquake and the 1926 Mitchell County, North Carolina earthquake (Figure 6.1.3 -1). The Skyland event occurred on February 21, 1916, and was felt over a large portion of the southern Appalachians, from Georgia to Virginia, but no significant damage was reported. The epicentral MMI was estimated to be VII, with the epicenter near Skyland, North Carolina. The felt area was reported to be about 600,000 km2 (Stover and Coffman 1993). A magnitude (mb) of 5.2 was estimated for the event. The Mitchell County event occurred on July 8, 1926, and caused light damage (epicentral MMI = VII) in a small area of southern Mitchell County. It was reported that houses rattled, chimneys and building foundations cracked, a water pipe broke, and glassware moved. The event was estimated to be Mb 5.2, but may have been overestimated, since no felt area was reported. The magnitude is based on the epicentral intensity only. The distance of the historic earthquakes discussed above in the Piedmont and Blue Ridge provinces (except the Giles County, Virginia earthquake) from the Keowee and Jocassee Developments are shown in Figure 6.1.3 -1. II -17 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Earthquakes have been associated with a number of reservoirs in the southeastern U.S. Lakes with various degrees of induced seismicity include Monticello Reservoir, Lake Keowee, Lake Jocassee, J. Strom Thurmond Lake, Richard B. Russell Lake, Lake Oconee, and Lake Sinclair. All of these are within the Piedmont province and are characterized by small, shallow earthquakes. The largest induced earthquake (ML = 3.2) at Lake Jocassee occurred in 1975 shortly after the initial filling of the reservoir. Seismic activity associated with Lake Jocassee has decreased significantly in the last 10 years. The largest induced earthquake (Mblg = 3.8) possibly associated with Lake Keowee is the "Seneca" earthquake in 1971 (location on Figure 6.1.3 -1) (Talwani et al. 1979). Earthquake swarms associated with Lake Keowee occurred in 1978, 1986, and 1988, with the largest magnitude of the swarms being an MD = 2.8 in 1986 (Talwani et al. 1979; Acree et al. 1988). The activity in the vicinity of Lake Keowee has decreased significantly since 1988, similar to the decrease in seismicity associated with Lake Jocassee, and has likely decreased to background levels (Schaeffer 1991 2000). 6.1.4 Economic Minerals A number of potential economic minerals are located in the vicinity of the Project including mica (sheet and scrap), molybdenum, kyanite, magnetite, thorium, sand and gravel, vermiculite, corundum, anthophyllite, kaolin, limestone, copper, talc, and crushed and dimension stone (Kenwill 1982). Other economic minerals reported in the area, without commercially significant amounts, include occurrences of silver, lead, chromium, and tantalum (Kenwill 1982). At present, only crushed stone is being produced in the Project vicinity. 6.1.5 Soils The Project lies within the Blue Ridge and Piedmont physiographic provinces of North and South Carolina. The Blue Ridge province is typically mountainous with steep ridges and valleys. II -18 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Soils in the vicinity of the Project are somewhat variable due to the geographic extent of the reservoirs and the local differences in topography and geology. Figures 6.1.5 -1 through 6.1.5 -3 provide the soil types within the Project vicinity. Soils in the vicinity of the Project primarily fall into the category of upland soils. Soils on uplands are located on higher elevation ridges and slopes adjacent to the present lakes. The soils are primarily sandy loam with some clay loam. In some locations, the soils are described as rocky or cobbly. Soils are typically derived in place from the parent rock materials. The soils in the Project area are generally susceptible to erosion by moving water. The erosion potential is enhanced by the relatively steep slopes forming the perimeter of the Project reservoirs. 6.1.5.1 Lake Jocassee Soils surrounding Lake Jocassee are fairly consistent due to the similar geologic conditions and topography in the reservoir area. Some variations based upon location and topography in the area of occurrence should be expected. Soil types that are present along larger portions of the reservoir shoreline or are more frequently present are described in additional detail in this section. Soils are typically sandy loam derived in place from metamorphic bedrock. Soils present in the Lake Jocassee area include Ashe, Cecil, Halewood, Hayesville, Talladega, Chandler, Porter, Grover, and Saluda. Although the soils are typically sandy loam at the surface these units often include a sandy clay, clay, or clay loam subsoil. Several soil types include a significant percentage of gravelly or cobbly soil. They are typically underlain by saprolite or weathered rock at depths ranging from 10 inches to greater than 60 inches. In some locations weathered or unweathered bedrock may be present below the surface soils at depths as shallow as 1 to 2 ft. The thickness of saprolite below the surface soil deposits can be considerable. Depths to weathered or unweathered crystalline bedrock are often several tens of feet or more. The surface soils are susceptible to erosion due to their location along moderately sloped to steeply sloped areas. The soils are generally defined as well drained. II -19 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5 -1 Soils map (Sheet l of 3) ="°,g ,m �mep � � � in° •ms's• � f rsku mmpa = -viazm lteaa Sy3t;ti AW _ m "�� "►�...�'�' Ste\ a� Mme �,aga,m _-.- �''4' �� / �✓+ +� :ae.,� -•..r - _ R� 3 n N9 j r. - ` S ` 4 x"oa xa�r mms� came r+✓v Kam y '- � f Tail ace Area r 326 RIF : r ;� -�$ '� - to P - `° 324 PA Ziy N Canc r / r - 7 J I,'-- -- - -- L'dtle Ricer Bypass Area J� :.; rth a ..t, fCeollVee -Toxa Way Relicensing [ c.a "ey Legend N — Limited Access River Miles FER�C Project No. 2503 3 "Ke "' Highway L_ -� Project aoureary 2 � Major Road JLake .Soils Map o—ee cou nay Sheet t of 3 �_ fl b,flfl0 12,flfl0 Data Sources: Data Sources: Soils DatamaV www.nres.usdagov). , USGS Topo Quadrangle htap. S[uc Loca[i oi5 Feet Projection SC State Plane Coordinate System, NAD83, International feet II -20 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5 -2 Soils map (Sheet 2 of 3) swop mnPeK Itt� 1 � s_ ttt� � my&mm � � •�� ��4 x }• � vbr ea 1r N� �A - kn � 5 rte '( v O•. �, et,wr� "Y , - >%, North T yl�an;a Legend nC Keowee-Toxaway Relicensing i -'fnl /3 aCOUmy fy o limited Access River Miles FERC Project No. 2543 Cmu my —H ay Project Boundary 2 Major Road Lake .Soils Map o� co��n ie Sheet2 of 3 6.900 12,000 a data Sources: data Sources: Beds Oatamart,( mwvJ.nres.usdagm)_ USGS Topo Quadrangle Idar. Stu Location Feet Projection SC State Plane Coordinate System, NADU I nlernational test II -21 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5 -3 Soils map (Sheet 3 of 3) „�, w � i u tk—d •." r l _ r l �- Jocass ee ailrace f and Spillwray Area II -22 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) n. IIAY oG Broorltirl artsriva��a County entl Legend ry Keowee-Toxawray Relicensing o L mdedACcess RIver Miles FERC Project No. 2503 3 c""' Highway �__7 Project Boundary c�u•4- . Major Road Lake Soils Neap o�a�ee County 5heet3 of 3 1 S 9 6(Ifl0 12000 C ollna Data Sources :0Eta Sources: Soils Data mart l(www nres.0 sda gov]., U SGS Top o Quad rangl e M a. p. 5 L..on Feet Projection SC State P l ane Cc ordinate System, NA DO 3, l nt emati onal feet II -22 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects 6.1.5.2 Lake Keowee Soils surrounding Lake Keowee are somewhat variable depending upon location and topography in the area of occurrence. Soil types that are present along larger portions of the reservoir shoreline or are more frequently present are described in additional detail in this section. Soils are typically sandy loam or clay loam derived in place from metamorphic crystaline bedrock. These soils in the Lake Keowee area include Cecil, Hayesville, Pacolet, Lloyd, Gwinnett, Grover, Toccoa, and Hiawassee. Subsoils are typically clay, clay loam, or sandy clay. These soils are typically underlain by saprolite or weathered rock at depths ranging from as little as 24 inches to greater than 60 inches. Variations to the typical profile are present in the Musella and the Rabun soils. The Musella soils typically are loam underlain by weathered bedrock at depths of a few feet or less. Rabun soils are cobbly and are categorized as cobbly loam with cobbly clay and cobbly sandy loam subsoils. Rabun soils are typically underlain by saprolite at depths of 48 to 60 inches. The thickness of saprolite below the surface soil deposits can be significant. Depth to weathered or unweathered crystalline bedrock can often be several tens of feet below the ground surface. These soils are susceptible to erosion due to their location along moderately sloped to steeply sloped areas. Soils in the general Lake Keowee area are generally defined as well drained. 6.1.5.3 Reservoir Shoreline Conditions The reservoirs' shorelines are almost entirely composed of residual soil deposits derived from the metamorphic parent rocks. Shoreline soils primarily consist of sandy loam with some clay loam. As a result of the residual composition and the relatively steep slopes surrounding the reservoirs, the shorelines are susceptible to erosion. Shoreline erosion has been observed at both Lake Jocassee and Lake Keowee. Erosion is an ongoing natural process, particularly in the Blue Ridge and Piedmont physiographic provinces, making the various influences on erosion along the Project reservoirs difficult to assess. II -23 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects In general, reservoir shorelines exposed to erosion may eventually reach equilibrium or erosion may slow to an insignificant rate. This process occurs because the topography in the vicinity of the shoreline flattens over time, thereby rendering the shoreline less susceptible to further erosion of a significant nature. These features, referred to as "beaches" for visualization purposes, provide a means by which the wave energy is dissipated over a distance as the wave reaches the shoreline instead of the full wave energy abruptly hitting a steep face of the erodible soils. In addition, flatter topography is less susceptible to erosion than steeper topography for several reasons, including gravitational forces, as well as the speed of runoff. It can be surmised that certain areas and shorelines of reservoirs are more susceptible to erosive forces than others. In general, it would be expected that shorelines on the main body of the reservoir would be the most susceptible to erosion by wave action, particularly the shorelines on the leeward side of the prevailing wind direction. Shorelines along the interiors of coves or arms of the reservoir would generally be more protected and less susceptible with the possible exception of features open to the prevailing wind direction. In addition, areas of the shoreline characterized by bluffs, steep topographic relief, and peninsulas would exhibit a higher susceptibility to erosion than flatter topography. Pre -PAD Erosion Evaluation Duke performed a pre -PAD evaluation of (1) the shoreline conditions and basic mechanisms potentially contributing to shoreline erosion at Lake Jocassee; (2) the meteorological data collected at ONS (located on Lake Keowee) to determine the potential for wave - induced erosion due to the fact that erosion appears to be occurring primarily in areas exposed to wave action along exposed shorelines; and (3) land cover changes occurring in the shoreline vegetation from 1976 to 2009. The observations and conclusions from these studies are summarized below. Three significant classifications of materials subject to potential erosion were observed and characterized using the Unified Soil Classification System (USCS) during the evaluation of the shoreline of Lake Jocassee. The three classifications were partially weathered to sound rock, II -24 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects weathered rock/residuum (SM), and weathered rock/residuum (ML). These materials were generally observed to comprise the exposed slopes and banks of the reservoir. Some of the actual materials may fall between these categories and could be classified in one or more of the groups listed. The following is a discussion of each material. • Partially Weathered to Sound Rock - For purposes of the evaluation, partially weathered to sound rock includes exposed bedrock, which may be weathered due to exposure to the elements but is intact for practical purposes. Based on observations, the rock exhibited fracturing ranging from massive to highly fractured. • Weathered Rock/Residuum (SM) - Weathered Rock/Residuum (SM) (PWR/SM) includes weathered material from the parent bedrock, referred to as saprolite or residuum, which would generally classify as a Silty Sand (SM), if sampled as a soil and classified under the USCS. Under the USCS system, a material classifying as SM primarily consists of sand -sized particles, and has less than 50 percent fines. Fines are considered soil particles that will pass a #200 sieve. Consistency of the SM generally ranged from materials that could be scraped or sampled with the human hand, to those that would require significant effort to sample with digging utensils. ■ Weathered Rock/Residuum (ML) - Weathered Rock/Residuum (ML) (PWR/ML) includes weathered material from the parent bedrock, referred to as saprolite or residuum, which would generally classify as a Sandy Silt (ML), if sampled as a soil and classified under the USCS. Under the USCS system, a material classifying as ML primarily consists of silt -sized or smaller particles. An ML material has greater than or equal to 50 percent fines, or soil particles that will pass the #200 sieve. Consistency of the PWR/ML generally ranged from materials which could be scraped or sampled with the human hand to those that would require significant effort to sample with digging utensils. From the limited observations made during a Pre -PAD evaluation, five basic mechanisms appear to be present that influence erosion of the Lake Jocassee shoreline. These are discussed below: 1. Physical Weathering - Physical weathering is a group of natural processes that in this case would include cyclical freeze /thaw and growth of root systems from trees. It would II -25 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects be anticipated that the exposed bedrock formations along the shoreline would be most susceptible to cyclical freeze /thaw and physical breaking by growth of root systems, although the partially weathered rock materials would also be susceptible to a lesser extent. These mechanisms attack the fractures and weak points within the formations, eventually resulting in a piece or pieces of the formation separating from the parent formation. These processes are completely natural and generally take months to years to occur. Although signs of physical weathering were observed, physical weathering would not be considered a significant source of erosion along the shoreline. 2. Wave Action - Wave action is generally a result of either boat traffic or wind. Because of the relatively low intensity of boat traffic on Lake Jocassee, the primary cause of erosion by wave action would be the result of wind, particularly along the shoreline opposite of the prevalent wind direction and where long reaches of open water (i.e., fetch) provide ample opportunity for wave buildup. Based on observations made during the limited evaluation of the shoreline, evidence exists that wave action is a significant contributing factor to erosion along the shoreline. 3. Concentrated Runoff - Lake Jocassee is generally surrounded by steep terrain with ravines and other drainage features that empty into the reservoir. Despite the well- forested landscape around the reservoir, evidence in several areas suggested that the runoff in some of these natural drainage features may be developing significant velocity, thus contributing to erosion in these areas. 4. Operation of Reservoir - Cyclic raising and lowering of the reservoir level may also contribute to erosion potential along the shoreline. Generally, the higher silt content of the SM and ML soil materials comprising the slopes along the shoreline are not free - draining materials, and therefore the wetted saturation line within the materials does not fall as quickly as the reservoir level. Generally, soil materials are weaker and exhibit a higher unit weight in their saturated state, resulting in a destabilizing effect in the surrounding slopes as the reservoir level drops. Erosion may occur in the form of shallow sloughing of the soils or deeper seated failures depending upon the slope geometry. Generally, slopes II -26 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects with steeper inclinations would be more susceptible to this type of erosion. In addition, cyclic saturation of the materials may remove, or "wash out," the finer grained soil particles from the SM weakening the soil matrix and making the weathered materials more susceptible to erosion. Operation of the reservoir does not likely affect the transported materials as much as the natural slopes along the reservoir. The drop in water level is generally not fast enough to result in transportation of the loosely deposited materials, particularly as these materials are deposited at relatively stable slope inclinations. The transported or deposited materials along the shoreline are more likely to be affected by wave action. 5. Development Along Shoreline - During the evaluation, former and new development along the shoreline was observed. Future development along the shoreline has the potential to exacerbate erosion in these areas. The shoreline of Lake Jocassee is a mixture of exposed rock, steep bluffs, and stretches of relatively mild grades. The exposed bedrock does not appear to be subject to significant erosion from wave action or operation of the reservoir. The milder grades along the shoreline were generally located in the recesses of the numerous coves of the reservoir. These stretches of shoreline with mild grades generally have topography that reduces the potential for erosion. Shoreline areas defined by steep to near vertical bluffs and other features with jutting soil faces were also observed. These steep faces appear more susceptible to erosion by both wave action and cyclic raising and lowering of the reservoir water level. Of the five mechanisms identified as potentially contributing to erosion along the shoreline, wave action due to wind and operation of the reservoir are considered the most significant mechanisms based on the observations made. The limited field observations made during the two days onsite are insufficient to determine the extent of contribution of these two mechanisms to the whole of the erosion occurring. A more detailed study might produce additional data regarding the magnitude and rate of erosion, but is unlikely to provide substantial evidence or proof as to the prevalent mechanism. II -27 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Meteorology Evaluation The hourly average meteorological (wind) data measured on the primary meteorological tower at ONS were used in this analysis. Given the location of this tower on the southeastern shore of Lake Keowee, the data should be fairly representative of prevailing winds along the main body of Lake Jocassee, particularly along its eastern shoreline. The 10 -m level wind speeds may be slightly higher at Lake Jocassee than at ONS, as the terrain appears to be more open to winds from the southerly direction, than at the ONS meteorological tower location. The wind data may not be representative of the arms of Lake Jocassee, in which the terrain may: ■ induce recirculation and diurnal flows up and down the valleys, regardless of regional wind directions; ■ produce higher wind speeds due to channeling of the flow through narrow passages; and ■ produce lighter wind speeds due to stagnation or blocked flow (i.e. calm conditions). Wind Direction Frequency For the period (1986- 2009), the prevailing wind directions within the ONS dataset, measured at the 10 -m level, were from the SW (12.7 percent) and ENE (8.8 percent) directions (see Figure 6.1.5.3 -1). The wind rose also shows other frequently occurring wind directions from the NE (8.25 percent), WSW (8.14 percent) and SSW (8.01 percent). Thus, the downwind sectors that could potentially be impacted more frequently by wave action on Lake Jocassee would be shoreline areas to the NE and WSW, in general, with potential impacts also in the SW, ENE, and NNE downwind sectors. II -28 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5.3 -1 Wind Rose of ONS 10m level Winds (1986 -2009) and Summary Wind Direction Frequency Plot' 10M WINQROSE M w WSCLSIA 0. M1 02 03 ❑1® ❑11 E12 E13 E S 4% 8% 12% 16% 04 05 ®6 ®i ®a 09 ONS 10m Wind Direction Frequency (%) Distribution (1986 -2009) N NNW 15. NNE NW 1 NE WNW ENE W E WSW ESE SW SE SSW SSE S i Wind Speed Classes. I1-29 Pre - Application Document Keowee- Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects WS Class Index WS Classes (mph) WS Classes (m/s) 1 Calm (LT 1.0 mph) Calm ( LT 0.45 m/s) 2 1.00 -1.67 mph 0.45 - 0.74 m/s 3 1.68 -2.19 mph 0.75 - 0.99 m/s 4 2.20 -2.79 mph 1.00 - 1.24 m/s 5 2.80 -3.59 mph 1.25 - 1.49 m/s 6 3.60 -4.49 mph 1.50 - 1.99 m/s 7 4.50 -6.69 mph 2.00 - 2.99 m/s 8 6.70 -8.89 mph 3.00 - 3.99 m/s 9 8.90 -11.19 mph 4.00 - 4.99 m/s 10 11.20 -13.39 mph 5.00 - 5.99 m/s 11 13.40 -17.89 mph 6.00 - 7.99 m/s 12 17.90 -22.39 mph 8.00 - 9.99 m/s 13 GE 22.40 mph GE 10.00 m/s Analysis of the seasonal 10 -m level ONS dataset shows a slight variability in prevailing wind directions (Table 6.1.5.3 -1). While all seasons support a bi -modal frequency between the southwest and northeast directions, the winter and spring seasons indicate a greater tendency for winds from a wider arc (WSW, SW, SSW). The analysis also shows that the WNW wind direction is the second highest wind direction frequency in winter, but it is only a minor feature in the other seasons. This feature in Figures 6.1.5.3 -2 and 6.1.5.3 -3 (i.e., secondary peak between the WNW and NW sectors) shifts clockwise and broadens to indicate flow from a northerly arc (NNW, N, NNE) in summer. Overall, the plotted wind direction frequencies in these figures indicate a seasonal variability of flow from the SW in spring, NE in summer and autumn, and predominantly SW again in winter. Table 6.1.5.3 -1 Seasonal and Total Wind Direction Frequency with Hourly Average Wind SDeed (mDh) Wind Direction Sector Autumn /O ( °) Winter (o /O ) Spring ( ° /O ) Summer ( %) Total Wind Direction Frequency ( %) Average Find Speed (mph) N 4.52 3.03 5.26 8.10 5.25 3.06 NNE 3.72 3.21 5.22 6.99 4.79 3.56 NE 8.80 6.69 7.34 10.04 8.25 4.94 ENE 10.08 7.58 7.67 9.87 8.84 5.04 E 6.77 5.52 3.74 5.44 5.39 4.04 ESE 3.82 3.12 2.18 3.14 3.08 3.47 SE 3.90 3.46 2.59 2.69 3.17 3.47 SSE 3.62 3.10 3.23 3.13 3.27 3.54 S 3.42 3.32 3.90 3.48 3.53 3.67 SSW 6.56 8.53 10.18 6.92 8.01 5.22 II -30 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5.3 -2 Spring and Summer 10m Wind Direction Frequency (ONS; 1986 -2009) WNV W WSV Spring & Summer 10m Wind Directions: % Frequency NE (1986 -2009; ONS) Spring ( %) SE --*- Summer ( %) II -31 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Total Wind Wind Average Autumn Winter Spring Summer Direction Direction Wind Speed o 0 /°) 0 ( /o) o ( /°) Frequency Sector (mph) M) SW 10.53 13.63 14.87 11.96 12.70 5.71 WSW 7.48 9.25 8.04 7.87 8.14 6.02 W 5.92 7.22 5.94 4.78 5.95 5.24 WNW 7.79 9.56 7.39 4.10 7.19 4.73 NW 7.61 8.75 7.29 4.42 7.00 3.91 NNW 5.46 4.01 5.16 7.07 5.44 3.05 Figure 6.1.5.3 -2 Spring and Summer 10m Wind Direction Frequency (ONS; 1986 -2009) WNV W WSV Spring & Summer 10m Wind Directions: % Frequency NE (1986 -2009; ONS) Spring ( %) SE --*- Summer ( %) II -31 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects Figure 6.1.5.3 -3 Autumn and Winter 10m Wind Direction Frec ME W WSV Z S Wind Speed Frequency ; 1986 -2009) Autumn & Winter 10m Wind Directions: Frequency NE (1986 -2009; ONS) I SE --*- Autumn ( %) (Winter ( %) The wind speed frequency distribution, based on the ONS dataset, indicates that the most frequently occurring wind speeds are approximately between 3 to 6 mph (Figure 6.1.5.3 -4), with a combined frequency of 41 percent (Table 6.1.5.3 -2). Lighter speeds are also common, with speeds between 1.6 to 3.5 mph occurring approximately 37 percent of the time. II -32 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) Figure 6.1.5.3 -4 ONS 10m Wind 25.00 20.00 15.00 10.00 5.00 0.00 6.0 Description of Environmental Resources and Project Effects r Distribution i ONS 10m Wind Speed Frequency Distribution ( %) for 1986 -2009 �QQQQQQQQQQQQ CD r- 1-+ rl- n �.O 00 m 00 M d rl N N M l6 o6 -4 M I-� N N 00 N 00 l0 Ln r� .-i c-I r-I N N J I-P N N M lD Ol N Cl W r1 1-4 00 c-I r-I c-I Table 6.1.5.3 -2 Wind Speed Class Freauencv: ONS 10m level (1986 -2009) WS Classes' Hours _ONS lOm WS (1986 -2009) Wind Speed Class Frequency M) CALM (LT 1.0 mph) 575 0.31 1.0 -1.67 mph 6004 3.27 1.68 -2.1 mph 21746 11.85 2.2 -2.7 mph 22282 12.14 2.8 -3.5 mph 24356 13.27 3.6 -4.4 mph 34680 18.89 4.5 -6.6 mph 40703 22.17 6.7 -8.8 mph 17933 9.77 8.9 -11.1 mph 8445 4.60 11.2 -13.3 mph 3625 1.97 13.4 -17.8 mph 2641 1.44 17.9 -22.3 mph 548 0.30 GE 22.4 mph 45 0.02 ' Units conversion factor for wind speed: 1 m/s = 2.237 mph Calms are defined as wind speeds less than the starting speed of the anemometer (i.e., 0.45 m/s or 1 mph). Calms were only observed 0.31 percent of the time in the ONS dataset (i.e., 575 hours in the 24 -year period). The mean hourly average wind speed for the entire dataset (1986 -2009) is 4.6 mph, with a maximum hourly average wind speed of 28 mph. The higher sustained wind speeds tend to occur when winds are from the prevailing wind directions (Figure 6.1.5.3 -5). Thus, the higher II -33 Pre- Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects average speeds of 5 to 6 mph occur generally with winds directions from the (WSW -SW -SSW) and (NE -ENE) arcs (Table 6.1.5.3 -1). re 6.1.5.3 -5 Average Hourlv Wind S WN\ W WS\ N versus Wind Direction Distribution ONS 10m Winds (1986- 2009): Average Speed per Wind --`ion (i.e. sectorfrom the winds ore coming) S Conclusions NE — Freq WD ( %) E —11—Avg WS (mph) 5E Analysis of a 24 -year period of wind data (1986 -2009) from ONS indicates prevailing winds from two directions: southwest (SW) and east - northeast (ENE). Waves generated by winds from these directions would impact downwind sectors on the northeast (NE) and west - southwest (WSW) shoreline of Lake Jocassee. During the period of record, higher average wind speeds are associated with both prevailing wind directions. Thus, wave - induced erosion from larger wave heights could be more frequent along the NE and WSW shorelines, which also have a longer fetch across the main body of the lake. Seasonal analysis shows a secondary peak in the frequency of winds from a third direction, the west - northwest (WNW). Prevailing winds for the winter season include this third direction II -34 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects (WNW). The secondary peak in WNW winds is less frequent in the other seasons, and shifts clockwise, out of the north in the summer months. Thus, this feature could produce slightly higher erosion potential along the east- southeast (ESE) shoreline of Lake Jocassee in the winter and the southern shoreline in the summer, than during other seasons. An additional consideration in the seasonal analysis of erosion potential is the occurrence of synoptic scale storm systems, which are more frequent in late autumn, winter, and early spring. These large systems can produce heavy rainfall and strong, sustained winds, which may contribute significantly to both waves and runoff induced erosion over timescales of one to two days. During the summer months, lighter winds and lower wave heights would be more common. Thunderstorms would produce short-lived events with strong winds and heavy rainfall, of only a couple hours duration or less. The Lake Jocassee shoreline is characterized by steep terrain in most areas, but with the southern exposure of the lake being more open. The main body of the lake provides a long fetch, allowing the prevailing winds from the SW and ENE to induce more frequent wave action and potential for erosion along the opposite NE and WSW shorelines in all seasons. Land Cover Evaluation While the Lake Jocassee shoreline is potentially vulnerable to erosion and some erosion has undoubtedly occurred, Duke was interested in quantifying the amount of shoreline that may have been lost to erosion over the life of the Project. This was accomplished by analyzing the change in land cover (vegetated area) between 1976 and 2009 using available geo- referenced digital orthophotos. The quality of the 1976 photography did not support the development of shoreline contours to compare directly with the contours developed using the 2009 photography, but did allow for the identification of vegetated shoreline areas. By comparing this imagery data, Orbis, Inc. was able to determine that there was an increase of about 39 acres in the vegetated shoreline area of Lake Jocassee from 1976 to 2009 ( Orbis, Inc. 2010a). Based on this analysis, some shoreline areas have undergone erosion while other areas have received deposited materials that II -35 Pre - Application Document Keowee - Toxaway Project (FERC No. 2503) 6.0 Description of Environmental Resources and Project Effects over time have become vegetated. Thus, there does not appear to have been a significant amount of shoreline erosion or a net loss of vegetated shoreline area in Lake Jocassee from 1976 to 2009. Summary While shoreline erosion at Lake Jocassee has occurred over the term of the Existing License, the amount of erosion does not appear to be severe. Further, the erosion may not be directly related to Project operations or maintenance, but may be caused by natural phenomena (i.e., wind and wave action). In Article 20 of the Existing License, the FERC required Duke to be responsible for and take reasonable measures to prevent soil erosion on lands adjacent to the streams and to prevent stream siltation or pollution resulting from construction, operations or maintenance of the Project. However, the FERC ruled (33 FERC §61,321, Duke Power Company, Project 2503- 009, December 4, 1985) that Article 20 does not require Duke to be responsible for erosion resulting from natural phenomena occurring within the lake. Duke realizes that erosion of the Lake Jocassee shoreline may impact various resources surrounding the lake and is proposing to evaluate and document the current status of erosion along the reservoir shoreline. The draft Lake Jocassee Shoreline Erosion Study Plan can be found in the Appendix D (located in Volume VI of this PAD). II -36 Pre- Application Document Keowee - Toxaway Project (FERC No. 2503)