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HomeMy WebLinkAboutREF VI Appendix F P14066_GartinaFalls_Exhibit ALICENSE APPLICATION Gartina Falls Hydroelectric Project FERC PROJECT NO. 14066-000 EXHIBIT A Inside Passage Electric Cooperative P.O. Box 210149 Juneau, Alaska 99821 May 2012 Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-i May 2012 EXHIBIT A PROJECT DESCRIPTION TABLE OF CONTENTS 1.0 INTRODUCTION......................................................................................................... A-1  1.1 General Project Setting and Location ......................................................................... A-1  1.2 Drainage Area ............................................................................................................. A-1  2.0 PROJECT FEATURES................................................................................................ A-3  2.1 Diversion/Intake .......................................................................................................... A-3  2.2 Penstock ...................................................................................................................... A-3  2.3 Powerhouse ................................................................................................................. A-3  2.4 Tailrace ....................................................................................................................... A-4  2.5 Access Roads .............................................................................................................. A-4  2.6 Transmission Line/Switchyard ................................................................................... A-4  3.0 MODE OF OPERATION ............................................................................................ A-9  4.0 ESTIMATED PROJECT COSTS ............................................................................. A-11  5.0 PURPOSE OF PROJECT .......................................................................................... A-13  LIST OF TABLES Table A-1. Summary of Project features. ................................................................................... A-5  LIST OF FIGURES Figure A-1. Gartina Falls Annual Flow Duration Curve. .......................................................... A-2  Figure A-2. Gartina Falls Average Monthly Flow. .................................................................... A-2  Figure A-3. Electrical One Line Diagram for the Gartina Falls Hydroelectric Project. ............ A-7  Figure A-4. Gartina Falls Average Monthly Generation. .......................................................... A-9  Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-ii May 2012 This page intentionally left blank. Section 1 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-1 May 2012 1.0 INTRODUCTION 1.1 General Project Setting and Location The proposed Gartina Falls Hydroelectric Project site is located on the northeast side of Chichagof Island in southeast Alaska approximately 5 air miles southeast of Hoonah. Specifically, the Project is located in Alaska, Copper River Meridian, T43S and T44S, R61E, in Sections 35 and 2, 11 respectively. Gartina Creek is a low-gradient stream that originates in the mountains to the south of Hoonah Harbor. The Gartina Falls Project would consist of a small diversion dam and intake just above Gartina Falls, a steel penstock, a powerhouse located at the base of Gartina Falls, access roads, and an overhead transmission line. The proposed project will have an installed capacity of 455 kW. 1.2 Drainage Area The Gartina Creek drainage area at the project site, consisting of 10.3 square miles, is primarily located in T43S 34-36 and T44S, R61E, Sections 11-15, 22-27. The elevation in the basin varies from elevation 218 at the diversion site to a high of approximately 2,900 feet and is generally oriented in a southwesterly direction. The mean basin elevation is approximately 1,240 feet. The drainage basin surrounding Gartina Creek is primarily steep with slopes averaging about 25%. The basin is generally forested with areas of muskeg near the creek and tributary streams and exposed bedrock outcroppings in the higher elevations. The estimated average annual flow at the point of diversion is 64 cfs. A flow duration curve and annual hydrograph are shown in Figures A-1 and A-2, respectively. Additional detailed hydrology is presented Appendix D of Exhibit E of this license application. Section 1 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-2 May 2012 Figure A-1. Gartina Falls Annual Flow Duration Curve. Figure A-2. Gartina Falls Average Monthly Flow. 0 100 200 300 400 500 600 700 800 900 1000 0 102030405060708090100Discharge (cfs)Probability of Exceedance (%) Gartina Falls Annual Flow Duration Curve 0 20 40 60 80 100 120 Discharge (cfs) Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-3 May 2012 2.0 PROJECT FEATURES Project features are summarized in Table A-1 and described below. 2.1 Diversion/Intake A diversion will be constructed approximately 125 upstream of the top of Gartina Falls. The crest of the diversion will be at elevation 228 fmsl. The diversion will consist of a center section with a moveable gate and a fixed crest overflow section. The fixed crest overflow section will be constructed with rock fill with a concrete core wall. The rock fill will be grouted on the downstream side to provide stability and durability. The crest length of the overflow section will be approximately 42 feet long and the section will act as a spillway with uncontrolled overflow when inflows exceed the powerhouse flow. The center gate section will consist of a 14-foot wide radial gate that will be raised during high flow events to add flood capacity and to pass accumulated sediment. Stoplog slots will be located at the upstream end of the radial gate section to provide a means to dewater the gate during periods of maintenance. The intake structure will consist of a small concrete box-type of structure located on the left side of the diversion. The front of the intake will be protected by a sluiceway and trash rack. Stoplog slots will be located at the upstream end of the sluiceway to provide a means to dewater the intake during periods of maintenance. A steel transition piece will connect the intake to the penstock. A small valve house will be located immediately downstream of the intake. The valve house will house the penstock shutoff valve and operator as well as batteries needed to ensure fail-safe operation and level control and flow sensors. Access to the diversion/intake site will be provided by the primary Project access road. 2.2 Penstock An approximate 225-ft-long welded steel penstock will convey water from the intake to the powerhouse. The penstock will have a diameter of 54 inches corresponding to a maximum flow rate of 110 cfs. The initial 125 feet of the pipeline will be buried and will be located on an existing bench parallel to the stream. The final 100 feet will be above ground and will drop steeply down the hillside to the powerhouse. The above-ground penstock will be supported by a simple saddle support at approximately mid-span. The penstock will have a polyurethane lining and coating to provide corrosion protection. Thrust blocks will be provided at changes in alignment and grade as well as at the powerhouse. The penstock will have a leak detection system installed on it that will automatically close the intake pipeline shutoff valve in the highly unlikely event that a leak occurs. 2.3 Powerhouse The powerhouse will be located approximately 80-ft downstream of the falls which are the location of the anadromous barrier of Gartina Creek. The powerhouse will sit on an excavated bench at or about elevation 170 which is above the ordinary high water mark of Gartina Creek. The powerhouse will be a concrete building 22-ft wide by 32-ft long and 12-ft high. The powerhouse will contain one 455 kW horizontal cross-flow turbine/generator set, inlet piping, guard valve, switchgear, and controls. Centerline of the turbine will be at approximately elevation 172.5. Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-4 May 2012 2.4 Tailrace Powerhouse flows will discharge into a chamber below the powerhouse and then through an opening in the powerhouse foundation directly to Gartina Creek approximately 80 feet downstream of the base of the falls. The opening in the powerhouse foundation will be protected by a movable picket fence. The picket fence can be lowered when migrating fish are present to protect against inadvertent entry into the discharge chamber. A 12-inch diameter pipeline will be routed from the discharge chamber below the powerhouse to the pool at the base of Gartina Falls. This pipeline will convey 8-10 cfs of the powerhouse flow to the pool whenever the project is in operation. When the project is not in operation, natural flows will pass by the diversion/intake structure and flow over the falls to the pool. This combination will ensure that a constant flow of water is introduced to the pool at the base of the falls at all times. 2.5 Access Roads A limited amount of new access road will be needed to construct and operate the project. Large portions of the drainage basin have already been logged and an extensive logging road system exists in the area. Approximately 0.5 miles of new road will be required to access both the powerhouse site and the diversion site from the existing road system. The primary project access road will originate at FR 8503 and will run approximately 0.4 miles ESE to the diversion/intake site. The primary access road will have a road width of 18-feet and with gravel surfacing similar to the existing logging roads in the area. A short, approximately 0.1 mile long spur road will provide access to the powerhouse site. The powerhouse spur road will have a road width of 14 feet and gravel surfacing. Access to the project site will be restricted by a gate located at the beginning of the project access road. This gate will be closed and locked as a normal operating procedure. 2.6 Transmission Line/Switchyard The switchyard at the powerhouse will consist of a pad-mounted disconnect switch and a pad- mounted step-up transformer located on the roof of the powerhouse. A buried 12.5 kV transmission line would follow the powerhouse access road from the powerhouse to the junction with the main project access road. The transmission line will then transfer to a 12.5kV overhead line that will follow the project access road and then the existing logging roads to a point of interconnection near the Hoonah airport. Total length of the transmission line will be approximately 3.8 miles. Poles would be designed as tangent line structures on about 300 foot centers. Design of the line using tangent construction will provide raptor protection. Collision avoidance devices will be installed on the line at appropriate locations to protect migratory birds. A communications cable will be installed parallel to the transmission line to allow operators in the diesel plant to monitor and control the hydroelectric project. An electrical one-line depicting the generation and interconnection is shown in Figure A-3. Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-5 May 2012 Table A-1. Summary of Project Features. Location Alaska, Copper River Meridian, T43S and T44S, R61E, in Sections 35 and 2, 11 respectively, Chichagof Island, Alaska, near the community of Hoonah. Approximate latitude 58 o 03’ and longitude 135o 23’. Intake Concrete box type located on left side of diversion. Diversion 56-ft. long, crest elevation = 228 msl. Reservoir None. Limited pool behind diversion structure. Usable storage: 0 AF Surface area: 1.7 acre Penstock Total Length: 225 ft. Diameter: 54 inches Material: Steel Components: Polyurethane exterior coating, Polyurethane interior lining Powerhouse Size: 22 ft. by 32 ft. Number of Units: One Type of Turbine: Cross-flow Design Flow: 110 cfs Range of Flow: 11-110 cfs Gross Head: 62 ft. Net Head: 58 ft. Turbine Power: 600 HP Generator: 455 kW Auxiliary Units N/A Future Units N/A Operation Run of river, Automatic Transmission Line Voltage: 12.5 kV Length: 3.8 miles Type: 0.1 miles buried in conduit, 3.7 miles overhead on timber poles, tangent line construction Access Roads Length: 0.5 mile new road Average Annual Energy 1,810 MWh Estimated Project Cost $6,694,000. (2012 dollars) Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-6 May 2012 This page intentionally left blank. Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-7 May 2012 Figure A-3. Electrical One Line Diagram for the Gartina Falls Hydroelectric Project. Section 2 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-8 May 2012 This page intentionally left blank. Section 3 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-9 May 2012 3.0 MODE OF OPERATION The Gartina Falls Hydroelectric Project will operate entirely in a run-of-the-river mode, generating electrical energy from available streamflow. Water up to the desired turbine flow will be diverted through the powerhouse and returned to Gartina Creek near the base of the falls. Turbine flow will range from a minimum of about 11 cfs to a maximum of 110 cfs depending on the electrical load of the system and the available water. This mode of operation is expected to result in 1,810 MWh of average annual generation. The average monthly generation is shown on Figure A-4 and represents a dependable capacity of 110 kW. Figure A-4. Gartina Falls Average Monthly Generation. The plant will be operated automatically and controlled remotely from the diesel power plant located in Hoonah. Operators will make periodic inspections to the Project at least weekly to inspect the facilities. Additionally, the Project’s Supervisory Control and Data Acquisition (SCADA) system will include level, pressure and temperature sensing, gate and valve position monitoring and generation monitoring. In the event of an alarm, an operator will be immediately notified. In the event of a shut-down for any reason, water will begin to immediately spill over the spillway and flow the short distance to falls. As such, flow will be maintained continuously downstream of the project. Inflows in excess of 110 cfs will initially flow over the uncontrolled spillway and into Gartina Creek. When inflows reach 500 cfs, the radial gate will be opened and inflows will flow past the Project along the natural creek bed simulating a natural flushing flow. This combined mode of operation will result in flows upstream of the diversion and downstream of the Project tailrace being exactly the same as flows would be if the Project was not constructed. 0 50 100 150 200 250 300 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepEnergy, MWhGartina Falls Average Monthly Generation Section 3 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-10 May 2012 This page intentionally left blank. Section 4 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-11 May 2012 4.0 ESTIMATED PROJECT COSTS The total cost of the Project is estimated to be approximately $6.7 million as shown below: Direct Construction Costs $4,200,000 Contingency $1,050,000 Engineering $420,000 Licensing $370,000 Owners General Administration $210,000 Construction Management $210,000 Interest During Construction $234,000 Total $6,694,000 Annual operation and maintenance costs are estimated as shown below: Financing $123,000* Operations & Maintenance $50,000 Insurance $67,000 Total $240,000 * Assumes 50% grant funding and 50% renewable energy fund loan from the State of Alaska. Section 4 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-12 May 2012 This page intentionally left blank. Section 5 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-13 May 2012 5.0 PURPOSE OF PROJECT The purpose of the Gartina Falls Hydroelectric Project is to generate renewable power and energy to serve the community of Hoonah, Alaska. The development of this renewable energy project will replace existing diesel generation in Hoonah. The replacement of this generation will reduce diesel consumption by approximately 135,000 gallons per year and carbon dioxide (CO2) emissions by approximately 1,500 tons annually. Section 5 Exhibit A Gartina Falls Hydroelectric Project Inside Passage Electric Cooperative FERC No. 14066 A-14 May 2012 This page intentionally left blank.