Middle Fork Project Project Description

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Middle Fork Project Project Description

• April 25, 2006

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Middle Fork American River Hydroelectric Project

• Provide a Project Overview
• Describe Major Project Features
• Describe Supporting Infrastructure
• Discuss Operating Constraints
• Describe General Operations and Maintenance
• Summary of Recreation Facilities
• Questions

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MFP - Overview

• Developed as a Water Supply and Generation
  Project
• Initial Operation 1967
• 224 MW Nameplate Generating Capacity
• 120,000 Acre-Feet Water Supply
• Operated by Placer County Water Agency
• PG E Acquires Power Output

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Major Project Features

• Two Large Dams and Storage Reservoirs
• Two Medium Dams and Reservoirs
• Three Small Dams and Diversion Pools
• Five Powerhouses
• Five Tunnels

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Supporting Infrastructure

• Electrical Switchyards and Substation
• Access Roads and Trails
• Communication and Power Lines
• Stream Gages
• Maintenance and Dormitory Facilities

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Duncan Creek Diversion

• Spillway Crest - 5,265 ft Elevation
• Diversion - Concrete Gravity - 165 ft Long
• Diversion Capacity - 400 cfs
• Surface Area - Approximately 1 Acre
• Gross Storage - 20 Acre-Feet

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Duncan Creek - Middle Fork Tunnel

• 1.5 Miles Long
• 10 ft Horseshoe Cross-Section
• Capacity 400 cfs
• Intake With Trash Rack

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French Meadows Damand Reservoir
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French Meadows Damand Reservoir

• Spillway Crest at 5,273 ft Elevation
• French Meadows Dam - Gravel and Earthfill -
  2,700 ft Long
• Surface Area - 1,404 Acres Maximum,434 Minimum
• Gross Storage - 134, 993 Acre-Feet
• Shoreline - 9 Miles

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French Meadows - Hell Hole Tunnel

• 2.6 miles long
• 12.3 ft Horseshoe Cross-Section
• Capacity 400 cfs
• Intake in French Meadows Reservoir and Trash Rack
• Terminates in a 6.25 ft Diameter - 691 ft Long
  Penstock to the French Meadows Powerhouse

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French Meadows Powerhouse
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French Meadows Powerhouse

• Located on Hell Hole Reservoir
• Water Supply - Discharge from French Meadows -
  Hell Hole Tunnel
• Single Francis Turbine
• 15.3 MW / 60,000 Volts
• Discharges to Hell Hole Reservoir

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Hell Hole Dam and Reservoir
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Hell Hole Dam and Reservoir

• Spillway Crest at 4,650 ft Elevation
• Hell Hole Dam - Rockfill - 1,570 ft Long
• Surface Area - 1,253 Acres Maximum, 185 Acres
  Minimum
• Gross Storage - 207,500 Acre-Feet
• Shoreline - 11 Miles

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Hell Hole Powerhouse
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Hell Hole Powerhouse

• Located at Outlet from Hell Hole Dam
• Water Supply - Hell Hole Dam Discharge Conduit
• Single Francis Turbine
• 0.725 MW / 12,000 Volts
• Discharges to Rubicon River

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Hell Hole - Middle Fork Tunnel

• 10.4 Miles Long
• 13.5 ft Horseshoe Cross-Section
• Capacity 920 cfs
• Intake in Hell Hole Reservoir
• Terminates in a 9 - 7.5 ft dia. - 3,653 ft Long
  Penstock to the Middle Fork Powerhouse

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North Fork Long Canyon Creek Diversion
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North Fork Long Canyon Creek Diversion

• Dam Crest at 4,720 ft Elevation
• Diversion - Concrete Gravity - 120 ft Long
• Diversion Capacity 100 cfs
• Surface Area - Less than 1 Acre
• Pipe and Shaft to the Hell Hole - Middle Fork
  Tunnel

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South Fork Long Canyon Creek Diversion
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South Fork Long Canyon Creek Diversion

• Dam Crest at 4,650 ft Elevation
• Diversion - Concrete Gravity - 145 ft Long
• Diversion Capacity 200 cfs
• Surface Area - Less than 1 Acre
• Pipe and Shaft to the Hell Hole - Middle Fork
  Tunnel

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Middle Fork Powerhouse
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Middle Fork Powerhouse

• Located on Middle Fork Interbay Reservoir
• Water Supply- Hell Hole - Middle Fork Tunnel
• Two Pelton Waterwheels
• 122.4 MW / 60,000 Volts
• Discharges to Middle Fork Interbay Reservoir

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Middle Fork Interbay Damand Reservoir
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Middle Fork Interbay Damand Reservoir

• Dam Crest at 2,536 ft Elevation
• Interbay Dam - Concrete Gravity - 233 ft Long
• Surface Area - 7 Acres
• Gross Storage - 175 Acre-Feet

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Middle Fork TunnelRalston Tunnel

• 6.7 Miles Long
• 13.5 Horseshoe Cross-Section
• Capacity 924 cfs
• Intake in Middle Fork Interbay Reservoir / Trash
  Rack
• Terminates in a 9.5 - 8 ft dia. - 1,670 ft Long
  Penstock to the Ralston Powerhouse

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Ralston Powerhouse
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Ralston Powerhouse

• Located on Ralston Afterbay Reservoir
• Water Supply - Middle Fork Tunnel - Ralston
  Tunnel
• Single Francis Turbine
• 79.2 MW / 60,000 Volts
• Discharges to Ralston Afterbay

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Ralston Afterbay and Afterbay Dam
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Ralston Afterbay and Afterbay Dam

• Dam Crest at 1,189 ft Elevation
• Ralston Afterbay Dam - Concrete Gravity - 560 ft
  Long
• Gross Storage - 2,782 Acre-Feet

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Ralston - Oxbow Tunnel

• 0.1 Miles Long
• 13.25 ft Horseshoe Cross-Section
• Capacity 1,075 cfs
• Intake in Ralston Afterbay Reservoir / Trash Rack
• Supplies Oxbow Powerhouse

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Oxbow Powerhouse
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Oxbow Powerhouse

• Located on Middle Fork American River
• Single Francis Turbine
• Generator - 6.1 MW / 60,000 Volts
• Discharges to Middle Fork American River below
  Ralston Afterbay Dam

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Other Project Components

• Project Power and Communication Lines
• Stream Gaging Stations
• Project Roads and Trails
• Microwave Reflector Stations and Radio Towers
• Support Facilities

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Project Operations

• Operating Constraints
• Water Rights (Storage and Diversion Allowances)
• Minimum Pool Requirements
• Stream Maintenance Flows (i.e. Minimum Instream
  Flows)
• Dam / Diversion Discharge Capacities

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Minimum Pool Requirements
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Minimum Instream Flow Requirements
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Minimum Instream Flow Requirements
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Minimum Instream Flow Requirements
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Dam and Diversion Discharges
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Dam and Diversion Discharges
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Dam and Diversion Discharges
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MFP Operations

• Operated to Meet Water Supply Requirements
• Operated to Meet Minimum Instream Flow
  Requirements
• Operated to Optimize Value of Generation

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Operations Overview

• Operations Governed By
• MF Project FERC License Conditions
• Water Rights Permits
• Contractual Obligations (Delivery of Water and
  Power)
• Physical Constraints (Size of Tunnels, Capacity
  of Powerhouses)
• Power Market High Value Periods of Operation

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Seasonal Pattern of Operations

• Reservoir Storage
• French Meadows and Hell Hole Reservoirs, 343,000
  Acre-Feet Total Storage
• Seasonal Pattern of Operations
• Store Water During Winter and Spring
  Precipitation and Runoff Periods (Refill Period)
• Releases During the Dry Summer and Fall Months
  (Drawdown Period)
• Reservoirs are Operated to Maintain Relative
  Balance between Reservoirs
• Dec. 31 Carry-Over Target for Dec. 31 of 150,000
  Acre-Feet (Two Reservoirs)

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Reservoir Operations

• Operations during refill period to meet demands,
  fill reservoirs, avoid spill
• Operations during drawdown to meet demands, hit
  end-of-year storage target
• Reservoir storage targets through the year
• Generally based on historic practice
• Refined during refill period based primarily on
  hydrologic conditions, with some consideration of
  power market conditions
• Storage managed during drawdown period based on
  consumptive obligations and power market trends
• At all times meet minimum release obligations

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Generation Scheduling

• Watershed provides sufficient water to operate
  about half of the time at full load (50
  capacity factor)
• Full-load operations are most efficient for
  generation
• Project typically operates in peaking mode
  8-16 hours per day, during the most valuable time
  periods
• Annual generation approximately 1 million MW
  hours.

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Scheduling and Operations

• Project operations have been much the same since
  the construction of the Project
• Variation in specific operations practices
  through time in response to
• Project maintenance requirements
• Changes in California power markets
• Recreation demands downstream of the Project

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Maintenance

• Facility Testing (powerhouse equipment testing
  and maintenance, gate and valve testing)
• Debris Removal Management
• Sediment Management
• Vegetation and Pest Management
• Facility Painting
• Road Maintenance

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Recreation Facilities

• Recreation Plan developed as required by the
  license
• Recreation Facilities include campgrounds, picnic
  areas, boat launch areas, and one scenic vista
• Operated by the Tahoe and Eldorado National
  Forests

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Recreation Sites

• French Meadows Reservoir
• Reservoir North Shore - picnicking, camping, boat
  ramp and parking (McGuire, Poppy)
• Reservoir East end - single-unit and group
  campgrounds (Lewis, Coyote Group, gates Group and
  Ahart)
• Reservoir South Shore - picnicking, camping, boat
  ramp and parking (French Meadows Complex)

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Recreation Sites

• Hell Hole Reservoir
• Hell Hole Reservoir - scenic vista, picnicking,
  camping, boat ramp and parking
• Big Meadows Campground
• Upper Hell Hole (boat-in/hike-in campground)
• Ralston / Oxbow
• Ralston Picnic Area
• South Fork Long Canyon
• One single-unit and one group campground (Big
  Meadows and Middle Meadows Group)