HomeMy WebLinkAboutCity & Borough of Sitka - Blue Lake Hydro - REF Grant 7060917 2016Sitka, Alaska
Blue Lake expansion project provides 50% more electricity
Quick Facts
FERC Project Number: P-2230
Total Project Costs: $150,000,000
Funding: Renewable Energy Fund, State & Local
Capital Costs
Development: $20,000
Construction: $130,000,000
Project Specifications
Make/Output: (3) 5.3 MW Francis Turbines
Make/Output: (1) 1.8 MW Francis Turbine
Static Head: 412 feet
Hydraulic Capacity: 600 cubic feet/second
Reservoir Storage Volume: 97,300 acre-feet
Annual Energy Generation: 94,500 MWh
Diesel Fuel Offset
Estimated Annual: 3,750,000 gallons
Jan. 2015-June 2015: 1,800,000 gallons
Expansion Cost
Total: $46,715,413
Construction Cost: $88,387,700
Development and Management: $58,328,113
Blue Lake Hydroelectric Expansion
Project Overview
In partnership with the Alaska Energy Authority
(AEA), the Blue Lake Hydroelectric Expansion project
upgraded the existing facility in November of 2014.
Located approximately five miles east of Sitka, the
dam was raised 83 feet, three new generating turbines
were added in conjunction with a new powerhouse
retiring the original turbines and powerhouse, and
additional improvements were made. The project
increases the capacity of the facility from 7.54 to 17.7
MW and increases the annual energy generation from
62,500 MWh to 100,200 MWh.
Objectives
The objectives of this project were to increase the
capacity and generating power of the Blue Lake hy-
droelectric dam and to maximize fuel displacement,
power to residents, and potable water availability.
Recent Performance
The expanded project became operational November
of 2014. In 2015 it produced nearly 60,000 mega-
watt-hours of electricity, displaceing 4,200,000 gallons
of petroleum fuel.
Project Specifications
The Blue Lake facility consists of the following major
features: the dam, a submerged intake structure, a
power conduit, powerhouses, switchyard, and trans-
mission lines. Located at stream mile 2.31 on Sawmill
Creek, the raised concrete arch dam is 294 ft high.The
140 ft wide spillway is centrally located in the dam. In
addition to raising the dam, Hatch Engineering and
Barnard Construction created a new gatehouse and
intake structure, a 900-foot long intake tunnel, a 110-
foot long vertical gatehouse shaft, a 415-foot long adit
tunnel, and a 350-foot long vertical shaft for an under-
ground surge chamber. The penstock, which supplies
both the powerhouse and Sitka’s water supply, had to
Blue Lake hydroelectric dam, photo courtesy of Bluelakeexpansion.com
be relined in several areas and 500 feet was replaced
to deliver water to the new powerhouse. Three 5.3
MW turbines were installed in the new powerhouse.
A new 1.8 MW turbine was also installed in the Fish
Valve Unit (FVU) along the penstock to maintain flow
of Sawmill Creek. The new powerhouse is the primary
generating facility and the FVU powerhouse provides
additional capacity.
Allocation of Funding
Learning Experiences/Challenges
1. Although hydroelectric projects are more than
worth the costs of construction and maintenance,
Sitka was forced to become creative to pay off the
$150,000,000 expansion project. As of May 11, 2015
the Sitka Assembly settled on a modest electric rate
increase of 6% over the next year to cushion expenses
and pay off the remaining debt.
2. Under the Federal Energy Regulatory Commission,
Sitka was required to amend the project’s license upon
expansion. This involved consultation with state and
federal resource agencies, the public and non-govern-
mental organizations, and special interest groups.
Community Benefits
1. A unique feature of this project is that it incorpo-
rates a release valve to provide water when the reser-
voir is below the spillway elevation. This automatic
bypass valve is a back-up to the Fish Valve Unit and
opens when the Fish Valve Unit is tripped off-line to
maintain the required flow between 50 and 70 cubic
feet per second (cfs) in the stream at all times. This
was put in place according to Alaska Department of
Fish & Game standards to promote a healthier habitat
for fish populations in the area.
2. The original goal of the project was to expand Sitka’s
electrical generating base in order to meet Sitka’s rising
energy needs. In 2006, Sitka experienced a 7% load
increase, followed by a 5% increase in 2007. Half of
this resulted from increased electric heating and the
other half from expansion of Sitka’s seafood processing
industry. This expansion project has more than met
the growing needs of the community.
Project Contact Information
Owner: City and Borough of Sitka
Phone: 907-747-3294
Engineer: Hatch Associates
Contractor: Barnard Construction, 907-747-3695
Case Study Author
AEA
Website: Akenergyauthority.org
Phone: 907-771-3000
Blue Lake Hydroelectric Expansion
AEA Grants $40,950,000
ADEC Grants $11,113,000
City Funds $676,000
Bonds $93,976,413
TOTAL FUNDING $146,715,413
Francis turbines, photo courtesy of AEA.
Published November 2016