Interesting Article for all Bear Lakers

 

 Dry Canyon Pumped Storage Hydropower Project

DRY CANYON PUMPED STORAGE HYDROPOWER  

PROJECT

 

APPLICATION FOR PRELIMINARY PERMIT

 

The Applicant, PacifiCorp, is a domestic corporation and is not claiming municipal

preference under section 7(a) of the FPA. PacifiCorp, a corporation located in Portland,

Oregon, is organized under the laws of the State of Oregon and, as such, is qualified under

§ 4(e) of the FPA to hold hydroelectric licenses issued under Part I of the FPA.

The proposed term of the requested permit is 48 months.

The proposed project would use the existing facilities and rights, as follows:

 

PacifiCorp Facilities Background

 

The Applicant owns and operates the over 100-year-old Bear Lake Facilities. These

existing facilities are used by the Applicant to divert water from the Bear River and to store

and release water from the Bear Lake Reservoir (Bear Lake and Mud Lake). The Bear Lake

Facilities include Stewart Dam, Rainbow Canal Headgates, Rainbow Canal, Ream-Crocket

Canal Intake, Ream-Crocket Canal, Bear Lake Causeway Inlet, Lifton Pumping Station,

Outlet Canal, Paris Dike and Outlet Canal Headgates. The Bear Lake Facilities were in

place and functioning in 1914 except for the Lifton Pumping Station, which became

operational in 1917. In addition to irrigation water storage and delivery, this system allows

the management of Bear River water for flood control and power generation.

 

Prior to the construction of these facilities, a right-of-way over the Bear Lake Reservoir

(Mud Lake and Bear Lake) for the storage and conveyance of water was granted by the

Secretary of the Interior in 1907. In 1927, the portion of the 1907 right-of-way north of

Paris Dike was reduced in size to only cover Outlet Canal. The current footprint of the Mud

Lake portion of the right-of-way is 15,487 acres.  

 

Within Mud Lake is the Mud Lake Regulation Reservoir, created by the facilities

mentioned above and habitat management dikes built by the U.S. Fish and Wildlife Service

(USFWS) as part of its management of the Bear Lake National Wildlife Refuge. The Mud

Lake Regulation Reservoir occupies approximately 8,286 acres (in normal operation)

within the larger Mud Lake area. During periods of high runoff, the water control structures

in the habitat management dikes are opened to allow the full water storage capability of the

15,487 acres of Mud Lake to be used. Normal maximum full pool of the Mud Lake

Regulation Reservoir is 5,930.78 feet NAVD88 (maximum flood full pool is 5,931.78

At the upstream end of this system, water is diverted from the Bear River at Stewart Dam

and then conveyed through the Rainbow Canal Headgate and Rainbow Canal to the Mud

Lake Regulation Reservoir. Once in the Mud Lake Regulation Reservoir water can be

stored, diverted back to the Bear River through Outlet Canal, or moved into Bear Lake

through the Bear Lake Causeway Inlet.

 

The Applicant currently holds water rights from the states of Idaho and Utah to divert the

Bear River at Stewart Dam and store diverted Bear River water in the Bear Lake Reservoir.

The Applicant has a right to use the stored water for irrigation, power generation, and other

beneficial purposes recognized by law.

 

In addition to the existing Bear Lake Facilities, right-of-way, and water rights, there are

three existing 345-kilovolt (kV) transmission lines located within 20 miles of the proposed

Project that could be used to support transmission needs. The Applicant’s proposed 500-kV

line (Gateway West) is near these corridors also.

 

Existing Facilities to be Utilized

 

The water for the Project will be diverted at Stewart Dam and conveyed through Rainbow

Canal to Mud Lake Regulation Reservoir using existing facilities, water rights and storage

rights. The Applicant is proposing to use a portion of the Mud Lake Regulation Reservoir

along with associated facilities and rights for development of a lower reservoir for the

Project. The Applicant is the sole owner of these existing facilities and right

General Project Configuration.

 

The proposed Dry Canyon Pumped Storage Hydropower Project (Project) is a closed-loop

pumped storage hydroelectric generating facility. 

 

1.1.1 Dam and Levee

A roller-compacted concrete dam with a height of 530 feet and a crest length of 2,900 feet would

create the upper reservoir in Dry Canyon. Dam Crest would be at approximately 7,437 feet

NAVD88. 

 

A rock-armored earthen levee with an average height of 22 feet above the bottom of the Mud

Lake Regulation Reservoir and a length of 24,242 feet would be constructed to form the lower

reservoir. Two inlet/outlet structures would be included, one each in the north and west levees.

The top of the levee would be approximately 5,942 feet NAVD88. 

 

1.1.2 Spillways

The need for an upper reservoir auxiliary spillway will be analyzed during engineering studies

proposed under Section 2.1.3.

 

1.1.3 Penstocks

Starting at the upper reservoir’s inlet/outlet structure behind the dam, three 22-foot-diameter

penstocks, each being approximately 6,650 feet in length, would connect to the

generating/pumping units in the underground chamber. A combination of exposed penstocks,

concrete-lined tunnels and steel-lined tunnels are proposed. 

 

1.1.4 Underground Generating/Pumping Station

Proposed dimensions of the underground generating/pumping station chamber are 660 feet long

and 110 feet wide. An access tunnel and a utility tunnel are proposed to provide access to the

underground chamber. The access tunnel would provide primary operations access from Merkley

Road and the upper utility tunnel would connect to the switch yard.  

 

1.1.5 Tailraces

Below the generating/pumping units, three 22-foot diameter concrete-lined tailrace tunnels

would connect to the inlet/outlet structure in the lower reservoir. The proposed tailrace tunnels

would each be approximately 2,200 feet in length.

 

1.2 Proposed Reservoirs

 

1.2.1 Lower Reservoir 

A lower reservoir with a surface area of 1,390 acres is proposed to be sited in the southeast

corner of the 8,286-acre Mud Lake Regulation Reservoir. The lower reservoir would have a

storage volume of 30,680 acre-feet (23,730 active and 4,170 dead pool). Reservoir full-pool

surface elevation is proposed to be approximately 5,938.88 feet NAVD88. The reservoir would

e lower

reservoir during times when surplus energy from other resources is available and generate

electricity during periods of high demand. Based on customer energy demands and available

energy production on PacifiCorp’s system, the Project could pump and generate multiple times

in a 24-hour period.

The total estimated annual energy production is 5.4 terawatt-hours (TWh). The installed capacity

of the Project would be 1,800 MW. The gross hydraulic head as proposed is 1,490 feet and the

typical daily output (based on a daily fill-and-run cycle with 8 hours of generation) would be

14,400 megawatt-hours (MWh). The Project would have an anticipated 80 percent round-trip

efficiency rating so daily pumping energy required (based on a daily fill-and-run cycle) would be

18,000 MWh.

 

Six 300-megawatt (MW) generating/pumping units are proposed. It is anticipated the turbines could be impulse or reaction type.