625/650 Line Upgrade
625/650 Line Upgrade
Project Description
The 625 and 650 Electrical Line Upgrade Project consists primarily of an upgrade of Liberty’s existing 625 and 650 electrical power lines and associated substations from 60 kilovolt (kV) to 120 kV to allow the entire North Lake Tahoe Transmission System to operate at 120 kV. The 650 Line runs from Truckee to Kings Beach, parallel to California State Route 267 for much of the alignment. The existing and proposed 625 Line alignments generally run in a northeast-southwest direction between the communities of Kings Beach and Tahoe City.
The Project consist of three primary elements: removing the existing 625 Line and constructing a new, rerouted 625 Line; rebuilding the 650 Line; and upgrading, modifying or decommissioning of six substations. These improvements will increase the ability to maintain the current maximum system loads during an outage on any one of the four sections of the system; decrease reliance on the Kings Beach Diesel Generation Station; reduce the likelihood of outages associated with environmental conditions (e.g., high winds); and will improve access to the lines for maintenance, emergency outage response, and repair activities.
The Project has been broken down into 3 phases:
- Phase 1 - Rebuild and Upgrade of the 650 Line from Martis Valley and Kings Beach substation (Including a new line fold from Highway 267 to Northstar substation and upgrades to the substation)
- Phase 2 – Kings Beach Substation Upgrades, Decommission Brockway Substation, Extension of half mile double circuit 120 kV construction to connect existing northern terminus of the 650 line to the North Truckee substation.
- Phase 3 – Upgrade the 625 line to 120 kV and Modifications to Tahoe City Substation
Project Benefit
The key benefit of the 625/650 Line Upgrade Project is to provide reliable service even if a portion of the closed loop system is damaged (known as a single-contingency outage).
Upon completion of the upgrade project, if any one line in the system fails (due to snow load, damage, etc.), the rest of the closed loop system will be able to maintain the current maximum system loads.
Service reliability would be significantly increased reducing the possibility of brownouts and full outages.
Other Benefits
Reduce dependence on the Kings Beach Diesel Generation Station. This source is used for backup only during single-contingency events but operations are limited due to environmental restrictions. Once the upgrade is completed, this source would only be used for rare multi-contingency events.
Reduce fire hazards and outage durations. Rebuilding the transmission lines with new, dark-colored steel poles and polymer insulators will dramatically reduce the number of outages experienced over the next decade, as well as blend in with the environment. Project will improve access to the line for maintenance and vegetation management.
Provide additional normal capacity for projected future loads. The system must be capable of supplying peak loads (i.e., demand) whenever they occur. Also, industry standards call for the system to supply peak loads with any one component out of service (i.e, single contingency).
Background
Liberty Utilities purchased the California electric service territory from Sierra Pacific Power Company/NV Energy in January 2011. The purchase included the existing electrical transmission system.
The transmission system serving the North Lake Tahoe area is a loop comprised of 60kV and 120kV transmission lines running from Truckee to Squaw Valley to Tahoe City to Kings Beach through Northstar and then back to Truckee. These five transmission lines are identified on the accompanying map and are collectively known as the 625/650 line.
In 1996, a Sierra Pacific Power Company study identified the need to upgrade the existing 625/650 transmission line for reliability purposes and proposed a continuous construction timeline.
In 2011, Liberty’s engineering consultant confirmed the 1996 findings but recommended a three-phased construction approach to reduce the project’s impacts and ensure success.
Phases of the Project
Phase 1: The existing 650 line (currently at 60kv) was upgraded to allow for future operation at 120kV at the end of Phase 2. The rebuild used existing right-of-way and alignment as much as possible, and included new structures, structure spacing and structure types and work at the Tahoe City Substation to address low-voltage conditions. Construction of Phase 1 was completed in 2015 – 2016.
Phase 2: The purpose of this phase is to continue upgrades that allow the 650 line to operate at 120kV and involves the portion of the loop from North Truckee Substation to Kings Beach Substation. Phase 2 has been broken down into Phase 2A and 2B. Phase 2A of the Project involves upgrading Kings Beach substation. Phase 2A was completed in 2020. Phase 2B includes upgrade of North Truckee and Northstar substations and decommissioning Brockway substation. Phase 2B involves a small segment of 120kV line construction near North Truckee Sub, upgrades and modifications to the North Truckee and Northstar Substations, decommissioning the Brockway Substation, and activating the Kings Beach Substation at 120 kV. Phase 2B work is currently underway.
Phase 3: Upgrade 625 line and upgrades to Tahoe City substation. The timeframe and scope of Phase 3 is currently under consideration.
Current Status
As discussed above, the Project is currently at Phase 2B which is scheduled for completion in 2021.
For More Information
Click the button below to learn more about the 2021 Phase 2 scope of work.
Additional Resources:
Project Summary
Project Proponent:
Liberty Utilities purchased the electric service territory and assets from Sierra Pacific/NV Energy in January 2011, and currently serves approximately 49,000 electric customers in the north and south shores of Lake Tahoe.
Project Location:
Northeastern Placer County and southeastern Nevada County, California.
Project Description:
These major transmission lines (known as the 625 and 650 power lines) serve the areas of Northstar, Kings Beach, Tahoe City and Squaw Valley and are some of the oldest in the State of California.
Project Benefit:
Upgrading the lines will improve reliability, even if a portion of the closed loop system is damaged, by allowing greater load transfer and switching ability that benefits the entire system.
Proposed Project:
Upgrade of the existing 625 and 650 power lines and associated substations from 60 kilovolt (kV) to 120 kV to allow the entire transmission loop to operate at 120 kV.
Project Need:
The 625 and 650 lines often operate at maximum capacity and must be supplemented by diesel generation to meet peak loads. The aging power lines were never designed to provide a reliable closed loop system which would reduce both the frequency and impact of outages, nor was it designed to carry the current peak load demands.
Project Environmental Impacts:
The environmental impact report (EIR) for the Project addresses potential impacts to scenic resources, agricultural and forestry resources, biological resources, recreation, earth resources (geology, soils, seismicity, land capability and coverage), hydrology and water quality, cultural resources, hazardous materials, transportation, parking and circulation, air quality and climate change, noise and vibration, socioeconomic and economic justice, public services and utilities, and growth-inducing impacts.
(See http://www.trpa.org/wp-content/uploads/CalPeco-DEIS-EIS-EIR.pdf). Mitigation measures have been identified to address each of the potential impacts.