Wildfire threat to Pacific AC Intertie reduced

Firefighters battling a wildfire that has blackened more than 10,000 acres in northern California have made sufficient progress that officials at the California ISO (Cal-ISO) are no longer concerned that the Pacific AC Intertie (PACI) is in imminent danger.

“The fire is moving away from the PACI lines and is about 75% contained,” a Cal-ISO spokesperson told TransmissionHub Aug. 27. As a result, the ISO is “no longer concerned that the lines are immediately threatened.”

Fire crews substantially increased the degree of containment over the prior 24 hours. As of midday Aug. 26, the Deer Fire was reported 45% contained by the California Department of Forestry and Fire Protection, which is overseeing the firefighting effort about 12 miles east of Los Molinos, Calif.

The PACI is part of the larger Pacific Intertie that consists of three AC lines and one 800-kV DC line. The AC lines begin at the Bonneville Power Administration’s (BPA) John Day substation near The Dalles, Ore. Two of the AC lines terminate at Southern California Edison’s (SCE) Lugo substation near Los Angeles, and the third line ends at Pacific Gas & Electric’s (PG&E) Tesla substation east of San Francisco. The DC line runs from BPA’s Celilo Converter Station near The Dalles Dam on the Columbia River through Oregon and Nevada, and terminates at the Los Angeles Department of Water and Power’s (LADWP) Sylmar Converter Station north of Los Angeles.

Utilities and other entities are continuing to monitor a second, larger fire that continues to burn out of control in northern California and continues to threaten power facilities belonging to PG&E and the San Francisco Public Utilities Commission (SFPUC).

Crews are making progress battling the Rim Fire, which started Aug. 17 in Stanslaus County, Calif., although the fire is considerably larger and progress is slower in coming.

As of midday Aug. 27, that fire had burned almost 180,000 acres of brush, oaks, and pine in the Stanislaus National Forest, Yosemite National Park, Bureau of Land Management and state land, representing a growth of nearly 31,000 acres from the day prior. However, the fire was reported 20% contained at midday, up from 15% contained the day prior.

To date, the Rim Fire has destroyed 12 miles of 230-kV transmission line connecting powerhouses on the Hetch Hetchy power system to SFPUC’s system, and forced two of the system’s three powerhouses out of service. However, those outages have not yet affected the organization’s customers.

“All of San Francisco’s municipal customers continue to be fully supplied; there will be no interruption in electric service,” SFPUC said in a statement on its website. Those customers comprise San Francisco’s municipal departments, including the city’s famous cable cars. SFPUC also supplies retail drinking water and wastewater services to San Francisco, and wholesale water to three Bay Area counties.

SFPUC is making up the difference by accessing power in an existing power bank and purchasing power on from the Cal-ISO market, according to its website.

SFPUC has dispatched 70 crewmembers to the Kirkwood powerhouse to continue assessment and repair work along the roadway and at the powerhouse, noting that its crews will only enter areas deemed safe by fire and incident command leadership. To date, the agency has no additional details about when those lines might be rebuilt and returned to service, SFPUC said.

On a related note, the organization reported no contamination or interruption of the water supply contained in Hetch Hetchy.

“There has been no impact to water quality and water deliveries from the Hetch Hetchy Reservoir, all regional and local customers of the Hetch Hetchy regional water system continue to be served,” the agency said. In addition to electricity, the organization provides retail drinking water and wastewater services to San Francisco, and wholesale water to three Bay Area counties.

A PG&E spokesperson told TransmissionHub the utility’s situation is unchanged from Aug. 26.

The Rim Fire forced PG&E to deenergize of at least one power line and has damaged some components of its infrastructure, but the utility has not been able to access the equipment to assess the damage, as it is not yet safe for PG&E crews. All told, fewer than 200 PG&E customers are without power as a result of those facilities being out of service.

SCE is a subsidiary of Edison International (NYSE:EIX), while PG&E is a subsidiary of PG&E Corporation (NYSE:PCG)