Equipment and machinery is seen on a ridge above a natural gas well known as SS25 in Southern California Gas Company's vast Aliso Canyon facility.

LOS ANGELES (CNS) – Elevated levels of methane were briefly observed Friday night at the Aliso Canyon Natural Gas Storage Facility in the Porter Ranch area, but did not pose a health risk to the public, utility officials said Saturday, Dec. 2.

The Southern California Gas Company sent a notice to residents in the community after the discovery, which occurred on two fence-line monitors along the edge of the facility Dec. 1. 

“…The brief elevated methane levels lasted about 20 minutes and do not present a health or safety risk to the community,” the notice said. “These elevated readings are related to planned venting associated with maintenance work being conducted at the facility.”

“While the maintenance was planned last night the elevated readings at the fence-line were not anticipated,” SoCalGas spokesman Chris Gilbride said Saturday. “Importantly the brief increase in readings did not present a hazard to the community.”

Utility officials said Friday’s elevated levels were reported to the relevant state and local agencies.

The Porter Ranch area was severely affected by a massive methane leak from the facility a couple years ago. That gas leak, which was discovered in October 2015 and continued emanating methane until February 2016, poured an estimated 109,000 tons of methane into the air and forced an estimated 15,000 residents to temporarily relocate.

Limited operations resumed at the facility in late July with the blessing of state regulators. Efforts by Los Angeles County officials to block the resumed operations failed in court.

Earlier this year, the Southern California Gas Co. reached an $8.5 million settlement with South Coast Air Quality Management District over the leak, which included $1 million in funding for an SCAQMD-sponsored health study on the impacts of the leak, although county health officials said that $35 million to $40 million would be needed for an adequate study.