PG&E California Natgas storage Facility Shut due to Leaks

Northern California power and gas company Pacific Gas & Electric (PG&E) said on Friday its McDonald Island gas storage facility in San Joaquin County remained out of service after the company detected small methane leaks from some of its wells in June.

PG&E discovered the small leaks during an inspection the state required of gas storage operators after the massive leak discovered in October from Southern California Gas' (SoCalGas) Aliso Canyon storage facility in the San Fernando Valley in Los Angeles. That leak, the state's largest ever, was not plugged until February and area homeowners had to relocate.

The PG&E Corp unit said it has enough gas in storage elsewhere to meet customer needs while McDonald is closed and hopes to resume withdrawals and injections at the underground field by September, according to local media reports.

PG&E said on its website the "low level emissions" at McDonald, on a man-made island in an unpopulated area near the Sacramento-San Joaquin River Delta, pose no risk to public safety, the environment or reliability.

State and PG&E officials determined the McDonald leaks range between 236 kilograms per hour (kg/hr) to 763 kg/hr, which state regulators said in a June 30 letter to PG&E was "similar to or only slightly above background levels at natural gas storage facilities."

For comparison, the emissions at Aliso Canyon peaked at over 60,000 kg/hr before that leak was fixed, PG&E said.

SoCalGas has said it hopes to have Aliso Canyon, the biggest gas storage facility in California, partially back in service by the end of the summer. SoCalGas is a unit of California energy company Sempra Energy (SRE).

State agencies have warned the Los Angeles area could suffer gas shortages that could lead to power blackouts on up to 14 days this summer due to the limited availability of Aliso Canyon.

McDonald is the second biggest storage facility in the state.

PG&E said it has identified 10 wells with detectable methane emissions and isolated two of those from the reservoir as of June 30, according to the letter to state regulators.

The state ordered PG&E to test all 87 wells at the facility.

Of the three gas storage facilities PG&E owns and operates, McDonald is the largest with a capacity of 82 billion cubic feet. It is capable of providing nearly 25 percent of Northern California's gas on days of high demand, PG&E said.

(Reporting by Scott DiSavino; Editing by David Gregorio)