Call it the invisible spill. You can’t see it, but it’s there — a steady stream of natural gas seeping out of a leaking well in Southern California that may spew as much greenhouse gas into the air as a half-million cars do in a year. Pipeline operator Sempra Energy says it may take three to four months to plug. Using the same tactic that eventually ended the massive 2010 oil spill in the Gulf of Mexico, the San Diego-based utility owner is boring a well that’ll intercept the damaged one to stop the seepage. Meanwhile, it’s relocating hundreds of people into temporary housing as health officials say the gas is making some sick. The company faces as much as $900 million in costs such as relocation and legal expenses, based on government data and Bloomberg Intelligence estimates. “You have this huge volcano of methane pollution and except for […]