The original gas leak detected on Oct. 23, 2015 at Aliso Canyon emitted 109,000 metric tons of methane and displaced at least 7,000 Porter Ranch area residents. PORTER RANCH – There are possible new concerns for Porter Ranch residents near the Aliso Canyon underground gas field today as a small amount of methane was detected seeping out of soil near a gas well plugged earlier this year following a four-month leak.