Mealey's (May 7, 2021, 11:50 AM EDT) -- SAN FRANCISCO — The U.S. Army Corps of Engineers on May 4 moved in the Ninth Circuit U.S. Court of Appeals for an order vacating environmental groups’ challenge to the Nationwide Permit 12 (NWP 12), which pertains to the construction of pipelines to carry hydraulically fractured oil and gas, on grounds the challenge is “prudentially moot” because President Joseph R. Biden Jr. has revoked a separate permit that allowed the pipeline to be constructed in the first place....