Helping Hand Tools, Sierra Club, and Mr. Rob Simpson (“Petitioners”) each petition the Environmental Appeals Board (“Board”) to review a prevention of significant deterioration (“PSD”) permit (“Permit”) that Region 9 (“Region”) of the United States Environmental Protection Agency issued to the Pio Pico Energy Center (“Pio Pico”) pursuant to the Clean Air Act. The Permit authorizes Pio Pico to construct and operate a 300-megawatt natural gas-fired peaking and/or intermediate load-shaping power plant (“Facility”) in Otay Mesa, California.