The Mariposa Energy Project is slated to be built in Alameda County, just more than 2½ miles from Byron Airport. If that happens, pilots would have to navigate around exhaust rising from four 80-foot-high stacks that stand in the approach pattern to the airport’s Runway 30, its most used runway.
Byron Airport sits in Contra Costa County and was built in 1994 to ease the burden on Buchanan Field Airport, the county’s main airport in Concord. The busy field has about 100 flights a day from a diverse mix of aircraft, from piston engine airplanes to jets and gliders. Nearby, parachutists float down to the ground as they jump from the Bay Area Skydiving Center, which has a touchdown zone just west of the airport’s two runways.
Airport manager Keith Freitas said that in a 1999, an economic impact report showed that Byron Airport generated $7,822,000 annually for the county.
But despite pilots’ worries that the 200-megawatt power plant could harm the airport, Contra Costa County is officially OK with the plant slated for the eastern corner of Alameda County.
“The board of supervisors supports the power plant, and it fits the master plan of the airport,” Freitas said.
A letter from the Contra Costa supervisors endorsed the plan, saying questions had been satisfactorily answered regarding impacts to the Byron Airport. The letter also said the county would profit from local spending, high-wage jobs and a community benefits package.
Freitas said the concerns were taken into account.
“The challenge (of the exhaust stack plumes) — the FAA found it not to be a significant hazard, but the FAA will look at it again,” he explained. “In general, there are things not to do — even though there are no flight restrictions over power plants, you just use common sense. (Such as) not flying low over power plants.”
However, questions linger.
In the supervisors’ letter endorsing the power plant, they deferred to the FAA, which gave the project a “determination of no hazards to air navigation” — essentially, that the project poses no risk.
Supervisors cited a 2006 FAA study on plume safety, stating “power plant exhaust plumes do not present an immediate or critical increase in human mental or physical workload.” The report further indicated that “the likelihood of an accident or incident caused by an over-flight of an exhaust plume is acceptably small.”
But in August, the FAA issued its latest update to the Aeronautical Information Manual, in which an entry reads, “Avoid flight in the vicinity of thermal plumes,” such as those that will be produced by the Mariposa power plant.
The FAA listed the potential hazards of flying above or near the exhaust of power plant stacks as turbulence and vertical shear, reduced visibility, oxygen depletion, engine particulate contamination, exposure to gaseous oxides and icing.
The report also warned of possible airframe damage and engine damage or failure. The FAA said the hazards are most critical in low-altitude flight, especially during takeoff and landing.
The supervisors’ letter said the board understood the FAA might release new information on plume safety, and that info could be used in future decisions. The letter was dated in October, almost two months after the FAA safety warning about power plant exhaust plumes was issued.
Chris Curry, who’s in charge of the Mariposa project for Diamond Generating, said that the company has done research into the effects exhaust stacks can have on aircraft and even hired pilots to zip in and through such plumes.
“I’ve personally flown through thermal plumes, probably over 70 times,” Curry said, describing his trips through exhaust plumes like those that will be produced by the Mariposa plant as “benign.”
He said his company kept pilots in mind while plotting out the project.
But pilot Randy Howell, a Byron Airport tenant, is waiting to hear more on the power plant and what it might mean for his business.
Howell is president of the Patriots Jet Team Inc. He operates 10 jets and three propeller-driven aircraft at the airport and hopes to expand from the 13,000 square feet of hangar spaces he rents now. But he worries that future flight-pattern restrictions could hamper flights and future growth, or that avoiding a power plant so close to the airport would create congested skies as pilots maneuver to Byron’s Runway 30.
“If the power plant were to affect the landing pattern, and especially the instrument landing pattern, I would be against it,” Howell said. “It could affect the future of the airport community. It is important to get new business to the airport — growth has to continue at the airport.”
n Associate editor Jon Mendelson contributed to this report.