Dark Skies

Light from the proposed Rosemont Mine could cause problems for Southern Arizona observatories

In more-innocent times, presumably unruffled by notions of light pollution, some thoughtful soul photographed a bulldozer paused in its task of carving a road up the side of Mount Hopkins, in the Santa Rita Mountains south of Tucson.

Leaning against that dozer, hardhat in hand, was pre-eminent astronomer and eventual observatory namesake Dr. Fred Lawrence Whipple.

At the time, Dr. Whipple likely believed himself to be in semi-remote wilderness, with Tucson a subtle wisp on flatlands to the north. And the glow from that far-off town, while growing, remained but a small nuisance.

Years earlier, the fathers of the Kitt Peak National Observatory, further west on the Tohono O'odham Reservation, had cultivated a robust network of influence among business and government leaders, aimed at protecting Arizona's astronomy industry by advocating strict new light standards. By 1972, Pima County had instituted some of the toughest light-pollution laws in the country.

Over time, the Mount Hopkins' Fred Lawrence Whipple Observatory would become renowned for gamma-ray astronomy and its Multiple Mirror Telescope, and Tucson would become a leader in the dark-sky movement. In 1988, we became home to the nonprofit International Dark-Sky Association.

Yet some 45 years after Whipple leaned against that bulldozer, a company from Canada announced plans to pull copper deposits from nearby land.

Canadian investment company Augusta Resource plans to dig an open-pit copper mine in bucolic Rosemont Valley, a mere 13 miles from the Whipple Observatory. The mine would use adjacent Coronado National Forest land to pile its tailings, which would require a full-blown federal analysis, known as an environmental impact statement, or EIS.

As part of that analysis, in 2009, Augusta released a lighting plan for the mine, which would operate around the clock, seven days a week.

To astronomers, that first plan was nothing short of disastrous. It pegged light output from the mine at 21.7 million light measurement units—known as lumens—from commonly used high-pressure sodium lamps. At that rate, the mine would produce roughly the same amount of light as 12,000 homes.

But astronomy is an industry of its own in these parts, adding around $250 million a year to Arizona's economy through everything from tourism to research salaries. So when astronomers raise a stink, plenty of people listen.

Perhaps that's why Augusta came out with a revised plan in January would that sharply cut the light from its proposed mine. (Rod Pace, CEO of the company's subsidiary, Rosemont Copper, didn't return a phone call seeking comment.)

The latest plan was produced by Monrad Engineering, an outdoor-lighting company run by Christian Monrad, onetime president of the Dark-Sky Association. Monrad's design would lop a full two-thirds from the earlier plan's projected light output. It would achieve this primarily through the use of specialized light-emitting diode (LED) systems

An improvement? Certainly. But would it be enough to negate huge impacts on the Whipple Observatory? And how would light output at the mine be enforced?

Curiously, the revised plan is believed to be in compliance with Pima County's lighting ordinance—although Augusta has steadily claimed an exemption from that code.

But all bets could be off should the federal Mine Safety and Health Administration decide that low-level lighting—which might be good for astronomy—would place workers at risk. And what recourse could there be if, at that point, Augusta had already received a green light from the Coronado?

"In looking through the latest (lighting-plan) revision, it looks like it actually would meet Pima County's outdoor-lighting ordinance, which is really bringing them a long way from where they were," says Scott Kardel, spokesman for the Dark-Sky Association. For instance, "there are more subtle things related to color, and the nature of how the light is produced."

He says the new plan restricts light in the blue end of the spectrum. "It's blue that scatters around and brightens the sky more than any other color. The same is true at night. And one of the things that was proposed in the new plan was to use light sources that have really gotten rid of all that blue. It still puts light on the ground for people to see, but wouldn't brighten the sky as much."

Still, that's just one of the nettlesome concerns. "Let's assume that's what they say they're going to do, and the mine is approved," Kardel says. "Then the question becomes: Do they really have to follow through? And what role—if any—do the requirements of the Mine Safety and Health Administration play? Someone could say, 'Gee, it's not safe, so we have to have more light.' That was not addressed in the lighting plan."

The Coronado's draft environmental statement, released in October, contained "no specifications or guidelines on what those (safety) requirements would be," says Kardel. "That was a little troubling."

Attempts to contact Coronado National Forest representatives were unsuccessful at press time. Without reviewing the plan, Mine Safety and Health Administration spokeswoman Amy Louviere was unable to say whether Augusta's latest lighting proposal would meet federal standards.

Still, if Augusta considers federal safety regulations its ticket to eventually scrap all that costly LED innovation, the company might want to think again. "They are under the authority of Pima County lighting regulations," says Yves Khawam, the county's chief building official. "We don't believe anything would trump that with regards to the mine-safety standards.

"They need to meet the requirements of the outdoor-lighting code, and if they can't do it when there's a safety standard they believe they need to meet, well, then they shouldn't be operating at night."

Kardel says he's also concerned that the Coronado's draft EIS—widely criticized as a weak and shoddy document—ceded far too much control to the Canadian company. "Oversight of how well the lighting is going would belong to Augusta. I think most people would agree that leaving people to police themselves doesn't always work in these kinds of situations."

But at day's end, no amount of industrial ingenuity is going to avoid impacts on the Whipple Observatory. "By just making the sky brighter, it becomes harder to see fainter things," he says.

"If you look at things in a continuum—in a whole range of possible choices and impacts to astronomy, and especially to the Whipple Observatory—you could pretty well put the lighting plan that had been previously proposed at one end, signifying how really bad things could be. The new plan that's been proposed is significantly better.

"But if you're imagining the range of possibilities," Kardel says, "clearly the best of them is what we have now: There is no mine."

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