Sunday, July 08, 2012

Development impacts on Tucson's dark skies

The Los Angeles Times weighed in on the Rosemont copper debate, focusing on the potential impacts of round the clock lighting for mining operations to the regions astronomical observatories.   An innovative lighting plan prepared for Rosemont by the former head of the International Dark Skies Association, would reduce the estimated visible light from 21.7 million lumens, or the equivalent of about 12,000 houses, down to about 5.1 million lumens according to the Times, a 76% reduction.  Using their numbers, this would be equivalent to the light from about 2,820 homes.  The plan relies in part on using LED lights and focusing the light downward.  [I've suggested that such an approach could be used at other mine sites as well]   [Top, standard lighting approach demonstrates spill light in background and excessive sky glow above.  Focused lighting system with high performance optics illuminates only the simulated waste rock dump area. From Monrad Engineering report on Rosemont]

The comparison raises the question as to how this compares to increased lighting in the Tucson area from the annual increase in number of houses.  The Pima Association of Governments lists building permits in the Tucson metro area from going from 12,465 in 2005 to 3,331 in 2008 (latest numbers I could find).    Construction is obviously down since then although I don't have the details.  This also doesn't count business or industrial lighting additions.  So, it looks like the Rosemont mine would add as much lighting as one-quarter of the new houses added annually prior to the recession, and perhaps as much as current construction would add.

In searching for a count of new housing in the area, one of the links that popped up was from the Green Valley News about plans to build 19,000 new housing units in the Sahuarita and Green Valley area, converting the world's largest irrigated pecan farm into a master community, west-northwest of the Santa Rita Mountains, where the Rosemont mine site is located.    Using the numbers in the Times article, that would be equal to the lighting from 6.7 Rosemont mines. 

Green Valley gave approval to the first phase of the project in March, although the news reports don't mention lighting concerns from the astronomical community being raised.

Interestingly, the developer is Farmers Investment Co. (FICO) which is one of the most vocal opponents of the Rosemont mine.


  1. Anonymous8:34 PM

    Gee, what a shock that farmers investment is an opponent. I guess their lumens are not as potent as rosemonts lumens.

  2. Anonymous7:34 AM

    A thorough read of the article would have resulted in knowing that it is the proximity of the proposed mine to the observatories that is the concern. I also doubt that new homes would be burning lights all night long like the proposed mine would.Add this very important concern to the long list of reasons this mine would be a disaster in the Santa Ritas.

  3. Yes, the proximity to observatories is why the housing developments in the Green Valley-Sahuarita area may be relevant for comparison. The subdivisions are only a few miles west-northwest of the proposed mine, putting them just slightly closer to Kitt Peak and Mt Lemmon observatories, and only slightly further from Mt Graham than the mine site. Wouldn't their light be just as polluting?

    The numbers I quote are from the LA Times article, which doesn't elaborate on how they came up with the figures. Is that the maximum number of lumens regardless of amount of time they are on? Or is it the total amount of light over the night?

    My point is that if you are really concerned about dark skies, there are many sources that are of concern and singling out one mine is not going to resolve the problem. If however, the goal is to use dark skies as a stalking horse to stop the mine, then to paraphrase 'Animal Farm', "subdivision light good, mine light bad."

  4. Personally, I'm not that thrilled about the housing development. Though it's not the focus of this article, I'd like to see cities and communities in general find ways to reduce light pollution at night. It would be so nice to see the stars again.

  5. Anonymous10:15 AM

    How can the light of a subdivision compare to the light from a 24/7 mine unless 19,000 homes were to turn every light on and leave them on all night? It's hardly an accurate comparison. In addition, what about the light needed for the park and ride lot which Rosemont will have to build for the car pooling, 24/7 employees?

  6. Anonymous10:37 AM

    The new lighting plan for the proposed mine is unproven, like everything and everyone involved with the project. It's all a HUGE chance to take, and we cannot afford even one of the many disastrous possibilities.

    1. Anonymous11:18 AM

      There is nothing unproven with the science of LED lighting and the talented Southern Arizona Engineers working towards innovative solutions. I have no problem with one being anti-mining, just please don't attack sound science.

    2. Anonymous2:13 PM

      If the lighting plan is so "sound", then why wasn't it part of the original scope of work and instead, is now totally revised?

  7. Anonymous10:55 AM

    Are we expected to believe that lighting is only needed at the waste rock dumping area as the article states, is the area of simulated lighting? How about the pit from whence the waste rock is derived? How about the headlights on the haul trucks delivering the rock to the dumping area? How about the many buildings associated with the mining operation, surely with outdoor flood lights, how about the heap leach pad where the copper is being leached for cathodes. How about the loading of the trucks to haul concentrate on Scenic Highway #83, said to be a 24 hour operation? The entire mine operation will have to be illuminated, not just the waste rock piles, so stop the sugar coating of this disastrous mining operation! Also this type of lighting is untried, computer generated as for results. Just like Augusta Resources having never operated a copper mine! The Santa Ritas are too precious to allow an unproven mining company with an unproven lighting plan to destroy the northern Santa Ritas to mine an unproven copper deposit, which by all indications is a very low quality deposit.

    1. Anonymous11:28 AM

      "The Santa Ritas are too precious to allow..."

      Pretty obvious motivations of Not In My Back Yard, but lets get the copper for my lifestyle and laptop to type anonymous anti-mining far fetched comments from some far flung place. You do realize most of us reading this blog ARE geologists familiar with grade, mining and mine technology and don't fall for your tirade?

    2. Anonymous12:18 PM

      And my information about the low grade of this deposit comes also from geologists and various articles regarding this deposit. My comment was not a tirade. Tell me, will the entire mining operation require lighting or just the waste piles? Yes this is in my backyard. This mine threatens to suck the water from the Cienega aquifer. It is not known if the Rosemont fractured water source is connected to the Cienega aquifer. If, indeed it is connected, when the pit reaches the depth lower than the Cienega water table, the Cienega could drain into the pit, seriously depleting the water in the Sonoita, Elgin areas. There is no CAP water to replace the Cienega Aquifer. See the Ostercamp hydrology study on the Sonoran Institute website. I only wish it were in your backyard and not mine! AS for the copper in my computer, there is no shortage of copper and this copper is going to China and/or South Korea, while it is our public lands and mountains that will be destroyed. If you find me biased against this project then I can say the same for those of you who are geologists and have your heads in the sand refusing to see the negative effects of this operation. You have all consumed the Rosemont kool aid, apparently.

    3. Anonymous12:55 PM

      Amen to that, and as Geologists, why not stick to Geology?

    4. Anonymous12:56 PM

      "You have all consumed the Rosemont kool aid, apparently." Apparently have consumed the hallucinogenic NIMBY Kool aid.

      I checked the Sonoran Institute website they should be embarrassed by their fantasy based fear model. Absolutely NO structure and completely flattened paleozoics under the "Sonoita Plain"??? Who are they (you) kidding? But their disclaimer is a nice touch.

      We're all geologists who use the scientific method for making a hypothesis - including clearly separating our observations from interpretations - instead of using a fear/ignorance based hypothesis.

    5. Anonymous1:55 PM

      The problem with your hypothesis is this: there is no going back once the damage is done. We cannot reclaim the water, air, night sky, property values, wildlife, or scenic mountains. Lives would be lost, and valuable properties and businesses become worthless. Tourism is gone in Santa Cruz County.

      Think Rosemont has all the answers just because they like to call it "state of the art "? Check out Carlotta Mine and all the disasters they have had to deal with.

    6. Seems light pollution from both the mine and the planned housing development will be inevitable. With strict regard to light pollution there will be more than there is currently, no debating that.

      I wonder what the change in water use in the planned community in former pecan groves will be. Who uses more water, people or pecans?

    7. In general, people use less water than agriculture. In the Sahuarita area, the AZ Dept. of Water Resources has been monitoring ground subsidence due to groundwater withdrawal - the maps for this area, centered on the agricultural areas going back to 2007 are posted at

  8. Anonymous2:18 PM

    I have worked for many years in open pit mines as well as underground mines. Open pits at night are not that lit up, do you think we have bleacher style lights up around the pit? We do not. Vehicles have headlights and dump areas have portable light plants. They are not going to cause any more problem than lights on cars on the highway, Hey theres an idea, lets all ban cars and trucks! Geez, get over it already.

  9. Anonymous2:56 PM

    Huh? Tourism, business, air, water, reclamation, Carlota (apples and oranges orebody!) lives lost??? Taking blind shots and seeing who’s hit? The blog entry is about an innovative approach to mitigating a lighting plan developed right here in Southern Arizona by a Southern Arizona firm, headed by Chris Monrad, a Registered Engineer, Past President of and current Board Member of the International Dark Sky Association.

    The problem with the LA Times article is what it implies without scientific validity, which is what I suspect caught Dr. Allison’s attention. Thankfully Dr. Allison points out the real threat is urban growth. One particular non sequitur in the LA Times article is, “In 2010, a study by the Lowell Observatory measured that the sky brightness at nearby Kitt Peak has stayed "remarkably constant" over the last 20 years.” I’m going to ignore the fact that Green Valley is between Kitt Peak and the Rosemont Mine and just look at US Census data. In 2010 the population in Pima County was 666,880 and in 2010 was 980,263. That’s an increase of over 313,000 plus people needing air, cars, water, Wal-Marts and houses with lights! These 313,000 plus moved to Pima County despite three (now two) operating large open pit copper mines. I’d even go out on a limb and say tourism has increased as well as property values generally risen, given 313k+ have moved here.

    The fact of the matter is humans have an impact on the environment. We have to provide for our basic needs and every person born has some sort of footprint on this planet. Just because you don’t want the mine, does not give you the license to use fears to insult our intelligence. The mining and geology industries are technologically driven has adapted and changed with time, and we can limit these impacts as they are identified. A perfect example is the LED lighting plan, and I’m proud of Monrad Engineering.

  10. The issue with your speculation is this: there is no going back once the destruction is done. We cannot recover the water, air, evening sky, real estate asset principles, creatures, or picturesque hills. Life would be missing, and useful qualities and companies become useless. Travel and leisure is gone in Santa Jackson Nation.

    Think Rosemonde has all the solutions just because they like to contact it "state of the art "? Examine out Carlotta My own and all the problems they have had to cope with.