May 2003 AGGMAN Geology

Ecological Footprints and Sustainability

In the aggregates industry, reclamation and permitting requirements offset any questions about sustainability.

I love potatoes — baked potatoes, scalloped potatoes, mashed potatoes, french fries, hash browns, potato chips — you name it. The best are those spiral-cut-deep-fried-in-fat potatoes! Every year I eat a finite amount of potatoes. It so happens that some part of the earth’s surface is dedicated solely to supplying my annual consumption of potatoes. That area is referred to as my “potato ecological footprint.”
The concept of ecological footprints commonly is applied to the issue of sustainability. The argument goes something like this: Every person requires a finite area of the Earth’s surface, an “ecological footprint,” to sustain his or her existence. There are a number of different ways to calculate your ecological footprint. A.R. Palmer calculated the per capita ecological footprint for the United States as 3.04 acres. A calculator designed by Dholakia and Wackernagel lets you determine your personal ecological footprint, and is available on the web at: http://www.lead.org/leadnet/footprint/intro.htm. (Try it — it is very interesting!) They calculate the footprint for an average American at 25.2 acres. There is a large disparity between the results each of these two methodologies produces — an order of magnitude difference! The reason is that, while the footprint model is fairly simple, the input variables are incredibly complex. But the Palmer and Dholakia/Wackernagel approaches do establish a range.
Part of my ecological footprint is the land under my house and driveway, as well as my share of land under our highways, airports, cities, shopping centers, landfills, and so forth, including the portion of the oil field that provides my energy, the portion of the forests for my paper products, the portion of the grazing land and feedlots that provide cattle for my hamburgers, and the portion of the farmland that provides corn for the cattle and the potatoes for me. My footprint also includes my portion of the quarries and pits that provide the aggregate to build much of our infrastructure. The question that comes to mind is, “How much of my ecological footprint is devoted to obtaining aggregate resources?”
I calculated an aggregate resource footprint for the average American. I made a “worst-case” scenario by making assumptions that would result in a larger footprint than if I had used more conservative figures. I assumed the average person uses 6.0 tons of crushed stone, that the average thickness of crushed stone being mined is 100 ft., and that one cubic foot of rock yields 150 lb. of crushed stone. Similarly, I assumed that the average person also uses 3.9 tons of sand and gravel per year, the average thickness of sand and gravel being mined is 25 ft., and one cubic foot of sand and gravel yields 100 lb. of sand and gravel.
The average food footprint is renewable — the same land can be used year after year (to a point) to graze hamburgers or grow french fries. But on a yearly time frame, the average aggregate footprint is not renewable. Therefore, I began by taking the absurd position that no aggregate operations would ever be returned to a beneficial use during an average lifetime of 79 years. I determined that under those conditions, an average aggregate footprint would be about 0.070 acres, or about 2.3 percent of the average ecological footprint as calculated by Palmer, or 0.3 percent as calculated by Dholakia/Wackernagel. That is not too bad — somewhere between 2.3 and 0.3 percent of the land that is used to make my life comfortable is devoted to providing aggregate, which is an absolutely necessary ingredient for almost our entire built environment.
But actually, an aggregate footprint is similar to a forest product footprint. Over time, the degraded land is returned to productive use. These days it is totally unreasonable to imagine that most aggregate operations will be left unreclaimed because it is almost unheard of to receive an aggregate operation permit without the guarantee of some sort of reclamation. Over a lifetime, most aggregate operations that contribute to an ecological footprint will be returned to some beneficial second use.
Therefore, I recalculated an average aggregate footprint assuming that reclamation would take place over time. Essentially I calculated how much land was quarried on someone’s behalf during one year. Under that scenario, the aggregate footprint was reduced to 0.00089 acres, about 0.03 percent of the total footprint as calculated by Palmer, or 0.004 percent as calculated by Dholakia/Wackernagel. An average aggregate footprint is nearly imperceptible under a scenario that involves reclamation.
So, what can we learn from this? First, aggregate extraction is not a major contributor to the “lack of sustainability” argument. Much of an ecological footprint is dependent on aggregate, but aggregate does not even make up the little toe on the footprint.
Second, reclamation clearly is an important part of sustainable aggregate resource management. By returning aggregate operations to some beneficial second use, the aggregate ecological footprint virtually disappears. Today, many aggregate operations are being returned to ecologically productive areas. Some may even be reclaimed as farmland to grow spiral-cut-deep-fried-in-fat potatoes! Mmmmmm!

William H. Langer is a geologist with the Mineral Resources Team of the U.S. Geological Survey.

May 2003 Carved in Stone Ecological Footprints and Sustainability				Ecological Footprints and Sustainability In the aggregates industry, reclamation and permitting requirements offset any questions about sustainability. By Bill Langer I love potatoes — baked potatoes, scalloped potatoes, mashed potatoes, french fries, hash browns, potato chips — you name it. The best are those spiral-cut-deep-fried-in-fat potatoes! Every year I eat a finite amount of potatoes. It so happens that some part of the earth’s surface is dedicated solely to supplying my annual consumption of potatoes. That area is referred to as my “potato ecological footprint.” The concept of ecological footprints commonly is applied to the issue of sustainability. The argument goes something like this: Every person requires a finite area of the Earth’s surface, an “ecological footprint,” to sustain his or her existence. There are a number of different ways to calculate your ecological footprint. A.R. Palmer calculated the per capita ecological footprint for the United States as 3.04 acres. A calculator designed by Dholakia and Wackernagel lets you determine your personal ecological footprint, and is available on the web at: http://www.lead.org/leadnet/footprint/intro.htm. (Try it — it is very interesting!) They calculate the footprint for an average American at 25.2 acres. There is a large disparity between the results each of these two methodologies produces — an order of magnitude difference! The reason is that, while the footprint model is fairly simple, the input variables are incredibly complex. But the Palmer and Dholakia/Wackernagel approaches do establish a range. Part of my ecological footprint is the land under my house and driveway, as well as my share of land under our highways, airports, cities, shopping centers, landfills, and so forth, including the portion of the oil field that provides my energy, the portion of the forests for my paper products, the portion of the grazing land and feedlots that provide cattle for my hamburgers, and the portion of the farmland that provides corn for the cattle and the potatoes for me. My footprint also includes my portion of the quarries and pits that provide the aggregate to build much of our infrastructure. The question that comes to mind is, “How much of my ecological footprint is devoted to obtaining aggregate resources?” I calculated an aggregate resource footprint for the average American. I made a “worst-case” scenario by making assumptions that would result in a larger footprint than if I had used more conservative figures. I assumed the average person uses 6.0 tons of crushed stone, that the average thickness of crushed stone being mined is 100 ft., and that one cubic foot of rock yields 150 lb. of crushed stone. Similarly, I assumed that the average person also uses 3.9 tons of sand and gravel per year, the average thickness of sand and gravel being mined is 25 ft., and one cubic foot of sand and gravel yields 100 lb. of sand and gravel. The average food footprint is renewable — the same land can be used year after year (to a point) to graze hamburgers or grow french fries. But on a yearly time frame, the average aggregate footprint is not renewable. Therefore, I began by taking the absurd position that no aggregate operations would ever be returned to a beneficial use during an average lifetime of 79 years. I determined that under those conditions, an average aggregate footprint would be about 0.070 acres, or about 2.3 percent of the average ecological footprint as calculated by Palmer, or 0.3 percent as calculated by Dholakia/Wackernagel. That is not too bad — somewhere between 2.3 and 0.3 percent of the land that is used to make my life comfortable is devoted to providing aggregate, which is an absolutely necessary ingredient for almost our entire built environment. But actually, an aggregate footprint is similar to a forest product footprint. Over time, the degraded land is returned to productive use. These days it is totally unreasonable to imagine that most aggregate operations will be left unreclaimed because it is almost unheard of to receive an aggregate operation permit without the guarantee of some sort of reclamation. Over a lifetime, most aggregate operations that contribute to an ecological footprint will be returned to some beneficial second use. Therefore, I recalculated an average aggregate footprint assuming that reclamation would take place over time. Essentially I calculated how much land was quarried on someone’s behalf during one year. Under that scenario, the aggregate footprint was reduced to 0.00089 acres, about 0.03 percent of the total footprint as calculated by Palmer, or 0.004 percent as calculated by Dholakia/Wackernagel. An average aggregate footprint is nearly imperceptible under a scenario that involves reclamation. So, what can we learn from this? First, aggregate extraction is not a major contributor to the “lack of sustainability” argument. Much of an ecological footprint is dependent on aggregate, but aggregate does not even make up the little toe on the footprint. Second, reclamation clearly is an important part of sustainable aggregate resource management. By returning aggregate operations to some beneficial second use, the aggregate ecological footprint virtually disappears. Today, many aggregate operations are being returned to ecologically productive areas. Some may even be reclaimed as farmland to grow spiral-cut-deep-fried-in-fat potatoes! Mmmmmm! William H. Langer is a geologist with the Mineral Resources Team of the U.S. Geological Survey.