How a former Arizona strip mine was turned into valuable farm land
Agriculture and strip mining are adversaries in the arid West. This, at least, is the current wisdom. It is a wisdom, however, that is brought into question by an experiment being conducted by researchers at the University of Arizona.
The site of this project is Black Mesa, a rugged wasteland in northeastern Arizona. It is on the Navajo Reservation and the site for a large coal mine operated by the Peabody Company.
There, the university scientists have stolen a trick or two from the Nabataeans, an ancient people who farmed the Negev Desert in the Middle East more than 2,000 years ago, They have shaped 15 acres of mine spoil into a catchment basin that channels the precious 10 inches of annual rainfall into a series of ponds. This water -- 8 million gallons have been harvested already this winter -- is pumped by solar power through five acres of orchards and gardens.
"We're above the national average in corn and beets, but we haven't had any luck with potatoes," proudly says John L. Thames, professor of the School of Renewable Natural Resources, who conceived of the idea.
"We've felt for some time that if you are spending $10,000 to $12,000 an acre to move dirt, you might as well restore it to a higher use," says Don Donner of the Bureau of Mines, which is funding the experiment. He is pleased with the results from the first year of operation.
The idea has a disarming simplicity. Instead of restoring thc stripped land to its original contour, it is graded so that thc runoff flows into a series of holding ponds. In the Black Mesa project two different surfacing techniques were used. About half the area was covered with asphalt and gravel: an expensive treatment that captures 95 percent of the water that falls on it. The other half was given an economy treatment. It was compacted and salted. Because of the soil chemistry in this area, the runoff was not salty but only 45 percent of the total precipitation was
delivered to the ponds. "If we discount the cost of reclamation, this system becomes quite economical," Professor Thames says. Because topsoil need not be saved, earthmoving costs are actually less than standard reclamation. But this is about balanced out by the cost of the pumps and other equipmemt needed, the scientist says.
"Actually, we need another season to estimate our cost effectiveness properly ," Thames acknowledges.
Inm 1974 a National Academy of Sciences report concluded that if coal is strip-mined in a large portion of the Southwest, the areas should be designated as national sacrifice areas because it would take centuries to revegetate. Thames and Mr. Donner both say they believe water harvesting techniques could mitigate this dismal scenario.
At present, it is still less expensive to drill wells and pump ground water for irragation, the Arizona water expert admits. But as the cost of energy continues to rise and water tables are drawn down ever lower by the mining of ground water faster than it is replenished, the economics should change, he says.
Another problem could be current stripmining regulations. Any alteration in the land from its prior shape or use involves additional red tape.
"If a company wants to use its operations to improve the lanmd, there is no problem," maintains Don Crane of the Office of Surface Mining (OSM). But he admits that there are two extra "hoops" that the parties involved must jump through.
The most difficult of the two is the requirement for a demonstration of the technology. This would be a pilot project lasting "more than a few years but less than a decade' MrCrane says. It would have to show that slopes would mot be subject to excessive erosion, that the catchment would provide enough water for the intended uses, and that the water produced remains of acceptable quality.
The Black Mesa project could serve as such a demonstration -- provided it is run long enough. Whether it will be is uncertain. Thames is concerned that this may be one of the programs axed under the current budgetcutting mood in Washington.
The second OSM condition would be an assurance that those proposimg such a water harvesting system have the means to utilize and maintain it, Crane says.
"Both are much bigger thresholds than simply replanting with native grasses," he acknowledges.
According the Thames, Black Mesa-style water harvesting would be limited to the Southwest because a long growing season is required. It would not work in high-altitude areas of the Rocky Mountains or in the northern Great Plains, where a great deal of strip mining is being carried out. However, there are variants that might prove useful in some of these areas as well.
For instance, smaller catchments can be used to provide water for livestock. And, in another experiment, water harvestimg is being used to concentrate rainwater on areas planted with wheat. Catchment ponds can also be used for aquaculture.
Next year, should all go well, the scientists hope to invite representatives of both local agricultural and mining interests to tour their experiment and possibly inspire some of them to t ry this on a commercial scale.