Back To The Future - Forward To The Past
Land reclamation and revegetation at Boron
September 1996

Great gardeners and landscape architects have always planned and planted for the benefit of future generations, seldom living to see the full fruits of their visions. Miners are in analogous positions - they are obliged to restore the landscapes they labor in, for the ultimate benefit of flora, fauna, and their children's children.

At Boron, the problems are both practical and creative. How do you deal with tons and tons of overburden each working day, and how do you emulate mother nature convincingly in such apparently arid surroundings as the Mojave Desert? Add to this a commitment to minimizing the impact of present-day operations and implementation of the environmental policies of the RTZ-CRA Group, to which Borax belongs - a code which in most respects is more stringent than either State or Federal law requires, and it all amounts to a formidable, immediate but ongoing challenge. Environmental reclamation is one of the costs of a continuing supply of high quality industrial minerals. And the solutions to this challenge are of vital interest to borate users all over the world.

In charge of the land reclamation project at Boron is U.S. Borax senior geologist, Joe Siefke. The assignment has also made him the mine's head gardener - gardener of the high desert. The soil he works with most is Boron's overburden, the sands, silt, and clay which have to be removed before the borate ores can be extracted, millions of tons of garden potential per year. For the Mojave Desert is by no means a barren, lifeless wilderness; it is a complex ecosystem to which dozens of plant species have adapted - plants which can thrive on a regime of intense heat, recurrent drought, sub-zero winters, and an evaporation/precipitation ratio of 25 to one.

There is archaeological evidence that some of the creosote bush shrubs growing in rings at Boron are the direct descendants of shrubs which were growing there 10,000 years ago. The creosote bush and desert saltbush scrub groups are among the most numerous perennial plant species growing today in the western Mojave Desert.

Joe began the reclamation project in 1991 by taking baseline measurements of undisturbed land at the site. On 200 plots of 100 square meters he measured, with the help of specialist consultants Dames & Moore, the natural plant density and diversity - in other words the number of plants and the number of species per plot. This data provides the yardstick or target for transforming huge banks of overburden into natural terrain.

The next step was to plant a number of gardens to act as laboratories for discovering optimum seed mixtures, planting techniques, and slopes. When the overburden is dumped outside the ultimate perimeter of the mine, it comes to rest at an angle of about 36 degrees. This was found to be much too steep and therefore vulnerable to erosion. Angles of up to 18 degrees, achieved by bulldozers, proved viable.

A form of terracing, the plowing of furrows along the contour of the slope, also helps to prevent erosion and 'harvest' the meager supply of water. Rain accumulates or 'puddles' in the furrows so that it lasts longer and brings maximum benefit to the plants. Siefke's horticultural labs also revealed that, unlike normal gardening, a rough, rocky surface makes a better nursery in this environment than a smooth seedbed or fine tilth. This is because rocky lumps offer very young plants both shade from the sun and protection from the desert winds.

Seed experiments began with several varieties of saltbush (Atriplex spp). Assisted by Jim Gude (Boron's training officer who also lectures in biology at a nearby community college), Siefke harvested local species by whacking the saltbushes with a tennis racquet and catching the seeds in a burlap bag. These local seeds germinated and grew significantly better than seeds purchased from professional seed suppliers. Some of Jim Gude's students became skilled and enthusiastic seed gatherers. Today Comstock Seed of Reno collects seed from locations on and around the 22,000-acre Borax property, and from nearby native plant locales. Comstock makes the seed available to U.S. Borax on a share-the-harvest basis or at nominal cost.

In 1994, another major experiment was conducted, involving 32 test plots and twelve different indigenous species. Half the plots were predominantly loam, the other half were predominantly sand and silt. Soils originated from different levels of the open pit and their fertility was compared with that of the natural desert floor. It was discovered that overburden taken from more than 200 feet below surface level supports plant life better than desert topsoil. Research on growth-medium characteristics continues, with the object of establishing the best possible final surfaces for the future wildlife habitat.

Current experiments involving different seed recipes seem to suggest that the standard seed mix of twelve pounds per acre may be wasteful and perhaps counter productive. All planting is now done by means of a machine which prepares the soil surface, plants a mixture of native seeds, then covers the seeds all in a single operation - one-pass farming. Sowing is normally carried out at the beginning of November, when it is not exactly wet, but is usually the onset of the rainy season.

Irrigation is taboo since the plants obviously have to be able to survive in ordinary desert conditions without help from man. Sometimes, however, very young plants are given a little 'drought assistance' to get them off to a healthy start. Joe Siefke reckons that the ideal natural start for most species is two wetter-than-average winters in succession. Statistically there is nearly a 15 percent chance of this happening - in fact it has occurred seven times over the last half century, most recently in 1992/1993.

The irrigation ban also applies to fertilizers and micronutrients, and for much the same reason. Every plant must be self-sustaining, as in the wild. One thing is reasonably certain, of course, there is no real likelihood of boron deficiency in the local soil.

One of the most interesting experiments at Boron is the macro imprint test area. Here overburden loads of about 190 tons each are clumped back to back to give a level but broken surface at the top of the dumps. With recesses up to five feet deep, the broken surface is perfect for erosion control, water harvesting, and natural germination by seeds such as saltbush and pepper grass, blown in on the desert winds.

After five years of leveling, planting, experimentation and research, parts of the Boron habitat already take us back to the future and forward to the past. But with the mine's estimated life of more than 40 years, Joe Siefke and his team will only be able to enjoy the full fruits of their current endeavors if they break several world records for longevity.