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News & Articles on Wind Energy & the Environment

January 1, 1996
Paul Gipe

Erosion Gullies in the Tehachapi Pass: An Example of Improper Wind Development


 

Note: This critique was originally written in 1996. Little has changed since then except on the former FloWind site as noted.

Gullies such as that in these photos conveys a callous disregard for the land, the environment, our common heritage, and ultimately the community at large.

[Image 1. View from Hwy. 58 in the Tehachapi Pass. The gully in the center of the photo is just one of several seen from this vantage point.]

In the preface to Geologic Processes at the Land Surface Howard Wilshire explains why erosion should concern us all. "Despite our total dependence on the land, we are endangering its richness by practices that cause such harm as irretrievable soil loss, degradation of forest and arid-land ecosystems, and pollution of soil and water . . ."

There are many sources of accelerated, human-induced erosion. Wilshire illustrates one example of erosional problems caused by human activities in a photo of runoff from service roads and wind turbine pads in the Tehachapi Pass. Wilshire's photograph of Zond's Victory Garden IV project accompanies those of erosion from mining, overgrazing and real-estate development.

[Image 2. View from Hwy 58 in the Tehachapi Pass toward Zond’s Wind Wall. The company is now owned by Enron Wind, a subsidiary of the giant energy trading company. Zond founder Jim Delhsen’s house is in the lower right corner of the photo.]

Wind energy is a relatively benign technology, but it does have impacts. One of these impacts is disturbance of the soil surface for service roads and tower foundations. It is a sad commentary on the diligence of California wind industry that one of wind energy's few environmental impacts should be singled out by an expert in erosion in the same vein as that of far more environmentally damaging practices as mining, overgrazing, and real-estate development.

[Image 3 and 4. Another view of erosion from a vantage point on Hwy 58 and a close up view of gully in previous photo. Gully is due to runoff from the former FloWind site on Cameron Ridge. Note that the site is now owned by Florida Power & Light and the eggbeater or Darrieus turbines have since been removed and several erosion control practices instituted. While these practices have reduced erosion in the gullies shown, new gullies have formed elsewhere along the ridge.]

In the universal soil loss equation erosion is a function of rainfall, erodibility, slope, slope length, cropping management (extent of grazing), and erosion control practices (or lack thereof). In the Tehachapi Pass each of these factors contributes to a high potential for erosion. Rainfall is sufficient to cause rapid runoff. The decomposed granite of the region is highly erodible. The affected slopes are steep, some may even exceed 50 percent. The slopes are long allowing runoff ample time to accelerate. The affected slopes are severely overgrazed and have been for many years. And erosion control structures have been lacking or are in a poor state of repair at several of the wind projects where erosion has been most severe. These factors lead to an exceptionally high soil loss per unit area.

While erosion is an ongoing natural process, human activities can accelerate erosion above that found in a natural system at or near equilibrium. When human activities accelerate erosion above a certain threshold, irreversible damage occurs to the land. This is the situation today in the Tehachapi Pass, a situation that could have--should have--been avoided. This damage is irreversible. The challenge now is to prevent further accelerated erosion, that is, to prevent new gullies from forming and to limit the headward expansion of existing gullies.

The following is an excerpt from Wind Energy Comes of Age on the subject of erosion.

Roads and Erosion

"In the spring of 1992, Tehachapi-area wind plants were ill-prepared for a deluge. After seven years of drought, runoff absorbing vegetation was sparse. Bankruptcies and lax management had taken their toll on maintenance of erosion-control structures. When heavy rains struck, runoff-surged along road cuts to cascade down steep slopes, gouging deep gullies into the mountainsides and leaving some wind turbines standing precariously on exposed foundations.

[Image 5. This gully, too, is visible from Hwy. 58. and is due to runoff from the Difko site and the former Cannon site on Cameron Ridge. Note that the alluvial fan is gradually burying the Joshua Trees at the base of the slope.]

Though the Tehachapi area is susceptible to so-called cloudbursts typical of the world's desert regions, and critics had warned developers during the mid 1980s that they were cutting roads in erodible soils too close to the edge of steep escarpments, the industry appeared dumbfounded when it awoke to the damage soon afterwards.

To some wind companies, erosion is a natural process. "So what, if it's a little more than usual?" they say. "There's no harm done." Environmentalists see the issue differently. Erosion is indeed natural. There are many barren, highly eroded slopes in the Tehachapi Mountains not unlike those found in the badlands of South Dakota. However, accelerated erosion, caused by artificially baring the earth to the impact of rainfall and concentrating the resulting runoff along roads, is not "natural."

Environmentalists' distaste of erosion, apart from the increased siltation of stream beds, alteration of stream courses, and increased flooding that accompany it, results from the scars it leaves on the land. The rill and gully erosion, seen in Tehachapi cuts deep into the surface of the landscape. More galling than the erosion itself is the abuse of the resource it represents, because accelerated erosion is unnecessary and can be avoided. The industry must control erosion or it will certainly suffer further at the pen of activists such as Audubon's Steve Ginsberg, to whom the erosion "is just one of many egregious examples of how wind energy is ripping up the Tehachapis, and its [the industry's] lack of true environmental concern."

[Image 6. Gully from the former FloWind site on Cameron Ridge. At one time this gully cut across the Pacific Crest Trail here. FloWind had built a bridge so hikers could cross the chasm. For scale, note the straw bales and fence posts in the gully. The site’s new operator, Florida Power & Light has instituted several erosion control practices that have mitigated the erosion seen in this gully. However, FPL found it necessary to construct a more substantial bridge so equestrians could again use the trail. See the accompanying images. Improved erosion control practices here have arrested gully formation as shown.]

Wind companies can reduce the risk of serious erosion by minimizing the amount of earth disturbed during construction, principally by eliminating unnecessary roads, avoiding construction on steep slopes, allowing buffers of undisturbed soil near drainages and at the edge of plateaus, assuring revegetation of disturbed soils, and designing erosion-control structures adequate to the task.

The single most reliable technique for limiting erosion is to avoid grading roads in the first place. Glenn Harris, a biologist for BLM's Ridgecrest office, suggests that driving overland, rather than grading roads, to install and service turbines will significantly lessen erosion damage in arid lands. He admits that the tires or treads of vehicles crush the surface of perennial plants, such as bunch grasses and shrubs, but that they leave the root systems intact. "Ninety percent of the plant is still there," says Harris. "They're root sprouters," he says, as they have adapted to frequent fires. The plants will continue to live and bind the soil in place. A bulldozer blade, in contrast, scrapes the earth bare, removing plants, root systems and all.

If traffic frequently follows the same overland route, the path can be "hardened," he adds, to prevent ruts from concentrating runoff. Hardening could entail selective placement of open paving blocks like those used in parking lots outside Copenhagen, that support the weight of the vehicle while allowing plants to grow between spaces in the blocks.

SeaWest's Jeff Ghilardi emphasizes that maintaining erosion-control structures is essential to fighting erosion. It is possible that the original practices on Tehachapi's Cameron Ridge, where the erosion is most serious, were sufficient, he says, but that over time, funds were diverted to other activities. With an extended drought, erosion control became secondary.

Once gullies form, they need treatment immediately, or else erosion will accelerate exponentially during subsequent storms. Though rills on moderate slopes can be graded and revegetated, gullies on steep slopes become a permanent feature of the landscape.Vehicles

Though the wind industry is clearly at fault, its sins should be seen in perspective. Nearby, 120 years after the Southern Pacific punched its way through the Tehachapi Mountains, the railroads' bare embankments continue to erode without treatment, and erosion from housing construction on steep hillsides overlooking Highway 58 in Tehachapi digs deeper gullies year by year. Even the Tejon Ranch, which brags about its environmental attentiveness, saw sheet and rill erosion wash silt down its steep slopes bordering Interstate 5 during the same heavy rains that afflicted Tehachapi.

Still, the industry must do better. The public expects it. To gauge the amount the wind industry should be willing to pay for site restoration and erosion control, consider that the average coal mine in Maryland spends $4,500 per acre ($11,000 per hectare) for reclamation. Certainly wind companies can do as least as much as the coal industry."

Erosion and the Marketability of Wind Energy

Most consider accelerated erosion unacceptable, especially when it can be avoided as it can in the Tehachapi Pass. Continuing erosion in the Tehachapi Pass will eventually restrict the marketing opportunities of California wind companies. The follwing comment by a Jason Edworthy, of Nor'wester Energy Systems (a Canadian wind company) is illustrative. The comment was posted to a public news group (awea-windnet) in answer to the following question.

Question: "Has development of windfarms caused much erosion? I don't recall seeing this problem ever addressed in the wind energy media (unlike thrown blades, for example)."

Answer: "Yes! Many visits over the years to these areas have caused me (and the visitors I have accompanied) grave concern over the erosion problem. We have taken steps to ensure that we avoid similar problems where we are active.

[Image 7. Alluvial debris from gully in previous photo. The fan has flooded across the Pacific Crest Trail. Note trail marker in background.]

"Further, a recent visit to the San Gorgonio Pass region shows that there remain, even in active developments, unsightly piles of junk, tires, old generators, blades, etc. Stuff that can/will never be used again, and should be recycled/junked. I suspect that those who work there everyday just don't see this anymore, it is part of the landscape.

"I could not, for example, take a prospective windland owner, from whom I would like to lease land for a development, to such a location. The person would run away from our industry.

"On the upside, during the same recent visit, I observed (from below) newer developments above Whitewater Hill on the top of steep slopes, which did not appear to have erosion problems. So, a pat on the back to these developers!" Canada.

That accelerated erosion is not an inevitable result of wind development is evident by Edworthy's compliment to developers near Palm Springs. But erosion cannot be ignored. The California wind industry must address the problem forthrightly and promptly to avoid the kind of public black eye it received for ignoring the bird problem for too long.


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