Steen Aagaard's Crippling Fall http://www.wind-works.org/articles/Aagaard.html

Steen Aagaard's Crippling Fall
July 7, 2006

by Paul Gipe


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This article was originally written July 19, 2000. A condensed version appears in Wind Power: Renewable Energy for Home, Farm, and Business (2004) by Paul Gipe Steen Aagaard and his employees at STS refused interview requests at the time this article was written.

On July 4, 2006 Steen Aagard posted the following comment in an email. "For the record we did use a quick grip and comalong but ALSO had the guy cable looped through the ground ancor and secured with the supplied cable clamps. I would never have let go of the crane trusting only a comalong, they are notorius for failing. Also we checked and rechecked everything because we were making an instructional video for future use."


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"Two Hurt in Turbine Accident" blared the headline in the Bakersfield Californian on Saturday, 23 October, 1999. This was the unsettling news that emerged from the National Renewable Energy Laboratory's fax machine early that morning, where professionals in the small wind turbine industry were meeting.


"The tower toppled while it was being erected, horrifying onlookers," continued the article by Jill Hoffman, a Californian correspondent at the scene. The article was accompanied by photos of the crumpled tower, a crushed pickup truck, and a close-up of Steen Aagaard clinging to the slender tower as it came down.


Several of those attending the NREL meeting that morning knew Steen personally, including Mike Bergey, chief executive of Bergey Windpower, the manufacturer of the wind turbine Steen was installing. The news cast a pall over the business at hand. If Steen had died, he would have brought the number of those killed working on wind turbines to 20 over the past 25 years. He would have been the fourth to die working on a small wind turbine.


Steen, 38 at the time, survived, but he suffered crippling injuries to his spine. Steen had been a vigorous, active man. He could often be seen cruising around Tehachapi on his Honda touring cycle. He was active in his church and loved by his employees at Specialized Turbine Services, a small contract maintenance company. Steen's ready smile and exuberance were a fixture at community events, such as the Tehachapi Wind Fair. Though his positive outlook on life remains, today Steen is wheelchair-bound.

The Accident


The details of what happened remain sketchy. Neither Steen nor his company are talking. But the general outline of events is clear from eyewitness accounts, from an accident report prepared by California's Division of Occupational Safety and Health (CalOSHA), and by comments from those in the industry familiar with the equipment used. What follows is a description of the accident taken from public and industry sources.


STS was installing a Bergey Excel on an 80-foot (24-meter) guyed lattice tower near Lake Isabella for Buckeye Farms. The small farm raises cattle and organic produce. The Excel uses a 7-meter (23-foot) rotor and weighs 1,000 pounds (460 kilograms). The tower was a lattice mast of solid steel rod held upright by two sets of three guy cables and three anchors. The turbine, tail vane, and rotor had been mounted to the tower while on the ground. STS was directing a rented mobile crane and operator to erect the turbine and tower assembly when the accident occurred.


The tower had been placed on its pier and the guy cables attached in STS' accustomed manner, when Steen climbed the tower to release the lifting sling from the crane boom. Prior to climbing the tower, he personally inspected the guy cables, Steen told CalOSHA. Steen also told CalOSHA that he climbed the tower, rather than delegating the task, specifically because of the hazards involved.


Steen climbed the tower wearing a safety harness and in the Californian photos appears to have been clipped to the tower with a fall-arresting lanyard. He released the crane without incident.


Subsequently, Steen was reported to be directing his ground crew in tensioning the guy cables when the cable on the "west end came loose from the come-along device" being used, says CalOSHA, California's agency regulating industrial safety. The remaining guy cables "caught and held the tower precariously for a moment," according to the Californian, before "the tower pivoted through the air and crashed to the ground."


Erik Slocum, the STS employee on the west anchor, was tensioning one of the guy cables with a "come-along tool," says CalOHSA's report, when it released. Slocum grabbed the guy cable and was pitched 15 feet into the air. Slocum suffered minor injuries and was taken to Kern Medical Center where he was treated and released.


Steen was not so fortunate. He was just below the turbine when the accident began. The wind turbine landed on an STS pickup, crushing the truck. The section of tower Steen was riding straddled the truck and the ground. Steen hit the ground hard, but the tower didn't fall on top of him.


When onlookers reached him, Steen wasn't breathing and didn't have a pulse. He eventually regained consciousness and was airlifted to Bakersfield.

Analysis


Though not stated in either the Californian's article or the CalOHSA report, the single most significant factor leading to the accident was STS' method of attaching the guy cables to the anchors. In fact, the guy cables were never directly attached to the guy anchors or the guy anchor turnbuckles. Instead, the guy cables were attached to a cam-actuated cable grip. This grip was then attached to a tensioning device, what CalOSHA calls a "come-along device." This tensioning tool was then attached to the guy anchor turnbuckle.


Cam-actuated cable grips grasp the cable under tension and release the cable under compression. They are designed for ease of use in rigging to allow quick and frequent take-up of slack in a cable or wire rope, as when stringing cable on a power line. They are not designed or intended for use where their ability to release under compression will endanger someone. One manufacturer, Klein, explains that the grips "are to be used for pulling up lines to tension only and are not to be used as anchors."


CalOSHA reports that the guy cable "came loose" from the tensioning tool. It's not clear whether the cable slipped through the "come-along device" or the cable grip used to hold the cable. In either case, the guy cable was never securely attached to the anchor turnbuckle before Steen climbed the tower. The turnbuckles are normally used to tension the guy cables after the tower has been set on its pier, but before anyone ascends the tower.


Item #16 in Bergey's installation manual under wind turbine assembly and erection states "Attach each of the guy wires to its turnbuckle . . ." This item goes on to say that a "chain-hoist and a guy-grip" can be used to pretension the guy cable. Subsequently, item #17 in the Bergey manual advises using "the turnbuckles to move the tower towards vertical and set tension in the guy wires." Finally, item #18 says, "After the guy wires are secure and adjusted, the crane rigging can be released."


There were contributing factors that may have played a part in the accident. Most of STS business is servicing medium-size or commercial wind turbines. Installing small turbines is a sideline. Steen and his crew had extensive experience installing and servicing commercial wind turbines. They had little or no experience installing Bergey Excels on guyed towers. The tools and techniques used in servicing commercial turbines may not apply to small wind turbines. STS may have been overconfident when working with a "small" wind turbine. The Excel was one-tenth the size of turbines then being installed in the Tehachapi Pass.


The media was present, and there was a host of onlookers. Even the most experienced crew can be distracted by curious passersby. And when the media is present, it takes willpower not to "perform."


Onlookers were clearly too close to the tower and the STS crew. "Many of those present had to rush clear of the tower as it fell," reported the Californian. In a subsequent interview, the reporter present reiterated her observation that onlookers had to run or they would have been hit by the tower. No one except the installation crew should ever be within the fall zone. STS erred by not stopping the installation until onlookers moved back to a safe distance. Item #1 under tower safety in Bergey's installation manual states that "Persons not involved in the installation should stay clear of the work area."


Aside from the error in using a cable grip on the guy cables, STS's other site practices may have been sloppy. Though the pickup truck saved Steen's life by supporting a portion of the tower after it fell, the fall zone should normally have been clear of vehicles and any other obstructions.


Crane rental fees typically accrue by the hour. For a mobile crane, Lake Isabella is possibly two or more hours from Tehachapi. Travel time and installation would probably require a full-day rental.


The accident occurred on a Friday.


There's little profit in small wind turbine installations. There may have been financial pressure to get in, get it up, and get out.

The Results


The fall broke Steen's back in two places, paralyzing him below the waist. After months of hospitalization and physical therapy Steen returned to manage his company. He now uses a specially modified van with lift and a motorized wheelchair. He's had his house adapted for wheelchair use. But Steen's spirit remains unbroken. He exhibits the same exuberance for life as before.


Eight months after the accident, CalOSHA issued its report, and fined STS $450 for two violations of its safety regulations. CalOSHA issued one violation for not obtaining a permit for a structure over 36 feet in height. They issued the second violation for not following the manufacturer's installation instructions.