By George Potter
The vast majority of high-angle rescue
specialists are very experienced and competent in a wide variety of incident scenarios: ravines, mountain faces, wells, caves, building façades, and industrial complexes. There are other high-angle rescue
situations, however, that require all of the rescuers’ accumulated knowledge and experience, along with very demanding material requirements to perform the operations successfully; rescue operations in radio antenna towers and wind energy turbines are examples and are addressed here.
Radio Antenna Response
Most of today’s radio antenna towers are built of slim section tubular metal structural elements, many of then in triangular form or squared. The base of the tower may be approximately 15 to 20 feet per side, and the towers are generally uniform all the way up. These towers can reach or surpass 1,000 foot in height and are sustained against the effects of high-velocity winds by metal guy cables fixed at several hundred feet up the tower and angled away to anchorages, often several hundred feet away.
Accidents have affected maintenance operators at several antenna towers during the past several decades. These accidents required mobilization of rescue specialists from many miles away from the incident sites. The most common incidents involve workers who may have fallen off the tower and are hanging by their harnesses, injuries caused by loose equipment, or sudden serious illness such as a heart attack. The two most challenging factors in responding to these towers are the extreme physical exertion needed to climb vertically upward through the tower’s structure and the need for literally “miles” of rescue rope and a variety of rescue accessories. Factor in high personnel requirements, the complexities of incident command, the absolute necessity for coordinating with the antenna’s operator, and the possible need for other agencies’ presence, and you have an incident not unlike a multistory high-rise incident in any major city.
More often than not, no personnel of the antenna’s operating entity are on site. There are, however, some exceptions, specifically concerning antennas operated by radio stations. Their antennas could well be situated at the broadcasting station or very close by. It is essential that local emergency services establish and maintain close working relations with these operators. This is also applicable to isolated antennas, in which case the operator must be notified as soon as possible on confirmation of the emergency so technicians can be sent to the site.
Probably no rescue company has the required materials available at a moment’s notice. Even those that have experienced numerous and varied rescue responses do not have thousands of feet of adequate rescue lines in stock: hundreds yes, thousands no. Emergency services that respond to incidents in towers hundreds of feet high must have instant knowledge of from who and where they can obtain the needed materials and how long it will take to get the materials on site.
Once the operation is underway, a safety coordinator must be assigned, and this officer must assume responsibility for all safety factors from the beginning through the finalization of the operation. These safety factors include supervision of all materials employed; ascent of the rescue team(s); the establishment of multiple safety lines; and all actions, primary and secondary, and support from the moment of initiation through the packaging of victim(s), transport to adequate medical assistance, and recovery of materials and equipment.
Wind Energy Turbine Response
Rescues in wind energy turbines can be even more complicated. Most wind turbines are grouped in what are known as “wind farms.” Although some “farms” may be a few acres in size with a dozen or two towers, there are many wind farms that cover hundreds of acres and may have several hundred towers. More often than not, the wind farms are in rural regions that are often difficult to access because of distance, terrain, and climatic conditions. The site location engineers prefer to situate their towers along hill crests to reduce and eliminate interferences from wind flows and velocities.
As in rescue situations in radio antenna towers, rescue operations in wind turbines require specific applications of high-angle techniques. The heights of the wind turbines, or aerogenerators, are much lower than radio antennas, generally around 300 feet, although some new technology systems can be as high as 350 or more feet. Atop the normally round and completely enclosed tower sits several tons of machinery, housed in what is called a “nacelle.” At one end of the nacelle, normally three 100-or-so foot-long blades are fixed to a rotor, which is connected to an electric power generator tucked neatly into the nacelle.
Access to the uppermost parts of the aerogenerator is normally by vertical interior ladders with platforms placed at strategic points. Some towers have inside elevators, but they are generally the rare exceptions to the more or less standard designs. However, nearly all aerogenerators have winch assemblies inside the nacelle, intended for hoisting heavy replacement parts and equipment. The winch can be used, under extremely close supervision, for hoisting rescue and medical aid equipment and for lowering victims. Among the most frequent emergency situations requiring rescue operations are entrapment of persons somewhere inside the nacelle, sudden illness, or falls inside or outside of the towers with victims suspended by their harnesses.
One emergency situation that will frustrate nearly all responding firefighters is a fire in the nacelle. The aerogenerators are equipped with sophisticated and reliable automatic fire detection and self-contained fire extinguishing systems. If a fire does occur in the aerogenerator, rule number one for firefighters is “let it burn itself out.” Do not attempt to ascend up to the nacelle, as this is extremely dangerous. The ascent would be extremely physically demanding, time consuming, and very cost-ineffective. There is also a very real danger that the fire could provoke dispersion of elements such as the blades, skin panels, and even mechanical parts over a several-hundred-foot radius. Some of this material could propagate the fire to ground level, causing possible ignition of vegetation or fires to structures in the immediate vicinity. In the case of a 300-foot-high fire, cordon off the surroundings and evacuate persons to at least 700 feet away. Lightning is the most common cause of fires in wind generators; mechanical friction and overheating are other frequent sources.
The potential for hazmat incidents is another hazard present at wind farms. Each turbine contains several hundred gallons of hydraulic fluid and other potentially combustible lubricants.
At ground level, there are normally structures in which the currents generated by the turbines are channelled into high-tension transmission lines for distribution through the electrical grids. There may be thousands of volts of electric current in many places in and around the wind farm. This makes coordination with the operators absolutely essential before initiating any emergency operations.
Thus it is of the utmost importance that standard operating procedures or guidelines be established with the cooperation and active participation of the operators. More often than not, operator technicians are not present full time at wind farms; indeed, they may well be several miles away, so informing them from the outset of an emergency response is an absolute priority. Most operators have emergency response protocols implemented, and their technicians are trained in high-angle and suspended working situations.
My article, “Response to Emergencies in Wind Turbines” in the April 2011 issue of Fire Engineering discusses the creation of SOP/SOGs for these emergency responses.
George H. Potter is a practicing fire protection specialist who has lived in Spain for the past 45 years. He served as an Anne Arundel County, Maryland, volunteer firefighter with the Riva Volunteer Fire Department and the Independent Hose Company in Annapolis and as an ambulance driver with the Wheaton (MD) Rescue Squad. He served six years in the United States Air Force as a firefighter, an apparatus driver/operator, and a crew chief. He has been involved in fire protection system installation, mobile fire apparatus design, and construction and fire safety training. He is a Spain-certified fire service instructor and a hazmat specialist, and is a member of the Board of Governors of the Spanish Firefighters' Association (ASELF).