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Missing in action Unexploded avalanche-control shells pose a hazard in Yellowstone Park By MICHAEL MILSTEIN Gazette Wyoming Bureau YELLOWSTONE NATIONAL PARK - One May day in 1995, a Yellowstone National Park visitor stopped in traffic near Sylvan Lake, left his wife and child in his car, walked up to park maintenance worker Devarold Selkirk and asked him to identify the item the man held in his hands.
 Gazette photo by Michael Milstein Rangers fire 75mm shells in Yellowstone National Park as part of the avalanche control program in this 1991 file photo. Selkirk did. It was a explosive shell designed and manufactured by the U.S. Army primarily to destroy tanks during the Korean War. The visitor said he had found the shell "up on top of the mountain," apparently referring to Sylvan Pass, near Yellowstone's east entrance, according to a park report. If the shell had detonated inside the visitor's car, experts say, it would almost certainly have killed the man and his family. A review of National Park Service records by The Gazette has found that more than 30 such unexploded military shells remain unaccounted for in three different places in Yellowstone Park where rangers had fired them for avalanche control. The so-called "dud" rounds did not explode as expected and may still be fully armed, experts say. Park managers say the leftover shells rest in remote locations rarely if ever traversed by visitors or wildlife. They are an unfortunate byproduct of an avalanche control program vital to the safety of winter visitors and snowplow operators who clear roads in the spring, they say. But park rangers as well as outside experts concede that such explosives pose a hazard, especially since when fired they sometimes skip across snow like a stone across a pond or slide down hillsides in subsequent avalanches, ending up far from the target zone and within reach of the public. The park visitor who presented the shell to Selkirk proved the point. Selkirk did not get the man's name, but took the shell, "put it in a soft place in the rear of the garbage truck" he was driving and took it to a ranger station, although experts now say the potentially live shell should never have been moved along roads open to public traffic. An explosives team later detonated the shell in a garbage pit. "When we know of a dud, we definitely consider it a hazard and we treat it as a very dangerous object," said Doug Abromeit, director of the U.S. Forest Service's National Avalanche Control Center. "Often they're not likely to detonate, but there's always that possibility." A 1990 report by the National Research Council said experience with military ordnance used in avalanche control suggests that 10 percent of dud explosives may later detonate spontaneously, without any obvious trigger, while the rest "remain fully armed in some unknown state of sensitivity." Explosives may grow more unstable with age. "Because military ammunition is well constructed and sealed to withstand long-term exposure to extreme environmental conditions," the report said, "duds may remain operational for years." Yellowstone and National Park Service officials said they would take three specific steps in response to questions raised by The Gazette during the reporting of this story:
In 1997, park avalanche control teams traded the 75mm recoilless rifle that fired most of the unexploded rounds for a more modern 105mm Howitzer, which has so far yielded no duds, officials said. Military specialists predict that about 5 percent of 105mm shells landing in snow will not explode as intended, said Steve Abney of the Army's Rock Island Arsenal in Illinois, which manufactures the shells.
 Projectiles starting from 105mm are shown in this Army training photo. Yellowstone officials say their attention to safety is demonstrated by the switch to the more reliable weapon, their installation of new magazines to safely store shells with the Howitzer stationed on Sylvan Pass, improved training and their attempts to recover unexploded rounds. "I feel we've made tremendous progress," said Alan Sumeriski, Yellowstone's head explosives specialist. "We still have a ways to go, but I don't think anyone can say we're turning our heads to this." Rangers in Yellowstone began using artillery to control avalanches in the late 1970s, as winter recreation in the park took off. Teams initially borrowed a 105mm recoilless rifle from the Army and fired shells onto snow-laden slopes above 8,530-foot Sylvan Pass to trigger avalanches so the snow would not later slide and bury travelers on the road over the pass, a mountainous gateway between Cody, Wyo., and the park's interior. Not every 105mm round detonated. Searchers in 1997 recovered one unexploded 105mm round that had deteriorated to the point it could no longer explode. Park officials responding to a Freedom of Information Act request from The Gazette could find no further records of how many 105mm shells were fired, how many failed to explode or how many may such shells remain unaccounted for. The 105mm recoilless rifle was so powerful that park rangers soon traded it to the Army for a smaller 75mm Korean War-era recoilless rifle. Records of the early use of the smaller weapon are sketchy and park officials concede they do not know for certain how many early dud rounds might have been recovered. The recoilless rifle shells used in Yellowstone weigh about 10 pounds, resemble an oversized Thermos bottle and carry more than a pound of high explosive. Most were manufactured during the early 1950s. They emerge from the rifle barrel spinning and arm themselves after a certain number of revolutions. Once armed, they detonate upon impact. Rounds that do not explode may carry a defective detonator or other flaw making them unlikely to explode at all. Some may also have deteriorated with age so they do not explode with their full force. In other cases, thick snow might cushion a shell's impact so its detonator does not trigger an explosion, although the shell remains armed to explode if sufficiently disturbed. "Firing it into a snowbank is like firing it into a bed of feathers - it might not have the impact necessary to detonate," said Randy King, a safety specialist and explosives disposal expert at the U.S. Army Corps of Engineers Engineering and Support Center in Huntsville, Ala., which specializes in finding and cleaning up unexploded ordnance.
 Gazette photo by Michael Milstein A shell is loaded into the 75mm recoilless rifle used in Yellowstone National Park to reduce the chance of avalanches. Records obtained under the Freedom of Information Act from the last 10 years show that rangers usually, but not always, noted the location of rounds that did not explode and then searched for them the following summer. Upon finding shells, rangers marked them with flags but did not touch them. In 1991, a U.S. Army team visited Yellowstone and disposed of dud rounds by detonating them with additional explosives, again without moving or touching them beforehand. "We treat them as live until we can prove they're not," said Robert DiMichele of the Engineering and Support Center. "Calling them 'duds' kind of implies they will never go off. Even a dud can go off given the right circumstances of handling or exposure." Since 1991, at least 44 more shells fired from the 75mm recoilless rifle did not explode, records show. Most of the shells had been fired on Sylvan Pass, but three had been aimed at the west slope of Mount Washburn near Dunraven Pass in 1995 and two were fired on a slope above Yellowstone's south entrance road near Lewis Falls in 1997. No one searched for the unexploded rounds on Mount Washburn, said Yellowstone District Ranger John Lounsbury, who heads the park's avalanche control program. He said the rounds ended up on the mountain's steep and rocky west slope, which is open to the public but away from trails and unlikely to attract visitors. Park rangers will search for those shells this coming summer, he said. Rangers found one shell near Lewis Falls but could not locate the other. An Army team in 1997 disposed of the shell found near Lewis Falls and 11 others located on Sylvan Pass, leaving more than 30 unexploded rounds still unaccounted for. Some ski areas and highway departments that use artillery for avalanche control face the same hazard. The National Research Council report said that "most areas using weapons have had this problem since the inception of weapons programs in the early 1950s, and the cumulative number of lost, fully armed, and sensitive explosive charges is probably in the thousands." In 1997, a Colorado construction worker picked up a small unexploded avalanche shell fired from a gas-powered device called an Avalauncher. The shell detonated in his hands, seriously injuring him with shrapnel. The artillery rounds used in Yellowstone are far more powerful and if one of those had exploded in his hands, "it would have killed him," said Don Bachman, executive director of the American Association of Avalanche Professionals in Bozeman.
 Gazette map by John Potter National Park Service staff in Washington, D.C., are now drafting an official policy on explosives use in national parks, but had been unaware of the unexploded shells left in Yellowstone until contacted by The Gazette, said James McCarthy, the agency's national blasting officer. He said they will now address the issue. "We need to review this and see what appropriate procedures need to be put in place to make sure we're not jeopardizing anyone's safety," he said. Every summer, rangers scout for unexploded shells on the high slopes of Sylvan Pass, which are marked as closed to the public, but "I can't say with any certainty that we'll find all of them," Lounsbury said. Some shells might lie buried beneath rocks or gradually tumble down the slope: Park crews, for instance, had located and flagged some shells before the Army's 1997 visit, but then could not find them again when the Army team arrived. "It's certainly possible one of those rounds is going to slide down" toward the road over the pass, Lounsbury said. "Certainly somebody else this summer could go up there and stumble into one."
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