1983 - Volume #7, Issue #2, Page #18[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
Midnight Silo Crash Creates Excitement
The collapse of the "almost full" steel and fiberglass structure was the unfortunate finale of slightly more than a week of watching and waiting for Penn-Jersey Harvestore Systems, Inc. and dairyman John Krall of South Lebanon Township and his family. Sons Tim and Tom, who work on the family dairy operation, were joined by John and daughter-in-law Shirley in a vigil Monday evening, anticipating the fall of the leaning blue tower.
"We thought the silo had to go on Monday," recalled Tom. "During the day, Tim said he heard something cracking in the feed room, next to the silo - sounded like an electrical short or something. What it was, we realized, was the splattering of glass as it cracked off the silo. By the end of the day, the silo had leaned three-quarters of the way over.
"It had leaned against the Star silo first," said Tom, pointing out the long, dark scratch in the concrete and the slightly squashed silo ladder. But then the weight must have shifted and it fell away from the barn and remaining silos, out toward the rye-covered corn fields, he said.
Curiosity more than dread marked the occasion that could have been termed disasterous except for the backing the Kralls received from Penn-Jersey Harvestore. Instead of wincing from the crushing blow the silos collapse could have dealt to their huge investment of feed and finances, the family gladly "sat back and watched" as the silo company took over the responsibility for cleanup and replacement of silo and feed.
According to Penn-Jersey's BobMcLean, what caused the silo to fall was a phenomenon known as "bridging." He explained that the ground high-moisture ear corn, which is a semi-free flowing material, created a shifting pattern in the feed inside the silo due to uneven unloading.
"The internal load shifted and put stress on the structure," McLean said, pointing out that this is the first case of its kind experienced by Penn-Jersey in more than 1,500 silos the company has constructed.
What is presumed to have happened is that while the Kralls were unloading the high-moisture corn, a gap in the feed layer was created - leaving a bridge potentially eight tons wide between the suspended feed layers. When the upper layer finally dropped down, a vacuum sucked the airtight Harvestore's panels in, causing a buckle about 15 ft. off the ground. The pressure of the shifted weight-load on the panels eventually caused the silo to split and fall to the ground.
McLean stated that various factors could have led to the bridging condition in the ground ear corn - moisture, length of cut and grinding, filling patterns, and outside temperatures.
Although McLean stressed the company is "not pointing its finger at anyone" for the structure's implosion, he hypothesized that if the signs of bridging had been noticed by the farmers after the silo was refilled in November, there may have been a possibility of "working the unloader pattern differently to pull feeds off different sides of the silo." He recommended farmers work closely with their structure sales people so that best management practices can be followed.
The feed which stayed in the up-right remains of the. 80-ft. tall silo was unloaded and sold, said Mc-Lean, adding that crews worked for 24 hours and finished early Thursday morning.
Five days after the mishap, Penn-Jersey had a brand new, 20 x 80 Harvestore standing where the one year-old structure had been. And the silo company replaced Krall's ground ear corn with high-moisture shelled corn.
McLean said the fact that the company rebuilt the same structure on the same spot answers the question in some farmers' minds: "Is 80 ft. too high a silo for ground high moisture corn?"
In summing up the mishap, Mc-Lean referred to a remark made to him by John Krall after the silo fell: "He said no one likes problems, but we have to take the good with the bad. It's how people respond that's important."
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