Two cement silo collapses, four dead

Bar a beetroot red face from embarrassment, Cement Australia got away lightly from its Port Adelaide silo collapse.

While the crash was heard a kilometre away, thankfully no-one was hurt and investigations by safety regulators are taking place against a fairly benign background.

That’s not been the case with two other cement silo collapses this year, one in Brazil, one in the USA.

A worker was killed in a silo collapse at an industrial complex in Bristol Township, north Philadelphia in January 2015.

48-year-old Tony Gabriele of Tullytown was trapped and died when a 125-foot high cement silo at the Riverside Industrial Complex collapsed.

AP said that the silo is part of a complex of facilities used to store scrap steel, gypsum, coal, grain, salt, fertilizer and other materials off loaded from cargo ships docking at an adjacent deep-water port on the Delaware River.

The cement import terminal is billed as the largest cement storage facility on the continent, with capacity of 130,000 tons.

Bristol Township police say a patrol officer discovered the collapse around 12.30 a.m. on the morning of January 8th after noticing the silo’s lights were off and a snow-like powder hung in the air.

Sometime between then and 3.15am, according to news site Philly.com, a 15-member task force started searching for Tony Gabriele who was last seen, via video, in a control room abutting the silo.

In freezing cold conditions, the search was then expanded over the next three days to a 60-person recovery effort, with cranes and vacuum trucks being used to dig through debris and 40-foot high mounds of cement.

Rescuers believed that Gabriele could only have survived in a void in the cement mound, but none was found. Gabriele’s body was eventually recovered on Sunday 11th January.

According to local US news site 6ABC.com, Dr David Jaslow of the Bucks County Technical Rescue said at the time of the incident, “This is the most complicated technical rescue incident you could ever come across in the United States.

“This is a combination of a building collapse and what we call an ‘engulfment scenario’ where all these potentially hundreds of thousands of pounds of dry concrete rushed down like an avalanche and bury everything in its sight.”

Regulatory body the Occupational Safety and Health Administration (OSHA) is investigating the incident.

In a separate incident in May 2015, three workers died and three were injured when a cement silo, at the construction site of a huge hydro-electric dam in Brazil’s Amazonian jungle, collapsed.

The accident occurred when a truck was delivering cement to silos at the site of the US$10.5bn Belo Monte hydroelectric power plant, being constructed by the Belo Monte Construction Consortium, or CCBM.

Three workers pulled from the wreckage suffered only minor injuries. The three dead were only recovered 15 hours after a search of the rubble began.

According to the Latin American Herald Tribune, “Para state police are investigating the collapse of the silo, which had the capacity to hold 500 tons of cement.

“Construction of Belo Monte, a controversial power project in the middle of the world’s largest rainforest, has been halted several times due to strikes by employees unhappy with working conditions and protests by groups opposed to the hydroelectric plant.

“Work on Belo Monte, which will be the world’s third-largest hydroelectric power plant, started in March 2011 in Altamira, a city in Para state, despite opposition from Indians, farmers, fishermen and environmentalists, who fear the project’s impact on the Amazon.

“Between 16,000 and 25,000 people had to be moved to make way for the US$10.5 billion project, according to different estimates.”

Meanwhile, Jess Chvez Sagarnaga, a senior project engineer at engineering firm Jenike & Johanson (J&J), has offered some insights into what can go wrong with silos.

J&J is a global leader in the field of bulk solids storage technology.

Sagarnaga said: “Bulk solids storage structures (bins and silos) are an integral part of nearly every industrial facility. It is vital to ensure both reliable flow and structural integrity when designing such structures. Unfortunately, failures in bins and silos are common and expensive. Failures represent a terrible loss for any operation. Not only for repairs, replacement and downtime but unfortunately even for injuries or fatalities.

“Silos and bins fail with a frequency that is much higher than almost any other industrial equipment. Sometimes the failure only involves distortion or deformation which, while unsightly, does not pose a safety or operational hazard. In other cases, failure involves complete collapse of the structure with accompanying loss of use and even loss of life.

“The major causes of silo failures are due to shortcomings in one or more of four categories: design, construction, usage, and maintenance.

“Engineers in charge of the structural design, construction and forensic investigations of silos face the challenging task of assessing, first, the flow behaviour of the stored material in the silo. Once this has been achieved, the next step is to calculate the loads exerted on the silo walls and then proceed with the structural design or investigation. However, this procedure is not intuitive and requires years of experience in the field of bulk solids and structural design of silos.”

ABHR will publish in a forthcoming print edition a more detailed technical paper from J&J looking at issues around silo failure.