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Earthquake Demonstrates Barrel Stack Vulnerability

October 2014
by Andrew Adams
RGB Industries racks
Trinchero Napa Valley winery uses Australian-made racks from RGB Industries that don't rest on the barrels when stacked to provide more stability in the event of an earthquake.

Napa, Calif.—The enduring image of the Napa earthquake will likely be the piles of barrels and racks from toppled barrel stacks.

While most winery buildings made it through the earthquake with little to no damage, aside from the dramatic exception of Trefethen Family Vineyards’ historic winery building, several wineries suffered damage, lost wine and had staff spending precious time at the onset of harvest cleaning and reorganizing their barrel rooms.

Despite the example of the 2003 San Simeon Earthquake, after which a forklift driver had to be rescued from beneath a pile of collapsed barrel stacks, most wineries throughout California still stack barrels up to six levels high with two-barrel racks laying on top of the barrels below. The setup provides for quick and relatively easy access to barrels and maximizes available space in a barrel room.

But the big drawback of this stacking method became all too apparent to several wineries near the epicenter of the quake in the Carneros American Viticultural Area and as far into Napa Valley as the Oak Knoll AVA.

Napa Barrel Care, located on a Highway 29 frontage road at the southern limit of the city of Napa, suffered extensive damage in the Aug. 24 earthquake. Employees there were still working to get everything back in order when Wines & Vines went to print Sept. 16.

Owner Mike Blom said the facility had 18,000 barrels owned by 43 different clients at the time of the earthquake, and half of them hit the floor. The cleanup was particularly challenging in the facility’s smaller, 10,000-square-foot room, where almost every barrel rack toppled.

Blom estimates he’ll have to sink $250,000 into cleaning up the mess. He is also planning to strap the top racks of his barrel stacks to try and minimize dangerous swaying in the event of another earthquake. “Oh we’re strapping everything. Absolutely,” he said. “I’m more devastated by clients losing wine than by anything else.”

Winery buildings suffered very little in the earthquake, said Josh Marrow, principal with the San Francisco, Calif.-based firm Partner Engineering and Science Inc. Marrow is an expert in structural and earthquake engineering who has consulted wineries and studied how earthquakes affect them.

In Carneros, Marrow said he saw the difference between four-barrel racks and two-barrel racks. One winery that had switched to four-barrel racks, which have twice as broad a base as two-barrel racks, had minimal damage, while a neighboring winery with two-barrel racks had nearly every rack tumble. “The four-barrel racks performed miraculously,” he said.

The two-rack system has a considerable weakness in that racks for levels two and above only need to slide a few inches before they slip off the barrels below them. It takes only one rack to slip off one barrel to trigger the domino effect on barrel stacks. Marrow said strapping the top sets of barrels works quite well with four-barrel racks, but it’s not as effective with two-barrel racks because it doesn’t solve the issue of racks “walking” or sliding off the ends of barrels.

Suppliers do offer some tools to help secure barrel racks. Topco offers its “topcap” rack, which is designed to secure the top barrels of a rack to help prevent the top barrels from falling off a rack into other stacks. The company will also modify old two-barrel racks into the more secure four-barrel racks. In 2009, Western Square developed a seismic-support system for barrel racks with engineering professor Charles Chadwell of California Polytechnic University in San Luis Obispo, Calif. The specialized racks employ ball bearings to securely move with the force of an earthquake rather than topple.

Chadwell said Western Square sold several of the new racks, but a few months later it became clear they couldn’t handle daily conditions inside a winery. He said some of the moving parts were housed in a semi-enclosed system that wasn’t completely watertight. When cellar workers washed the barrels, water made its way into the mechanism, and eventually it rusted solid.

Soon after Chadwell and Western Square realized they had a problem, wineries lost interest in a new redesigned product because of the recession. “This type of safety equipment was not of interest in the recession,” he said. When the economy improved, Chadwell said he and Western Square started working on the redesign once more and, “After this earthquake we certainly kickstarted the work in high gear.”

Chadwell said he has developed a new prototype with a spring system to reset the bearings, and everything will be stainless steel, Teflon or high-grade plastic. He said the final design should be fairly quick to manufacture once it’s been thoroughly tested. Wineries will only need to purchase one per stack, and the idea is to enable those set up for two-barrel racks to add a degree of seismic safety.

Nothing is ever fully earthquake-proof, and Chadwell said certain existing practices just are not safe at all.

“Stacking six high is a bad idea just all the way around,” he added. Based on shaker table studies he performed at Cal Poly, Chadwell said barrels stacked four high with one of the specialized racks on the bottom could handle shaking similar to the recent major earthquake in California, and even stacks five high seemed to manage. “At six high, I don’t condone that for any system.”

He added that seismic regulations have so far addressed ensuring the buildings and key infrastructure can withstand earthquakes, but there may be more interest in securing “heavy contents,” which would include barrels. He said wineries may soon see policy in place requiring them to have some type of seismic restraint system to help keep workers safe from toppling barrel racks. “Something that will come out of this is heavy contents and how it relates to life safety,” he said.

Marrow said he’d also like to see winery “shark cages,” or heavy-duty steel cages placed in easily accessible parts of the barrel room. If an earthquake hits a winery, or a forklift accide nt triggers a stack collapse, workers could run to the cage and be protected from falling barrels. “If anything goes wrong, at least they have a fighting chance to get into the cage,” he said. “They may be stuck there for a while, but at least they’ll be alive.”

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