Craiker’s Corner: California wineries need to prepare for next big shake
The 2014 West Napa Fault 6.0 magnitude earthquake damage to homes, historic buildings and infrastructure was estimated to be close to $1 billion with approximately 170 people injured and 2 deaths. The strongest Bay Area quake in 25 years, Napa officials estimated the financial cost of damage to wineries and agriculture at over $80 million with around 120 wine and agriculture businesses suffered at least some damage in the quake.
If you think about it, earthquakes and wine go together, since our rich volcanic soil is the result of eons of seismic activity.
The county and industry report at the time claimed roughly 60% of Napa Valley wineries sustained some damage, with 25% suffered damage exceeding $50,000. While historic structures such as the Trefethen McIntyre Building in Yountville saw significant damage, its wood elasticity made it repairable.
As an architect, I rely on structural engineering voodoo to hold down buildings. Of course, we are all familiar with gravity or weight forces but lateral forces are energies applied horizontally to the ground such as wind and earthquakes. And the higher above the ground plane, the more horizontal energy to be reckoned with.
Bulk wine in 60-gallon barrels stacked to warehouse ceilings proved to be the majority of the industry losses. Most wineries throughout California stack barrels up to six levels high with two-barrel racks on top of the barrels below. This provides quick and relatively easy access to barrels and maximizes available space in a barrel warehouse. But the big drawback of this stacking method is earthquake vulnerability. Some try to strap the top racks of barrel stacks to try and minimize dangerous swaying but this is unproven.
Wine barrel stacking options
There are so many options that I can only mention a couple. The proof might be in the testing. UC Berkeley’s Pacific Earthquake Engineering Research Center has America’s largest shake table, the device used to test building components such as stacked barrels. The preformed a series of earthquake tests on various six-high wine barrel stacking systems that I’ve note here.
Rack Master plastic wine racks by DACO of Washington state. The plastic constructed racks allowed up to six double barrels stacked to absorb almost twice the energy of conventional steel counterparts, resulting in less stress the wine barrels themselves.
EQX Global LLC is a Napa based research and engineering company dedicated to providing base isolation solutions to protect against earthquake damage. Base isolation is used for high value buildings such as data centers, hospitals, museums and municipal structures, such as the entire San Francisco City Hall. The object is to allow the stacked barrels to move independently, slide if you may, to minimize the earthquake’s energy transfer into the stacks. The system consists of a stainless-steel tray under the first barrel rack on a special epoxy coated concrete floor to minimize friction and allow the stacks to move. As Paul Simon would sing, “Slip Slidin’ Away.”
While both systems were tested and to some degree passed their lab tests, nothing is ever fully earthquake-proof. Stacking barrels six high can be dangerous if not properly secured. The problem with earthquakes are, they are unpredictable for location, duration and direction. A magnitude 6.0 shake in one direction can have a totally different structural effect if it moved in the opposite direction. And up and down motions can be totally a mess. That’s an architectural term. The next big shake won’t be a matter of ‘if’, but ‘when’.