Into the Earth: Wine Caves

For centuries, ever since hunter-gatherers turned their inventive minds to agriculture, humans have faced the dilemma of how to mitigate the effects of weather on food. Seasonal–even daily–shifts in temperature and humidity make it difficult to simply pile your harvest somewhere and not see it rot, desiccate or become contaminated.

At first, stashing food underground was probably a way to keep it away from scavengers, but someone likely noticed that over time the food stayed edible longer when it was protected by a mass of earth, that underground storage gave your tribe an advantage over weather and allowed you to become more productive.

Greater productivity led to increased wealth and opportunity, which gave way to art, engineering, punk rock, and the iPad (perhaps not in that exact order). Along the way, someone got tired of piling rocks to form pyramids and looked forward to a glass of wine as a way to relax after work. Of course, the wine had to be stored underground.

European wine makers, all the way back to the Romans, have stored wine in caves. The French stored wine in abandoned quarries, and it was an easy leap of invention to begin digging caves just for the purpose. Wine caves tend to be dug into hillsides, with the entrance convenient to a lower elevation and the caves extending back into a hill.

At Thomas George Estates (TGE) winery on Westside Road, engineers have carved out an enchanting underground space from a very challenging hillside. “We started in March of 2009 and it was Murphy’s Law every day,” said Jeremy Baker, President of TGE. “We hit everything: underground streams, different types of rock, serpentine, clay...”

David Provost of Bacchus Wine Caves was hired to construct the cave, 520 linear feet underground, in a series of interconnecting tunnels. “That was probably the most varied ground we’ve been in,” he said. “At first, all indications were that the ground would cooperate, but at Intersection Number One–we were in about 20 feet–it just started falling in.” Provost and his crew had to alter how they reinforced the walls as they dug, beefing up their support system, “and the rest of it was really slow, we couldn’t go in more than two feet at a time. We fought it the entire time.”

The technique Bacchus used is the most common wine cave-making technique in this area. The general outline of the cave mouth is spray-painted onto the hillside and crews start digging. Once the hole is in a little ways, the walls are reinforced with steel mesh and concrete is sprayed on to form a rigid arch. Once that sets up, you start digging again, all the while measuring and testing to make sure the hole is the right dimension and the hill isn’t about to fall into the cave.

But sometimes, the hill falls in anyway. In a large tunnel intersection in the TGE cave, an area of the ceiling simply collapsed overnight. “We came in one morning and found it in a pile,” said Baker. Rather than try to pack the soil back up into the ceiling, the crew reinforced it and kept it as nature created it. The extra steel and concrete reinforcement was tricky and added to the cost, but the effect is captivating. After walking along the tunnels with their gently curving walls, looking up into the naturally-shaped bowl of the salvaged cave-in is a reminder that you’re inside the earth.

Baker calls the space his cathedral ceiling. “It’s not what we planned, but now it’s an asset. It’s an expensive asset, but the things that make this cave special are the unexpected things, including the cave-in.”
After battling unpredictable soils, underground streams, cave-ins, and walls that shifted overnight and had to be reinforced, the cave-building crew ran into another formidable obstacle–hard rock, really hard rock that did not respond to drilling equipment. Provost gave Baker the unsettling news that the only way to finish the cave was to bring in explosives to fracture the rock.

Baker said, “Imagine setting off dynamite when you’ve just spent all that time reinforcing the rest of the cave...it was a very stressful time in my life.”

Provost felt it too. “It was the last tunnel, we just had 26 feet left, and the rock was so hard we couldn’t cut it with the roto hammer. We talked ourselves into it (blasting) and out of it a few times.”

Baker gave the go-ahead to blast and the Bacchus crew brought in a special blend of dynamite that would shatter the rock quickly and hopefully not send a lot of vibration throughout the rest of the cave. Three small, precise blasts later, the rock was sufficiently fractured that it could be dug out and the cave completed.

The cave at TGE will open officially this month and Baker is putting the finishing touches on it now. Baker collects unusual light fixtures and they are installed throughout the cave, including a group of fixtures that came from a World War II munitions factory in Europe and an ancient candle sconce that he retrofitted with electricity. Special dinners will be served on tables made of massive redwood slabs salvaged from a fallen tree.

While the TGE cave will accommodate VIP tastings and events, the primary use is wine storage. The protection of the soil creates consistent temperatures and humidity, perfect for aging and storing wine.

The first known wine caves in the region were built in Napa Valley, but the Wetzel family built one of the first in Sonoma County. They finished the first cave at Alexander Valley Vineyards (AVV) in 1997. According to Harry Wetzel, “We’ve built our cave system in three phases. The most recent was finished in September 2008.”

The built-out cave complex at AVV is large at 25,000 square feet. The AVV property is at the toe of the foothills of the Mayacamas Mountain Range and there’s not a lot of flat area that could be devoted to a large barrel warehouse. The Wetzels estimate that the cave saves as much as 400,000 pounds of carbon dioxide annually that would otherwise be generated by heating, cooling and humidifying a warehouse.

“Caves are a little pricy to put in, but once they’re in you only pay for electricity for lights,” said Wetzel. Does the cave attract visitors to AVV? “It does have some marketing value,” he admits. “We do take some tours, but it’s really a working cave.”
Thomas George Estates and Alexander Valley Vineyards are not the only wineries to dig into a hillside. Robert Young Estate Winery and Bella Vineyards & Wine Caves (and others) have built caves nearby in the last decade. Scott Adams, co-founder of Bella, says his cave has an average temperature of 61 degrees and a steady humidity of 51 percent, an especially valuable asset during our dry summers.

Adams built the cave during 2002 and 2003, when California was experiencing rolling blackouts due to electricity shortages. The idea of not paying an electricity bill for refrigeration was very appealing, as was the ecological and esthetic aspects of a cave.
“It was important to us to maintain the integrity of our site,” Adams said. “We have a very natural setting up at the end of Dry Creek Valley and it made sense to build into the hillside rather than put up a big warehouse.”

Adams says the cave also appeals to his clientele. “People like to come and check it out; it’s similar to how wines have been stored since antiquity.”