Champagne’s dark and damp, centuries-old wine caves are a remarkable sight. The underground tunnels run for miles, sometimes one on top of another, storing millions of bottles of precious sparkling wine.
Given that grandeur, it’s not really a question whether wine producers in other regions would want caves of their own for wine storage. But rather, can they, and should they?
The benefits of storing wine underground are many. Namely, it’s Mother Nature’s free cooler. Hubert de Billy, director of public relations and business development of Champagne Pol Roger, says caves level the winemaking playing field. “As soon as you are five to 10 meters [16 to 32 feet] underground, it’s roughly [50°F] no matter where you are,” he says.
“It provides for a constant temperature,” says Hugh Davies, president of Schramsberg Vineyards in Calistoga, California. “It might have minor fluctuation, but not much at all. We’ve effectively got 32,000 square feet of refrigerated space.”
Coincidentally, the oldest portions of Pol Roger’s nine kilometers, or roughly five and a half miles, of caves, and the original section of the 12,000 square feet of underground storage at Schramsberg, both hover around 150 years old.
“I think the beauty of the caves is that they are super durable,” says Davies. “We’ve made a lot of technological progress over the years, but the caves serve the same purpose they did 150 years ago.”
Don Magorian is a mining engineer and owner of California-based Magorian Mine Services. He notes that technology in caves has only recently evolved.
“Two decades ago, we seldomly saw any type of waterproofing or leak mitigation,” says Magorian. “Today, they’re built with computerized ventilation, lighting and occupancy sensors, and have Wi-Fi throughout.”
Magorian’s business focuses solely on building caves and mines, 90% of which are for wine producers. From a financial perspective, despite recent tech improvements, Magorian estimates that building a cave can still cost three to four times less than an above-ground structure.
“Some winery facilities might be upwards of $1,500 per square foot, whereas my average costs is somewhere around $300,” he says. “Not only does a cave have the economics going into the project in terms of costs, but it has economics for the four- or five-hundred years that it can be used to store wine.”
Aside from natural temperature control, caves have a firm upper hand for long-term sparkling wine storage. The darkness means that transparent glass bottles won’t see the adverse effects of natural or artificial light.
“You don’t want to cook or expose bottles to too much light, so cold and dark is fantastic,” says Davies.
“We store bottles for up to 10 years,” says de Billy. “We need dark space, which is why we have nine kilometers of cave. We have nearly 10 million bottles in our cellars.”
Based in Épernay, space isn’t an issue at Pol Roger. Its tunnel system spans three levels. The first level below the surface is 15 meters high, while the lower two are both approximately 10 meters high, for a total depth of 35 meters [abut 115 feet].
“We could do deeper, but it’s much too expensive to make sure that the water can’t get in,” says de Billy.
Ten minutes across the River Marne in Ay, 1.5 miles of caves under Champagne Billecart-Salmon are situated. Only blocks away from the river, digging deeper is a challenge. Instead, Billecart-Salmon looks to acquire land outward.
“You started digging under somebody else’s garden—I don’t think they would take it lightly in 2021,” says CEO Mathieu Roland-Billecart. The estate’s solution, in one instance, was to purchase the neighboring land and link its cellars with the existing tunnels under the newly purchased house.
As many benefits as there are to building caves and storing wine underground, there are a few requirements to check before the digging starts.
“The main thing is to ensure that the geology is appropriate for a cave in the first place,” says Magorian.
In the Napa Valley specifically, this means staying outside the thermal zone, where the rock is warm, not cool. Magorian explains, “For example, in northern Napa Valley on the Calistoga side, temperatures are normal, between 57- or 58-degrees Fahrenheit. But just a quarter mile away in the thermal zone, it can be above 80.”
While the temperature of the rock is one consideration, the type of rock is also a determinant. Many cite Champagne’s unique conditions to exemplify this.
It’s not to say that any other kind of rock can’t be transformed into a cave. Thanks to modern machinery and technology, it’s possible almost anywhere. “They’re digging into rocks now that would have never happened hundreds of years ago,” says Quigley.
Despite advancements, one roadblock that can’t be overcome is an area’s water table level. A water table, not to be confused with water or ocean level, is the depth at which the ground is saturated. In some areas, the water table can fluctuate with seasonal precipitation, adding variation to structural integrity or site vulnerability.
A great example of this is in Burgundy, explains Quigley, “because you can dig caves in Meursault, but not in Puligny because the water table is higher.”
The geological risks of building underground should be heavily weighed before blasting begins. Additionally, the inherent risks of people working below Earth’s surface day-to-day should also be considered.
“Most of our workers, for health reasons, are given a variety of different tasks,” says Mathieu Roland-Billecart. “They’ll work underground for a few days, and then they’ll do something else.”
The depth and extent of the caves at Pol Roger provides additional health concerns. “One of the biggest risks is if someone has a heart attack, and we need to get them out,” says de Billy. For this reason, three EKG defibrillator machines are placed throughout the tunnels.
As a fifth generation of the Pol Roger family lineage, Hubert de Billy recalls exploring the caves as a child. “We used to carry matches in our pockets in case the lights went out.” But today, “we have lights on their own battery system,” which turn on automatically if the power is cut.
In California, seismic activity is one of the biggest concerns for Hugh Davies at Schramsberg. “We have never had anything particularly catastrophic happen in that regard, but we do have markers in the caves that track movement in the walls over time,” he says.
As with traditional, above-ground structures, maintenance is necessary. “We have structural engineers evaluate the integrity and durability of the cave network,” says Davies. “And some recommendations have been made to reinforce those walls.”
Upgrades and improvements are unavoidable, regardless of the structure type. Above-ground structures might require a new roof or a fresh coat of paint. Aside from annual engineer inspections, the odd cement reinforcement and the cost of electricity, the operating cost of a cave is nearly nil. Add to that, the lifespan and durability of a cave are decades, if not centuries, longer than any building.
“The cave business is good because people see its value,” says Magorian. “Part of that value is once it’s built, you can’t see it or hear it. Once it is built, the hillside is natural with exception to the portals.”
“From a green perspective, you can hardly do better,” says Davies. “There’s a lot of hidden infrastructure on our property.”
Despite their tradition and history, wine caves still have a place in the modern wine world. “Underground cellars are, in fact, the future,” says de Billy.