Wine caves are subterranean structures for the storage and aging of wine

Aging of wine

The aging of wine, and its ability to potentially improve wine quality, distinguishes wine from most other consumable goods. While wine is perishable and capable of deteriorating, complex chemical reactions involving a wine's sugars, acids and phenolic compounds can alter the aroma, color,...

. They are an integral component of the wine industry world wide. The design and construction of wine caves represents a unique application of underground construction techniques.

The storage of wine underground offers the benefits of energy efficiency and optimum use of limited land area. Wine caves naturally provide both high humidity and cool temperatures; key to the storage and aging of wine

Wine

Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

.

History

The history of wine cave construction in the United States dates back to the 1870s in the Napa Valley region. Jacob Schram, a German immigrant and barber, founded Schramsberg Vineyards

Schramsberg Vineyards

Schramsberg Vineyards is a well-known winery located in Calistoga, California in the Napa Valley region. The vineyard, which was originally founded in 1862 produces a series of sparkling wines using the same method as champagne. Schramsberg is considered one of the premium brands in the...

 near Calistoga, California

Calistoga, California

Calistoga is a city in Napa County, California, United States. The population was 5,155 at the 2010 census.-Geography:According to the United States Census Bureau, the city has a total area of , 99.30% of it land and 0.70% of it water.-Climate:...

 in 1862. Eight years later, Schram found new employment for the Chinese laborers who had recently finished constructing tunnels and grades over the Sierra Nevada Mountains for the Union Pacific Transcontinental Railroad. He hired them to dig a network of caves through the soft Sonoma Volcanics Formation rock underlying his vineyard.

Another Chinese workforce took time away from their regular vineyard work to excavate a labyrinth of wine-aging caves beneath the Beringer Vineyards near St. Helena, California. These caves exceeded 1,200 ft (365 m) long, 17 ft (5 m) wide and 7 ft (2 m) high. The workers used pick-axes and shovels – and on occasion, chisel steel, double jacks and black powder – to break the soft rock. They worked by candlelight, and removed the excavated material in wicker baskets. At least 12 wine storage caves were constructed by these methods.

From the late 19th century to the early 1970s, the development of wine caves went through a long period of “dark ages.” No new caves were built, and many existing caves were abandoned or fell into disrepair. A “renaissance” of cave building began in 1972 when Alf Burtleson Construction started the rehabilitation of the old Beringer wine caves, and was followed by the design and construction of new caves.

In 1982, the Far Niente Winery completed the first of these “new age” wine caves in the Napa Valley AVA

Napa Valley AVA

Napa Valley AVA is an American Viticultural Area located in Napa County, California, United States. Napa Valley is considered one of the top wine regions in the United States...

. The cave was only 60 ft (18 m) long and was used exclusively to age the wine and to store empty barrels. In 1991, 1995, and 2001, the caves were expanded. New rooms and storage areas were added, featuring different crown heights and intriguing shapes. An octagonal room was constructed for a wine library and a round domed room was added in the complex’s center. Far Niente Winery caves now encompass about 40,000 sq ft (3,700 m²).

In 1991, Condor Earth Technologies Inc. joined with Alf Burtleson on the design and construction of the elaborate Jarvis Wine Cave project. Over 45,000 sq ft (4,200 m²) of underground winery and cave space was constructed, with cave spans exceeding 85 ft (25.5 m) in width. At Jarvis, the entire winery is contained within the tunneled areas, including crushing, fermentation, barrel storage, bottling, lab, office, marketing, and hospitality areas. These caves are open for public tours by appointment.

Humidity

High humidity

Humidity

Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

 minimizes evaporation

Evaporation

Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

. Wine makers consider humidity over 75% for reds and over 85% for whites to be ideal for wine aging and barrel storage. Humidity in wine caves ranges naturally from 70 to 90%.

In Northern California, wine barrel

Wine barrel

The use of oak plays a significant role in winemaking and can have a profound effect on the resulting wine, affecting the color, flavor, tannin profile and texture of the wine. Oak can come into contact with wine in the form of a barrel during the fermentation or aging periods...

 evaporation in a surface warehouse is on the order of 4 gallons (15.1 liters) per each 60 gallon (227 liter) barrel per year. In a wine cave, barrel evaporation is reduced to about 1 gallon (3.8 liters) per barrel per year.

Since red wines are usually barreled and aged for two years, this represents a 10% gross volume loss difference. For white wines, which are barreled and aged for about one year, a 5% loss difference is realized, a significant savings.

Temperature

The wine industry has long considered a constant temperature between 55 °F and 60 °F (13.0 °C and 15.5 °C) to be optimal for wine storage and aging. The air temperatures in Northern California result in a uniform underground temperature of about 58 °F (14.5 °C), optimal for wine caves. A surface warehouse requires energy to cool, heat, and humidify. While the most basic wine cave can cost over $100 per sq ft to construct, reduced energy costs result in a net savings over the long term.

Land use

In the Napa-Sonoma wine growing region, as in many areas of California, land values are high. Non-agricultural development is often restricted. A storage warehouse reduces the land available to grow grapes, impacts open space and natural habitats, and precludes other land uses. Land-use regulation in California places limitations on the types and locations of land development. Many land use restrictions and permitting requirements do not apply to underground space. In Northern California there are an estimated 130 to 150 caves used for wine aging, barrel storage, and tasting rooms.

Marketing

Marketing is an important component of the modern wine industry, and many caves serve varied marketing and public relations functions. Recently constructed caves contain commercial and private kitchens, wine libraries, concert and exhibit halls, staff offices, elevators, restrooms, and other amenities. Some have high-end interiors, including ceramic and stone flooring, masonry-lined walls and ceilings, sculpture and artwork, mood lighting, fountains, waterfalls, and chandeliers. At Stag's Leap Wine Cellars

Stag's Leap Wine Cellars

Stag's Leap Wine Cellars is a winery established by Warren Winiarski in 1970 and based in the Stags Leap District of Napa Valley, California. The winery was sold to a joint venture by Chateau Ste...

, a Foucault pendulum

Foucault pendulum

The Foucault pendulum , or Foucault's pendulum, named after the French physicist Léon Foucault, is a simple device conceived as an experiment to demonstrate the rotation of the Earth. While it had long been known that the Earth rotated, the introduction of the Foucault pendulum in 1851 was the...

 swings continuously across a bed of black sand in the central exhibit hall.

Wine cave construction

The challenge for the design and construction of most wine caves is to create a fairly wide span in weak rock with low cover. The size of a typical wine barrel storage cave is 13 to 18 ft (4 to 5.5 m) wide and 10 to 13 ft (3 to 4 m) high. Constructed caves, however, range up to 85 ft (30 m) in width and 50 ft (15 m) in height; difficult to achieve in poor quality rock.

In areas of complex geology, good portal sites are hard to find. A typical wine cave is constructed with two or more portal sites, for safety and operational reasons. At least one portal leads directly outside, but in many cases at least one portal makes a direct connection to a winery building.
Most portals into the wine caves have rock/soil overburden heights less than 0.2 times their entrance heights and widths. The height of the portal face normally ranges from 12 to 20 ft (3.5 to 6 m). The portal areas are seldom stripped of the loose soil material and the portals are cut from the native ground surface using excavators. The side slopes of the portal are often laid back to 0.5H:1V or steeper, and the portal face is excavated to vertical or near vertical.

The construction of cave interiors can be complicated by the elaborate curves and labyrinth-style floor plans selected by some owners for their wine caves. As the ground surface slopes upward, providing more cover and usually sounder rock, caves can accommodate multiple drifts. Where possible, the cave is designed and constructed to provide at least 1.2 times their width of cover at intersections. Room and pillar layouts, similar to underground mine design, provide an economical construction arrangement. Tunnel legs are usually 30 to 100 ft (9 to 30 m) in length and pillars are typically a minimum of 20 ft (6 m) wide.

On most occasions, the New Austrian Tunneling Method

New Austrian Tunnelling method

The New Austrian Tunnelling method was developed between 1957 and 1965 in Austria. It was given its name in Salzburg in 1962 to distinguish it from old Austrian tunnelling approach. The main contributors to the development of NATM were Ladislaus von Rabcewicz, Leopold Müller and Franz Pacher...

 (single or multiple face), also known now as Sequential Excavation Method (SEM), with minor innovative technology advances, is used to excavate and support wine caves.

The caves are typically excavated in an inverted horseshoe shape with a crown radius and with straight or curved legs. The tunnels are usually excavated using a tunnel roadheader or a milling head attachment on an excavator. The spoils behind the roadheader conveyor belt are dumped on the invert and mucked out using a rubber-tired skid loader or a load-haul-dump (LHD) mining machine.

Initially, the excavation advance is likely to be limited to 2 ft (0.6 m) without initial ground support. Once turned under, and depending on ground conditions, the unsupported advance may be increased to 4 ft (1.2 m), 6 ft (1.8 m), and longer increments. The maximum advance without initial ground support may reach 20 ft (6 m) or more in stable volcanic ash tuff. In sheared serpentinite, deeply weathered lava rock or wet clayey ground, however, unstable ground conditions may limit the unsupported advance to less than 2 ft (0.6 m).

Shotcrete

Shotcrete

Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....

 reinforcement and ground support is utilized at the tunnel portals and in the interior of the wine caves. At the portals, soil nail and shotcrete walls are typically used for permanent support and are constructed from the top down in lifts. Soil nails are installed 4 to 6 ft (1.2 to 1.8 m) apart in the horizontal and vertical directions. The shotcrete is typically a minimum of 6 inches (15 cm) thick and reinforced with welded wire fabric. The typical 4,000 psi (28 MPa) design strength mix is applied using the wet process.

Within the caves, the initial ground support is usually fiber-reinforced shotcrete

Shotcrete

Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....

. A minimum of 2 inches (5 cm) thickness of wet mix shotcrete is applied around the exposed ground perimeter following each day’s advance. As cave dimensions and ground conditions require, additional layers of shotcrete and welded wire fabric follow on subsequent days. The shotcrete mix is a 4,000 psi (28 MPa) compressive strength design. In some cases, pattern or spot rock bolts are also installed. Where wider and taller halls are used, modeling is employed to assist with the liner design.

Interior finishing of the caves is an integral part of the construction process. Waterproofing

Waterproofing

Waterproof or water-resistant describes objects relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or under water to specified depths...

 details are important for the interiors of wine caves. Wet spots and water seeps are unsightly, and can cause maintenance and safety problems. Moisture vapor migration through the cave liner, however, is desirable to maintain humidity.

Most contractors install prefabrication drainage strips at regular intervals between the native ground and the shotcrete liner. The drain strips relieve the hydrostatic pressure, but have little effect on wet spots and water seeps. Xypex

Xypex

Xypex is a non-toxic, chemical treatment for the permanent waterproofing and protection of concrete. Its primary performance feature is its unique ability to stop water penetration within concrete by generating a non-soluble crystalline formation within the capillary tracts.Xypex crystalline...

has been used for many years to mitigate seepage, either as a shotcrete admixture or spray applied, with relatively good success. Where excessive groundwater is present, membranes placed between successive shotcrete layers have been used. Many new products, including admixtures and membranes, are being evaluated and tested to improve moisture conditions. The wine cave industry in Northern California is at the forefront of waterproofing technology implementation.

After the cave complex has been completely excavated, waterproofed, and initially supported, a 2 inches (5 cm) thickness of final shotcrete or plain/colored gunite is applied to the walls and arch. Utility conduits and piping are encased within the final layer of shotcrete in the walls and arch and placed under the concrete floor slab. Reinforced concrete slabs are usually 6 in. (15 cm) thick and are underlain by subdrain.

To support their varied uses, wine cave complexes may contain as many as 13 different utility systems. These include systems for hot and cold domestic water and processing water, electric power, lighting, sound and water features, battery emergency power, compressed gas systems, communications and radio relays, automatic ventilation, and computerized sensors and climate controls.

External links

• Lewis, Scott (February 2004). "Wine Caves Beneath the Northern California Vineyards". Tunnel Business Magazine.
• Building a professional wine cellar at home
• Specifications for building a personal wine cellar