Organic shape is sculpted with wet shotcrete, hand raked and troweled.


Exterior portal leads to 150-foot long tunnel and various chambers to create a wine cave 45-feet under the owners new home.


Schwing S 17 with 180-degree discharge serves as line pump for shotcreting up to 400-feet inside the tunnel.


Wet shotcrete was applied six inches thick over wire mesh in four passes.


Brady Mitchell is a modern day cave man that specializes in wine cave construction, having built many in the Napa, CA area.

Creating A Wine Cave

The perfect temperature for storing wine is between 58-61 degrees. In Springfield, MO where temperatures vary 80-degrees between January and July, there’s only one way to assure those ideal wine storage temperatures – go underground. For one private homeowner, the appreciation for wine extends to the construction of a wine cave under his home for storage and enjoyment of his collection. Drawing on the talents of architects, engineers, cave contractors and a wine cave consultant from Napa Valley, this personal tribute to fermented grapes is being built with extensive use of shotcrete.

Wine caves have been constructed for more than a hundred years in northern California’s Napa Valley where land values are high and the evaporation from wine kegs can result in up to 10% product loss in two years if humidity isn’t properly controlled. 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%. “Ideal wine temperature is between 58 and 60-degrees,” explains wine cave consultant Brady Mitchell, a hands on cave construction specialist from Napa. The temperature 45-feet under the home of the Missouri wine aficionados’ new home is 60-degrees. “Perfect,” states Mitchell.

Excavation into a hillside below the home site began in 2012. Bacchus Caves, The Woodlands, TX dug the tunnels, including a150-feet long shaft that will be used for wine storage. A two-foot diameter cutting head attached to a hydraulic excavator breaks up the limestone and red clay earth. A skid steer removes the spoils. Dry-mix shotcreting is used for the soil stabilization. “Because they would excavate then shotcrete sporadically, they elected to use the dry mix method because it could be applied on demand without a pump truck and ready-mix truck standing by,” Mitchell explains. The Quickcrete used for dry mix shotcreting is a micro silica enhanced, Portland cement based, high strength structural material.

Over the two years of excavation and shotcreting by Bacchus Caves’, their efforts resulted in the 10-foot diameter x 150’ cask storage tunnel, a 17’ wide x 15’ tall x 23’ long bottling storage room, an 18’ x 15’ x 40’ tasting room a 17’ x 15’ x 48’ dining roomwith butlers pantry and 10’ x 10’ x 30’ wine library. “The excavation and shotcreting moved pretty slowly because it is clay soil with huge suspended boulders interspersed throughout the area.” Mitchell explains, “They did have a cave-in for an area we were calling the Grotto which was finally abandoned.” The cave has two portals, the outside entrance and an access point from the basement of the house with a spiral staircase and elevator. Hundreds of yards of the dry-mix shotcrete was consumed during the process. “Every couple of feet they would apply a structural coat of shotcrete and then reapply additional coats over previously applied shotcrete as they came back out,” according to Mitchell.

After excavating and structural shotcreting was competed, 4” x 4” wire mesh was applied to the entire interior surface and spaced off the walls. The electrical conduits were placed between the two layers of shotcrete. “We placed six inches of wet mix shotcrete for the final tunnel liner applied in one and a half-inch layers,” Mitchell, who is also the nozzle man, explains, “This would result in about four passes to achieve six inches of wet shotcrete applied over as much as fourteen inches of dry mix.” The wet mix speeds up the process by spraying at a much higher rate than dry mix shotcrete. Screed rakes are used to contour the larger radii such as the arches. Hand trowels are used to knock down any high points. Three color samples were test batched for the owner. Mitchell and co-worker Rich Lederer work together to create the organic shapes. “Nature drives the design.”

Shotcrete pumping is being handled by Brundage-Bone from their Springfield location. “We have pumped steadily everyday in March, April and May,” Mitchell says, “The Brundage operators have been great and most of the time the Springfield district manager, Andy Baugh, is onsite to lend a hand.” The company has been utilizing several of their pumps on the project including a Schwing S17 boom pump discharging directly out the back, a SP 500 and a SPT 1000 truck-mounted pump. All pumps are equipped with fast switching Rock Valves for surge free operation at the hose. Pumping distances have exceeded 400-feet with line diameter at 2-inches where it enters the shotcrete nozzle. “At the end of the day, we wash out the two-inch hose and blow out the three-inch line back to the pump,” explains Mitchell, “Being that far from the pump I need to trust the operator and Brundage-Bone’s crew is real good. I don’t feel like I have to look over my shoulder.”

Mitchell hand forms 200 recesses for light fixtures with some eight-inches deep. “There is an art to forming the arches and recesses for dramatic shadows,” explains Mitchell, “For utilitarian purposes we can leave a naturally coarse finish, but this wine cave will be enjoyed by the owner and his guests so some rooms will have a smooth finish and some will be covered in plaster or woodwork.” A chandelier in the tasting room will appear like a tree root growing through the ceiling. The wine library houses the bottles in racks with sufficient lighting to easily read the labels. Wine of sufficient potential will be sourced and the barrels aged in the cave to be rotated every few months so the sediment can be drawn off. After a couple of years of barrel aging the wine will be blended and bottled. Humidity will be carefully controlled.

For Mitchell, a 40-plus year veteran of the wine industry (he began cleaning tasting rooms at 13), it is a satisfying construction career in an area, not many people have chosen. “Most of the people in the wine cave industry know each other,” explains Mitchell. “I have poured more than a million square feet of cave floors in my career. I still have a 1986 Schwing BP 750-15 back in Napa that pumped most of those cave floors and still works fine.” Mitchell will add to his cave floor square footage when he pours the cave floors with Brundage-Bone pumps later this year.

 

Specs:

Excavation: Bacchus Caves, The Woodlands, TX
Engineering: Brierley Associates, Denver, CO
Architects: Slone and Associates, Springfield, MO
Cave Finishing Contractor: Brady Mitchell, Napa, CA
Pumping Equipment: Schwing S 17, SP 500 stationary pump, SPT 1000 truck-mounted pump