This project involved the design and construction sequencing of a 50-foot high by 75-foot wide wine cave in Napa, California. The cave was constructed as a dome in lahar that consisted of fresh andesite boulders in a matrix of highly weathered rhyolite. Cover over the dome is sloping and relatively shallow, with an average cover of approximately 30 feet. The design included construction sequencing and ground support details using the New Austrian Tunneling Method (NATM), also known as the Sequential Excavation Method (SEM). Final dome geometry was a multi-radius section, which was designed taking into account both architectural concept drawings and previously excavated tunnel geometry. An 8-foot wide walkway circles the inner edge of the mushroom-shaped dome and is elevated 18-feet above the invelt. Ground support for the dome consisted of 16-foot long, I-inch diameter steel threadbar rock dowels and a shotcrete lining reinforced with welded wire fabric.


Most of the wine making industry in northern California is located in Napa Valley and in adjacent Sonoma Valley. This region has seen tremendous agricultural growth in the last 40 years, which has put a premium on land available for growing wine grapes. The wine making process also requires significant space for fermentation and storage of wine in barrels until the wines mature and can be bottled.

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