(Wines&Vines) - The first phase of restoration and repair of the historic winery at Trefethen Family Vineyards is nearing completion with the building already standing straighter.

The structure, which dates back to 1886, suffered significant damage in the Aug. 24 earthquake that occurred just south of Napa, Calif. While the building had been stabilized in the days immediately after the quake, there was some uncertainty about whether it could be saved or restored to its former historical appearance.

The winery’s president Jon Ruel told Wines & Vines that after assembling a team of contractors, engineers, architects and historians the first goal of the restoration project involved getting the building back into vertical alignment. After the earthquake, the upper floors of the structure were leaning precipitously to the west by nearly 4 feet. The exterior of the structure was reinforced with a framework of stout metal beams, and the interior was reinforced with “cribbing,” or stacks of timber as thick as railroad ties and large jacks.

‘Chiropractic’ treatment to get building back in shape
About a month ago work began to get the building realigned. The process involved tightening cables anchored in the building’s cement foundation and in specific spots on the walls. The initial hope was to get the building back into alignment at a rate of about 1 inch per day. “Well, the building reacted positively and quickly, and most of the 40+ inches needed was achieved in just one day,” Ruel said. “It truly felt like a miracle.…It's like we did chiropractic work, and you could almost hear the building say ‘Ahhhh, that feels better.’”

Ruel said the experts on site were also impressed by the elasticity of wood structures snapping back in to place. To keep the building straight, the engineers adjusted the cribbing and jacks and added steel beams to the external frame. “Anyhow, that is the first phase, nearly complete, but there remains much work to be done,” Ruel said.

Santa Rosa, Calif.-based ZFA Structural Engineers, which helped build Dominus Estate, Alpha Omega, Quintessa Vineyards and the seismic retrofit at Chateau Montelena Winery is the structural engineering firm on the project. Executive principal and CEO Kevin Zucco said despite the building being righted into place, “A large percentage of the structural members were damaged during the earthquake, and the structure remains in a very vulnerable state.”

He said ZFA used a 3-D scan of the building created by the construction team to build a model of the structure’s framing elements. “It was very interesting to see the building’s damaged shape overlaid with the true structural model,” Zucco said.

ZFA’s plan to strengthen the building includes reinforcing the existing walls, incorporating a new steel frame into the architectural design and upgrading the foundation and anchorage. “There are still too many variables involved in the design to accurately predict a completion date, but the building stabilization process was completed much quicker than anticipated,” Zucco said.