The centerpiece of Stone Brewing Co.’s new production and distribution facility in Richmond is what is referred to as the “Tank Farm,” an elevated concrete platform that will eventually hold 40 fermentation tanks at full capacity. The shining stainless steel tanks rise majestically out of the building, their weight supported by tons of concrete and rebar. Inside the Tank Farm, brewers are able to walk underneath the equipment to access piping and brewing systems in an efficient manner while being protected from the weather.
The Tank Farm structure was a complex one to create, and required the Hourigan Design-Build team, comprised of Draper Aden Associates structural engineers, Hourigan’s pre-construction planning group, and engineers at Stone to spend time researching existing facilities of a similar structural nature. Through detailed reviews with Stone Brewing’s engineering team, the group analyzed the systems, production needs, and expansion requirements to define the most efficient design concept for the facility. Because very few comparable structures exist to meet the owner’s demands, the Hourigan Design-Build Team, along with project managers at Stone, took a close look at a few unique facilities around the country.
Studying peer beer breweries
While multiple breweries were studied, Hourigan was able to get hands-on at Sierra Nevada’s North Carolina location, which has a similar Tank Farm structure to the one Stone ultimately decided upon. The team visited the Asheville facility and received an inside look at its systems and structures, ultimately giving consideration to the efficiencies of the comparable design as it related to the use of concrete and rebar.
The challenge before the design team was to ensure that the weight of each of the 400,000-pound brewing tanks would be supported in an effort to maximize production efficiencies and to prevent the tanks – which reach 34 feet into the sky – from moving laterally due to wind and seismic loads. Hourigan considered framing the structure with solid exterior walls to gain shear strength for the support platform. However, a perimeter wall would have limited the expansion potential and process piping accessibility for Stone, anticipating as many as 20 additional tanks to be placed outside of the building on a future foundation mat slab.
Ultimately, interior columns that were a necessity to hold the weight of the individual tanks were made larger to support the lateral loads and reduce the exterior structural wall requirements. The interior shear piers provide enough strength to support the tanks as well as resist the potential lateral loads imposed on the tanks, each of which hold more than 40,000 gallons of beer.
The finished platform, by the numbers
The elevated concrete platform, when viewed from above, is reminiscent of a round-checkered Othello game board, with tanks each 16-feet in diameter fitting neatly into the circular molds. To support such enormous weight, engineers developed an elevated concrete deck that is five-feet thick, with beams that contain 118 tons of rebar, including #12 & #14 bars (1 ¼” & 1 ¾” diameter respectively) at 6-inches on center. The beams run laterally in between the tanks, catching the weight of the slab and tanks, transferring the load down to the ground.
The rebar was prefabricated in 40-foot lengths weighing over 300 pounds each. Notably, the waste was less than ten single drops between 12-24” that became coveted mementos to the team.
The concrete shear piers for the tank farm are three-feet thick and 12-feet wide. Each pier contains over 27 yards of concrete, equivalent to three concrete trucks worth of material. The structure not only supports the tanks above, but an extensive network of stainless steel process piping from below through the use of over 400 steel embed plates for connection and support of pipe bridges and equipment.
Tightening the soils and laying the foundation
And then there was the foundation.
The Stone Brewing Co. team enjoyed the idea of building upon a brownfield site. However, the soils on the site were not able to bear the immense weight of the operation’s extensive brewing equipment needs without improvement. Engineers determined that the soil required 6,000 pounds per square foot of bearing capacity, so Hourigan had to inject grout-and-gravel filled rigid inclusions below the tank farm to tighten the earth. Five-hundred rigid inclusions were drilled below the tank farm to meet the bearing capacity requirements.
Between the foundation and the Tank Farm engineering, the end result for the client is ultimately a lower cost and more efficient design. Through careful planning and research, detailed engineering, and coordination of process needs and specialty structures among many parties, Hourigan was able to deliver a world-class facility on time and within budget in only 14 months.
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