Preserving the San Francisco Emporium
The 1906 earthquake crumbled many of San Francisco's landmark buildings and inflicted significant damage to the Emporium, the first department store on the West Coast. The earthquake, which registered 8.25 on the Richter scale, brought down the building's signature glass dome, but the Emporium's façade survived. Following a fire that swept through the city immediately after the earthquake, a single brick and sandstone wall stood amidst the burning rubble. Soon after the earthquake, a construction team integrated the historic façade into a new building and reconstructed the 500,000-pound signature dome.
Nearly a century after the earthquake, the Emporium is undergoing another transformation. A construction team, including Santa Clara, Calif.-based SASCO, is working on a $410 million project that blends both new construction and historical renovation. The Emporium's dome and façade will become part of the 1.5-million-square foot Westfield San Francisco Centre, the largest urban shopping center in the West with 200 retail outlets, five floors of retail, and a nine-screen cinema. The building will be constructed next to the San Francisco Shopping Centre, which will remain open during the construction process.
Paul Kuhn, senior project manager for SASCO, says his crew of 10 electricians is currently installing underground conduit for power feeders. SASCO will be responsible for the main electrical distribution system, the installation of electrical lighting systems in the main concourse, and telecommunications and security work for the entire center. Kuhn expects the project to peak in Spring 2006, when about 50 electricians will be on-site. Throughout the project, the electrical team needs to work closely with the general contractor and preservation team to make sure that all the historical elements of the existing property are preserved. Rather than viewing this as a challenge, however, Kuhn considers it a rare opportunity.
“It's exciting to be involved in this project because of the continuity it builds between the past, present, and future,” he says. “We have the opportunity to do things we don't do on every job.”
The electricians will soon be able to rewire and relight a piece of San Francisco's history — the Emporium dome, which features eight structural ribs and 800 pieces of glass. Prior to demolishing the existing six-level San Francisco Emporium building, the construction team preserved the dome by lifting it on top of a 120-foot temporary tower. San Francisco-based Swinerton Builders and Sheedy Drayage Co. developed a special rigging procedure in which a steel platform was secured to the bottom of the dome, bringing the structure's total combined weight to 680,000 pounds. Four strand jacks gently lifted the dome 60 feet higher than its original location. The construction team accomplished the engineering feat in two separate 30-foot lifts one week apart.
“It took a minute to go up one foot, and then we'd stop to make sure that everything was level,” says Barry Widen, senior project manager for Westfield, the general contractor. “We'd then kick in the jacks again and go up another foot. We lifted a lot of the ornamental sheet metal and plaster with the dome because the goal was to keep as many of the historical pieces intact as possible.”
The historical dome will serve as the centerpiece of the new retail, entertainment, and office complex. It's currently secured on a freestanding tower, but once the construction crew builds the new structural steel frame, it will be lowered 2 feet to its final resting place. At that point, the electricians will disassemble all the lighting fixtures, remove the existing wiring, and rewire the entire inside of the dome. Kuhn says the electricians will select a few sample locations, disassemble the fixtures, and assess the condition of the historic materials. If the surface isn't solid, then they'll meet with the design team and discuss how to proceed. Throughout the rewiring process, they'll adhere a piece of plastic film to the electrical boxes to avoid scratches and other damage to the historical building materials. After removing the wiring and light fixtures, the electricians will install new LED light fixtures, which have a rated 100,000-hour life.
“They are very precisely colored, globe-style lamps,” Kuhn says. “I think the intent was to try to mimic the types of lamps that were used in the original building.”
In addition to lighting the dome, the electricians will also install metal halide fixtures to showcase the original façade. The construction workers installed six steel towers to temporarily support the historic façade until a permanent concrete wall is constructed. The original wall spans 275 feet on Market Street and measures 100 feet high. Along with Kuhn, Widen considers the job a landmark project.
“It's a once-in-a-lifetime job with unique engineering challenges, such as raising the dome and preserving the front façade,” he says. “We're saving a historic piece of San Francisco.”