Contractors find downtown a tight fit

By MARK SPANGLER
Hoffman Construction

Building a high-rise tower in a busy downtown environment is never easy. In Seattle, one of the hottest construction markets in the country, the challenges become even more formidable.

The Millennium Tower's sloping site meant lifts couldn't unload material. Temporary ramps were built to get the trucks level for unloading.

For Hoffman Construction, erecting the 21-story Millennium Tower at the corner of Second Avenue and Columbia has demanded flexibility and creativity at every stage of construction. The 375,000-square-foot building will provide 13 levels of offices, six levels of residences, one level of retail space, one level of common use space and six levels of below-street parking with 250 spaces.

Hoffman’s Project Manager Tom Shourd says that in this saturated market, the first hurdle is getting enough labor. “There’s plenty of work out there,” he says. “A lot of the trades, when they have a choice, don’t want the hassles of coming downtown, where they have to deal with traffic and pay out of pocket for parking.”

The answer, according to Shourd, is building a core group of loyal subcontractors. On recent projects such as the Experience Music Project and work at the University of Washington campus, Hoffman has established a reputation for running organized, safe projects and paying bills promptly. This creates a profitable environment for subcontractors and helps ensure a steady supply of skilled workers.

The restricted urban site has presented a long list of challenges, beginning with the excavation. The Millennium Tower's 72-foot dig, among the deepest in the city, was adjacent to the historic Hoge Building. In addition to typical surveying, Hoffman performed a weekly walk-through of every floor of the Hoge Building to physically inspect the building for changes or damage.

With no area for staging and laydown, material deliveries are limited to off hours and must be precisely timed. “Everything is coordinated on the half hour,” says Shourd. ”If you’re early, there’s no place to wait. If you’re late, they send you away.”

To further alleviate congestion, concrete pours begin at 3 a.m. Sparse traffic in the wee hours permits a steady flow of trucks, and crews can complete a deck by 6:30, ahead of the morning rush hour.

In addition, an innovative “jump form” building system has helped make the building’s core erection faster and safer and produced significant cost savings. With the jump-form system, the structure essentially builds upon itself, as a platform of concrete forms moves steadily upward, one floor at a time. The building’s central concrete elevator shaft was poured in 12-foot sections, one every five to seven days. This helped save time on an aggressive construction schedule, resulting in less disruption to downtown streets.

The sloping site also called for innovative solutions. When the curtainwall panels were delivered, the truck was on such an angle that the lifts couldn’t get a good hold. The answer was building temporary ramps to make the trucks level and allow off-loading.

With pedestrians and businesses in such close proximity, safety and protection for the public take on critical importance. The city required that the sidewalk along Second Avenue remain open, requiring construction of a substantial covered walkway. Protective netting on the building protects against falling debris, and a heightened safety awareness is crucial on the part of every worker, to ensure nothing is left on the slabs where it might blow off the building.

For project manager Shourd, working in such a high-profile location has a built-in performance incentive: “When you’re downtown, anybody can look through the fence. It could be an inspector or it could be your next client.”