Sitework Obstacles Give Workout to Sports Center Crews

230-ft.-long roof panels cover roof of Marquette University's Al McGuire Center

by Elaine Schmidt

From excavation to roofing, the $31 million Al McGuire Center on Milwaukee's Marquette University campus has demanded creative design and construction solutions.

Construction began July 1 on the 117,400-sq.-ft. facility that will house a 4,000-seat arena for women's basketball and volleyball games and men's basketball practice. There also will be training and weight rooms and a sports medicine component.

The arena is named for the coach that took the university's men's basketball team, previously known as the Warriors, to a national championship in the 1977 National Collegiate Athletic Association tournament. The facility will open for basketball practice on Oct. 1, with final completion slated for the following January.

Underground Surprises

A host of complications on the L-shaped site, which shares a city block with Cobeen Residence Hall, influenced design and construction decisions.

"On the surface the site looked good," said Aleisha Palaniuk, associate project manager for Opus North of Milwaukee, the design-builder on the project. "We knew that there were at least two tanks filled with low-level petroleum from row houses and a gas station that used to be there.

"As we were digging, we hit 12 or 13 more tanks," she said. The tanks were drained, but some had leaked. The contaminated soil was removed.

"For awhile we had barrels all over the site and the smell was just atrocious."

Even uncontaminated areas of the excavation presented obstacles.

"There was a lot of rubble from the old row houses because they used to just demo the buildings back into the hole," Palaniuk said. "On the south side we had to protect a Marquette duct package that runs through the alley and a gas main that runs directly into Cobeen."

The gas main had to be excavated, shut down and altered to serve the new site as well as the dorm.

"We found out that there was a fiber optic line below the sidewalk on the north side of the site," she said. "We could locate it on the east and west end of the site, but didn't know what happened to it in the middle. We were told this connected to the banks and some of the buildings downtown."

Crews had to resort to hand excavation, gingerly searching for the fiber-optic line.

Keeping Neighbors Happy

Minimizing disruptions to Cobeen Hall and the city streets surrounding the site was essential.

"We put a cantilevered foundation wall on that whole north length, so we could excavate down, build the wall and backfill right away instead of bracing on top," said Dave Pettit, project engineer with Opus Architects and Engineers Inc. in Minneapolis, the architect of record. "We didn't want a hole open for several months where we would worry about the street falling in."

Palaniuk said a system of wood lagging and piles on the north side of the site was used, "where we are just a foot off the property line because you can leave it in place."

She said that during excavation, Cobeen Hall began taking on a significant amount of water, and Opus had to waterproof the entire side of the exposed residence hall foundation.

The University decided that Cobeen's exposed foundation presented the perfect time to remove an old boiler, which meant that Opus had to tear into the building's exposed foundation while maintaining structural stability.

Adapting Design to Site

Removing oil tanks, contaminated soil and row-house rubble necessitated a 16-ft.-deep excavation on the north end of the site, where the arena was to be located.

"Our first design did not push the bowl of the arena into the ground," said Kent Davidson, director-architecture for Opus Architects and Engineers.

"But we were confronted with below-grade issues that meant we either needed to depress the structure into the dirt or haul in engineered fill, which had a lot of negative construction cost issues associated with it."

He said Opus worked with NBBJ Sports Facilities, the project's Marina del Rey, Calif.-based design architect, and the university to study ways to sink the bowl and fit the structure into the campus architecture and surroundings.

"One of the benefits of sinking the bowl is that you are able to come into the facility at concourse level," said Chuck O'Connell, architectural coordinator for Opus Architects and Engineers. "You don't have to ramp up to get to the seats." The lower profile of the sunken bowl also preserved views from Cobeen Hall.

"When we pressed the facility into the ground, it allowed the weighttraining area, locker rooms and other areas that didn't have a lot of daylight to be built in a more efficient and compact way and kept the footprint at a manageable level," Davidson said.

Chicken or Egg

As the project came out of the ground, careful planning and coordination were required to maintain structural stability as precast concrete panels, some of them 52 ft. long, were set in place and shoring was removed.

"We had to have the steel structure of the roof diaphragms in place before we could take the shoring off the precast," Pettit said. "This is typical. It is done in warehouse construction all the time.

"But it is easier when you have access to both sides of the precast. With Cobeen Hall less than 10 ft. away, we could only shore into the new structure. We had to leave out portions of the main concourse floor because we couldn't pour the level-one slab until we had the shoring out. We couldn't take the shoring out until we had the roof in place."

He called it a "chicken and the egg scenario," explaining that they had to work with all the subs so that everyone knew what could come out and what could go in at any given moment.

Lifting Long Loads

With Cobeen Hall less than 10 ft. away from the southern wall of the arena, lifting precast panels into place required detailed safety plans.

"We had to have an evacuation plan in Cobeen," Palaniuk said. "We made sure no one was in the rooms adjacent to where we were working." These lifts had to be planned well in advance so that the University could make arrangements with students ahead of time.

Lifting roof joists into place in the tight quarters also required careful planning.

"The original design called for three major steel trusses that would span the arena," said O'Connell. "We were pretty far along in that design, to the point of looking at how it would be staged and erected, when we came up with an alternative design of long-span joists.
"It gave us the same structural support, was less expensive and was much more conducive to the staging of construction."

Davidson said the result is a simple, elegant structure.

In fact, looking up at the joists from the concourse level or the arena floor, the effect is one of filigree, rather than heavy trusses.

The joists may look light, but installation was tricky. Davidson said the 23 joists, which span 156 ft., 6 in., were delivered in two pieces. They were bolted together on the arena floor and hoisted into place.

The lifts required evacuation of all areas beneath and adjacent to them. Lifts could only occur in optimal wind conditions.

Topping it Off

"The most interesting part of the arena is the roof," Pettit said. In addition to the long-span joists that are visible inside the arena, the standing-seam, steel roof is a distinctive architectural feature.

O'Connell said the material choice "expressed the geometry of the barrel roof better than anything else."

Installing the 230-ft.-long continuous panels of roofing steel required careful staging and a lot of manpower.

"We have done many projects, but at 230 ft., this is the longest one to date," said David Wiess, general manager of Specialty Associates Inc. of West Allis, Wis.

The panels are run onsite in a process O'Connell described as a combination of rolling and pressing.

Crews pressed the panels on the flat roof of the McGuire Center's administration building, walking them from that lower roof to the barrel roof via a crane-built scaffold.

"Ten guys walked the panels up the scaffold rigging onto the barrel roof and set them there," Wiess said.

Starting on the north end, with a worker positioned about every 20 ft. along the length of the panel, crews would pick up one panel and set it in place, clipping it on 4-ft. centers.

Wiess added that two mechanical seamers are clamped on at the roof's high point. As they seam, they roll gravity down the arch of the roof to workers waiting at the roof line to receive them.

The seamers, which overlap to create a seal at the center point of the roof, run about 30 ft. per minute, covering 60 ft. per minute when two seamers are running in opposite directions.

In addition to being impervious to water, the parallel ribs of the standing-seam steel add graceful lines over the arch of the barrel roof.