$162M Skyscraper Grows Roots on Mobile Waterfront

Wed August 20, 2003 - Southeast Edition
Kerry Lynn Kirby

Workers currently are laying the groundwork for the tallest skyscraper in Alabama and one of the tallest buildings in the Southeast.

The Retirement Systems of Alabama’s (RSA) $162-million, 800-ft. (243.8 m) tall office building is scheduled to be complete in late 2005, according to Ron Blount, project manager.

In January, Skanska USA Building, Atlanta, GA, won the $6-million contract for the foundation portion of the Battle House Office Tower and Hotel project, which overlooks Mobile’s waterfront.

The project includes the building of a 35-story office tower located on approximately 1.5 acres (.6 ha) of land and the major renovation of a historic hotel adjacent to the tower, said Blount

The $6-million contract for demolition and stabilization of the old hotel, which will contain approximately 240 rooms, was awarded to W.G. Yates & Sons Construction Co., of Mobile, AL, he said. Both companies started work in January.

Most of the heavy equipment that has been visible on the job site is being used for the foundation package, Blount said. As of late July, approximately 30 percent of that package was complete.

As of the first week in August, Skanska was employing approximately 40 workers on one shift, according to Tony Davis, Skanska’s project superintendent.

“They’re working pretty much six days a week, 50 to 55 hours a week,” he said.

A Manitowoc 4000 crane, leased from Essex Crane Rental Corp., is one of two crawler cranes subcontractor L.G. Barcus & Sons, Kansas City, KS, is using to install augercast piles for the 7.5-ft. (2.9 m) thick, 170-sq. ft. (15.8 sq m) high-rise mat foundation to sit upon, Davis said. The other crawler crane, a Link-Belt 518, was leased from Conmaco in Kansas City, KS.

A Bauer BG25 drill rig was used by Kansas City-based Berkel & Co. Contractors Inc. to install its auger pressure grouter displacement piling for the 5.5-ft (1.7 m) thick mat foundation of the new three-story building that will link the office tower and hotel, Davis said. Approximately 12,000 yds. (11,000 m) of concrete will be used just in the foundation.

With Mobile’s low elevation and the site’s location near the Mobile River, designers anticipated the need for a dewatering system, which had to be installed before work could begin on the foundation, Davis said.

The system, installed by Burns Dewatering Service in Theodore, AL, pumps out 2,500 to 3,000 gallons (9,463 to 11,356 L) of water per minute, 24 hours a day in order “to keep it so we can work,” he said.

“We have somebody here all the time watching the pumps,” Davis said.

A component of the foundation’s design had to be reviewed because of soil conditions at the site, Blount said. “We have had some challenges,” he said. “We’ve had to do some stabilization.”

To adapt to the soil and drilling conditions at the site, augercast piles were changed from 24 in. (61 cm) in diameter to 18 in. (45.7 cm), although the piles remained at the 115-ft. (35 m) depth, according to Todd Kalwei, project manager for L.G. Barcus & Sons.

L.G. Barcus & Sons has been using J&M 55AT drill units, leased from American Pile Equipment of Dallas, TX, along with the Manitowoc 4000 and Link-Belt 518 for that portion of the pile installation, Kalwei said.

After the pile redesign, crews used a Bauer BG25 drill rig, equipped with Berkel’s tooling, for installation of 185 38-ft. (10.7 m) deep auger pressure grouter displacement piles for the low-rise building, Davis said.

The special equipment was used to install approximately 560 14-in. (35.6 cm) and 16-in. (40.6 cm) displacement piles ranging from 25 to 50 ft. (7.6 to 15.2 m) deep, Blum said.

Unlike regular augercast piles, displacement piles don’t entail removal of soil. Instead, a tool compacts the soil and holds it into place until grout is placed into the pile under pressure — creating a lateral displacement of soil, he said. “The process has the benefit of improving the soil so you don’t have to go as deep.”

“We’re densifying the soil instead of depleting it by drilling a hole in it,” he said. “With soft soils like you have on that project, it’s especially beneficial.”

As of the first week in August, Barcus had installed 500 of the 18-in. (45.7 cm), 115-ft. (35 m) deep augercast piles, Kalwei said.

Earlier, it installed 245 16-in. (40.6 cm), 30-ft. (9.1 m) deep piles for the shoring wall using a 13-ton (11.8 t) Mantis 2610 track hydraulic crane, he said.

Also, as of early August, 32,000 cu. yds. (24,466 cu m) of dirt had been moved out of the site with at least 12,000 cu. yds. (9,175 cu m) more to go, Davis said.

Two Komatsu 220 excavators are being used to excavate and remove dirt from the foundation site by subcontractor Hill Trucking Co., of Saraland, AL. Both were purchased from Tractor & Equipment Co. in Mobile.

Skanska is using an additional excavator, a Kobelco 135, rented from Cowin Equipment Co. on the site, Davis said. The company also rented a 6,000-lb. (2,722 kg) Traverse Lift forklift from Cowin for the project, he said.

Concrete for the mat foundations is scheduled to be poured Nov. 7, according to Davis. Four to six concrete pumps will be used for approximately 24 hours of steady pouring, he said. That first pour will involve 8,500 yds. (7.8 m) or more of concrete.

W.G. Yates & Sons also employed a number of pieces on the Battle House Hotel. Among them are two hydraulic cranes — an 85-ton (77.1 t) Grove and a 135-ton (122.5 t) Liebherr. Crews also used a Caterpillar forklift, a Lull telescopic forklift, a JLG 1350 lift and a small Bobcat excavator, said Stan Akers, Yates project manager.

The most unusual piece of equipment used on the job was a Spyder mast-climber, featuring a center column that attaches to the outside of the building and a 50-ft. (15.2 m) long, 5-ft. (1.5 m) deep platform that goes up and down, Akers said. That equipment, leased from Spyder Equipment, Pensacola, FL, was used for laying brick.

The demolition portion of the job included removing all of the original eight-story hotel’s plaster and brick interior walls — approximately 3 mi. (4.8 km) — by hand, Akers said. It also entailed taking out and repouring concrete floors and knocking down an eight-story annex to the hotel, which was built in 1949.

“We literally sawed it loose and knocked it down with a headache ball on the end of a crane,” said Akers, who noted that it took approximately a month to saw off the annex using saws weighing approximately 3,000 lbs. (1,361 kg) each. The annex had to be sawed off first so the vibrations from knocking it down wouldn’t disturb the rest of the building. Approximately 7,000 dumpsters full of rubble had been removed from the site by early August.

Although it’s taking place in the midst of the downtown commercial area, the project thus far has not hindered mobility in Mobile, according to Blount.

Before work started, the RSA agreed its contractors wouldn’t block the streets during rush times. For example, there are no deliveries to contractors during those times.

The project is expected to strongly impact the community in some positive ways, said Lee Perry Herndon, Mobile Area Chamber of Commerce vice president of communications. Herndon projects that approximately 1,000 construction workers will be employed at the site during the course of the project.

“It’s a huge opportunity not only for some displaced workers in the community but also for young people looking to get some experience in the construction trades,” she said.

Once the skyscraper is built, Mobile will be poised for recruitment of new industries seeking “Class A office space,” which it doesn’t have now, Herndon said.

While a portion of the building will be occupied by local businesses that relocate there, the remaining open space can be marketed along with Alabama’s low taxes and high quality of life to Fortune 500 companies, among others, she said.