PUMPING BY MOONLIGHT

Concrete Pumper keeps on schedule with midnight pours

Berkeley Concrete Pumping, Inc., Berkeley, CA, recently wrapped up pumping on a unique cast-in-place highrise structure in San Francisco. Concrete construction of Block N1 of the new Mission Bay development posed challenges for every contractor involved. With the 16-month long project behind them, general contractors and subcontractors alike are satisfied with their common sense solution to several logistical problems.

Block N1, officially known as Mission Place, consists of eight separate low-, mid- and highrise buildings that will house approximately 595 residential apartments. The highrises were designed to integrate with a giant parking garage and 80,000 square feet of retail space, creating what project owner Catellus Development Corporation, LLC refers to as a “mixed-use” structure. Catellus has also designed other “blocks” to create an entirely new neighborhood called Mission Bay. Adjacent to Pacific Bell Park, home of the MLB San Francisco Giants, the 303-acre, $295 million site will also house other amenities, including a new 2.65 million square foot University of California at San Francisco Research Campus. Another 670,000 square feet of retail space, 2.5 million square feet of office space, 49 acres of parks and recreational areas and a new 500-room hotel are also in the plans.

Ground breaking and minor demolition on the Block N1 project began in September 2001. Later that winter, general contractors Webcor Builders, Inc., San Mateo, and Dolan Concrete, Inc., San Jose, set out to erect two 16-story, two 9-story, two 8-story and two-seven story buildings. The residential buildings rest atop a 4-level cast-in-place structure that serves as both a parking garage and 80,000 square feet of retail space. The 4-level garage and shopping area is one level below grade, three levels above. The 4th above grade “podium” level stretches over the parking and retail space, integrating all of the highrise structures. The level will serve as courtyard area equipped with common facilities such as swimming pools and party areas for Mission Place residents. With 70,000 yards of concrete to pour in the massive cast-in-place structures, contractors needed to find solid solutions to several pressing issues.

“We first looked at the day-to-day pedestrian and traffic problem in that area,” said Webcor Project Manager Mike Sprecher. “We were adjacent to the baseball stadium, which meant a lot of traffic around game time, not to mention morning and afternoon rush hour. It posed job site access problems. Mission Bay is also located near the train station and bus depot that service the San Francisco area. People were constantly milling around. Not only were there logistical problems, but safety issues to address.”

The warm California weather also posed questions about mix performance. Meetings between superintendents from Berkeley, Webcor, Dolan, and San-Francisco-based ready mix suppliers Bode Gravel Co., and Pacific Cement, Inc. produced a common sense solution. Work at night.

As concrete construction began, pumping and ready-mix crews were generally on site beginning at midnight and wrapping up finishing work around 5:00 or 6:00 in the morning. 50,000 yards of the 5,000 psi concrete with Pronto accelerator was pumped into the project with the use of several Schwing truck-mounted boom pumps. Steve Pryde, Berkeley General Manager, said the pumping operation used every model in their fleet over the course of the project. The S 58 SX and truck mounted pumps with booms measuring 52, 42 and 36-meters provided 4-section reach capabilities for slab and deck pours.

Pumping at night afforded Berkeley’s pumps the room they needed to keep up with the production schedule on the huge projects. “We were typically using two pumps per pour. With all of that activity surrounding the job site during the day, we wouldn’t have been able to even set them up. And with the roll and fold design on the longer booms, we were able to reach up and then directly into the structure on deck pours. They came in handy under those tight conditions.”

To pump over 12,500 square feet of deck and all vertical columns and walls, Berkeley also brought in the all-hydraulic BP 3001-18R trailer pump equipped with Rock Valve connected to a KVM 39 placing boom. The concrete was pumped through a stand pipe that ran from the ground floor straight up to supply concrete to all of the project’s vertical work. With the KVM 39 providing 113 feet of vertical reach, Berekley was able to meet accelerated production needs of a six-hour workday. The placing boom was first mounted on cross frames with bolt-on foundation and later stabilized through foundation mounting.

Bode and Pacific Cement supplied the total 70,000 yards of concrete that went into the project.

Contractors finished the project in April after 16 months of carefully scheduled pours. “Working at night was the only way,” said Sprecher. “We were safe, accountable and on schedule by doing things this way. And everyone involved was very accommodating, especially considering our pour schedules. Berkeley made it real easy by bringing in a solid reputation and reliable equipment.”

Catellus management anticipates residential leasing opportunities and retail occupancy for Mission Place in late 2003. Several office spaces in the surrounding blocks have already been leased; most are still available.