READY MIX PRODUCER NABS BIG PROJECTS WITH PUMPING AND PLACING EQUIPMENT 2003

On April 5, 2001, Walker Art Center Director Kathy Halbreich, joined by award-winning Swiss architectural firm Jerzog & de Meuron and Minneapolis-based Hammel, Green and Abrahamson, Inc., unveiled the conceptual design for expansion of the Walker Art Center in Minneapolis, MN. Further development and design of the $90 million project took two years, and a groundbreaking ceremony was held September 3, 2002.

With an estimated grand opening date for late 2005, ready mix supplier and pumping contractor Cemstone Products, Mendota Heights, MN, is right on schedule to complete concrete construction by January 2004. Deb Cooper, Job Site Superintendent for project manager M.A. Mortenson, Minneapolis, estimates 28,000 cubic yards of concrete will go in to the overall project. Several concrete pumps from Cemstone’s pumping fleet have contributed to the concrete work. Schwing engineering offered the job site an extra hand for some difficult wall pours. A specially designed Schwing adapter allowed contractors to mount Cemstone’s 39 X detachable placing boom with split #1 to lattis tower sections on two cranes erected in the center of the excavation.

Walker authorities have been anticipating the reconstruction for several years. In January 1999, the organization announced their purchase of the neighboring Allianz Life Insurance Company of North America building and the grounds, a total of 3.4 acres. Starting September 3, 2002, Mortenson went to work demolishing the Allianz building and the adjacent parking lot, and stabilizing the excavation. Less than four months later, Cemstone brought in their extensive ready-mix truck fleet and truck-mounted concrete boom pumps as well as the 39-meter boom to pour the first yards of concrete. Concrete projects include the heavy concrete on structural metal deck portions of the new expansion and a cast-in-place underground parking garage, co-owned by the City of Minneapolis and the Walker Art Center.

Mortenson’s extensive history providing total facility services for the entertainment industry nation-wide was instrumental on the tight urban job site. Job Site Superintendent Deb Cooper said the crammed setting posed challenges for the extensive roster of sub-contractors and the transport of large amounts of materials to the site. In addition to the 28,000 cubic yards of concrete, 2,100 tons of rebar and almost 1,100 tons of structural steel will be incorporated into the expansion at its completion, and contractors needed access. The surrounding neighborhood needed normalcy.

“The bottom line was to impact the Groveland community as least as possible,” said Cooper, commenting on the mainly residential neighborhood and Hennepin Avenue, a six-lane artery to the city, immediately adjacent to the expansion to the Walker. “We devised a very minimal fenced in working area around the job site to slide pumps, trucks and other equipment around. We couldn’t afford lane closures on the street either – that would have caused a more problems than the subcontractors and the city could afford.”

Minneapolis council members have always encouraged the community to be involved with the Walker expansion. Since September of 2000, the Community Participation Committee has been meeting to discuss plans for and construction of the Walker additions. Among other topics, the committee provided input and feedback to Walker authorities about increased access for transportation and pedestrians to their neighborhoods from the Walker site.

With the minimal working area and ever-changing specs, the project team went to great lengths in pre-pour management to protect the community from too much interference and ensure safe set-up for several of Cemstone’s long boom pumps, brought on to the site to complete pours on the outer edge of the excavation. “We had to weigh the impacts of the outriggers against earth retention systems. We poured additional footings and used steel rod plates to make sure the system could sustain that kind of weight,” said Cooper.

Ready mix trucks were allowed access to the site by several public entrances to the Walker and adjacent neighborhoods. So far, the team has placed over 5500 yards into the expansion. To complete difficult wall pours from the bottom of the hole, contractors devised a tower crane system to hold Cemstone’s 39-meter detachable placing boom for maximum reach and minimal set-up space. “It was the only efficient way to complete this job,” said Cooper. “A truck boom with a rubber hose on these kinds of wall pours just wouldn’t cut it. The placing boom fed by hard line kept labor needs down and efficiency up.”

As the placing boom is relocated between the two mounts inside the excavation, crews maneuver the hard line only once, but as the project proceeds out of the hole, Cemstone crews have had to remain creative. “It’s really evolved since the first pour,” said Cooper, “Specs are changing all the time.”

The placing boom has been fed through a hard line from a variety of Cemstone pumps and powered by a Schwing-engineered electronic power pack. On several occasions the pump section of the 39-meter boom pump was used to pump the concrete. The placing boom was alternated between two crane mounts for multiple deck pours to the expansion.

Mortenson originally teamed with the Walker in 1984 to complete minor remodeling and expansion. The main objective for Walker authorities this time around is to create a more inviting space for education, cultural exploration and recreation. World-renown architects and designers have been commissioned to create the facility that will integrate indoor and outdoor spaces to create a “town square” feeling and double the size of the current facility. As the 8th most visited art museum in the nation, accommodating a growing number of visitors was a major objective with the new expansion. Mortenson will follow designer’s specs to add on 100,000-110,000 square feet of interior space, 4 additional acres of green space, rooftop terraces. A new two-level structure will feature galleries and education spaces, more than doubling museum’s permanent collection installations. Space for temporary exhibitions will also be reconfigured under the new design plans. In all, the gallery space will grow from 15,000 square feet to a total of 45,000 square feet. A four story building at the southern most point of expansion will include the multidisciplinary performance studio, gift shop, and a restaurant overlooking nearby Loring Park and downtown Minneapolis. A new on-site 380-seat performing arts studio will house theater, dance opera and musical performances. The full-service restaurant will feature indoor seating and 14,000 square feet of outdoor rooftop terrace. Event space for museum events and private rentals will also be incorporated. The existing facility, which remains in operation as construction continues, is also undergoing renovation to accommodate the Walker’s film and video programs.

Integrating technology was also a priority. Surrounding the performance studio will be several new-media laboratories and digital galleries. A new Info Lounge will allow for film and video screenings, educational programs and meeting area, and an Art Lab will provide hands-on experiences for visitors on school trips and tours.

Commissioned by the city of Minneapolis, a new $25 million 620-space underground parking garage consists of 4 _ levels below grade and above and will provide on-site parking for Walker visitors. The below grade sections of the expansion share an elevator with the parking garage, where new non-public spaces will be incorporated, including expanded art storage, exhibition services, receiving, loading dock areas, and security and staff office areas.

Cooper says the supplier/pumper was contracted mainly based on their production of micro-silica mixes, an important mix for the garage decks. “They put out a great product,” she said. So far, Cemstone has pumped over 16,000 yards into the garage.

In addition to new buildings, the Walker has been working for a few years to accommodate a four-acre addition to the famous Minneapolis Sculpture Garden. The Guthrie Theatre, currently an integrated part of the Walker Art Center, may be moved to a new facility on the Minneapolis riverfront in 2004. Pending an agreement between Walker officials and a community activist group known as “Save the Guthrie,” the Walker will take advantage of that space for the garden’s expansion. The addition will bring the total acreage of the Sculpture Garden from 11 to 15, and will serve as a park for public gatherings and a display area for sculptures.

Contractors and Walker authorities estimate the new space will be completed and open to the general public in 2005.

“This is one of the more interesting projects I’ve been involved in,” said Cooper, “Seeing the completion of this huge expansion will really be something.”