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Freeing Up Space in Philadelphia

By Russell Verano, for LASN

The retaining walls seen in this cutaway view support a new landscaped area that will be created over the structure. The MSE (mechanically-stabilized earth) walls built with large interlocking blocks rise on the left and the right of this view. Between the retaining walls and the parking structure itself is a unique design feature"wells that open to the surface to ventilate the structure without fans or a forced-air system.
Image courtesy of Atkin Olshin Schade Architects.

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Large segmental wall blocks are helping to create new space for visitors at the Philadelphia Museum of Art. LASN received an update from block manufacturer Techo-Bloc as the project moves towards its 2009 completion date. (Article text by Russell Verano.)

Notable among the project team is landscape architect Susan Weiler of the Olin Partnership in Philadelphia. Weiler is known (with Katrin Scholz-Barth) as author of_ Green Roof Systems: A Guide to the Planning, Design and Construction of Building Over Structure_. She also led the team behind the expansive, eight-acre rooftop garden that crowns the Church of Jesus Christ of Latter-day Saints Conference Center at Salt Lake City.

Weiler, who prefers the term "landscape over structure" to "green roof," said the museum project presents a number of unique challenges.

"It's going to have soil depths of 18 inches to four feet and sculptures that weigh in the tens of thousands of pounds," she told LASN. "There's a lot of weight and other factors to be considered"that's why you need a really collaborative team that includes the architect (Atkin Olshin Schade), the landscape architect, building engineers and geotechnical engineers," Weiler explained. "The challenge is trying to create a sustainable system, with irrigation, on top of an artificial structure."

"Erik Skindrud, editor

Blocks were lifted into place with a hydraulic crane system and pinned into place. A dump truck is seen adding backfill behind the wall in this view. Layers of fill were added above several stabilizing layers of geogrid.
Photo courtesy of Techo-Bloc

Ambitious Project Scope

When the Philadelphia Museum of Art began its first major expansion in almost 80 years, it developed a 10-year master plan that included new spaces, renovating the infrastructure, and reclaiming existing spaces for public use. By project's end, a 60 percent increase of new space is anticipated.

Doug Rose of Rock Products, Inc. outside of Philadelphia recalled a lot of buzz over the start of construction.

"It is one of the largest museums in the United States, and its renovation has been talked about for a long time, and now that construction is finally underway, the entire city is really excited," he said.

This view takes in the museum parking area following its excavation from a hill created with fill during the construction of the original museum building (visible at top right). The photo was taken midway through the construction of the retaining walls that will enclose the museums underground parking structure. Sawtooth oaks and other native trees will be added on top to join the trees seen from this angle.
Photo courtesy of Techo-Bloc

Interestingly, the first phase of the project is the construction of a landscaped parking facility, complete with a rooftop sculpture garden designed by Olin Partnership. When completed, the facility is expected to add close to 400 parking spaces. In addition, the garden will have two paved, tree-shaded seating areas, sunny, gently-sloping lawns, and panoramic views of the Schuylkill River.

Building the walls of the facility would prove to be a challenge, however, since they would reach heights of close to 38 feet, including the buried course, and the total size of the walls is roughly 30,000 square feet. Frank Lomangino of contractor Tough Turf, which is building the walls, explained the choice of block material. "Precast panels were going to be too expensive," he said.

A close-up look displays details of the interlocking block system. The parts are designed to resist pressure from the earth loaded behind the wall. The wall itself rises at an angle to resist the force of gravity. Each block has an attachment point that lets workers position it with a single hydraulic crane.
Photo by Gregory Cazillo

Matching Rock Palette

Yet because the exterior of the museum is already covered with large panels of stone, smaller wall blocks wouldn"t fit into the existing architecture. So thoughts turned to a large-scale product called Monumental Blok. Lomangino said he liked the product because, "It would reduce the amount of earth work. And once we began working with it, I noticed that my crew wasn"t as beat up at the end of the day. We just hook up the connecting pin, hydraulically lift it into place, and that's it. The only real manual work is properly installing the geogrid."

Jason Austin, an architect with Atkin Olshin Schade, said, "There are a limited number of products available that can handle the different loads a job like this presents. Monumental Blok has a good scale to it, and a nice aesthetic. And because it is considerably larger than the standard MSE (mechanically-stabilized earth) stone, its size makes it quite efficient."

Since the parking facility is set into a hillside, its exterior will be covered in landscaping. Inside, however, the big blocks" granite-like face will be fully exposed to the general public. "It has a monolithic texture," Austin said. "And will fit in well with the overall appearance of the museum and its surrounding structures."

The mechanical system that anchors these MSE products from Canadian manufacturer Techo-Bloc can be seen here. Note how the geogrid material is anchored to the blocks. The structure rises close to 38 feet in height.
Photo courtesy of Techo-Bloc

"In fact, along the road leading into the garage is a wall built almost one hundred years ago," Lomangino added. "And the casual observer will not be able to tell the difference between the (wall surface) inside the parking facility and the stones used to build that much older wall."

It is this natural appearance, an uncanny engineering flexibility and lower building cost due to reduced labor that is making the large block product a popular choice"even for home applications.

The walls are completed and the parking structure itself is being built in this photo, which was taken in January 2008. (Compare with the image taken months earlier on page 108.) A series of interior supports are about to be added (note rebar) to take the weight of sculpture garden, soil and trees that will be positioned above.
Photo by Gregory Cazillo

Blocks in Context

As Lincoln Paiva, a Techo-Bloc engineer, explained, "Because you can build a wall as high as 10 to 12 feet, including the base block unit, without geogrid reinforcement, we are seeing these blocks being used as a cost-efficient material for residential retaining walls. And it's a good-looking stone, so it can be used on a complementary garden or seat wall, as well."

Paiva's role at Techo-Bloc is to provide engineers, architects and contractors product information on the company's wall stones, as well as lending technical support on their projects. He draws up preliminary engineering plans for estimating purposes, and can help ensure the walls are constructed properly and the stones are utilized according to spec.

When completed, the parking structure will be covered with a sculpture garden that includes trees, turfgrass and a fountain area paved with granite. The parking structure lies under the hillside between the traffic circle and fountain (left) and the main museum building (far right). Water jets speckle the square-shaped fountain just above the long lawn that extends from left to right near the bottom of this rendering.
Image courtesy of Olin Partnership

The museum's landscaped parking facility broke ground in the spring of 2007, with completion of the entire project expected in spring 2009.

To discover more about the project, or to learn about current and planned exhibits, visit

Russell Verano is a writer who works with Techo-Bloc in St. Hubert, Quebec, Canada.

A worker uses a concrete saw to trim a detail of the wall system as workers position another block at left. Note how gravel fill is placed against the earthen side of the wall to allow water to drain from this critical area.
Photo courtesy of Techo-Bloc

Philadelphia Museum of Art " Sculpture Garden and Parking Facility, Philadelphia, PA

From Olin Partnership design team

Opened in 1928, the Philadelphia Museum of Art is a beloved icon of the city and experiences a steadily growing audience, drawing over one million visitors a year. The museum now finds itself in critical need of repairs, amenities and modernization. In addition to the demand for increased parking capacity, the desire to add to the expanding audience's enjoyment has led to the design of a sculpture garden in the park-like setting adjacent to the museum.

In hopes of unifying the landscape, Olin Partnership designed a new, underground parking facility that will provide the necessary space without sacrificing land currently enjoyed by visitors. The design aims to rejoin rather than divide the open space, connecting significant portions of Fairmount Park with the museum grounds.

The landscape will also be revitalized by transforming an under-utilized green space into a vibrant sculpture garden, which will form an outdoor extension of the facility's vast art collection. The new dramatic views created by the redesign will open to the Schuylkill River and extend through to Fairmount Park. This will serve as a scenic gateway, connecting the museum and Fairmount Park to the river and to a major scenic Philadelphia thoroughfare, the Benjamin Franklin Parkway.

The Greeks and Romans used large stone blocks to create platforms for their temples. Ancient engineers would be impressed by this view"and surprised that just two workers can position the blocks using a 21st-century hydraulic crane.
Photo courtesy of Techo-Bloc

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June 17, 2019, 8:45 am PDT

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