Intensive Industrial/Commercial

Project: West Podium Park, Boston World Trade Center
Award Recipient: Roofscapes, Inc
Client: Pembroke Real Estate
Landscape Architect: Pressley Associates, Inc.
Architect: Kallmann McKinnell & Wood Architects, Inc.
Structural Engineer: Weidlinger Associates, Inc.
Waterproofing Consultants: (corrected) Building Envelope Technologies, Inc.
General Contractor: Turner Construction
Landscape Contractors: J. Michael Landscaping & Valley Crest
Irrigation Consultant: General Irrigation Engineering
Waterproofing Manufacturer: Carlisle Syntec Inc.

West Podium Park overlies part of the underground parking facility of Boston's World Trade Center complex between the World Trade Center West Tower and the Seaport Hotel. The green roof area covers 29,000 sq. ft. at an average cost of $60 per square foot and is developed on two levels, each comprising about 50% of the total surface area. The upper level is an un-irrigated extensive green roof, and the lower level is an intensive landscape. Including both levels, the growing medium ranges in depth from five to 36 inches.

The upper extensive podium roof is a Type III Roofmeadow® Savannah assembly which utilizes FLL-compliant drainage and growth media based on lightweight aggregate and includes a variety of flowering Sedum ground cover species, selected for their uniform height and multi-seasonal interest. On the lower level, a strong reinforced concrete deck supports a luxuriant landscape utilizing conventional lightweight landscaping soils and dominated by trees and shrubs. The Elizabeth Banks/Pressley Associates design includes 55 varieties of trees and shrubs, including large Japanese Zelkova. The plant community also includes 23 perennials, groundcovers, and vines.

Besides offering one of the best examples of integrating extensive and intensive green roof approaches in a single landscape, this project is noteworthy for two other reasons: 1) it is the first project to be completed in America that utilizes pregrown Sedum mats, and 2) it was the first project to utilize a network of buried ballasts to stabilize an extensive green roof in a high wind velocity zone. The extensive green roof on the upper podium level is designed to resist wind velocities of up to 94 mph without experiencing any disruption. In this design by Roofscapes, Inc. buried concrete ballasts are tethered to high strength geogrid. In addition, the pre-grown Sedum mats incorporate internal reinforcing layers. The green roof sandwich includes three fabrics and two reinforcing layers. The plant roots also assist by knitting these layers together. The 2-square yard mats were custom grown at a remote location and installed like Sedum 'sod.'

Completed in 2003, the three-story podium was one of the first buildings in the Boston area to incorporate an environmentally conscious green roof. The green roof is part of an overall program for the World Trade Center West Tower, designed to meet the most stringent energy conservation standards. State-of-the-art systems were installed to maximize the efficiency of all mechanical equipment. For example, watercooled package units on each floor supply the necessary cooling to each floor through a series of fan boxes.

All of the intensive landscape on the lower podium level of the Park is accessible and invites pedestrians to linger and enjoy the landscape, while occupants of local offices and hotels are treated to a visual juxtaposition of the two components of the Park.

The West Podium park roof is not only a beautiful refuge from the surrounding cityscape, but a pioneering piece of living architecture that exemplifies the potential of green roofs on industrial and commercial buildings.

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