Sustainable Design Towers Anchor $2 Billion Redevelopment Project
The Meriwether Condominium Towers that topped out in August, are achieving instant landmark status in Portland, Oregon. Rising 21 and 25 stories, they anchor a $2 billion redevelopment project.
The South Waterfront/The River Blocks development, the largest redevelopment effort in Portland history. The ambitious plan converts an abandoned 130-acre industrial brownfield south of downtown Portland into mixed-use development including retail, commercial, housing, parks, and open space, to meet neighborhood community needs as well as support the larger downtown community.
The Meriwether’s towers are being constructed with innovation and sustainable design. With this in mind, they are striving to earn Gold LEED® Certification, the rating system of the U.S. Green Building Council. To achieve this goal they are required to earn LEED credits in each of the following areas: rapidly renewable materials; low emitting materials; certified wood; local/regional materials; resource and reuse; and innovation in design.
The Towers are being built almost entirely with concrete. Its lateral system and core is concrete and creates wind resistance. The cement for the foundation and slabs came from a local distributor, Ross Island Sand and Gravel. KPFF Constructing Engineers used a cast-in-place foundation design with concrete pile caps and piles. “An interesting challenge at this development site revolved around the variable ground conditions, ranging from debris fill to soft sand, and the potential high water levels from the river’s floor plain,”–said Jeff Huddleston, KPFF Consulting Engineers in the Portland Daily Journal of Commerce.
Most of the concrete is being batched off-site.
Seven inch post tension slab concrete floor plates are being used along with a lightweight, flowable concrete cap. The post tension design provides flexible column spacing and structural depth. The thinner floors allow an additional 4 to 5 stories to the towers than a steel structure, and still provide each floor with generous 9 foot ceilings. This concrete system is also an efficient choice with respect to reducing sound and vibration. The project team is using an additional ¾ inch poured Gypcrete sub-flooring for an extra sound barrier on all floors.
“The design was influenced to the greatest extent by the Vancouver, B.C., model of “point towers” – smaller floor plate buildings than the traditional rectangular slab buildings common to Portland. This building type is designed to maximize views through and from the district, and to minimize the shadowing of the pedestrian level environment,” said Richard Dobrot, GBD Architects in the Portland Daily Journal of Commerce.
KPFF designed the garage with an exposed lid and scored concrete. The plaza slab sits above the garage. The terrace was designed with crystalline waterproof concrete, instead of using a membrane.
The project is receiving national recognition, is 99 percent sold and is scheduled for completion and occupancy in summer, 2006.
Developer: Joint venture of Gerding/Edlen, Portland, Oregon, and Williams/Dame, Portland, Oregon
Architects: JBD Architects, Pawtucket, Rhode Island, and Busby, Perkins and Will, San Francisco, California
Structural Engineer: KPFF Consulting Engineers, Portland, Oregon
Contractor: Hoffman Construction Co., Portland, Oregon
Waterproof Concrete Distributor: Vancouver, British Columbia, Canada