Precast Concrete Protects Critical Infrastructure

AFTER THE PERFECT STORM: NEW NORMAL FOR STORM-RESISTANT BUILDING CONSTRUCTION FEATURES PRECAST CONCRETE

BY MONICA SCHULTES

No one was prepared for a storm the magnitude of Superstorm Sandy in 2012. Sandy was exceptionally large, with hurricane-force winds 175 miles from the eye, and tropical-storm-force winds extending beyond 500 miles. With such wind velocity and range, more than 8.6 million people were without power, leaving more people in the dark than any other storm in history.

In addition to assessing the aftermath, the newly formed New York City Building Resiliency Task Force developed specific proposals to create “resilient” buildings: buildings that, in the face of hurricanes, heavy rains, heat waves, blackouts, blizzards, and flooding, will resist damage, protect occupants, and allow evacuated residents to return quickly to their homes.

The recommendations issued by the task force include a category entitled “Stronger Buildings.” The chapter on stronger buildings includes recommendations related to managing flooding, resisting wind, and advancing building systems in preparation for natural hazards. As a direct result, many such projects focus on relocating infrastructure systems from lower levels to elevations above the flood zone. A classic example is the work being completed at the New York City Housing Authority’s Redfern Houses development.

PROJECT SPOTLIGHT

LOCATION: Queens, N.Y.

Designer: MDSzerbaty Associates Architecture, New York, N.Y.

Owner: New York City Housing Authority, New York, N.Y.

Engineer: YAS Consulting Engineers, New York, N.Y.

Contractor: Navillus Contracting, New York, N.Y.

PCI-Certified Precast Concrete Producer: Coreslab Structures (CONN), Thomaston, Conn. (Redfern Houses)

NPCA Precast Concrete Producer: Coastal Pipeline, Calverton, N.Y. (Bayside retaining wall)

Precast Concrete Components: 14,021 ft 2 , 48 structural walls, 117 hollow-core pieces, 60 cladding panels, 9 copings (Redfern Houses), 5200 ft of perimeter floodwall (Bayside)

Redfern Houses, Far Rockaway, Queens, N.Y.

During Sandy, apartments at Redfern Houses—a nine-building, 604- unit housing development in Far Rockaway—were flooded and without power and heat for weeks. The New York City Housing Authority (NYCHA), as part of its Recovery and Resiliency Department, is completing upgrades to infrastructure and building a new community center and daycare facility to replace the one severely damaged. Five electrical power service buildings, a boiler plant, and a two-story, 14,295-ft 2 community center are under construction. The latter includes the daycare center, offices, storage space on the ground floor, and community space on the second floor.

The new electric service buildings are elevated above the NYC-codeprescribed design flood elevation to prevent future power loss from flood conditions. In addition, these structures house gas-driven standby emergency generators to provide full power capacity for the entire residential complex. A new boiler plant, also elevated above flood level, is being constructed on top of an existing coal bunker to replace the current boiler room, which was below grade and completely flooded.

MDSzerbaty Associates Architecture (MDSA) in New York has been involved in five Sandy Resiliency Projects for NYCHA. “Developing resilient methods for each site, funded by FEMA [Federal Emergency Management Agency] grant dollars, has been challenging. Working with the updated FEMA guidelines, MDSA is relocating the electric service and other utilities into new structures at the Far Rockaway site,” says Michael D. Szerbaty, principal at MDSA.

“Redfern Houses were inundated with water during the storm. We needed to raise up the critical infrastructure and buildings, including the community and childcare center to meet the 500-year flood elevation,” explains Szerbaty.

Hardened Building Envelope

“MDSA has used precast concrete for decades and we turned to it for these structures, since a hardened envelope was desirable,” continues Szerbaty. “For these types of structures, a precast concrete building was simple and appropriate. It also minimized the number of trades on-site.”

The insulated architectural panels provide a finished appearance as well as durable interior. The community/childcare center features a distinctive façade with insulated precast concrete panels and hurricane-resistant glazing.

“The precast solution has enabled rebuilding the NYCHA critical systems in a rapid yet cost-effective manner,” says Aldo Rodhani, project manager with Coreslab Structures (CONN). “In addition to expedited construction time, selecting total–precast makes project coordination easier and reduces the risk of errors during construction,” he adds.

The boiler plant and electric service buildings were enclosed in just a matter of days, allowing construction to progress. “Precast panels have been proven to be economically viable, and we don’t have to worry about waterproofing, installing insulation in the field, vapor barriers, and flashing—it is all in the insulated precast panel. It is as simple as you can get,” says Szerbaty.

The light sandblast on the childcare center is offset by reveals and rustications in the large precast concrete walls to break up the scale and create shadow lines. “You use a precast insulated wall panel and many basic technical problems are solved without a lot of concern,” says Szerbaty. In addition, while the revised NYC energy codes are becoming more stringent, precast concrete insulated panels help meet or exceed those goals. “With insulated precast wall panels, we don’t have to worry,” he explains. “We now have a fully protected, elevated building that will serve as shelter should a similar weather event occur.”

Bayside Stem Wall at Ocean Bay Apartments, Far Rockaway, Queens, N.Y.

MDSA directed another project in Far Rockaway with NYCHA’s Recovery and Resiliency Department. The 24 Bayside apartment buildings provide housing for over 6000 residents. The entire 32-acre site is now encircled with a below-grade precast concrete barrier.

The floodwall design is about one mile in length below grade and was originally designed as a cast-in-place concrete wall, but the retaining walls were converted to precast concrete to facilitate the schedule and simplify on-site construction.

The program provides flood protection following FEMA-prescribed requirements and includes electric service buildings similar to the Redfern project. The precast concrete perimeter floodwall surrounds the two city blocks to prevent surface flood waters from entering above grade and prevent subsurface water seepage below grade. The floodwalls are hidden beneath sloped berms and include flood gates for pedestrian and vehicular use.

Precast concrete is often a logistical challenge in the New York metro area due to narrow and crowded streets. These projects in the outer boroughs were better able to accommodate the crane and delivery of the precast concrete pieces.

Whether above or below grade, precast concrete demonstrates it can be part of the Stronger Buildings initiative. These and other changes ensure New York will make people, property, and infrastructure more resilient to increasing hazards and vulnerabilities in the future. ●