This Product Spotlight details how Flood Glass can be the answer for lessons learned from Hurricane Sandy.
by Gene Kennedy
One of the enduring images of Hurricane Sandy, which hit the NYC area with winds and storm surge in October 2012, is that of water cascading down the stairways leading to the city’s subway stations. Flooding caused by the slow-moving storm also impacted elevators, rendering them inoperable and dangerous. The message since has become clear, as such storms are becoming more the norm than the exception. Municipalities must respond by adopting new building codes and recognize that ever-changing flood maps are altering how commercial and residential structures are built.
The Federal Emergency Management Agency (FEMA), National Flood Insurance Program (NFIP) and U.S. Army Corps of Engineers have repeatedly redrawn flood maps and implemented new standards for construction that will protect buildings — and elevators — from future storms.
Few builders, architects or engineers anticipated the extent of mandatory changes in the aftermath of Sandy and other flood-causing events. Sandy ravaged a 600-mi. path of destruction in New York and New Jersey, resulting in more than US$19 billion in damages to the region. Lower Manhattan’s Battery Park was hit by 14-ft waves. More than 80% of Atlantic City was underwater, and parts of its famed Boardwalk were swept away.
In addition to the mandatory protections mandated by FEMA, NYC and other cities are taking additional steps to safeguard subway stations and other public facilities. Fortunately, as the threat of flooding increases, so has the development of technologies that can efficiently meet FEMA and NFIP standards and codes. Today, Flood Glass has emerged as an effective, permanent and convenient way to provide safeguards that meet the evolving standards.
One major change has been in the construction of elevators, which must now meet similar standards, especially those that go below ground. Such was the case with the Cortlandt Street subway station at the World Trade Center (WTC). The goal with new commercial structures is to make the buildings and, when necessary, elevators, substantially impermeable to floodwaters using Flood Glass.
In creating an elevator Flood Glass Enclosure for the WTC, Riviera Beach, Florida-based Flood Glass, Flood Barrier, Floodgate and Flood Door developer and manufacturer Savannah Trims worked closely with architecture and planning firm Downtown Design Partnership; our facilitator/erector Atlantech Systems, which designed and supplied the steel substructure and coordinated the field logistics for the complete installation; and the WTC owners. NYC is on the leading edge of flood protection, and it’s important to note that its building codes actually exceed the standards established by FEMA and the NFIP.
Designing a flood-resistant glass enclosure for an aboveground elevator that travels from street level to a subway station below comes with some challenges:
- The glass enclosure must be able to resist more than 7 ft of water and impact forces (as determined by FEMA and other standards).
- The Savannah team was provided with an inner structural subframe that supported the elevator car. The Flood Glass had to be manufactured and designed to support the flood loads.
- Structurally glazed, flood-resistant prefabricated glass units with custom extrusions were designed to be attached to the inner steel subframe.
- The lower glass units were thicker than the upper units but had to remain in the same plane on the outer surface of the elevator.
- The most challenging aspects, so that all components would fit without field measurements, were the overall engineering, design of custom extrusions, detailing of connections and 3D modeling.
Some unique features include:
- Prefabricated bolt-on units.
- Two 1/2-in. layers of tempered, laminated glass, bonded together to create an overall thickness of about 1 in., with 45° bevels on 45° corner extrusions. Thickness can vary depending on the pressure requirements.
- Trapezoidal roof glass
The benefit of this approach to elevator flood protection is that it provides a passive system requiring no deployment assembly or storage of materials. From an architectural standpoint, this solution provides the least visual impact, as there are no visible means of barrier attachments.
Subway stations are extremely vulnerable to flooding. Since Hurricane Sandy, flood barriers and gates have been installed to prevent damage to stations so that, in the event of another catastrophic flooding event, trains can quickly return to operation. Retrofitting elevators is the next phase of improvements to protect commuters. Similar Flood Glass Enclosures designed by Savannah Trims and installed by Atlantech Systems are now in place at other stations in the area, such as at Canal Street and South Ferry in Lower Manhattan, and in Hoboken, New Jersey.
The same standards for new and renovated buildings are now being applied to elevators. FEMA (FEMA Sections 102/3-93) dictates the levels and strength for adjustments and additions to buildings that include floodgates, flood doors, flood barriers and sealed reinforced glass. Flood windows are rapidly becoming a popular option, because they are permanent and don’t require difficult installation as a storm approaches. They are a convenient and affordable flood-protection initiative that, when properly installed, are compliant with all FEMA standards and codes. FEMA works in conjunction with the American Society of Civil Engineers (ASCE/SEI 7-10) and the U.S. Army Corps of Engineers (Chapter 7/Section 701.2.2 Type 2 Closures) in developing these constantly changing standards.
The complex issue is that every job — whether it’s floodgates, flood doors, flood barriers or glass — is custom-designed, because different criteria can be applied on a block-by-block basis. The openings are all different, requiring different frames and window strengths.
The same is true for elevators. Protections are based on FEMA’s projections that include:
- Flood warning time
- Use of building
- Floodwater velocities
- Floodwater depths
- Debris impact
- Flood frequency
Research will dictate the height of flood windows, how much water pressure they can withstand and their effectiveness in resisting penetration by floating debris. All components used by Savannah Trims are designed, engineered, tested and verified to secure a FEMA Floodproofing Certificate for nonresidential buildings. Other protection criteria include:
- Anchoring of the building to resist flotation, collapse and lateral movement
- Installation of watertight closures for all doors, windows and openings
- Use of membranes and other sealants to reduce seepage of floodwater and other wall penetrations
- Installation of pumps to control interior water levels
- Installation of check valves to prevent floodwater or sewage flows through utilities
- Location of electrical, mechanical, utility and other valuable equipment and contents vulnerable to water damage above the expected flood level
The introduction of flood windows represents the continuing evolution of protection and is being applied to glass-enclosed elevators. Elevators using Flood Glass are permanently protected and don’t require the use of manpower and installation expertise as a storm and floods approach. As seen with Hurricane Sandy, those in the path are dealing with many other survival issues. This product can help protect services such as subways to be protected and operational soon after the threat has passed.