Superstorm Sandy inundated the underground caverns of lower Manhattan and caused enough personal and financial disruption elsewhere in the city and region to spawn a boom in flood-resiliency efforts. As a consequence, the engineering community has been tasked with delivering cost-effective resiliency for assets that range from single-family homes to entire cities.
The foundation of flood damage prevention efforts lies at the local level, and a number of relatively low-cost solutions exist to reduce flood damages and associated claims. For many building owners and managers, having a plan is the first step to a successful program.
Here are eight practical ways to reduce the impact of the next major flood event:
Products such as water-tight windows, doors and louvers can help seal the building envelope. (Photo iStock)
1. Seal the envelope
The vast majority of assets within the floodplain are existing structures.
Raising entire structures, while feasible and cost-effective for smaller facilities, is not usually an option.
The dry flood-proofing industry, which has grown considerably in the past few years, provides cost-effective solutions for sealing a structure's envelope against floodwaters. Products now exist to make all building openings watertight, including flood-resistant windows, doors and louvers.
Likewise, timber and masonry exteriors can be sealed to prevent the entry of floodwaters. Of course, even a well-sealed structure is at risk: As water rises and pools outside of a building, it introduces the possibility of overloading the walls. A structural engineering industry has grown to meet this potential problem..
Unpressurized utilities are vulnerable to flood inundation. (Photo iStock)
2. Prevent "back door" entry
The world was introduced to the dirty little secret of flood inundation in an episode of Netflix's hit series, "Orange is the New Black," which is set in a women's prison.
It chronicled the arrival of a major hurricane and its impact on the fictional inmates' flooded dorms. While the storm raged outside, the incarcerated women were enjoying the warm and dry conditions of their facility when the toilets and sinks erupted with floodwaters.
This event illustrated the phenomenon of flood inundation through utility conduits. All unpressurized utilities are vulnerable, including sewer, telephone and electric conduits. Thankfully, the fix is simple and inexpensive, whether or not you're behind bars. Install a backflow preventer — a small, off-the-shelf device — and the problem is solved.
Place air conditioners, ventilation systems and other infrastructure on the roof or on a elevated structure to protect them from flooding. (Photo iStock)
3. Secure the power
Loss of power has far-reaching damage-claim implications, in both the physical world and in the arena of economic opportunity losses.
At the local level, the risk of power loss can be mitigated by elevating the building-specific power infrastructure above the design flood elevation, and securing a means of backup power. Elevation of infrastructure is a particularly important improvement in older buildings, where traditional architectural planning sited the power infrastructure in the basement.
In instances where the infrastructure cannot be repositioned to higher floors, the resiliency marketplace has stepped in to offer flood-proof safe-room technology. These technologies provide perimeter vaults that keep critical infrastructure dry, even during extreme flooding events.
A backup generator can protect against damages caused by a power outage. (Photo iStock)
4. Back it up
Taking a page from the disaster-planning handbook, cloud computing provides system redundancy that allows work to continue, even if a local system is off-line.
When it comes to flood resiliency, a facility's backup power system — a key element of claims management — is analogous to the cloud. Backup generator use has grown exponentially, providing a cost-effective means to hedge against damages caused by power loss.
Flood berms can be deployed around buildings and complexes to protect against storm surges. (Photo iStock)
5. Feel the berm
Flood berms and levees are civilizations' longest-standing and most effective means of flood protection.
The flood-resiliency industry has recognized this fact, and has developed products that can be deployed in advance of a storm to provide an impenetrable barrier around an asset.
Portable products, many of which are modular, have been deployed to protect facilities of all sizes, from small substations to around entire campuses. Originally developed for river flooding, the products are equally effective at protecting against tidal and storm surges.
A well-devised flood plan is an extremely cost-effective way to minimize a storm's impact. (Photo iStock)
6. Heed the warnings
Thanks in part to new computer-modeling software, weather forecasters are experiencing greater success at providing multiple days' advance warning of impending storms, including where, when and how hard a storm will hit.
The information is often highly specific, for instance, laying out storm-surge levels and pinpointing vulnerable areas. Unfortunately, the practical response to these warnings often fails to match the methodical nature of the forecasts.
For example, when Superstorm Sandy bore down on the New York metro area, New Jersey Transit parked thousands of rail cars in a floodplain, resulting in more than $100 million in damage.
A thoughtfully developed flood-response plan, with regular training and practice, provides an exceptionally cost-effective way to minimize a storm's negative effects. A well-devised plan includes the complex, large-scale measures — such as deploying temporary berms — as well as the absolute basics, such as making sure your generator's fuel tank is full.
Be familiar with state and federal building and flood-resiliency standards. (Photo iStock)
7. Know the rules
None of these tool-kit components can be effective without a concerted effort to understand the risks associated with flooding.
In the United States, the bulk of responsibility for risk evaluation falls on the Federal Emergency Management Agency (FEMA), the International Building Code (IBC), and the American Society of Civil Engineers (ASCE).
In the aftermath of Sandy, FEMA's 100-year return period flood elevations provided the baseline for stronger building codes, mandating a flood-resiliency standard for new and substantially improved structures.
Other measures present a more conservative (read: less stringent) approach, based not on the 100-year flood levels but on projections of sea-level rise.
For example, President Obama's 2015 Executive Order requires the design of all federally funded projects to consider these effects. Likewise, IBC and ASCE building codes have incorporated safety measures to increase the elevation at which facilities are considered reasonably safe from flooding, with the strictest requirements reserved for critical facilities such as hospitals and first-responder facilities.
Most owners fail to adequately prepare for a storm. (Photo iStock)
8. Make a plan — and rehearse it
Ultimately, most owners of flood-vulnerable real estate and infrastructure fail to prepare adequately for a storm for the simple reason that they don't know where to start.
Despite the dire results and increasing frequency of severe floods, evaluating their risk and creating plans to mitigate it is still a niche business, and one which requires multiple professional disciplines.
However, in response to the need for better disaster response — and not to mention, the opportunities it presents — teams of professionals, most often led by engineers, are cropping up, particularly in more-vulnerable locations. The level of planning and preparedness measures vary, depending upon the complexity of a site. But the typical process includes the following steps:
- Survey the asset.
- Determine the vulnerabilities.
- Consider a range of solutions (economic and engineering feasibility).
- Select, design and implement a solution.
- Prepare and implement a flood-response plan.
The least expensive, yet most critical component is the flood response plan. The infrastructure and mechanical features of flood-protection systems almost always require some human intervention. Although the systems will rarely be called into action, a plan that's both well-designed and regularly rehearsed is critical to risk mitigation.
Andrew Raichle, P.E., is vice president of Florham Park, N.J. environmental services company Matrix New World Engineering.
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