Specifying Flood Protection Barriers
Health facility planners and managers have seen more flood news lately than they have for decades. Some have felt the impact directly-and not just those from New Orleans, Hurricane Alley, or the Ohio River Valley. Every year, the National Flood Insurance Program (NFIP) handles flood claims from every state. Moreover, losses from interrupted operations often far exceed those arising from the physical damage itself. These losses are preventable.
A case in point: During recent hurricane floods that shut down most other Houston hospitals, Texas Children's Hospital (TCH) kept running at 100% capacity, even taking in patients from nearby hospitals that had been flooded out. The reason: effective flood protection. “Although floodwaters were up to five feet deep around some entrances, not a single drop of water got in through the flood doors,” says Dan Samora, TCH's facilities manager.
Lesser flash floods recur three to six times a year in Houston. Yet TCH operations have never been hampered by floodwater, even though some subbasements and loading docks are as many as 25 feet below grade.
How does a health facility obtain this level of protection? In fact, there is no “single best way.” A variety of generic barrier solutions are available.
A lift-out barrier panel.
Lift-out barriers (figure 1) have the lowest cost, but take more time, labor, tools, physical strength, and skill to deploy than hinged barriers (described below). They are usually stored near the point of deployment.
Stop logs (figure 2) are lift-out barriers built up one “log” at a time to reach required protection height. They are suitable for wide openings where a single lift-out barrier would be too heavy. They do create a fully watertight seal but, like lift-out barriers, require considerable deployment time and bolting.
Stop logs used in a trial fit-up at a coastal hospital.
Side-hinged gates (figure 3) swing quickly into place and close easily to seal out floodwater. Closing and sealing these is typically a two-minute job. Side-hinged gates do require swing room and will be visible at all times unless concealed by some appropriate type of architectural feature.
A side-hinged gate protects the ramp to an underground loading dock at a Houston hospital.
Note that all three of the above types provide “three-sided protection”; i.e., bottom and sides but not the top. Side-hinged flood doors (figure 4) provide “four-sided protection” and are commonly used to protect equipment rooms and basements. They deploy quickly and seal even if water rises above the top of the opening. In short, not a drop gets through.
A side-hinged flood door in the open position, ready to protect the basement of a coastal hospital.
Sliding flood barriers (figure 5) work like waterproof pocket doors-out of sight when not needed, but deployable in seconds. They also provide a solution where no swing room is available. Sliding flood barriers cost more than side-hinged barriers but are ideal for appearance-sensitive areas.
Sliding flood gates in the lobby of CHRISTUS St. Joseph Hospital, Houston, in the open (A) and closed (B) positions.
Bottom-hinged floodgates (figure 6) are designed primarily for openings in floodwalls and parking garage entrances. A gate is concealed under a plate in the roadway in normal times and swings up when a flood threatens. Because of the added mechanical equipment required, these are the most expensive type of flood barrier.
Bottom-hinged flood barrier in deployed (up) position protects a low-lying senior care campus in California.
Selection Factors: The Essentials
When properly specified and installed, flood barriers can reduce water invasion to literally zero. The selection process is fourfold:
Define the flood threat, including typical warning time.
Understand all applicable codes and Federal Emergency Management Agency (FEMA) and NFIP guidelines.
Define the facility's normal operating mode and aesthetic requirements.
Define who will be expected to deploy the barriers.
The nature of the threat may justify going beyond code minimums. Most local building codes follow FEMA guidelines and NFIP standards exactly (see http://www.fema.gov). Thus, the required flood-protection height for a hospital is the 500-year Base Flood Elevation (or the 500-year flood level). That should be regarded as a starting point only, especially if there's moving water. Also, adding one foot of protection height will buy you lower flood insurance premiums. We recommend protection heights at least 18 inches above FEMA guidelines or local building code minimums. This virtually insures against dirty, noxious floodwater lapping over the top of a barrier.
To assess the true nature of the threat in your area, review its flood history, and apply judgment to determine the type of flooding usually involved (moving or still water), frequency, and anticipated worst-case depth. Establish the typical warning time; this directly affects the choice of barrier type. Hurricane warning times are measured in days, and flash floods in hours. Mandatory evacuations can significantly cut those lead times short. Deploying 30 lift-out barriers can take a two-man crew 15 hours and requires wrenches and bolts that can disappear during deployment. On the other hand, closing 30 side-hinged doors will take any able-bodied individual less than a half hour and require no tools.
Layout and Functionality Issues
Next, look at the physical aspects and normal use patterns of the opening to be protected and the surrounding area. Is there any swing room? Is the area appearance-sensitive? What about routine foot and gurney traffic through the openings?
There is virtually no limit to the width of an opening that a side-hinged barrier can handle-usually the limitation is swing room. If no swing room is available, consider either a sliding, lift-out, or bottom-hinged barrier. All three will require some form of sill to seal properly. Sills can be recessed for lift-out-and-slide barriers, eliminating a bump that might trip people or impede carts, wheelchairs, or walkers.
A handful of manufacturers offer flood barriers of one or more types. Some vendors are regional, a few are national. Unfortunately, there is no Good Housekeeping Seal or industry certification to qualify these vendors. Evaluating them will be up to you. This checklist can help you know what to look for:
Installed base and track record in healthcare facilities. Remember, you are specifying an emergency-protection component, not a lobby ornament. Performance track record is critical.
Performance guarantee. Some vendors offer it, but most do not.
Breadth of selection. Most hospital projects require a mix of barriers types. The fewer vendors needed to obtain these, the better.
Installation services. Most flood barrier failures occur because of improper installation. Vendors should ideally both handle installation and guarantee it.
Deployment speed. There are substantial differences among vendors' products, especially with lift-out barriers. Comparing performance data is important.
Although quality flood barriers are maintenance-free under laboratory conditions, in the real world seals can be damaged by mishandling, debris, or frequent bumps by carts, gurneys, or other vehicles. It's advisable, therefore, with any installation to conduct at least one physical inspection and one deployment proficiency exercise per year. HD
Robin Ringler, PE, is an application engineer for Presray Critical Containment Solutions, Wassaic, New York. A graduate of Rensselaer Polytechnic Institute and a registered Professional Engineer since 1976, Ringler has been involved in scores of flood protection projects and in the design and manufacture of seals and nuclear containment barriers. Presray Critical Containment Solutions has performed some 5,000 flood-proofing installations nationwide.